SemaChecking.cpp revision e720ce7a3b1c1bfa5f7482183caa6e31fca9a3fb 
1//===--- SemaChecking.cpp - Extra Semantic Checking -----------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This file implements extra semantic analysis beyond what is enforced
11//  by the C type system.
12//
13//===----------------------------------------------------------------------===//
14
15#include "clang/Sema/Initialization.h"
16#include "clang/Sema/Sema.h"
17#include "clang/Sema/SemaInternal.h"
18#include "clang/Sema/Initialization.h"
19#include "clang/Sema/ScopeInfo.h"
20#include "clang/Analysis/Analyses/FormatString.h"
21#include "clang/AST/ASTContext.h"
22#include "clang/AST/CharUnits.h"
23#include "clang/AST/DeclCXX.h"
24#include "clang/AST/DeclObjC.h"
25#include "clang/AST/ExprCXX.h"
26#include "clang/AST/ExprObjC.h"
27#include "clang/AST/EvaluatedExprVisitor.h"
28#include "clang/AST/DeclObjC.h"
29#include "clang/AST/StmtCXX.h"
30#include "clang/AST/StmtObjC.h"
31#include "clang/Lex/Preprocessor.h"
32#include "llvm/ADT/BitVector.h"
33#include "llvm/ADT/SmallString.h"
34#include "llvm/ADT/STLExtras.h"
35#include "llvm/Support/raw_ostream.h"
36#include "clang/Basic/TargetBuiltins.h"
37#include "clang/Basic/TargetInfo.h"
38#include "clang/Basic/ConvertUTF.h"
39#include <limits>
40using namespace clang;
41using namespace sema;
42
43SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL,
44                                                    unsigned ByteNo) const {
45  return SL->getLocationOfByte(ByteNo, PP.getSourceManager(),
46                               PP.getLangOpts(), PP.getTargetInfo());
47}
48
49/// Checks that a call expression's argument count is the desired number.
50/// This is useful when doing custom type-checking.  Returns true on error.
51static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) {
52  unsigned argCount = call->getNumArgs();
53  if (argCount == desiredArgCount) return false;
54
55  if (argCount < desiredArgCount)
56    return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args)
57        << 0 /*function call*/ << desiredArgCount << argCount
58        << call->getSourceRange();
59
60  // Highlight all the excess arguments.
61  SourceRange range(call->getArg(desiredArgCount)->getLocStart(),
62                    call->getArg(argCount - 1)->getLocEnd());
63
64  return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args)
65    << 0 /*function call*/ << desiredArgCount << argCount
66    << call->getArg(1)->getSourceRange();
67}
68
69/// Check that the first argument to __builtin_annotation is an integer
70/// and the second argument is a non-wide string literal.
71static bool SemaBuiltinAnnotation(Sema &S, CallExpr *TheCall) {
72  if (checkArgCount(S, TheCall, 2))
73    return true;
74
75  // First argument should be an integer.
76  Expr *ValArg = TheCall->getArg(0);
77  QualType Ty = ValArg->getType();
78  if (!Ty->isIntegerType()) {
79    S.Diag(ValArg->getLocStart(), diag::err_builtin_annotation_first_arg)
80      << ValArg->getSourceRange();
81    return true;
82  }
83
84  // Second argument should be a constant string.
85  Expr *StrArg = TheCall->getArg(1)->IgnoreParenCasts();
86  StringLiteral *Literal = dyn_cast<StringLiteral>(StrArg);
87  if (!Literal || !Literal->isAscii()) {
88    S.Diag(StrArg->getLocStart(), diag::err_builtin_annotation_second_arg)
89      << StrArg->getSourceRange();
90    return true;
91  }
92
93  TheCall->setType(Ty);
94  return false;
95}
96
97ExprResult
98Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
99  ExprResult TheCallResult(Owned(TheCall));
100
101  // Find out if any arguments are required to be integer constant expressions.
102  unsigned ICEArguments = 0;
103  ASTContext::GetBuiltinTypeError Error;
104  Context.GetBuiltinType(BuiltinID, Error, &ICEArguments);
105  if (Error != ASTContext::GE_None)
106    ICEArguments = 0;  // Don't diagnose previously diagnosed errors.
107
108  // If any arguments are required to be ICE's, check and diagnose.
109  for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) {
110    // Skip arguments not required to be ICE's.
111    if ((ICEArguments & (1 << ArgNo)) == 0) continue;
112
113    llvm::APSInt Result;
114    if (SemaBuiltinConstantArg(TheCall, ArgNo, Result))
115      return true;
116    ICEArguments &= ~(1 << ArgNo);
117  }
118
119  switch (BuiltinID) {
120  case Builtin::BI__builtin___CFStringMakeConstantString:
121    assert(TheCall->getNumArgs() == 1 &&
122           "Wrong # arguments to builtin CFStringMakeConstantString");
123    if (CheckObjCString(TheCall->getArg(0)))
124      return ExprError();
125    break;
126  case Builtin::BI__builtin_stdarg_start:
127  case Builtin::BI__builtin_va_start:
128    if (SemaBuiltinVAStart(TheCall))
129      return ExprError();
130    break;
131  case Builtin::BI__builtin_isgreater:
132  case Builtin::BI__builtin_isgreaterequal:
133  case Builtin::BI__builtin_isless:
134  case Builtin::BI__builtin_islessequal:
135  case Builtin::BI__builtin_islessgreater:
136  case Builtin::BI__builtin_isunordered:
137    if (SemaBuiltinUnorderedCompare(TheCall))
138      return ExprError();
139    break;
140  case Builtin::BI__builtin_fpclassify:
141    if (SemaBuiltinFPClassification(TheCall, 6))
142      return ExprError();
143    break;
144  case Builtin::BI__builtin_isfinite:
145  case Builtin::BI__builtin_isinf:
146  case Builtin::BI__builtin_isinf_sign:
147  case Builtin::BI__builtin_isnan:
148  case Builtin::BI__builtin_isnormal:
149    if (SemaBuiltinFPClassification(TheCall, 1))
150      return ExprError();
151    break;
152  case Builtin::BI__builtin_shufflevector:
153    return SemaBuiltinShuffleVector(TheCall);
154    // TheCall will be freed by the smart pointer here, but that's fine, since
155    // SemaBuiltinShuffleVector guts it, but then doesn't release it.
156  case Builtin::BI__builtin_prefetch:
157    if (SemaBuiltinPrefetch(TheCall))
158      return ExprError();
159    break;
160  case Builtin::BI__builtin_object_size:
161    if (SemaBuiltinObjectSize(TheCall))
162      return ExprError();
163    break;
164  case Builtin::BI__builtin_longjmp:
165    if (SemaBuiltinLongjmp(TheCall))
166      return ExprError();
167    break;
168
169  case Builtin::BI__builtin_classify_type:
170    if (checkArgCount(*this, TheCall, 1)) return true;
171    TheCall->setType(Context.IntTy);
172    break;
173  case Builtin::BI__builtin_constant_p:
174    if (checkArgCount(*this, TheCall, 1)) return true;
175    TheCall->setType(Context.IntTy);
176    break;
177  case Builtin::BI__sync_fetch_and_add:
178  case Builtin::BI__sync_fetch_and_add_1:
179  case Builtin::BI__sync_fetch_and_add_2:
180  case Builtin::BI__sync_fetch_and_add_4:
181  case Builtin::BI__sync_fetch_and_add_8:
182  case Builtin::BI__sync_fetch_and_add_16:
183  case Builtin::BI__sync_fetch_and_sub:
184  case Builtin::BI__sync_fetch_and_sub_1:
185  case Builtin::BI__sync_fetch_and_sub_2:
186  case Builtin::BI__sync_fetch_and_sub_4:
187  case Builtin::BI__sync_fetch_and_sub_8:
188  case Builtin::BI__sync_fetch_and_sub_16:
189  case Builtin::BI__sync_fetch_and_or:
190  case Builtin::BI__sync_fetch_and_or_1:
191  case Builtin::BI__sync_fetch_and_or_2:
192  case Builtin::BI__sync_fetch_and_or_4:
193  case Builtin::BI__sync_fetch_and_or_8:
194  case Builtin::BI__sync_fetch_and_or_16:
195  case Builtin::BI__sync_fetch_and_and:
196  case Builtin::BI__sync_fetch_and_and_1:
197  case Builtin::BI__sync_fetch_and_and_2:
198  case Builtin::BI__sync_fetch_and_and_4:
199  case Builtin::BI__sync_fetch_and_and_8:
200  case Builtin::BI__sync_fetch_and_and_16:
201  case Builtin::BI__sync_fetch_and_xor:
202  case Builtin::BI__sync_fetch_and_xor_1:
203  case Builtin::BI__sync_fetch_and_xor_2:
204  case Builtin::BI__sync_fetch_and_xor_4:
205  case Builtin::BI__sync_fetch_and_xor_8:
206  case Builtin::BI__sync_fetch_and_xor_16:
207  case Builtin::BI__sync_add_and_fetch:
208  case Builtin::BI__sync_add_and_fetch_1:
209  case Builtin::BI__sync_add_and_fetch_2:
210  case Builtin::BI__sync_add_and_fetch_4:
211  case Builtin::BI__sync_add_and_fetch_8:
212  case Builtin::BI__sync_add_and_fetch_16:
213  case Builtin::BI__sync_sub_and_fetch:
214  case Builtin::BI__sync_sub_and_fetch_1:
215  case Builtin::BI__sync_sub_and_fetch_2:
216  case Builtin::BI__sync_sub_and_fetch_4:
217  case Builtin::BI__sync_sub_and_fetch_8:
218  case Builtin::BI__sync_sub_and_fetch_16:
219  case Builtin::BI__sync_and_and_fetch:
220  case Builtin::BI__sync_and_and_fetch_1:
221  case Builtin::BI__sync_and_and_fetch_2:
222  case Builtin::BI__sync_and_and_fetch_4:
223  case Builtin::BI__sync_and_and_fetch_8:
224  case Builtin::BI__sync_and_and_fetch_16:
225  case Builtin::BI__sync_or_and_fetch:
226  case Builtin::BI__sync_or_and_fetch_1:
227  case Builtin::BI__sync_or_and_fetch_2:
228  case Builtin::BI__sync_or_and_fetch_4:
229  case Builtin::BI__sync_or_and_fetch_8:
230  case Builtin::BI__sync_or_and_fetch_16:
231  case Builtin::BI__sync_xor_and_fetch:
232  case Builtin::BI__sync_xor_and_fetch_1:
233  case Builtin::BI__sync_xor_and_fetch_2:
234  case Builtin::BI__sync_xor_and_fetch_4:
235  case Builtin::BI__sync_xor_and_fetch_8:
236  case Builtin::BI__sync_xor_and_fetch_16:
237  case Builtin::BI__sync_val_compare_and_swap:
238  case Builtin::BI__sync_val_compare_and_swap_1:
239  case Builtin::BI__sync_val_compare_and_swap_2:
240  case Builtin::BI__sync_val_compare_and_swap_4:
241  case Builtin::BI__sync_val_compare_and_swap_8:
242  case Builtin::BI__sync_val_compare_and_swap_16:
243  case Builtin::BI__sync_bool_compare_and_swap:
244  case Builtin::BI__sync_bool_compare_and_swap_1:
245  case Builtin::BI__sync_bool_compare_and_swap_2:
246  case Builtin::BI__sync_bool_compare_and_swap_4:
247  case Builtin::BI__sync_bool_compare_and_swap_8:
248  case Builtin::BI__sync_bool_compare_and_swap_16:
249  case Builtin::BI__sync_lock_test_and_set:
250  case Builtin::BI__sync_lock_test_and_set_1:
251  case Builtin::BI__sync_lock_test_and_set_2:
252  case Builtin::BI__sync_lock_test_and_set_4:
253  case Builtin::BI__sync_lock_test_and_set_8:
254  case Builtin::BI__sync_lock_test_and_set_16:
255  case Builtin::BI__sync_lock_release:
256  case Builtin::BI__sync_lock_release_1:
257  case Builtin::BI__sync_lock_release_2:
258  case Builtin::BI__sync_lock_release_4:
259  case Builtin::BI__sync_lock_release_8:
260  case Builtin::BI__sync_lock_release_16:
261  case Builtin::BI__sync_swap:
262  case Builtin::BI__sync_swap_1:
263  case Builtin::BI__sync_swap_2:
264  case Builtin::BI__sync_swap_4:
265  case Builtin::BI__sync_swap_8:
266  case Builtin::BI__sync_swap_16:
267    return SemaBuiltinAtomicOverloaded(move(TheCallResult));
268#define BUILTIN(ID, TYPE, ATTRS)
269#define ATOMIC_BUILTIN(ID, TYPE, ATTRS) \
270  case Builtin::BI##ID: \
271    return SemaAtomicOpsOverloaded(move(TheCallResult), AtomicExpr::AO##ID);
272#include "clang/Basic/Builtins.def"
273  case Builtin::BI__builtin_annotation:
274    if (SemaBuiltinAnnotation(*this, TheCall))
275      return ExprError();
276    break;
277  }
278
279  // Since the target specific builtins for each arch overlap, only check those
280  // of the arch we are compiling for.
281  if (BuiltinID >= Builtin::FirstTSBuiltin) {
282    switch (Context.getTargetInfo().getTriple().getArch()) {
283      case llvm::Triple::arm:
284      case llvm::Triple::thumb:
285        if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall))
286          return ExprError();
287        break;
288      default:
289        break;
290    }
291  }
292
293  return move(TheCallResult);
294}
295
296// Get the valid immediate range for the specified NEON type code.
297static unsigned RFT(unsigned t, bool shift = false) {
298  NeonTypeFlags Type(t);
299  int IsQuad = Type.isQuad();
300  switch (Type.getEltType()) {
301  case NeonTypeFlags::Int8:
302  case NeonTypeFlags::Poly8:
303    return shift ? 7 : (8 << IsQuad) - 1;
304  case NeonTypeFlags::Int16:
305  case NeonTypeFlags::Poly16:
306    return shift ? 15 : (4 << IsQuad) - 1;
307  case NeonTypeFlags::Int32:
308    return shift ? 31 : (2 << IsQuad) - 1;
309  case NeonTypeFlags::Int64:
310    return shift ? 63 : (1 << IsQuad) - 1;
311  case NeonTypeFlags::Float16:
312    assert(!shift && "cannot shift float types!");
313    return (4 << IsQuad) - 1;
314  case NeonTypeFlags::Float32:
315    assert(!shift && "cannot shift float types!");
316    return (2 << IsQuad) - 1;
317  }
318  llvm_unreachable("Invalid NeonTypeFlag!");
319}
320
321/// getNeonEltType - Return the QualType corresponding to the elements of
322/// the vector type specified by the NeonTypeFlags.  This is used to check
323/// the pointer arguments for Neon load/store intrinsics.
324static QualType getNeonEltType(NeonTypeFlags Flags, ASTContext &Context) {
325  switch (Flags.getEltType()) {
326  case NeonTypeFlags::Int8:
327    return Flags.isUnsigned() ? Context.UnsignedCharTy : Context.SignedCharTy;
328  case NeonTypeFlags::Int16:
329    return Flags.isUnsigned() ? Context.UnsignedShortTy : Context.ShortTy;
330  case NeonTypeFlags::Int32:
331    return Flags.isUnsigned() ? Context.UnsignedIntTy : Context.IntTy;
332  case NeonTypeFlags::Int64:
333    return Flags.isUnsigned() ? Context.UnsignedLongLongTy : Context.LongLongTy;
334  case NeonTypeFlags::Poly8:
335    return Context.SignedCharTy;
336  case NeonTypeFlags::Poly16:
337    return Context.ShortTy;
338  case NeonTypeFlags::Float16:
339    return Context.UnsignedShortTy;
340  case NeonTypeFlags::Float32:
341    return Context.FloatTy;
342  }
343  llvm_unreachable("Invalid NeonTypeFlag!");
344}
345
346bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
347  llvm::APSInt Result;
348
349  unsigned mask = 0;
350  unsigned TV = 0;
351  int PtrArgNum = -1;
352  bool HasConstPtr = false;
353  switch (BuiltinID) {
354#define GET_NEON_OVERLOAD_CHECK
355#include "clang/Basic/arm_neon.inc"
356#undef GET_NEON_OVERLOAD_CHECK
357  }
358
359  // For NEON intrinsics which are overloaded on vector element type, validate
360  // the immediate which specifies which variant to emit.
361  unsigned ImmArg = TheCall->getNumArgs()-1;
362  if (mask) {
363    if (SemaBuiltinConstantArg(TheCall, ImmArg, Result))
364      return true;
365
366    TV = Result.getLimitedValue(64);
367    if ((TV > 63) || (mask & (1 << TV)) == 0)
368      return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code)
369        << TheCall->getArg(ImmArg)->getSourceRange();
370  }
371
372  if (PtrArgNum >= 0) {
373    // Check that pointer arguments have the specified type.
374    Expr *Arg = TheCall->getArg(PtrArgNum);
375    if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg))
376      Arg = ICE->getSubExpr();
377    ExprResult RHS = DefaultFunctionArrayLvalueConversion(Arg);
378    QualType RHSTy = RHS.get()->getType();
379    QualType EltTy = getNeonEltType(NeonTypeFlags(TV), Context);
380    if (HasConstPtr)
381      EltTy = EltTy.withConst();
382    QualType LHSTy = Context.getPointerType(EltTy);
383    AssignConvertType ConvTy;
384    ConvTy = CheckSingleAssignmentConstraints(LHSTy, RHS);
385    if (RHS.isInvalid())
386      return true;
387    if (DiagnoseAssignmentResult(ConvTy, Arg->getLocStart(), LHSTy, RHSTy,
388                                 RHS.get(), AA_Assigning))
389      return true;
390  }
391
392  // For NEON intrinsics which take an immediate value as part of the
393  // instruction, range check them here.
394  unsigned i = 0, l = 0, u = 0;
395  switch (BuiltinID) {
396  default: return false;
397  case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break;
398  case ARM::BI__builtin_arm_usat: i = 1; u = 31; break;
399  case ARM::BI__builtin_arm_vcvtr_f:
400  case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break;
401#define GET_NEON_IMMEDIATE_CHECK
402#include "clang/Basic/arm_neon.inc"
403#undef GET_NEON_IMMEDIATE_CHECK
404  };
405
406  // Check that the immediate argument is actually a constant.
407  if (SemaBuiltinConstantArg(TheCall, i, Result))
408    return true;
409
410  // Range check against the upper/lower values for this isntruction.
411  unsigned Val = Result.getZExtValue();
412  if (Val < l || Val > (u + l))
413    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
414      << l << u+l << TheCall->getArg(i)->getSourceRange();
415
416  // FIXME: VFP Intrinsics should error if VFP not present.
417  return false;
418}
419
420/// CheckFunctionCall - Check a direct function call for various correctness
421/// and safety properties not strictly enforced by the C type system.
422bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) {
423  // Get the IdentifierInfo* for the called function.
424  IdentifierInfo *FnInfo = FDecl->getIdentifier();
425
426  // None of the checks below are needed for functions that don't have
427  // simple names (e.g., C++ conversion functions).
428  if (!FnInfo)
429    return false;
430
431  // FIXME: This mechanism should be abstracted to be less fragile and
432  // more efficient. For example, just map function ids to custom
433  // handlers.
434
435  // Printf and scanf checking.
436  for (specific_attr_iterator<FormatAttr>
437         i = FDecl->specific_attr_begin<FormatAttr>(),
438         e = FDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) {
439    CheckFormatArguments(*i, TheCall);
440  }
441
442  for (specific_attr_iterator<NonNullAttr>
443         i = FDecl->specific_attr_begin<NonNullAttr>(),
444         e = FDecl->specific_attr_end<NonNullAttr>(); i != e; ++i) {
445    CheckNonNullArguments(*i, TheCall->getArgs(),
446                          TheCall->getCallee()->getLocStart());
447  }
448
449  unsigned CMId = FDecl->getMemoryFunctionKind();
450  if (CMId == 0)
451    return false;
452
453  // Handle memory setting and copying functions.
454  if (CMId == Builtin::BIstrlcpy || CMId == Builtin::BIstrlcat)
455    CheckStrlcpycatArguments(TheCall, FnInfo);
456  else if (CMId == Builtin::BIstrncat)
457    CheckStrncatArguments(TheCall, FnInfo);
458  else
459    CheckMemaccessArguments(TheCall, CMId, FnInfo);
460
461  return false;
462}
463
464bool Sema::CheckObjCMethodCall(ObjCMethodDecl *Method, SourceLocation lbrac,
465                               Expr **Args, unsigned NumArgs) {
466  for (specific_attr_iterator<FormatAttr>
467       i = Method->specific_attr_begin<FormatAttr>(),
468       e = Method->specific_attr_end<FormatAttr>(); i != e ; ++i) {
469
470    CheckFormatArguments(*i, Args, NumArgs, false, lbrac,
471                         Method->getSourceRange());
472  }
473
474  // diagnose nonnull arguments.
475  for (specific_attr_iterator<NonNullAttr>
476       i = Method->specific_attr_begin<NonNullAttr>(),
477       e = Method->specific_attr_end<NonNullAttr>(); i != e; ++i) {
478    CheckNonNullArguments(*i, Args, lbrac);
479  }
480
481  return false;
482}
483
484bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) {
485  const VarDecl *V = dyn_cast<VarDecl>(NDecl);
486  if (!V)
487    return false;
488
489  QualType Ty = V->getType();
490  if (!Ty->isBlockPointerType())
491    return false;
492
493  // format string checking.
494  for (specific_attr_iterator<FormatAttr>
495       i = NDecl->specific_attr_begin<FormatAttr>(),
496       e = NDecl->specific_attr_end<FormatAttr>(); i != e ; ++i) {
497    CheckFormatArguments(*i, TheCall);
498  }
499
500  return false;
501}
502
503ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult,
504                                         AtomicExpr::AtomicOp Op) {
505  CallExpr *TheCall = cast<CallExpr>(TheCallResult.get());
506  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
507
508  // All these operations take one of the following forms:
509  enum {
510    // C    __c11_atomic_init(A *, C)
511    Init,
512    // C    __c11_atomic_load(A *, int)
513    Load,
514    // void __atomic_load(A *, CP, int)
515    Copy,
516    // C    __c11_atomic_add(A *, M, int)
517    Arithmetic,
518    // C    __atomic_exchange_n(A *, CP, int)
519    Xchg,
520    // void __atomic_exchange(A *, C *, CP, int)
521    GNUXchg,
522    // bool __c11_atomic_compare_exchange_strong(A *, C *, CP, int, int)
523    C11CmpXchg,
524    // bool __atomic_compare_exchange(A *, C *, CP, bool, int, int)
525    GNUCmpXchg
526  } Form = Init;
527  const unsigned NumArgs[] = { 2, 2, 3, 3, 3, 4, 5, 6 };
528  const unsigned NumVals[] = { 1, 0, 1, 1, 1, 2, 2, 3 };
529  // where:
530  //   C is an appropriate type,
531  //   A is volatile _Atomic(C) for __c11 builtins and is C for GNU builtins,
532  //   CP is C for __c11 builtins and GNU _n builtins and is C * otherwise,
533  //   M is C if C is an integer, and ptrdiff_t if C is a pointer, and
534  //   the int parameters are for orderings.
535
536  assert(AtomicExpr::AO__c11_atomic_init == 0 &&
537         AtomicExpr::AO__c11_atomic_fetch_xor + 1 == AtomicExpr::AO__atomic_load
538         && "need to update code for modified C11 atomics");
539  bool IsC11 = Op >= AtomicExpr::AO__c11_atomic_init &&
540               Op <= AtomicExpr::AO__c11_atomic_fetch_xor;
541  bool IsN = Op == AtomicExpr::AO__atomic_load_n ||
542             Op == AtomicExpr::AO__atomic_store_n ||
543             Op == AtomicExpr::AO__atomic_exchange_n ||
544             Op == AtomicExpr::AO__atomic_compare_exchange_n;
545  bool IsAddSub = false;
546
547  switch (Op) {
548  case AtomicExpr::AO__c11_atomic_init:
549    Form = Init;
550    break;
551
552  case AtomicExpr::AO__c11_atomic_load:
553  case AtomicExpr::AO__atomic_load_n:
554    Form = Load;
555    break;
556
557  case AtomicExpr::AO__c11_atomic_store:
558  case AtomicExpr::AO__atomic_load:
559  case AtomicExpr::AO__atomic_store:
560  case AtomicExpr::AO__atomic_store_n:
561    Form = Copy;
562    break;
563
564  case AtomicExpr::AO__c11_atomic_fetch_add:
565  case AtomicExpr::AO__c11_atomic_fetch_sub:
566  case AtomicExpr::AO__atomic_fetch_add:
567  case AtomicExpr::AO__atomic_fetch_sub:
568  case AtomicExpr::AO__atomic_add_fetch:
569  case AtomicExpr::AO__atomic_sub_fetch:
570    IsAddSub = true;
571    // Fall through.
572  case AtomicExpr::AO__c11_atomic_fetch_and:
573  case AtomicExpr::AO__c11_atomic_fetch_or:
574  case AtomicExpr::AO__c11_atomic_fetch_xor:
575  case AtomicExpr::AO__atomic_fetch_and:
576  case AtomicExpr::AO__atomic_fetch_or:
577  case AtomicExpr::AO__atomic_fetch_xor:
578  case AtomicExpr::AO__atomic_fetch_nand:
579  case AtomicExpr::AO__atomic_and_fetch:
580  case AtomicExpr::AO__atomic_or_fetch:
581  case AtomicExpr::AO__atomic_xor_fetch:
582  case AtomicExpr::AO__atomic_nand_fetch:
583    Form = Arithmetic;
584    break;
585
586  case AtomicExpr::AO__c11_atomic_exchange:
587  case AtomicExpr::AO__atomic_exchange_n:
588    Form = Xchg;
589    break;
590
591  case AtomicExpr::AO__atomic_exchange:
592    Form = GNUXchg;
593    break;
594
595  case AtomicExpr::AO__c11_atomic_compare_exchange_strong:
596  case AtomicExpr::AO__c11_atomic_compare_exchange_weak:
597    Form = C11CmpXchg;
598    break;
599
600  case AtomicExpr::AO__atomic_compare_exchange:
601  case AtomicExpr::AO__atomic_compare_exchange_n:
602    Form = GNUCmpXchg;
603    break;
604  }
605
606  // Check we have the right number of arguments.
607  if (TheCall->getNumArgs() < NumArgs[Form]) {
608    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
609      << 0 << NumArgs[Form] << TheCall->getNumArgs()
610      << TheCall->getCallee()->getSourceRange();
611    return ExprError();
612  } else if (TheCall->getNumArgs() > NumArgs[Form]) {
613    Diag(TheCall->getArg(NumArgs[Form])->getLocStart(),
614         diag::err_typecheck_call_too_many_args)
615      << 0 << NumArgs[Form] << TheCall->getNumArgs()
616      << TheCall->getCallee()->getSourceRange();
617    return ExprError();
618  }
619
620  // Inspect the first argument of the atomic operation.
621  Expr *Ptr = TheCall->getArg(0);
622  Ptr = DefaultFunctionArrayLvalueConversion(Ptr).get();
623  const PointerType *pointerType = Ptr->getType()->getAs<PointerType>();
624  if (!pointerType) {
625    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
626      << Ptr->getType() << Ptr->getSourceRange();
627    return ExprError();
628  }
629
630  // For a __c11 builtin, this should be a pointer to an _Atomic type.
631  QualType AtomTy = pointerType->getPointeeType(); // 'A'
632  QualType ValType = AtomTy; // 'C'
633  if (IsC11) {
634    if (!AtomTy->isAtomicType()) {
635      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic)
636        << Ptr->getType() << Ptr->getSourceRange();
637      return ExprError();
638    }
639    ValType = AtomTy->getAs<AtomicType>()->getValueType();
640  }
641
642  // For an arithmetic operation, the implied arithmetic must be well-formed.
643  if (Form == Arithmetic) {
644    // gcc does not enforce these rules for GNU atomics, but we do so for sanity.
645    if (IsAddSub && !ValType->isIntegerType() && !ValType->isPointerType()) {
646      Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
647        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
648      return ExprError();
649    }
650    if (!IsAddSub && !ValType->isIntegerType()) {
651      Diag(DRE->getLocStart(), diag::err_atomic_op_bitwise_needs_atomic_int)
652        << IsC11 << Ptr->getType() << Ptr->getSourceRange();
653      return ExprError();
654    }
655  } else if (IsN && !ValType->isIntegerType() && !ValType->isPointerType()) {
656    // For __atomic_*_n operations, the value type must be a scalar integral or
657    // pointer type which is 1, 2, 4, 8 or 16 bytes in length.
658    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
659      << IsC11 << Ptr->getType() << Ptr->getSourceRange();
660    return ExprError();
661  }
662
663  if (!IsC11 && !AtomTy.isTriviallyCopyableType(Context)) {
664    // For GNU atomics, require a trivially-copyable type. This is not part of
665    // the GNU atomics specification, but we enforce it for sanity.
666    Diag(DRE->getLocStart(), diag::err_atomic_op_needs_trivial_copy)
667      << Ptr->getType() << Ptr->getSourceRange();
668    return ExprError();
669  }
670
671  // FIXME: For any builtin other than a load, the ValType must not be
672  // const-qualified.
673
674  switch (ValType.getObjCLifetime()) {
675  case Qualifiers::OCL_None:
676  case Qualifiers::OCL_ExplicitNone:
677    // okay
678    break;
679
680  case Qualifiers::OCL_Weak:
681  case Qualifiers::OCL_Strong:
682  case Qualifiers::OCL_Autoreleasing:
683    // FIXME: Can this happen? By this point, ValType should be known
684    // to be trivially copyable.
685    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
686      << ValType << Ptr->getSourceRange();
687    return ExprError();
688  }
689
690  QualType ResultType = ValType;
691  if (Form == Copy || Form == GNUXchg || Form == Init)
692    ResultType = Context.VoidTy;
693  else if (Form == C11CmpXchg || Form == GNUCmpXchg)
694    ResultType = Context.BoolTy;
695
696  // The type of a parameter passed 'by value'. In the GNU atomics, such
697  // arguments are actually passed as pointers.
698  QualType ByValType = ValType; // 'CP'
699  if (!IsC11 && !IsN)
700    ByValType = Ptr->getType();
701
702  // The first argument --- the pointer --- has a fixed type; we
703  // deduce the types of the rest of the arguments accordingly.  Walk
704  // the remaining arguments, converting them to the deduced value type.
705  for (unsigned i = 1; i != NumArgs[Form]; ++i) {
706    QualType Ty;
707    if (i < NumVals[Form] + 1) {
708      switch (i) {
709      case 1:
710        // The second argument is the non-atomic operand. For arithmetic, this
711        // is always passed by value, and for a compare_exchange it is always
712        // passed by address. For the rest, GNU uses by-address and C11 uses
713        // by-value.
714        assert(Form != Load);
715        if (Form == Init || (Form == Arithmetic && ValType->isIntegerType()))
716          Ty = ValType;
717        else if (Form == Copy || Form == Xchg)
718          Ty = ByValType;
719        else if (Form == Arithmetic)
720          Ty = Context.getPointerDiffType();
721        else
722          Ty = Context.getPointerType(ValType.getUnqualifiedType());
723        break;
724      case 2:
725        // The third argument to compare_exchange / GNU exchange is a
726        // (pointer to a) desired value.
727        Ty = ByValType;
728        break;
729      case 3:
730        // The fourth argument to GNU compare_exchange is a 'weak' flag.
731        Ty = Context.BoolTy;
732        break;
733      }
734    } else {
735      // The order(s) are always converted to int.
736      Ty = Context.IntTy;
737    }
738
739    InitializedEntity Entity =
740        InitializedEntity::InitializeParameter(Context, Ty, false);
741    ExprResult Arg = TheCall->getArg(i);
742    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
743    if (Arg.isInvalid())
744      return true;
745    TheCall->setArg(i, Arg.get());
746  }
747
748  // Permute the arguments into a 'consistent' order.
749  SmallVector<Expr*, 5> SubExprs;
750  SubExprs.push_back(Ptr);
751  switch (Form) {
752  case Init:
753    // Note, AtomicExpr::getVal1() has a special case for this atomic.
754    SubExprs.push_back(TheCall->getArg(1)); // Val1
755    break;
756  case Load:
757    SubExprs.push_back(TheCall->getArg(1)); // Order
758    break;
759  case Copy:
760  case Arithmetic:
761  case Xchg:
762    SubExprs.push_back(TheCall->getArg(2)); // Order
763    SubExprs.push_back(TheCall->getArg(1)); // Val1
764    break;
765  case GNUXchg:
766    // Note, AtomicExpr::getVal2() has a special case for this atomic.
767    SubExprs.push_back(TheCall->getArg(3)); // Order
768    SubExprs.push_back(TheCall->getArg(1)); // Val1
769    SubExprs.push_back(TheCall->getArg(2)); // Val2
770    break;
771  case C11CmpXchg:
772    SubExprs.push_back(TheCall->getArg(3)); // Order
773    SubExprs.push_back(TheCall->getArg(1)); // Val1
774    SubExprs.push_back(TheCall->getArg(4)); // OrderFail
775    SubExprs.push_back(TheCall->getArg(2)); // Val2
776    break;
777  case GNUCmpXchg:
778    SubExprs.push_back(TheCall->getArg(4)); // Order
779    SubExprs.push_back(TheCall->getArg(1)); // Val1
780    SubExprs.push_back(TheCall->getArg(5)); // OrderFail
781    SubExprs.push_back(TheCall->getArg(2)); // Val2
782    SubExprs.push_back(TheCall->getArg(3)); // Weak
783    break;
784  }
785
786  return Owned(new (Context) AtomicExpr(TheCall->getCallee()->getLocStart(),
787                                        SubExprs.data(), SubExprs.size(),
788                                        ResultType, Op,
789                                        TheCall->getRParenLoc()));
790}
791
792
793/// checkBuiltinArgument - Given a call to a builtin function, perform
794/// normal type-checking on the given argument, updating the call in
795/// place.  This is useful when a builtin function requires custom
796/// type-checking for some of its arguments but not necessarily all of
797/// them.
798///
799/// Returns true on error.
800static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) {
801  FunctionDecl *Fn = E->getDirectCallee();
802  assert(Fn && "builtin call without direct callee!");
803
804  ParmVarDecl *Param = Fn->getParamDecl(ArgIndex);
805  InitializedEntity Entity =
806    InitializedEntity::InitializeParameter(S.Context, Param);
807
808  ExprResult Arg = E->getArg(0);
809  Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg);
810  if (Arg.isInvalid())
811    return true;
812
813  E->setArg(ArgIndex, Arg.take());
814  return false;
815}
816
817/// SemaBuiltinAtomicOverloaded - We have a call to a function like
818/// __sync_fetch_and_add, which is an overloaded function based on the pointer
819/// type of its first argument.  The main ActOnCallExpr routines have already
820/// promoted the types of arguments because all of these calls are prototyped as
821/// void(...).
822///
823/// This function goes through and does final semantic checking for these
824/// builtins,
825ExprResult
826Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) {
827  CallExpr *TheCall = (CallExpr *)TheCallResult.get();
828  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
829  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
830
831  // Ensure that we have at least one argument to do type inference from.
832  if (TheCall->getNumArgs() < 1) {
833    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
834      << 0 << 1 << TheCall->getNumArgs()
835      << TheCall->getCallee()->getSourceRange();
836    return ExprError();
837  }
838
839  // Inspect the first argument of the atomic builtin.  This should always be
840  // a pointer type, whose element is an integral scalar or pointer type.
841  // Because it is a pointer type, we don't have to worry about any implicit
842  // casts here.
843  // FIXME: We don't allow floating point scalars as input.
844  Expr *FirstArg = TheCall->getArg(0);
845  ExprResult FirstArgResult = DefaultFunctionArrayLvalueConversion(FirstArg);
846  if (FirstArgResult.isInvalid())
847    return ExprError();
848  FirstArg = FirstArgResult.take();
849  TheCall->setArg(0, FirstArg);
850
851  const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>();
852  if (!pointerType) {
853    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
854      << FirstArg->getType() << FirstArg->getSourceRange();
855    return ExprError();
856  }
857
858  QualType ValType = pointerType->getPointeeType();
859  if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
860      !ValType->isBlockPointerType()) {
861    Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr)
862      << FirstArg->getType() << FirstArg->getSourceRange();
863    return ExprError();
864  }
865
866  switch (ValType.getObjCLifetime()) {
867  case Qualifiers::OCL_None:
868  case Qualifiers::OCL_ExplicitNone:
869    // okay
870    break;
871
872  case Qualifiers::OCL_Weak:
873  case Qualifiers::OCL_Strong:
874  case Qualifiers::OCL_Autoreleasing:
875    Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
876      << ValType << FirstArg->getSourceRange();
877    return ExprError();
878  }
879
880  // Strip any qualifiers off ValType.
881  ValType = ValType.getUnqualifiedType();
882
883  // The majority of builtins return a value, but a few have special return
884  // types, so allow them to override appropriately below.
885  QualType ResultType = ValType;
886
887  // We need to figure out which concrete builtin this maps onto.  For example,
888  // __sync_fetch_and_add with a 2 byte object turns into
889  // __sync_fetch_and_add_2.
890#define BUILTIN_ROW(x) \
891  { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \
892    Builtin::BI##x##_8, Builtin::BI##x##_16 }
893
894  static const unsigned BuiltinIndices[][5] = {
895    BUILTIN_ROW(__sync_fetch_and_add),
896    BUILTIN_ROW(__sync_fetch_and_sub),
897    BUILTIN_ROW(__sync_fetch_and_or),
898    BUILTIN_ROW(__sync_fetch_and_and),
899    BUILTIN_ROW(__sync_fetch_and_xor),
900
901    BUILTIN_ROW(__sync_add_and_fetch),
902    BUILTIN_ROW(__sync_sub_and_fetch),
903    BUILTIN_ROW(__sync_and_and_fetch),
904    BUILTIN_ROW(__sync_or_and_fetch),
905    BUILTIN_ROW(__sync_xor_and_fetch),
906
907    BUILTIN_ROW(__sync_val_compare_and_swap),
908    BUILTIN_ROW(__sync_bool_compare_and_swap),
909    BUILTIN_ROW(__sync_lock_test_and_set),
910    BUILTIN_ROW(__sync_lock_release),
911    BUILTIN_ROW(__sync_swap)
912  };
913#undef BUILTIN_ROW
914
915  // Determine the index of the size.
916  unsigned SizeIndex;
917  switch (Context.getTypeSizeInChars(ValType).getQuantity()) {
918  case 1: SizeIndex = 0; break;
919  case 2: SizeIndex = 1; break;
920  case 4: SizeIndex = 2; break;
921  case 8: SizeIndex = 3; break;
922  case 16: SizeIndex = 4; break;
923  default:
924    Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size)
925      << FirstArg->getType() << FirstArg->getSourceRange();
926    return ExprError();
927  }
928
929  // Each of these builtins has one pointer argument, followed by some number of
930  // values (0, 1 or 2) followed by a potentially empty varags list of stuff
931  // that we ignore.  Find out which row of BuiltinIndices to read from as well
932  // as the number of fixed args.
933  unsigned BuiltinID = FDecl->getBuiltinID();
934  unsigned BuiltinIndex, NumFixed = 1;
935  switch (BuiltinID) {
936  default: llvm_unreachable("Unknown overloaded atomic builtin!");
937  case Builtin::BI__sync_fetch_and_add:
938  case Builtin::BI__sync_fetch_and_add_1:
939  case Builtin::BI__sync_fetch_and_add_2:
940  case Builtin::BI__sync_fetch_and_add_4:
941  case Builtin::BI__sync_fetch_and_add_8:
942  case Builtin::BI__sync_fetch_and_add_16:
943    BuiltinIndex = 0;
944    break;
945
946  case Builtin::BI__sync_fetch_and_sub:
947  case Builtin::BI__sync_fetch_and_sub_1:
948  case Builtin::BI__sync_fetch_and_sub_2:
949  case Builtin::BI__sync_fetch_and_sub_4:
950  case Builtin::BI__sync_fetch_and_sub_8:
951  case Builtin::BI__sync_fetch_and_sub_16:
952    BuiltinIndex = 1;
953    break;
954
955  case Builtin::BI__sync_fetch_and_or:
956  case Builtin::BI__sync_fetch_and_or_1:
957  case Builtin::BI__sync_fetch_and_or_2:
958  case Builtin::BI__sync_fetch_and_or_4:
959  case Builtin::BI__sync_fetch_and_or_8:
960  case Builtin::BI__sync_fetch_and_or_16:
961    BuiltinIndex = 2;
962    break;
963
964  case Builtin::BI__sync_fetch_and_and:
965  case Builtin::BI__sync_fetch_and_and_1:
966  case Builtin::BI__sync_fetch_and_and_2:
967  case Builtin::BI__sync_fetch_and_and_4:
968  case Builtin::BI__sync_fetch_and_and_8:
969  case Builtin::BI__sync_fetch_and_and_16:
970    BuiltinIndex = 3;
971    break;
972
973  case Builtin::BI__sync_fetch_and_xor:
974  case Builtin::BI__sync_fetch_and_xor_1:
975  case Builtin::BI__sync_fetch_and_xor_2:
976  case Builtin::BI__sync_fetch_and_xor_4:
977  case Builtin::BI__sync_fetch_and_xor_8:
978  case Builtin::BI__sync_fetch_and_xor_16:
979    BuiltinIndex = 4;
980    break;
981
982  case Builtin::BI__sync_add_and_fetch:
983  case Builtin::BI__sync_add_and_fetch_1:
984  case Builtin::BI__sync_add_and_fetch_2:
985  case Builtin::BI__sync_add_and_fetch_4:
986  case Builtin::BI__sync_add_and_fetch_8:
987  case Builtin::BI__sync_add_and_fetch_16:
988    BuiltinIndex = 5;
989    break;
990
991  case Builtin::BI__sync_sub_and_fetch:
992  case Builtin::BI__sync_sub_and_fetch_1:
993  case Builtin::BI__sync_sub_and_fetch_2:
994  case Builtin::BI__sync_sub_and_fetch_4:
995  case Builtin::BI__sync_sub_and_fetch_8:
996  case Builtin::BI__sync_sub_and_fetch_16:
997    BuiltinIndex = 6;
998    break;
999
1000  case Builtin::BI__sync_and_and_fetch:
1001  case Builtin::BI__sync_and_and_fetch_1:
1002  case Builtin::BI__sync_and_and_fetch_2:
1003  case Builtin::BI__sync_and_and_fetch_4:
1004  case Builtin::BI__sync_and_and_fetch_8:
1005  case Builtin::BI__sync_and_and_fetch_16:
1006    BuiltinIndex = 7;
1007    break;
1008
1009  case Builtin::BI__sync_or_and_fetch:
1010  case Builtin::BI__sync_or_and_fetch_1:
1011  case Builtin::BI__sync_or_and_fetch_2:
1012  case Builtin::BI__sync_or_and_fetch_4:
1013  case Builtin::BI__sync_or_and_fetch_8:
1014  case Builtin::BI__sync_or_and_fetch_16:
1015    BuiltinIndex = 8;
1016    break;
1017
1018  case Builtin::BI__sync_xor_and_fetch:
1019  case Builtin::BI__sync_xor_and_fetch_1:
1020  case Builtin::BI__sync_xor_and_fetch_2:
1021  case Builtin::BI__sync_xor_and_fetch_4:
1022  case Builtin::BI__sync_xor_and_fetch_8:
1023  case Builtin::BI__sync_xor_and_fetch_16:
1024    BuiltinIndex = 9;
1025    break;
1026
1027  case Builtin::BI__sync_val_compare_and_swap:
1028  case Builtin::BI__sync_val_compare_and_swap_1:
1029  case Builtin::BI__sync_val_compare_and_swap_2:
1030  case Builtin::BI__sync_val_compare_and_swap_4:
1031  case Builtin::BI__sync_val_compare_and_swap_8:
1032  case Builtin::BI__sync_val_compare_and_swap_16:
1033    BuiltinIndex = 10;
1034    NumFixed = 2;
1035    break;
1036
1037  case Builtin::BI__sync_bool_compare_and_swap:
1038  case Builtin::BI__sync_bool_compare_and_swap_1:
1039  case Builtin::BI__sync_bool_compare_and_swap_2:
1040  case Builtin::BI__sync_bool_compare_and_swap_4:
1041  case Builtin::BI__sync_bool_compare_and_swap_8:
1042  case Builtin::BI__sync_bool_compare_and_swap_16:
1043    BuiltinIndex = 11;
1044    NumFixed = 2;
1045    ResultType = Context.BoolTy;
1046    break;
1047
1048  case Builtin::BI__sync_lock_test_and_set:
1049  case Builtin::BI__sync_lock_test_and_set_1:
1050  case Builtin::BI__sync_lock_test_and_set_2:
1051  case Builtin::BI__sync_lock_test_and_set_4:
1052  case Builtin::BI__sync_lock_test_and_set_8:
1053  case Builtin::BI__sync_lock_test_and_set_16:
1054    BuiltinIndex = 12;
1055    break;
1056
1057  case Builtin::BI__sync_lock_release:
1058  case Builtin::BI__sync_lock_release_1:
1059  case Builtin::BI__sync_lock_release_2:
1060  case Builtin::BI__sync_lock_release_4:
1061  case Builtin::BI__sync_lock_release_8:
1062  case Builtin::BI__sync_lock_release_16:
1063    BuiltinIndex = 13;
1064    NumFixed = 0;
1065    ResultType = Context.VoidTy;
1066    break;
1067
1068  case Builtin::BI__sync_swap:
1069  case Builtin::BI__sync_swap_1:
1070  case Builtin::BI__sync_swap_2:
1071  case Builtin::BI__sync_swap_4:
1072  case Builtin::BI__sync_swap_8:
1073  case Builtin::BI__sync_swap_16:
1074    BuiltinIndex = 14;
1075    break;
1076  }
1077
1078  // Now that we know how many fixed arguments we expect, first check that we
1079  // have at least that many.
1080  if (TheCall->getNumArgs() < 1+NumFixed) {
1081    Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
1082      << 0 << 1+NumFixed << TheCall->getNumArgs()
1083      << TheCall->getCallee()->getSourceRange();
1084    return ExprError();
1085  }
1086
1087  // Get the decl for the concrete builtin from this, we can tell what the
1088  // concrete integer type we should convert to is.
1089  unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex];
1090  const char *NewBuiltinName = Context.BuiltinInfo.GetName(NewBuiltinID);
1091  IdentifierInfo *NewBuiltinII = PP.getIdentifierInfo(NewBuiltinName);
1092  FunctionDecl *NewBuiltinDecl =
1093    cast<FunctionDecl>(LazilyCreateBuiltin(NewBuiltinII, NewBuiltinID,
1094                                           TUScope, false, DRE->getLocStart()));
1095
1096  // The first argument --- the pointer --- has a fixed type; we
1097  // deduce the types of the rest of the arguments accordingly.  Walk
1098  // the remaining arguments, converting them to the deduced value type.
1099  for (unsigned i = 0; i != NumFixed; ++i) {
1100    ExprResult Arg = TheCall->getArg(i+1);
1101
1102    // GCC does an implicit conversion to the pointer or integer ValType.  This
1103    // can fail in some cases (1i -> int**), check for this error case now.
1104    // Initialize the argument.
1105    InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
1106                                                   ValType, /*consume*/ false);
1107    Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
1108    if (Arg.isInvalid())
1109      return ExprError();
1110
1111    // Okay, we have something that *can* be converted to the right type.  Check
1112    // to see if there is a potentially weird extension going on here.  This can
1113    // happen when you do an atomic operation on something like an char* and
1114    // pass in 42.  The 42 gets converted to char.  This is even more strange
1115    // for things like 45.123 -> char, etc.
1116    // FIXME: Do this check.
1117    TheCall->setArg(i+1, Arg.take());
1118  }
1119
1120  ASTContext& Context = this->getASTContext();
1121
1122  // Create a new DeclRefExpr to refer to the new decl.
1123  DeclRefExpr* NewDRE = DeclRefExpr::Create(
1124      Context,
1125      DRE->getQualifierLoc(),
1126      SourceLocation(),
1127      NewBuiltinDecl,
1128      /*enclosing*/ false,
1129      DRE->getLocation(),
1130      NewBuiltinDecl->getType(),
1131      DRE->getValueKind());
1132
1133  // Set the callee in the CallExpr.
1134  // FIXME: This leaks the original parens and implicit casts.
1135  ExprResult PromotedCall = UsualUnaryConversions(NewDRE);
1136  if (PromotedCall.isInvalid())
1137    return ExprError();
1138  TheCall->setCallee(PromotedCall.take());
1139
1140  // Change the result type of the call to match the original value type. This
1141  // is arbitrary, but the codegen for these builtins ins design to handle it
1142  // gracefully.
1143  TheCall->setType(ResultType);
1144
1145  return move(TheCallResult);
1146}
1147
1148/// CheckObjCString - Checks that the argument to the builtin
1149/// CFString constructor is correct
1150/// Note: It might also make sense to do the UTF-16 conversion here (would
1151/// simplify the backend).
1152bool Sema::CheckObjCString(Expr *Arg) {
1153  Arg = Arg->IgnoreParenCasts();
1154  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
1155
1156  if (!Literal || !Literal->isAscii()) {
1157    Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
1158      << Arg->getSourceRange();
1159    return true;
1160  }
1161
1162  if (Literal->containsNonAsciiOrNull()) {
1163    StringRef String = Literal->getString();
1164    unsigned NumBytes = String.size();
1165    SmallVector<UTF16, 128> ToBuf(NumBytes);
1166    const UTF8 *FromPtr = (UTF8 *)String.data();
1167    UTF16 *ToPtr = &ToBuf[0];
1168
1169    ConversionResult Result = ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
1170                                                 &ToPtr, ToPtr + NumBytes,
1171                                                 strictConversion);
1172    // Check for conversion failure.
1173    if (Result != conversionOK)
1174      Diag(Arg->getLocStart(),
1175           diag::warn_cfstring_truncated) << Arg->getSourceRange();
1176  }
1177  return false;
1178}
1179
1180/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
1181/// Emit an error and return true on failure, return false on success.
1182bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
1183  Expr *Fn = TheCall->getCallee();
1184  if (TheCall->getNumArgs() > 2) {
1185    Diag(TheCall->getArg(2)->getLocStart(),
1186         diag::err_typecheck_call_too_many_args)
1187      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1188      << Fn->getSourceRange()
1189      << SourceRange(TheCall->getArg(2)->getLocStart(),
1190                     (*(TheCall->arg_end()-1))->getLocEnd());
1191    return true;
1192  }
1193
1194  if (TheCall->getNumArgs() < 2) {
1195    return Diag(TheCall->getLocEnd(),
1196      diag::err_typecheck_call_too_few_args_at_least)
1197      << 0 /*function call*/ << 2 << TheCall->getNumArgs();
1198  }
1199
1200  // Type-check the first argument normally.
1201  if (checkBuiltinArgument(*this, TheCall, 0))
1202    return true;
1203
1204  // Determine whether the current function is variadic or not.
1205  BlockScopeInfo *CurBlock = getCurBlock();
1206  bool isVariadic;
1207  if (CurBlock)
1208    isVariadic = CurBlock->TheDecl->isVariadic();
1209  else if (FunctionDecl *FD = getCurFunctionDecl())
1210    isVariadic = FD->isVariadic();
1211  else
1212    isVariadic = getCurMethodDecl()->isVariadic();
1213
1214  if (!isVariadic) {
1215    Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
1216    return true;
1217  }
1218
1219  // Verify that the second argument to the builtin is the last argument of the
1220  // current function or method.
1221  bool SecondArgIsLastNamedArgument = false;
1222  const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts();
1223
1224  if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) {
1225    if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) {
1226      // FIXME: This isn't correct for methods (results in bogus warning).
1227      // Get the last formal in the current function.
1228      const ParmVarDecl *LastArg;
1229      if (CurBlock)
1230        LastArg = *(CurBlock->TheDecl->param_end()-1);
1231      else if (FunctionDecl *FD = getCurFunctionDecl())
1232        LastArg = *(FD->param_end()-1);
1233      else
1234        LastArg = *(getCurMethodDecl()->param_end()-1);
1235      SecondArgIsLastNamedArgument = PV == LastArg;
1236    }
1237  }
1238
1239  if (!SecondArgIsLastNamedArgument)
1240    Diag(TheCall->getArg(1)->getLocStart(),
1241         diag::warn_second_parameter_of_va_start_not_last_named_argument);
1242  return false;
1243}
1244
1245/// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and
1246/// friends.  This is declared to take (...), so we have to check everything.
1247bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) {
1248  if (TheCall->getNumArgs() < 2)
1249    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1250      << 0 << 2 << TheCall->getNumArgs()/*function call*/;
1251  if (TheCall->getNumArgs() > 2)
1252    return Diag(TheCall->getArg(2)->getLocStart(),
1253                diag::err_typecheck_call_too_many_args)
1254      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1255      << SourceRange(TheCall->getArg(2)->getLocStart(),
1256                     (*(TheCall->arg_end()-1))->getLocEnd());
1257
1258  ExprResult OrigArg0 = TheCall->getArg(0);
1259  ExprResult OrigArg1 = TheCall->getArg(1);
1260
1261  // Do standard promotions between the two arguments, returning their common
1262  // type.
1263  QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false);
1264  if (OrigArg0.isInvalid() || OrigArg1.isInvalid())
1265    return true;
1266
1267  // Make sure any conversions are pushed back into the call; this is
1268  // type safe since unordered compare builtins are declared as "_Bool
1269  // foo(...)".
1270  TheCall->setArg(0, OrigArg0.get());
1271  TheCall->setArg(1, OrigArg1.get());
1272
1273  if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent())
1274    return false;
1275
1276  // If the common type isn't a real floating type, then the arguments were
1277  // invalid for this operation.
1278  if (!Res->isRealFloatingType())
1279    return Diag(OrigArg0.get()->getLocStart(),
1280                diag::err_typecheck_call_invalid_ordered_compare)
1281      << OrigArg0.get()->getType() << OrigArg1.get()->getType()
1282      << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd());
1283
1284  return false;
1285}
1286
1287/// SemaBuiltinSemaBuiltinFPClassification - Handle functions like
1288/// __builtin_isnan and friends.  This is declared to take (...), so we have
1289/// to check everything. We expect the last argument to be a floating point
1290/// value.
1291bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) {
1292  if (TheCall->getNumArgs() < NumArgs)
1293    return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
1294      << 0 << NumArgs << TheCall->getNumArgs()/*function call*/;
1295  if (TheCall->getNumArgs() > NumArgs)
1296    return Diag(TheCall->getArg(NumArgs)->getLocStart(),
1297                diag::err_typecheck_call_too_many_args)
1298      << 0 /*function call*/ << NumArgs << TheCall->getNumArgs()
1299      << SourceRange(TheCall->getArg(NumArgs)->getLocStart(),
1300                     (*(TheCall->arg_end()-1))->getLocEnd());
1301
1302  Expr *OrigArg = TheCall->getArg(NumArgs-1);
1303
1304  if (OrigArg->isTypeDependent())
1305    return false;
1306
1307  // This operation requires a non-_Complex floating-point number.
1308  if (!OrigArg->getType()->isRealFloatingType())
1309    return Diag(OrigArg->getLocStart(),
1310                diag::err_typecheck_call_invalid_unary_fp)
1311      << OrigArg->getType() << OrigArg->getSourceRange();
1312
1313  // If this is an implicit conversion from float -> double, remove it.
1314  if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) {
1315    Expr *CastArg = Cast->getSubExpr();
1316    if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) {
1317      assert(Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) &&
1318             "promotion from float to double is the only expected cast here");
1319      Cast->setSubExpr(0);
1320      TheCall->setArg(NumArgs-1, CastArg);
1321    }
1322  }
1323
1324  return false;
1325}
1326
1327/// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
1328// This is declared to take (...), so we have to check everything.
1329ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
1330  if (TheCall->getNumArgs() < 2)
1331    return ExprError(Diag(TheCall->getLocEnd(),
1332                          diag::err_typecheck_call_too_few_args_at_least)
1333      << 0 /*function call*/ << 2 << TheCall->getNumArgs()
1334      << TheCall->getSourceRange());
1335
1336  // Determine which of the following types of shufflevector we're checking:
1337  // 1) unary, vector mask: (lhs, mask)
1338  // 2) binary, vector mask: (lhs, rhs, mask)
1339  // 3) binary, scalar mask: (lhs, rhs, index, ..., index)
1340  QualType resType = TheCall->getArg(0)->getType();
1341  unsigned numElements = 0;
1342
1343  if (!TheCall->getArg(0)->isTypeDependent() &&
1344      !TheCall->getArg(1)->isTypeDependent()) {
1345    QualType LHSType = TheCall->getArg(0)->getType();
1346    QualType RHSType = TheCall->getArg(1)->getType();
1347
1348    if (!LHSType->isVectorType() || !RHSType->isVectorType()) {
1349      Diag(TheCall->getLocStart(), diag::err_shufflevector_non_vector)
1350        << SourceRange(TheCall->getArg(0)->getLocStart(),
1351                       TheCall->getArg(1)->getLocEnd());
1352      return ExprError();
1353    }
1354
1355    numElements = LHSType->getAs<VectorType>()->getNumElements();
1356    unsigned numResElements = TheCall->getNumArgs() - 2;
1357
1358    // Check to see if we have a call with 2 vector arguments, the unary shuffle
1359    // with mask.  If so, verify that RHS is an integer vector type with the
1360    // same number of elts as lhs.
1361    if (TheCall->getNumArgs() == 2) {
1362      if (!RHSType->hasIntegerRepresentation() ||
1363          RHSType->getAs<VectorType>()->getNumElements() != numElements)
1364        Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1365          << SourceRange(TheCall->getArg(1)->getLocStart(),
1366                         TheCall->getArg(1)->getLocEnd());
1367      numResElements = numElements;
1368    }
1369    else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) {
1370      Diag(TheCall->getLocStart(), diag::err_shufflevector_incompatible_vector)
1371        << SourceRange(TheCall->getArg(0)->getLocStart(),
1372                       TheCall->getArg(1)->getLocEnd());
1373      return ExprError();
1374    } else if (numElements != numResElements) {
1375      QualType eltType = LHSType->getAs<VectorType>()->getElementType();
1376      resType = Context.getVectorType(eltType, numResElements,
1377                                      VectorType::GenericVector);
1378    }
1379  }
1380
1381  for (unsigned i = 2; i < TheCall->getNumArgs(); i++) {
1382    if (TheCall->getArg(i)->isTypeDependent() ||
1383        TheCall->getArg(i)->isValueDependent())
1384      continue;
1385
1386    llvm::APSInt Result(32);
1387    if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context))
1388      return ExprError(Diag(TheCall->getLocStart(),
1389                  diag::err_shufflevector_nonconstant_argument)
1390                << TheCall->getArg(i)->getSourceRange());
1391
1392    if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2)
1393      return ExprError(Diag(TheCall->getLocStart(),
1394                  diag::err_shufflevector_argument_too_large)
1395               << TheCall->getArg(i)->getSourceRange());
1396  }
1397
1398  SmallVector<Expr*, 32> exprs;
1399
1400  for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) {
1401    exprs.push_back(TheCall->getArg(i));
1402    TheCall->setArg(i, 0);
1403  }
1404
1405  return Owned(new (Context) ShuffleVectorExpr(Context, exprs.begin(),
1406                                            exprs.size(), resType,
1407                                            TheCall->getCallee()->getLocStart(),
1408                                            TheCall->getRParenLoc()));
1409}
1410
1411/// SemaBuiltinPrefetch - Handle __builtin_prefetch.
1412// This is declared to take (const void*, ...) and can take two
1413// optional constant int args.
1414bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
1415  unsigned NumArgs = TheCall->getNumArgs();
1416
1417  if (NumArgs > 3)
1418    return Diag(TheCall->getLocEnd(),
1419             diag::err_typecheck_call_too_many_args_at_most)
1420             << 0 /*function call*/ << 3 << NumArgs
1421             << TheCall->getSourceRange();
1422
1423  // Argument 0 is checked for us and the remaining arguments must be
1424  // constant integers.
1425  for (unsigned i = 1; i != NumArgs; ++i) {
1426    Expr *Arg = TheCall->getArg(i);
1427
1428    llvm::APSInt Result;
1429    if (SemaBuiltinConstantArg(TheCall, i, Result))
1430      return true;
1431
1432    // FIXME: gcc issues a warning and rewrites these to 0. These
1433    // seems especially odd for the third argument since the default
1434    // is 3.
1435    if (i == 1) {
1436      if (Result.getLimitedValue() > 1)
1437        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1438             << "0" << "1" << Arg->getSourceRange();
1439    } else {
1440      if (Result.getLimitedValue() > 3)
1441        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1442            << "0" << "3" << Arg->getSourceRange();
1443    }
1444  }
1445
1446  return false;
1447}
1448
1449/// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
1450/// TheCall is a constant expression.
1451bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
1452                                  llvm::APSInt &Result) {
1453  Expr *Arg = TheCall->getArg(ArgNum);
1454  DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
1455  FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
1456
1457  if (Arg->isTypeDependent() || Arg->isValueDependent()) return false;
1458
1459  if (!Arg->isIntegerConstantExpr(Result, Context))
1460    return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type)
1461                << FDecl->getDeclName() <<  Arg->getSourceRange();
1462
1463  return false;
1464}
1465
1466/// SemaBuiltinObjectSize - Handle __builtin_object_size(void *ptr,
1467/// int type). This simply type checks that type is one of the defined
1468/// constants (0-3).
1469// For compatibility check 0-3, llvm only handles 0 and 2.
1470bool Sema::SemaBuiltinObjectSize(CallExpr *TheCall) {
1471  llvm::APSInt Result;
1472
1473  // Check constant-ness first.
1474  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1475    return true;
1476
1477  Expr *Arg = TheCall->getArg(1);
1478  if (Result.getSExtValue() < 0 || Result.getSExtValue() > 3) {
1479    return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
1480             << "0" << "3" << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1481  }
1482
1483  return false;
1484}
1485
1486/// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val).
1487/// This checks that val is a constant 1.
1488bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) {
1489  Expr *Arg = TheCall->getArg(1);
1490  llvm::APSInt Result;
1491
1492  // TODO: This is less than ideal. Overload this to take a value.
1493  if (SemaBuiltinConstantArg(TheCall, 1, Result))
1494    return true;
1495
1496  if (Result != 1)
1497    return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
1498             << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
1499
1500  return false;
1501}
1502
1503// Handle i > 1 ? "x" : "y", recursively.
1504bool Sema::SemaCheckStringLiteral(const Expr *E, Expr **Args,
1505                                  unsigned NumArgs, bool HasVAListArg,
1506                                  unsigned format_idx, unsigned firstDataArg,
1507                                  FormatStringType Type, bool inFunctionCall) {
1508 tryAgain:
1509  if (E->isTypeDependent() || E->isValueDependent())
1510    return false;
1511
1512  E = E->IgnoreParenCasts();
1513
1514  if (E->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull))
1515    // Technically -Wformat-nonliteral does not warn about this case.
1516    // The behavior of printf and friends in this case is implementation
1517    // dependent.  Ideally if the format string cannot be null then
1518    // it should have a 'nonnull' attribute in the function prototype.
1519    return true;
1520
1521  switch (E->getStmtClass()) {
1522  case Stmt::BinaryConditionalOperatorClass:
1523  case Stmt::ConditionalOperatorClass: {
1524    const AbstractConditionalOperator *C = cast<AbstractConditionalOperator>(E);
1525    return SemaCheckStringLiteral(C->getTrueExpr(), Args, NumArgs, HasVAListArg,
1526                                  format_idx, firstDataArg, Type,
1527                                  inFunctionCall)
1528       && SemaCheckStringLiteral(C->getFalseExpr(), Args, NumArgs, HasVAListArg,
1529                                 format_idx, firstDataArg, Type,
1530                                 inFunctionCall);
1531  }
1532
1533  case Stmt::ImplicitCastExprClass: {
1534    E = cast<ImplicitCastExpr>(E)->getSubExpr();
1535    goto tryAgain;
1536  }
1537
1538  case Stmt::OpaqueValueExprClass:
1539    if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) {
1540      E = src;
1541      goto tryAgain;
1542    }
1543    return false;
1544
1545  case Stmt::PredefinedExprClass:
1546    // While __func__, etc., are technically not string literals, they
1547    // cannot contain format specifiers and thus are not a security
1548    // liability.
1549    return true;
1550
1551  case Stmt::DeclRefExprClass: {
1552    const DeclRefExpr *DR = cast<DeclRefExpr>(E);
1553
1554    // As an exception, do not flag errors for variables binding to
1555    // const string literals.
1556    if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
1557      bool isConstant = false;
1558      QualType T = DR->getType();
1559
1560      if (const ArrayType *AT = Context.getAsArrayType(T)) {
1561        isConstant = AT->getElementType().isConstant(Context);
1562      } else if (const PointerType *PT = T->getAs<PointerType>()) {
1563        isConstant = T.isConstant(Context) &&
1564                     PT->getPointeeType().isConstant(Context);
1565      } else if (T->isObjCObjectPointerType()) {
1566        // In ObjC, there is usually no "const ObjectPointer" type,
1567        // so don't check if the pointee type is constant.
1568        isConstant = T.isConstant(Context);
1569      }
1570
1571      if (isConstant) {
1572        if (const Expr *Init = VD->getAnyInitializer())
1573          return SemaCheckStringLiteral(Init, Args, NumArgs,
1574                                        HasVAListArg, format_idx, firstDataArg,
1575                                        Type, /*inFunctionCall*/false);
1576      }
1577
1578      // For vprintf* functions (i.e., HasVAListArg==true), we add a
1579      // special check to see if the format string is a function parameter
1580      // of the function calling the printf function.  If the function
1581      // has an attribute indicating it is a printf-like function, then we
1582      // should suppress warnings concerning non-literals being used in a call
1583      // to a vprintf function.  For example:
1584      //
1585      // void
1586      // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
1587      //      va_list ap;
1588      //      va_start(ap, fmt);
1589      //      vprintf(fmt, ap);  // Do NOT emit a warning about "fmt".
1590      //      ...
1591      //
1592      if (HasVAListArg) {
1593        if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(VD)) {
1594          if (const NamedDecl *ND = dyn_cast<NamedDecl>(PV->getDeclContext())) {
1595            int PVIndex = PV->getFunctionScopeIndex() + 1;
1596            for (specific_attr_iterator<FormatAttr>
1597                 i = ND->specific_attr_begin<FormatAttr>(),
1598                 e = ND->specific_attr_end<FormatAttr>(); i != e ; ++i) {
1599              FormatAttr *PVFormat = *i;
1600              // adjust for implicit parameter
1601              if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1602                if (MD->isInstance())
1603                  ++PVIndex;
1604              // We also check if the formats are compatible.
1605              // We can't pass a 'scanf' string to a 'printf' function.
1606              if (PVIndex == PVFormat->getFormatIdx() &&
1607                  Type == GetFormatStringType(PVFormat))
1608                return true;
1609            }
1610          }
1611        }
1612      }
1613    }
1614
1615    return false;
1616  }
1617
1618  case Stmt::CallExprClass:
1619  case Stmt::CXXMemberCallExprClass: {
1620    const CallExpr *CE = cast<CallExpr>(E);
1621    if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
1622      if (const FormatArgAttr *FA = ND->getAttr<FormatArgAttr>()) {
1623        unsigned ArgIndex = FA->getFormatIdx();
1624        if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
1625          if (MD->isInstance())
1626            --ArgIndex;
1627        const Expr *Arg = CE->getArg(ArgIndex - 1);
1628
1629        return SemaCheckStringLiteral(Arg, Args, NumArgs, HasVAListArg,
1630                                      format_idx, firstDataArg, Type,
1631                                      inFunctionCall);
1632      }
1633    }
1634
1635    return false;
1636  }
1637  case Stmt::ObjCStringLiteralClass:
1638  case Stmt::StringLiteralClass: {
1639    const StringLiteral *StrE = NULL;
1640
1641    if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
1642      StrE = ObjCFExpr->getString();
1643    else
1644      StrE = cast<StringLiteral>(E);
1645
1646    if (StrE) {
1647      CheckFormatString(StrE, E, Args, NumArgs, HasVAListArg, format_idx,
1648                        firstDataArg, Type, inFunctionCall);
1649      return true;
1650    }
1651
1652    return false;
1653  }
1654
1655  default:
1656    return false;
1657  }
1658}
1659
1660void
1661Sema::CheckNonNullArguments(const NonNullAttr *NonNull,
1662                            const Expr * const *ExprArgs,
1663                            SourceLocation CallSiteLoc) {
1664  for (NonNullAttr::args_iterator i = NonNull->args_begin(),
1665                                  e = NonNull->args_end();
1666       i != e; ++i) {
1667    const Expr *ArgExpr = ExprArgs[*i];
1668    if (ArgExpr->isNullPointerConstant(Context,
1669                                       Expr::NPC_ValueDependentIsNotNull))
1670      Diag(CallSiteLoc, diag::warn_null_arg) << ArgExpr->getSourceRange();
1671  }
1672}
1673
1674Sema::FormatStringType Sema::GetFormatStringType(const FormatAttr *Format) {
1675  return llvm::StringSwitch<FormatStringType>(Format->getType())
1676  .Case("scanf", FST_Scanf)
1677  .Cases("printf", "printf0", FST_Printf)
1678  .Cases("NSString", "CFString", FST_NSString)
1679  .Case("strftime", FST_Strftime)
1680  .Case("strfmon", FST_Strfmon)
1681  .Cases("kprintf", "cmn_err", "vcmn_err", "zcmn_err", FST_Kprintf)
1682  .Default(FST_Unknown);
1683}
1684
1685/// CheckPrintfScanfArguments - Check calls to printf and scanf (and similar
1686/// functions) for correct use of format strings.
1687void Sema::CheckFormatArguments(const FormatAttr *Format, CallExpr *TheCall) {
1688  bool IsCXXMember = false;
1689  // The way the format attribute works in GCC, the implicit this argument
1690  // of member functions is counted. However, it doesn't appear in our own
1691  // lists, so decrement format_idx in that case.
1692  IsCXXMember = isa<CXXMemberCallExpr>(TheCall);
1693  CheckFormatArguments(Format, TheCall->getArgs(), TheCall->getNumArgs(),
1694                       IsCXXMember, TheCall->getRParenLoc(),
1695                       TheCall->getCallee()->getSourceRange());
1696}
1697
1698void Sema::CheckFormatArguments(const FormatAttr *Format, Expr **Args,
1699                                unsigned NumArgs, bool IsCXXMember,
1700                                SourceLocation Loc, SourceRange Range) {
1701  bool HasVAListArg = Format->getFirstArg() == 0;
1702  unsigned format_idx = Format->getFormatIdx() - 1;
1703  unsigned firstDataArg = HasVAListArg ? 0 : Format->getFirstArg() - 1;
1704  if (IsCXXMember) {
1705    if (format_idx == 0)
1706      return;
1707    --format_idx;
1708    if(firstDataArg != 0)
1709      --firstDataArg;
1710  }
1711  CheckFormatArguments(Args, NumArgs, HasVAListArg, format_idx,
1712                       firstDataArg, GetFormatStringType(Format), Loc, Range);
1713}
1714
1715void Sema::CheckFormatArguments(Expr **Args, unsigned NumArgs,
1716                                bool HasVAListArg, unsigned format_idx,
1717                                unsigned firstDataArg, FormatStringType Type,
1718                                SourceLocation Loc, SourceRange Range) {
1719  // CHECK: printf/scanf-like function is called with no format string.
1720  if (format_idx >= NumArgs) {
1721    Diag(Loc, diag::warn_missing_format_string) << Range;
1722    return;
1723  }
1724
1725  const Expr *OrigFormatExpr = Args[format_idx]->IgnoreParenCasts();
1726
1727  // CHECK: format string is not a string literal.
1728  //
1729  // Dynamically generated format strings are difficult to
1730  // automatically vet at compile time.  Requiring that format strings
1731  // are string literals: (1) permits the checking of format strings by
1732  // the compiler and thereby (2) can practically remove the source of
1733  // many format string exploits.
1734
1735  // Format string can be either ObjC string (e.g. @"%d") or
1736  // C string (e.g. "%d")
1737  // ObjC string uses the same format specifiers as C string, so we can use
1738  // the same format string checking logic for both ObjC and C strings.
1739  if (SemaCheckStringLiteral(OrigFormatExpr, Args, NumArgs, HasVAListArg,
1740                             format_idx, firstDataArg, Type))
1741    return;  // Literal format string found, check done!
1742
1743  // Strftime is particular as it always uses a single 'time' argument,
1744  // so it is safe to pass a non-literal string.
1745  if (Type == FST_Strftime)
1746    return;
1747
1748  // Do not emit diag when the string param is a macro expansion and the
1749  // format is either NSString or CFString. This is a hack to prevent
1750  // diag when using the NSLocalizedString and CFCopyLocalizedString macros
1751  // which are usually used in place of NS and CF string literals.
1752  if (Type == FST_NSString && Args[format_idx]->getLocStart().isMacroID())
1753    return;
1754
1755  // If there are no arguments specified, warn with -Wformat-security, otherwise
1756  // warn only with -Wformat-nonliteral.
1757  if (NumArgs == format_idx+1)
1758    Diag(Args[format_idx]->getLocStart(),
1759         diag::warn_format_nonliteral_noargs)
1760      << OrigFormatExpr->getSourceRange();
1761  else
1762    Diag(Args[format_idx]->getLocStart(),
1763         diag::warn_format_nonliteral)
1764           << OrigFormatExpr->getSourceRange();
1765}
1766
1767namespace {
1768class CheckFormatHandler : public analyze_format_string::FormatStringHandler {
1769protected:
1770  Sema &S;
1771  const StringLiteral *FExpr;
1772  const Expr *OrigFormatExpr;
1773  const unsigned FirstDataArg;
1774  const unsigned NumDataArgs;
1775  const bool IsObjCLiteral;
1776  const char *Beg; // Start of format string.
1777  const bool HasVAListArg;
1778  const Expr * const *Args;
1779  const unsigned NumArgs;
1780  unsigned FormatIdx;
1781  llvm::BitVector CoveredArgs;
1782  bool usesPositionalArgs;
1783  bool atFirstArg;
1784  bool inFunctionCall;
1785public:
1786  CheckFormatHandler(Sema &s, const StringLiteral *fexpr,
1787                     const Expr *origFormatExpr, unsigned firstDataArg,
1788                     unsigned numDataArgs, bool isObjCLiteral,
1789                     const char *beg, bool hasVAListArg,
1790                     Expr **args, unsigned numArgs,
1791                     unsigned formatIdx, bool inFunctionCall)
1792    : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr),
1793      FirstDataArg(firstDataArg),
1794      NumDataArgs(numDataArgs),
1795      IsObjCLiteral(isObjCLiteral), Beg(beg),
1796      HasVAListArg(hasVAListArg),
1797      Args(args), NumArgs(numArgs), FormatIdx(formatIdx),
1798      usesPositionalArgs(false), atFirstArg(true),
1799      inFunctionCall(inFunctionCall) {
1800        CoveredArgs.resize(numDataArgs);
1801        CoveredArgs.reset();
1802      }
1803
1804  void DoneProcessing();
1805
1806  void HandleIncompleteSpecifier(const char *startSpecifier,
1807                                 unsigned specifierLen);
1808
1809  void HandleNonStandardLengthModifier(
1810      const analyze_format_string::LengthModifier &LM,
1811      const char *startSpecifier, unsigned specifierLen);
1812
1813  void HandleNonStandardConversionSpecifier(
1814      const analyze_format_string::ConversionSpecifier &CS,
1815      const char *startSpecifier, unsigned specifierLen);
1816
1817  void HandleNonStandardConversionSpecification(
1818      const analyze_format_string::LengthModifier &LM,
1819      const analyze_format_string::ConversionSpecifier &CS,
1820      const char *startSpecifier, unsigned specifierLen);
1821
1822  virtual void HandlePosition(const char *startPos, unsigned posLen);
1823
1824  virtual void HandleInvalidPosition(const char *startSpecifier,
1825                                     unsigned specifierLen,
1826                                     analyze_format_string::PositionContext p);
1827
1828  virtual void HandleZeroPosition(const char *startPos, unsigned posLen);
1829
1830  void HandleNullChar(const char *nullCharacter);
1831
1832  template <typename Range>
1833  static void EmitFormatDiagnostic(Sema &S, bool inFunctionCall,
1834                                   const Expr *ArgumentExpr,
1835                                   PartialDiagnostic PDiag,
1836                                   SourceLocation StringLoc,
1837                                   bool IsStringLocation, Range StringRange,
1838                                   FixItHint Fixit = FixItHint());
1839
1840protected:
1841  bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc,
1842                                        const char *startSpec,
1843                                        unsigned specifierLen,
1844                                        const char *csStart, unsigned csLen);
1845
1846  void HandlePositionalNonpositionalArgs(SourceLocation Loc,
1847                                         const char *startSpec,
1848                                         unsigned specifierLen);
1849
1850  SourceRange getFormatStringRange();
1851  CharSourceRange getSpecifierRange(const char *startSpecifier,
1852                                    unsigned specifierLen);
1853  SourceLocation getLocationOfByte(const char *x);
1854
1855  const Expr *getDataArg(unsigned i) const;
1856
1857  bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS,
1858                    const analyze_format_string::ConversionSpecifier &CS,
1859                    const char *startSpecifier, unsigned specifierLen,
1860                    unsigned argIndex);
1861
1862  template <typename Range>
1863  void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc,
1864                            bool IsStringLocation, Range StringRange,
1865                            FixItHint Fixit = FixItHint());
1866
1867  void CheckPositionalAndNonpositionalArgs(
1868      const analyze_format_string::FormatSpecifier *FS);
1869};
1870}
1871
1872SourceRange CheckFormatHandler::getFormatStringRange() {
1873  return OrigFormatExpr->getSourceRange();
1874}
1875
1876CharSourceRange CheckFormatHandler::
1877getSpecifierRange(const char *startSpecifier, unsigned specifierLen) {
1878  SourceLocation Start = getLocationOfByte(startSpecifier);
1879  SourceLocation End   = getLocationOfByte(startSpecifier + specifierLen - 1);
1880
1881  // Advance the end SourceLocation by one due to half-open ranges.
1882  End = End.getLocWithOffset(1);
1883
1884  return CharSourceRange::getCharRange(Start, End);
1885}
1886
1887SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) {
1888  return S.getLocationOfStringLiteralByte(FExpr, x - Beg);
1889}
1890
1891void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
1892                                                   unsigned specifierLen){
1893  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_incomplete_specifier),
1894                       getLocationOfByte(startSpecifier),
1895                       /*IsStringLocation*/true,
1896                       getSpecifierRange(startSpecifier, specifierLen));
1897}
1898
1899void CheckFormatHandler::HandleNonStandardLengthModifier(
1900    const analyze_format_string::LengthModifier &LM,
1901    const char *startSpecifier, unsigned specifierLen) {
1902  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard) << LM.toString()
1903                       << 0,
1904                       getLocationOfByte(LM.getStart()),
1905                       /*IsStringLocation*/true,
1906                       getSpecifierRange(startSpecifier, specifierLen));
1907}
1908
1909void CheckFormatHandler::HandleNonStandardConversionSpecifier(
1910    const analyze_format_string::ConversionSpecifier &CS,
1911    const char *startSpecifier, unsigned specifierLen) {
1912  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard) << CS.toString()
1913                       << 1,
1914                       getLocationOfByte(CS.getStart()),
1915                       /*IsStringLocation*/true,
1916                       getSpecifierRange(startSpecifier, specifierLen));
1917}
1918
1919void CheckFormatHandler::HandleNonStandardConversionSpecification(
1920    const analyze_format_string::LengthModifier &LM,
1921    const analyze_format_string::ConversionSpecifier &CS,
1922    const char *startSpecifier, unsigned specifierLen) {
1923  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_conversion_spec)
1924                       << LM.toString() << CS.toString(),
1925                       getLocationOfByte(LM.getStart()),
1926                       /*IsStringLocation*/true,
1927                       getSpecifierRange(startSpecifier, specifierLen));
1928}
1929
1930void CheckFormatHandler::HandlePosition(const char *startPos,
1931                                        unsigned posLen) {
1932  EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
1933                               getLocationOfByte(startPos),
1934                               /*IsStringLocation*/true,
1935                               getSpecifierRange(startPos, posLen));
1936}
1937
1938void
1939CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
1940                                     analyze_format_string::PositionContext p) {
1941  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_positional_specifier)
1942                         << (unsigned) p,
1943                       getLocationOfByte(startPos), /*IsStringLocation*/true,
1944                       getSpecifierRange(startPos, posLen));
1945}
1946
1947void CheckFormatHandler::HandleZeroPosition(const char *startPos,
1948                                            unsigned posLen) {
1949  EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
1950                               getLocationOfByte(startPos),
1951                               /*IsStringLocation*/true,
1952                               getSpecifierRange(startPos, posLen));
1953}
1954
1955void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {
1956  if (!IsObjCLiteral) {
1957    // The presence of a null character is likely an error.
1958    EmitFormatDiagnostic(
1959      S.PDiag(diag::warn_printf_format_string_contains_null_char),
1960      getLocationOfByte(nullCharacter), /*IsStringLocation*/true,
1961      getFormatStringRange());
1962  }
1963}
1964
1965const Expr *CheckFormatHandler::getDataArg(unsigned i) const {
1966  return Args[FirstDataArg + i];
1967}
1968
1969void CheckFormatHandler::DoneProcessing() {
1970    // Does the number of data arguments exceed the number of
1971    // format conversions in the format string?
1972  if (!HasVAListArg) {
1973      // Find any arguments that weren't covered.
1974    CoveredArgs.flip();
1975    signed notCoveredArg = CoveredArgs.find_first();
1976    if (notCoveredArg >= 0) {
1977      assert((unsigned)notCoveredArg < NumDataArgs);
1978      EmitFormatDiagnostic(S.PDiag(diag::warn_printf_data_arg_not_used),
1979                           getDataArg((unsigned) notCoveredArg)->getLocStart(),
1980                           /*IsStringLocation*/false, getFormatStringRange());
1981    }
1982  }
1983}
1984
1985bool
1986CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex,
1987                                                     SourceLocation Loc,
1988                                                     const char *startSpec,
1989                                                     unsigned specifierLen,
1990                                                     const char *csStart,
1991                                                     unsigned csLen) {
1992
1993  bool keepGoing = true;
1994  if (argIndex < NumDataArgs) {
1995    // Consider the argument coverered, even though the specifier doesn't
1996    // make sense.
1997    CoveredArgs.set(argIndex);
1998  }
1999  else {
2000    // If argIndex exceeds the number of data arguments we
2001    // don't issue a warning because that is just a cascade of warnings (and
2002    // they may have intended '%%' anyway). We don't want to continue processing
2003    // the format string after this point, however, as we will like just get
2004    // gibberish when trying to match arguments.
2005    keepGoing = false;
2006  }
2007
2008  EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_conversion)
2009                         << StringRef(csStart, csLen),
2010                       Loc, /*IsStringLocation*/true,
2011                       getSpecifierRange(startSpec, specifierLen));
2012
2013  return keepGoing;
2014}
2015
2016void
2017CheckFormatHandler::HandlePositionalNonpositionalArgs(SourceLocation Loc,
2018                                                      const char *startSpec,
2019                                                      unsigned specifierLen) {
2020  EmitFormatDiagnostic(
2021    S.PDiag(diag::warn_format_mix_positional_nonpositional_args),
2022    Loc, /*isStringLoc*/true, getSpecifierRange(startSpec, specifierLen));
2023}
2024
2025bool
2026CheckFormatHandler::CheckNumArgs(
2027  const analyze_format_string::FormatSpecifier &FS,
2028  const analyze_format_string::ConversionSpecifier &CS,
2029  const char *startSpecifier, unsigned specifierLen, unsigned argIndex) {
2030
2031  if (argIndex >= NumDataArgs) {
2032    PartialDiagnostic PDiag = FS.usesPositionalArg()
2033      ? (S.PDiag(diag::warn_printf_positional_arg_exceeds_data_args)
2034           << (argIndex+1) << NumDataArgs)
2035      : S.PDiag(diag::warn_printf_insufficient_data_args);
2036    EmitFormatDiagnostic(
2037      PDiag, getLocationOfByte(CS.getStart()), /*IsStringLocation*/true,
2038      getSpecifierRange(startSpecifier, specifierLen));
2039    return false;
2040  }
2041  return true;
2042}
2043
2044template<typename Range>
2045void CheckFormatHandler::EmitFormatDiagnostic(PartialDiagnostic PDiag,
2046                                              SourceLocation Loc,
2047                                              bool IsStringLocation,
2048                                              Range StringRange,
2049                                              FixItHint FixIt) {
2050  EmitFormatDiagnostic(S, inFunctionCall, Args[FormatIdx], PDiag,
2051                       Loc, IsStringLocation, StringRange, FixIt);
2052}
2053
2054/// \brief If the format string is not within the funcion call, emit a note
2055/// so that the function call and string are in diagnostic messages.
2056///
2057/// \param inFunctionCall if true, the format string is within the function
2058/// call and only one diagnostic message will be produced.  Otherwise, an
2059/// extra note will be emitted pointing to location of the format string.
2060///
2061/// \param ArgumentExpr the expression that is passed as the format string
2062/// argument in the function call.  Used for getting locations when two
2063/// diagnostics are emitted.
2064///
2065/// \param PDiag the callee should already have provided any strings for the
2066/// diagnostic message.  This function only adds locations and fixits
2067/// to diagnostics.
2068///
2069/// \param Loc primary location for diagnostic.  If two diagnostics are
2070/// required, one will be at Loc and a new SourceLocation will be created for
2071/// the other one.
2072///
2073/// \param IsStringLocation if true, Loc points to the format string should be
2074/// used for the note.  Otherwise, Loc points to the argument list and will
2075/// be used with PDiag.
2076///
2077/// \param StringRange some or all of the string to highlight.  This is
2078/// templated so it can accept either a CharSourceRange or a SourceRange.
2079///
2080/// \param Fixit optional fix it hint for the format string.
2081template<typename Range>
2082void CheckFormatHandler::EmitFormatDiagnostic(Sema &S, bool InFunctionCall,
2083                                              const Expr *ArgumentExpr,
2084                                              PartialDiagnostic PDiag,
2085                                              SourceLocation Loc,
2086                                              bool IsStringLocation,
2087                                              Range StringRange,
2088                                              FixItHint FixIt) {
2089  if (InFunctionCall)
2090    S.Diag(Loc, PDiag) << StringRange << FixIt;
2091  else {
2092    S.Diag(IsStringLocation ? ArgumentExpr->getExprLoc() : Loc, PDiag)
2093      << ArgumentExpr->getSourceRange();
2094    S.Diag(IsStringLocation ? Loc : StringRange.getBegin(),
2095           diag::note_format_string_defined)
2096      << StringRange << FixIt;
2097  }
2098}
2099
2100//===--- CHECK: Printf format string checking ------------------------------===//
2101
2102namespace {
2103class CheckPrintfHandler : public CheckFormatHandler {
2104public:
2105  CheckPrintfHandler(Sema &s, const StringLiteral *fexpr,
2106                     const Expr *origFormatExpr, unsigned firstDataArg,
2107                     unsigned numDataArgs, bool isObjCLiteral,
2108                     const char *beg, bool hasVAListArg,
2109                     Expr **Args, unsigned NumArgs,
2110                     unsigned formatIdx, bool inFunctionCall)
2111  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2112                       numDataArgs, isObjCLiteral, beg, hasVAListArg,
2113                       Args, NumArgs, formatIdx, inFunctionCall) {}
2114
2115
2116  bool HandleInvalidPrintfConversionSpecifier(
2117                                      const analyze_printf::PrintfSpecifier &FS,
2118                                      const char *startSpecifier,
2119                                      unsigned specifierLen);
2120
2121  bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
2122                             const char *startSpecifier,
2123                             unsigned specifierLen);
2124
2125  bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k,
2126                    const char *startSpecifier, unsigned specifierLen);
2127  void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS,
2128                           const analyze_printf::OptionalAmount &Amt,
2129                           unsigned type,
2130                           const char *startSpecifier, unsigned specifierLen);
2131  void HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2132                  const analyze_printf::OptionalFlag &flag,
2133                  const char *startSpecifier, unsigned specifierLen);
2134  void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS,
2135                         const analyze_printf::OptionalFlag &ignoredFlag,
2136                         const analyze_printf::OptionalFlag &flag,
2137                         const char *startSpecifier, unsigned specifierLen);
2138};
2139}
2140
2141bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier(
2142                                      const analyze_printf::PrintfSpecifier &FS,
2143                                      const char *startSpecifier,
2144                                      unsigned specifierLen) {
2145  const analyze_printf::PrintfConversionSpecifier &CS =
2146    FS.getConversionSpecifier();
2147
2148  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2149                                          getLocationOfByte(CS.getStart()),
2150                                          startSpecifier, specifierLen,
2151                                          CS.getStart(), CS.getLength());
2152}
2153
2154bool CheckPrintfHandler::HandleAmount(
2155                               const analyze_format_string::OptionalAmount &Amt,
2156                               unsigned k, const char *startSpecifier,
2157                               unsigned specifierLen) {
2158
2159  if (Amt.hasDataArgument()) {
2160    if (!HasVAListArg) {
2161      unsigned argIndex = Amt.getArgIndex();
2162      if (argIndex >= NumDataArgs) {
2163        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_missing_arg)
2164                               << k,
2165                             getLocationOfByte(Amt.getStart()),
2166                             /*IsStringLocation*/true,
2167                             getSpecifierRange(startSpecifier, specifierLen));
2168        // Don't do any more checking.  We will just emit
2169        // spurious errors.
2170        return false;
2171      }
2172
2173      // Type check the data argument.  It should be an 'int'.
2174      // Although not in conformance with C99, we also allow the argument to be
2175      // an 'unsigned int' as that is a reasonably safe case.  GCC also
2176      // doesn't emit a warning for that case.
2177      CoveredArgs.set(argIndex);
2178      const Expr *Arg = getDataArg(argIndex);
2179      QualType T = Arg->getType();
2180
2181      const analyze_printf::ArgTypeResult &ATR = Amt.getArgType(S.Context);
2182      assert(ATR.isValid());
2183
2184      if (!ATR.matchesType(S.Context, T)) {
2185        EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_wrong_type)
2186                               << k << ATR.getRepresentativeTypeName(S.Context)
2187                               << T << Arg->getSourceRange(),
2188                             getLocationOfByte(Amt.getStart()),
2189                             /*IsStringLocation*/true,
2190                             getSpecifierRange(startSpecifier, specifierLen));
2191        // Don't do any more checking.  We will just emit
2192        // spurious errors.
2193        return false;
2194      }
2195    }
2196  }
2197  return true;
2198}
2199
2200void CheckPrintfHandler::HandleInvalidAmount(
2201                                      const analyze_printf::PrintfSpecifier &FS,
2202                                      const analyze_printf::OptionalAmount &Amt,
2203                                      unsigned type,
2204                                      const char *startSpecifier,
2205                                      unsigned specifierLen) {
2206  const analyze_printf::PrintfConversionSpecifier &CS =
2207    FS.getConversionSpecifier();
2208
2209  FixItHint fixit =
2210    Amt.getHowSpecified() == analyze_printf::OptionalAmount::Constant
2211      ? FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(),
2212                                 Amt.getConstantLength()))
2213      : FixItHint();
2214
2215  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_optional_amount)
2216                         << type << CS.toString(),
2217                       getLocationOfByte(Amt.getStart()),
2218                       /*IsStringLocation*/true,
2219                       getSpecifierRange(startSpecifier, specifierLen),
2220                       fixit);
2221}
2222
2223void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS,
2224                                    const analyze_printf::OptionalFlag &flag,
2225                                    const char *startSpecifier,
2226                                    unsigned specifierLen) {
2227  // Warn about pointless flag with a fixit removal.
2228  const analyze_printf::PrintfConversionSpecifier &CS =
2229    FS.getConversionSpecifier();
2230  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_flag)
2231                         << flag.toString() << CS.toString(),
2232                       getLocationOfByte(flag.getPosition()),
2233                       /*IsStringLocation*/true,
2234                       getSpecifierRange(startSpecifier, specifierLen),
2235                       FixItHint::CreateRemoval(
2236                         getSpecifierRange(flag.getPosition(), 1)));
2237}
2238
2239void CheckPrintfHandler::HandleIgnoredFlag(
2240                                const analyze_printf::PrintfSpecifier &FS,
2241                                const analyze_printf::OptionalFlag &ignoredFlag,
2242                                const analyze_printf::OptionalFlag &flag,
2243                                const char *startSpecifier,
2244                                unsigned specifierLen) {
2245  // Warn about ignored flag with a fixit removal.
2246  EmitFormatDiagnostic(S.PDiag(diag::warn_printf_ignored_flag)
2247                         << ignoredFlag.toString() << flag.toString(),
2248                       getLocationOfByte(ignoredFlag.getPosition()),
2249                       /*IsStringLocation*/true,
2250                       getSpecifierRange(startSpecifier, specifierLen),
2251                       FixItHint::CreateRemoval(
2252                         getSpecifierRange(ignoredFlag.getPosition(), 1)));
2253}
2254
2255bool
2256CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
2257                                            &FS,
2258                                          const char *startSpecifier,
2259                                          unsigned specifierLen) {
2260
2261  using namespace analyze_format_string;
2262  using namespace analyze_printf;
2263  const PrintfConversionSpecifier &CS = FS.getConversionSpecifier();
2264
2265  if (FS.consumesDataArgument()) {
2266    if (atFirstArg) {
2267        atFirstArg = false;
2268        usesPositionalArgs = FS.usesPositionalArg();
2269    }
2270    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2271      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2272                                        startSpecifier, specifierLen);
2273      return false;
2274    }
2275  }
2276
2277  // First check if the field width, precision, and conversion specifier
2278  // have matching data arguments.
2279  if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0,
2280                    startSpecifier, specifierLen)) {
2281    return false;
2282  }
2283
2284  if (!HandleAmount(FS.getPrecision(), /* precision */ 1,
2285                    startSpecifier, specifierLen)) {
2286    return false;
2287  }
2288
2289  if (!CS.consumesDataArgument()) {
2290    // FIXME: Technically specifying a precision or field width here
2291    // makes no sense.  Worth issuing a warning at some point.
2292    return true;
2293  }
2294
2295  // Consume the argument.
2296  unsigned argIndex = FS.getArgIndex();
2297  if (argIndex < NumDataArgs) {
2298    // The check to see if the argIndex is valid will come later.
2299    // We set the bit here because we may exit early from this
2300    // function if we encounter some other error.
2301    CoveredArgs.set(argIndex);
2302  }
2303
2304  // Check for using an Objective-C specific conversion specifier
2305  // in a non-ObjC literal.
2306  if (!IsObjCLiteral && CS.isObjCArg()) {
2307    return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
2308                                                  specifierLen);
2309  }
2310
2311  // Check for invalid use of field width
2312  if (!FS.hasValidFieldWidth()) {
2313    HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0,
2314        startSpecifier, specifierLen);
2315  }
2316
2317  // Check for invalid use of precision
2318  if (!FS.hasValidPrecision()) {
2319    HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1,
2320        startSpecifier, specifierLen);
2321  }
2322
2323  // Check each flag does not conflict with any other component.
2324  if (!FS.hasValidThousandsGroupingPrefix())
2325    HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen);
2326  if (!FS.hasValidLeadingZeros())
2327    HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen);
2328  if (!FS.hasValidPlusPrefix())
2329    HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen);
2330  if (!FS.hasValidSpacePrefix())
2331    HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen);
2332  if (!FS.hasValidAlternativeForm())
2333    HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen);
2334  if (!FS.hasValidLeftJustified())
2335    HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen);
2336
2337  // Check that flags are not ignored by another flag
2338  if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+'
2339    HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(),
2340        startSpecifier, specifierLen);
2341  if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-'
2342    HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(),
2343            startSpecifier, specifierLen);
2344
2345  // Check the length modifier is valid with the given conversion specifier.
2346  const LengthModifier &LM = FS.getLengthModifier();
2347  if (!FS.hasValidLengthModifier())
2348    EmitFormatDiagnostic(S.PDiag(diag::warn_format_nonsensical_length)
2349                           << LM.toString() << CS.toString(),
2350                         getLocationOfByte(LM.getStart()),
2351                         /*IsStringLocation*/true,
2352                         getSpecifierRange(startSpecifier, specifierLen),
2353                         FixItHint::CreateRemoval(
2354                           getSpecifierRange(LM.getStart(),
2355                                             LM.getLength())));
2356  if (!FS.hasStandardLengthModifier())
2357    HandleNonStandardLengthModifier(LM, startSpecifier, specifierLen);
2358  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
2359    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
2360  if (!FS.hasStandardLengthConversionCombination())
2361    HandleNonStandardConversionSpecification(LM, CS, startSpecifier,
2362                                             specifierLen);
2363
2364  // Are we using '%n'?
2365  if (CS.getKind() == ConversionSpecifier::nArg) {
2366    // Issue a warning about this being a possible security issue.
2367    EmitFormatDiagnostic(S.PDiag(diag::warn_printf_write_back),
2368                         getLocationOfByte(CS.getStart()),
2369                         /*IsStringLocation*/true,
2370                         getSpecifierRange(startSpecifier, specifierLen));
2371    // Continue checking the other format specifiers.
2372    return true;
2373  }
2374
2375  // The remaining checks depend on the data arguments.
2376  if (HasVAListArg)
2377    return true;
2378
2379  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2380    return false;
2381
2382  // Now type check the data expression that matches the
2383  // format specifier.
2384  const Expr *Ex = getDataArg(argIndex);
2385  const analyze_printf::ArgTypeResult &ATR = FS.getArgType(S.Context,
2386                                                           IsObjCLiteral);
2387  if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) {
2388    // Check if we didn't match because of an implicit cast from a 'char'
2389    // or 'short' to an 'int'.  This is done because printf is a varargs
2390    // function.
2391    if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Ex))
2392      if (ICE->getType() == S.Context.IntTy) {
2393        // All further checking is done on the subexpression.
2394        Ex = ICE->getSubExpr();
2395        if (ATR.matchesType(S.Context, Ex->getType()))
2396          return true;
2397      }
2398
2399    // We may be able to offer a FixItHint if it is a supported type.
2400    PrintfSpecifier fixedFS = FS;
2401    bool success = fixedFS.fixType(Ex->getType(), S.getLangOpts(),
2402                                   S.Context, IsObjCLiteral);
2403
2404    if (success) {
2405      // Get the fix string from the fixed format specifier
2406      SmallString<128> buf;
2407      llvm::raw_svector_ostream os(buf);
2408      fixedFS.toString(os);
2409
2410      EmitFormatDiagnostic(
2411        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2412          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2413          << Ex->getSourceRange(),
2414        getLocationOfByte(CS.getStart()),
2415        /*IsStringLocation*/true,
2416        getSpecifierRange(startSpecifier, specifierLen),
2417        FixItHint::CreateReplacement(
2418          getSpecifierRange(startSpecifier, specifierLen),
2419          os.str()));
2420    }
2421    else {
2422      EmitFormatDiagnostic(
2423        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2424          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2425          << getSpecifierRange(startSpecifier, specifierLen)
2426          << Ex->getSourceRange(),
2427        getLocationOfByte(CS.getStart()),
2428        true,
2429        getSpecifierRange(startSpecifier, specifierLen));
2430    }
2431  }
2432
2433  return true;
2434}
2435
2436//===--- CHECK: Scanf format string checking ------------------------------===//
2437
2438namespace {
2439class CheckScanfHandler : public CheckFormatHandler {
2440public:
2441  CheckScanfHandler(Sema &s, const StringLiteral *fexpr,
2442                    const Expr *origFormatExpr, unsigned firstDataArg,
2443                    unsigned numDataArgs, bool isObjCLiteral,
2444                    const char *beg, bool hasVAListArg,
2445                    Expr **Args, unsigned NumArgs,
2446                    unsigned formatIdx, bool inFunctionCall)
2447  : CheckFormatHandler(s, fexpr, origFormatExpr, firstDataArg,
2448                       numDataArgs, isObjCLiteral, beg, hasVAListArg,
2449                       Args, NumArgs, formatIdx, inFunctionCall) {}
2450
2451  bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
2452                            const char *startSpecifier,
2453                            unsigned specifierLen);
2454
2455  bool HandleInvalidScanfConversionSpecifier(
2456          const analyze_scanf::ScanfSpecifier &FS,
2457          const char *startSpecifier,
2458          unsigned specifierLen);
2459
2460  void HandleIncompleteScanList(const char *start, const char *end);
2461};
2462}
2463
2464void CheckScanfHandler::HandleIncompleteScanList(const char *start,
2465                                                 const char *end) {
2466  EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_scanlist_incomplete),
2467                       getLocationOfByte(end), /*IsStringLocation*/true,
2468                       getSpecifierRange(start, end - start));
2469}
2470
2471bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier(
2472                                        const analyze_scanf::ScanfSpecifier &FS,
2473                                        const char *startSpecifier,
2474                                        unsigned specifierLen) {
2475
2476  const analyze_scanf::ScanfConversionSpecifier &CS =
2477    FS.getConversionSpecifier();
2478
2479  return HandleInvalidConversionSpecifier(FS.getArgIndex(),
2480                                          getLocationOfByte(CS.getStart()),
2481                                          startSpecifier, specifierLen,
2482                                          CS.getStart(), CS.getLength());
2483}
2484
2485bool CheckScanfHandler::HandleScanfSpecifier(
2486                                       const analyze_scanf::ScanfSpecifier &FS,
2487                                       const char *startSpecifier,
2488                                       unsigned specifierLen) {
2489
2490  using namespace analyze_scanf;
2491  using namespace analyze_format_string;
2492
2493  const ScanfConversionSpecifier &CS = FS.getConversionSpecifier();
2494
2495  // Handle case where '%' and '*' don't consume an argument.  These shouldn't
2496  // be used to decide if we are using positional arguments consistently.
2497  if (FS.consumesDataArgument()) {
2498    if (atFirstArg) {
2499      atFirstArg = false;
2500      usesPositionalArgs = FS.usesPositionalArg();
2501    }
2502    else if (usesPositionalArgs != FS.usesPositionalArg()) {
2503      HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
2504                                        startSpecifier, specifierLen);
2505      return false;
2506    }
2507  }
2508
2509  // Check if the field with is non-zero.
2510  const OptionalAmount &Amt = FS.getFieldWidth();
2511  if (Amt.getHowSpecified() == OptionalAmount::Constant) {
2512    if (Amt.getConstantAmount() == 0) {
2513      const CharSourceRange &R = getSpecifierRange(Amt.getStart(),
2514                                                   Amt.getConstantLength());
2515      EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_nonzero_width),
2516                           getLocationOfByte(Amt.getStart()),
2517                           /*IsStringLocation*/true, R,
2518                           FixItHint::CreateRemoval(R));
2519    }
2520  }
2521
2522  if (!FS.consumesDataArgument()) {
2523    // FIXME: Technically specifying a precision or field width here
2524    // makes no sense.  Worth issuing a warning at some point.
2525    return true;
2526  }
2527
2528  // Consume the argument.
2529  unsigned argIndex = FS.getArgIndex();
2530  if (argIndex < NumDataArgs) {
2531      // The check to see if the argIndex is valid will come later.
2532      // We set the bit here because we may exit early from this
2533      // function if we encounter some other error.
2534    CoveredArgs.set(argIndex);
2535  }
2536
2537  // Check the length modifier is valid with the given conversion specifier.
2538  const LengthModifier &LM = FS.getLengthModifier();
2539  if (!FS.hasValidLengthModifier()) {
2540    const CharSourceRange &R = getSpecifierRange(LM.getStart(), LM.getLength());
2541    EmitFormatDiagnostic(S.PDiag(diag::warn_format_nonsensical_length)
2542                         << LM.toString() << CS.toString()
2543                         << getSpecifierRange(startSpecifier, specifierLen),
2544                         getLocationOfByte(LM.getStart()),
2545                         /*IsStringLocation*/true, R,
2546                         FixItHint::CreateRemoval(R));
2547  }
2548
2549  if (!FS.hasStandardLengthModifier())
2550    HandleNonStandardLengthModifier(LM, startSpecifier, specifierLen);
2551  if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
2552    HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
2553  if (!FS.hasStandardLengthConversionCombination())
2554    HandleNonStandardConversionSpecification(LM, CS, startSpecifier,
2555                                             specifierLen);
2556
2557  // The remaining checks depend on the data arguments.
2558  if (HasVAListArg)
2559    return true;
2560
2561  if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
2562    return false;
2563
2564  // Check that the argument type matches the format specifier.
2565  const Expr *Ex = getDataArg(argIndex);
2566  const analyze_scanf::ScanfArgTypeResult &ATR = FS.getArgType(S.Context);
2567  if (ATR.isValid() && !ATR.matchesType(S.Context, Ex->getType())) {
2568    ScanfSpecifier fixedFS = FS;
2569    bool success = fixedFS.fixType(Ex->getType(), S.getLangOpts(),
2570                                   S.Context);
2571
2572    if (success) {
2573      // Get the fix string from the fixed format specifier.
2574      SmallString<128> buf;
2575      llvm::raw_svector_ostream os(buf);
2576      fixedFS.toString(os);
2577
2578      EmitFormatDiagnostic(
2579        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2580          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2581          << Ex->getSourceRange(),
2582        getLocationOfByte(CS.getStart()),
2583        /*IsStringLocation*/true,
2584        getSpecifierRange(startSpecifier, specifierLen),
2585        FixItHint::CreateReplacement(
2586          getSpecifierRange(startSpecifier, specifierLen),
2587          os.str()));
2588    } else {
2589      EmitFormatDiagnostic(
2590        S.PDiag(diag::warn_printf_conversion_argument_type_mismatch)
2591          << ATR.getRepresentativeTypeName(S.Context) << Ex->getType()
2592          << Ex->getSourceRange(),
2593        getLocationOfByte(CS.getStart()),
2594        /*IsStringLocation*/true,
2595        getSpecifierRange(startSpecifier, specifierLen));
2596    }
2597  }
2598
2599  return true;
2600}
2601
2602void Sema::CheckFormatString(const StringLiteral *FExpr,
2603                             const Expr *OrigFormatExpr,
2604                             Expr **Args, unsigned NumArgs,
2605                             bool HasVAListArg, unsigned format_idx,
2606                             unsigned firstDataArg, FormatStringType Type,
2607                             bool inFunctionCall) {
2608
2609  // CHECK: is the format string a wide literal?
2610  if (!FExpr->isAscii()) {
2611    CheckFormatHandler::EmitFormatDiagnostic(
2612      *this, inFunctionCall, Args[format_idx],
2613      PDiag(diag::warn_format_string_is_wide_literal), FExpr->getLocStart(),
2614      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
2615    return;
2616  }
2617
2618  // Str - The format string.  NOTE: this is NOT null-terminated!
2619  StringRef StrRef = FExpr->getString();
2620  const char *Str = StrRef.data();
2621  unsigned StrLen = StrRef.size();
2622  const unsigned numDataArgs = NumArgs - firstDataArg;
2623
2624  // CHECK: empty format string?
2625  if (StrLen == 0 && numDataArgs > 0) {
2626    CheckFormatHandler::EmitFormatDiagnostic(
2627      *this, inFunctionCall, Args[format_idx],
2628      PDiag(diag::warn_empty_format_string), FExpr->getLocStart(),
2629      /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
2630    return;
2631  }
2632
2633  if (Type == FST_Printf || Type == FST_NSString) {
2634    CheckPrintfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
2635                         numDataArgs, isa<ObjCStringLiteral>(OrigFormatExpr),
2636                         Str, HasVAListArg, Args, NumArgs, format_idx,
2637                         inFunctionCall);
2638
2639    if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen,
2640                                                  getLangOpts()))
2641      H.DoneProcessing();
2642  } else if (Type == FST_Scanf) {
2643    CheckScanfHandler H(*this, FExpr, OrigFormatExpr, firstDataArg,
2644                        numDataArgs, isa<ObjCStringLiteral>(OrigFormatExpr),
2645                        Str, HasVAListArg, Args, NumArgs, format_idx,
2646                        inFunctionCall);
2647
2648    if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen,
2649                                                 getLangOpts()))
2650      H.DoneProcessing();
2651  } // TODO: handle other formats
2652}
2653
2654//===--- CHECK: Standard memory functions ---------------------------------===//
2655
2656/// \brief Determine whether the given type is a dynamic class type (e.g.,
2657/// whether it has a vtable).
2658static bool isDynamicClassType(QualType T) {
2659  if (CXXRecordDecl *Record = T->getAsCXXRecordDecl())
2660    if (CXXRecordDecl *Definition = Record->getDefinition())
2661      if (Definition->isDynamicClass())
2662        return true;
2663
2664  return false;
2665}
2666
2667/// \brief If E is a sizeof expression, returns its argument expression,
2668/// otherwise returns NULL.
2669static const Expr *getSizeOfExprArg(const Expr* E) {
2670  if (const UnaryExprOrTypeTraitExpr *SizeOf =
2671      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
2672    if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType())
2673      return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
2674
2675  return 0;
2676}
2677
2678/// \brief If E is a sizeof expression, returns its argument type.
2679static QualType getSizeOfArgType(const Expr* E) {
2680  if (const UnaryExprOrTypeTraitExpr *SizeOf =
2681      dyn_cast<UnaryExprOrTypeTraitExpr>(E))
2682    if (SizeOf->getKind() == clang::UETT_SizeOf)
2683      return SizeOf->getTypeOfArgument();
2684
2685  return QualType();
2686}
2687
2688/// \brief Check for dangerous or invalid arguments to memset().
2689///
2690/// This issues warnings on known problematic, dangerous or unspecified
2691/// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp'
2692/// function calls.
2693///
2694/// \param Call The call expression to diagnose.
2695void Sema::CheckMemaccessArguments(const CallExpr *Call,
2696                                   unsigned BId,
2697                                   IdentifierInfo *FnName) {
2698  assert(BId != 0);
2699
2700  // It is possible to have a non-standard definition of memset.  Validate
2701  // we have enough arguments, and if not, abort further checking.
2702  unsigned ExpectedNumArgs = (BId == Builtin::BIstrndup ? 2 : 3);
2703  if (Call->getNumArgs() < ExpectedNumArgs)
2704    return;
2705
2706  unsigned LastArg = (BId == Builtin::BImemset ||
2707                      BId == Builtin::BIstrndup ? 1 : 2);
2708  unsigned LenArg = (BId == Builtin::BIstrndup ? 1 : 2);
2709  const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
2710
2711  // We have special checking when the length is a sizeof expression.
2712  QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
2713  const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
2714  llvm::FoldingSetNodeID SizeOfArgID;
2715
2716  for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) {
2717    const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts();
2718    SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange();
2719
2720    QualType DestTy = Dest->getType();
2721    if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
2722      QualType PointeeTy = DestPtrTy->getPointeeType();
2723
2724      // Never warn about void type pointers. This can be used to suppress
2725      // false positives.
2726      if (PointeeTy->isVoidType())
2727        continue;
2728
2729      // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by
2730      // actually comparing the expressions for equality. Because computing the
2731      // expression IDs can be expensive, we only do this if the diagnostic is
2732      // enabled.
2733      if (SizeOfArg &&
2734          Diags.getDiagnosticLevel(diag::warn_sizeof_pointer_expr_memaccess,
2735                                   SizeOfArg->getExprLoc())) {
2736        // We only compute IDs for expressions if the warning is enabled, and
2737        // cache the sizeof arg's ID.
2738        if (SizeOfArgID == llvm::FoldingSetNodeID())
2739          SizeOfArg->Profile(SizeOfArgID, Context, true);
2740        llvm::FoldingSetNodeID DestID;
2741        Dest->Profile(DestID, Context, true);
2742        if (DestID == SizeOfArgID) {
2743          // TODO: For strncpy() and friends, this could suggest sizeof(dst)
2744          //       over sizeof(src) as well.
2745          unsigned ActionIdx = 0; // Default is to suggest dereferencing.
2746          if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest))
2747            if (UnaryOp->getOpcode() == UO_AddrOf)
2748              ActionIdx = 1; // If its an address-of operator, just remove it.
2749          if (Context.getTypeSize(PointeeTy) == Context.getCharWidth())
2750            ActionIdx = 2; // If the pointee's size is sizeof(char),
2751                           // suggest an explicit length.
2752          unsigned DestSrcSelect =
2753            (BId == Builtin::BIstrndup ? 1 : ArgIdx);
2754          DiagRuntimeBehavior(SizeOfArg->getExprLoc(), Dest,
2755                              PDiag(diag::warn_sizeof_pointer_expr_memaccess)
2756                                << FnName << DestSrcSelect << ActionIdx
2757                                << Dest->getSourceRange()
2758                                << SizeOfArg->getSourceRange());
2759          break;
2760        }
2761      }
2762
2763      // Also check for cases where the sizeof argument is the exact same
2764      // type as the memory argument, and where it points to a user-defined
2765      // record type.
2766      if (SizeOfArgTy != QualType()) {
2767        if (PointeeTy->isRecordType() &&
2768            Context.typesAreCompatible(SizeOfArgTy, DestTy)) {
2769          DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest,
2770                              PDiag(diag::warn_sizeof_pointer_type_memaccess)
2771                                << FnName << SizeOfArgTy << ArgIdx
2772                                << PointeeTy << Dest->getSourceRange()
2773                                << LenExpr->getSourceRange());
2774          break;
2775        }
2776      }
2777
2778      // Always complain about dynamic classes.
2779      if (isDynamicClassType(PointeeTy)) {
2780
2781        unsigned OperationType = 0;
2782        // "overwritten" if we're warning about the destination for any call
2783        // but memcmp; otherwise a verb appropriate to the call.
2784        if (ArgIdx != 0 || BId == Builtin::BImemcmp) {
2785          if (BId == Builtin::BImemcpy)
2786            OperationType = 1;
2787          else if(BId == Builtin::BImemmove)
2788            OperationType = 2;
2789          else if (BId == Builtin::BImemcmp)
2790            OperationType = 3;
2791        }
2792
2793        DiagRuntimeBehavior(
2794          Dest->getExprLoc(), Dest,
2795          PDiag(diag::warn_dyn_class_memaccess)
2796            << (BId == Builtin::BImemcmp ? ArgIdx + 2 : ArgIdx)
2797            << FnName << PointeeTy
2798            << OperationType
2799            << Call->getCallee()->getSourceRange());
2800      } else if (PointeeTy.hasNonTrivialObjCLifetime() &&
2801               BId != Builtin::BImemset)
2802        DiagRuntimeBehavior(
2803          Dest->getExprLoc(), Dest,
2804          PDiag(diag::warn_arc_object_memaccess)
2805            << ArgIdx << FnName << PointeeTy
2806            << Call->getCallee()->getSourceRange());
2807      else
2808        continue;
2809
2810      DiagRuntimeBehavior(
2811        Dest->getExprLoc(), Dest,
2812        PDiag(diag::note_bad_memaccess_silence)
2813          << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)"));
2814      break;
2815    }
2816  }
2817}
2818
2819// A little helper routine: ignore addition and subtraction of integer literals.
2820// This intentionally does not ignore all integer constant expressions because
2821// we don't want to remove sizeof().
2822static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) {
2823  Ex = Ex->IgnoreParenCasts();
2824
2825  for (;;) {
2826    const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex);
2827    if (!BO || !BO->isAdditiveOp())
2828      break;
2829
2830    const Expr *RHS = BO->getRHS()->IgnoreParenCasts();
2831    const Expr *LHS = BO->getLHS()->IgnoreParenCasts();
2832
2833    if (isa<IntegerLiteral>(RHS))
2834      Ex = LHS;
2835    else if (isa<IntegerLiteral>(LHS))
2836      Ex = RHS;
2837    else
2838      break;
2839  }
2840
2841  return Ex;
2842}
2843
2844// Warn if the user has made the 'size' argument to strlcpy or strlcat
2845// be the size of the source, instead of the destination.
2846void Sema::CheckStrlcpycatArguments(const CallExpr *Call,
2847                                    IdentifierInfo *FnName) {
2848
2849  // Don't crash if the user has the wrong number of arguments
2850  if (Call->getNumArgs() != 3)
2851    return;
2852
2853  const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context);
2854  const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context);
2855  const Expr *CompareWithSrc = NULL;
2856
2857  // Look for 'strlcpy(dst, x, sizeof(x))'
2858  if (const Expr *Ex = getSizeOfExprArg(SizeArg))
2859    CompareWithSrc = Ex;
2860  else {
2861    // Look for 'strlcpy(dst, x, strlen(x))'
2862    if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) {
2863      if (SizeCall->isBuiltinCall() == Builtin::BIstrlen
2864          && SizeCall->getNumArgs() == 1)
2865        CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context);
2866    }
2867  }
2868
2869  if (!CompareWithSrc)
2870    return;
2871
2872  // Determine if the argument to sizeof/strlen is equal to the source
2873  // argument.  In principle there's all kinds of things you could do
2874  // here, for instance creating an == expression and evaluating it with
2875  // EvaluateAsBooleanCondition, but this uses a more direct technique:
2876  const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg);
2877  if (!SrcArgDRE)
2878    return;
2879
2880  const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc);
2881  if (!CompareWithSrcDRE ||
2882      SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl())
2883    return;
2884
2885  const Expr *OriginalSizeArg = Call->getArg(2);
2886  Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size)
2887    << OriginalSizeArg->getSourceRange() << FnName;
2888
2889  // Output a FIXIT hint if the destination is an array (rather than a
2890  // pointer to an array).  This could be enhanced to handle some
2891  // pointers if we know the actual size, like if DstArg is 'array+2'
2892  // we could say 'sizeof(array)-2'.
2893  const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts();
2894  QualType DstArgTy = DstArg->getType();
2895
2896  // Only handle constant-sized or VLAs, but not flexible members.
2897  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) {
2898    // Only issue the FIXIT for arrays of size > 1.
2899    if (CAT->getSize().getSExtValue() <= 1)
2900      return;
2901  } else if (!DstArgTy->isVariableArrayType()) {
2902    return;
2903  }
2904
2905  SmallString<128> sizeString;
2906  llvm::raw_svector_ostream OS(sizeString);
2907  OS << "sizeof(";
2908  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
2909  OS << ")";
2910
2911  Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size)
2912    << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(),
2913                                    OS.str());
2914}
2915
2916/// Check if two expressions refer to the same declaration.
2917static bool referToTheSameDecl(const Expr *E1, const Expr *E2) {
2918  if (const DeclRefExpr *D1 = dyn_cast_or_null<DeclRefExpr>(E1))
2919    if (const DeclRefExpr *D2 = dyn_cast_or_null<DeclRefExpr>(E2))
2920      return D1->getDecl() == D2->getDecl();
2921  return false;
2922}
2923
2924static const Expr *getStrlenExprArg(const Expr *E) {
2925  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
2926    const FunctionDecl *FD = CE->getDirectCallee();
2927    if (!FD || FD->getMemoryFunctionKind() != Builtin::BIstrlen)
2928      return 0;
2929    return CE->getArg(0)->IgnoreParenCasts();
2930  }
2931  return 0;
2932}
2933
2934// Warn on anti-patterns as the 'size' argument to strncat.
2935// The correct size argument should look like following:
2936//   strncat(dst, src, sizeof(dst) - strlen(dest) - 1);
2937void Sema::CheckStrncatArguments(const CallExpr *CE,
2938                                 IdentifierInfo *FnName) {
2939  // Don't crash if the user has the wrong number of arguments.
2940  if (CE->getNumArgs() < 3)
2941    return;
2942  const Expr *DstArg = CE->getArg(0)->IgnoreParenCasts();
2943  const Expr *SrcArg = CE->getArg(1)->IgnoreParenCasts();
2944  const Expr *LenArg = CE->getArg(2)->IgnoreParenCasts();
2945
2946  // Identify common expressions, which are wrongly used as the size argument
2947  // to strncat and may lead to buffer overflows.
2948  unsigned PatternType = 0;
2949  if (const Expr *SizeOfArg = getSizeOfExprArg(LenArg)) {
2950    // - sizeof(dst)
2951    if (referToTheSameDecl(SizeOfArg, DstArg))
2952      PatternType = 1;
2953    // - sizeof(src)
2954    else if (referToTheSameDecl(SizeOfArg, SrcArg))
2955      PatternType = 2;
2956  } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(LenArg)) {
2957    if (BE->getOpcode() == BO_Sub) {
2958      const Expr *L = BE->getLHS()->IgnoreParenCasts();
2959      const Expr *R = BE->getRHS()->IgnoreParenCasts();
2960      // - sizeof(dst) - strlen(dst)
2961      if (referToTheSameDecl(DstArg, getSizeOfExprArg(L)) &&
2962          referToTheSameDecl(DstArg, getStrlenExprArg(R)))
2963        PatternType = 1;
2964      // - sizeof(src) - (anything)
2965      else if (referToTheSameDecl(SrcArg, getSizeOfExprArg(L)))
2966        PatternType = 2;
2967    }
2968  }
2969
2970  if (PatternType == 0)
2971    return;
2972
2973  // Generate the diagnostic.
2974  SourceLocation SL = LenArg->getLocStart();
2975  SourceRange SR = LenArg->getSourceRange();
2976  SourceManager &SM  = PP.getSourceManager();
2977
2978  // If the function is defined as a builtin macro, do not show macro expansion.
2979  if (SM.isMacroArgExpansion(SL)) {
2980    SL = SM.getSpellingLoc(SL);
2981    SR = SourceRange(SM.getSpellingLoc(SR.getBegin()),
2982                     SM.getSpellingLoc(SR.getEnd()));
2983  }
2984
2985  if (PatternType == 1)
2986    Diag(SL, diag::warn_strncat_large_size) << SR;
2987  else
2988    Diag(SL, diag::warn_strncat_src_size) << SR;
2989
2990  // Output a FIXIT hint if the destination is an array (rather than a
2991  // pointer to an array).  This could be enhanced to handle some
2992  // pointers if we know the actual size, like if DstArg is 'array+2'
2993  // we could say 'sizeof(array)-2'.
2994  QualType DstArgTy = DstArg->getType();
2995
2996  // Only handle constant-sized or VLAs, but not flexible members.
2997  if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(DstArgTy)) {
2998    // Only issue the FIXIT for arrays of size > 1.
2999    if (CAT->getSize().getSExtValue() <= 1)
3000      return;
3001  } else if (!DstArgTy->isVariableArrayType()) {
3002    return;
3003  }
3004
3005  SmallString<128> sizeString;
3006  llvm::raw_svector_ostream OS(sizeString);
3007  OS << "sizeof(";
3008  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
3009  OS << ") - ";
3010  OS << "strlen(";
3011  DstArg->printPretty(OS, Context, 0, getPrintingPolicy());
3012  OS << ") - 1";
3013
3014  Diag(SL, diag::note_strncat_wrong_size)
3015    << FixItHint::CreateReplacement(SR, OS.str());
3016}
3017
3018//===--- CHECK: Return Address of Stack Variable --------------------------===//
3019
3020static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3021                     Decl *ParentDecl);
3022static Expr *EvalAddr(Expr* E, SmallVectorImpl<DeclRefExpr *> &refVars,
3023                      Decl *ParentDecl);
3024
3025/// CheckReturnStackAddr - Check if a return statement returns the address
3026///   of a stack variable.
3027void
3028Sema::CheckReturnStackAddr(Expr *RetValExp, QualType lhsType,
3029                           SourceLocation ReturnLoc) {
3030
3031  Expr *stackE = 0;
3032  SmallVector<DeclRefExpr *, 8> refVars;
3033
3034  // Perform checking for returned stack addresses, local blocks,
3035  // label addresses or references to temporaries.
3036  if (lhsType->isPointerType() ||
3037      (!getLangOpts().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
3038    stackE = EvalAddr(RetValExp, refVars, /*ParentDecl=*/0);
3039  } else if (lhsType->isReferenceType()) {
3040    stackE = EvalVal(RetValExp, refVars, /*ParentDecl=*/0);
3041  }
3042
3043  if (stackE == 0)
3044    return; // Nothing suspicious was found.
3045
3046  SourceLocation diagLoc;
3047  SourceRange diagRange;
3048  if (refVars.empty()) {
3049    diagLoc = stackE->getLocStart();
3050    diagRange = stackE->getSourceRange();
3051  } else {
3052    // We followed through a reference variable. 'stackE' contains the
3053    // problematic expression but we will warn at the return statement pointing
3054    // at the reference variable. We will later display the "trail" of
3055    // reference variables using notes.
3056    diagLoc = refVars[0]->getLocStart();
3057    diagRange = refVars[0]->getSourceRange();
3058  }
3059
3060  if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) { //address of local var.
3061    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_stack_ref
3062                                             : diag::warn_ret_stack_addr)
3063     << DR->getDecl()->getDeclName() << diagRange;
3064  } else if (isa<BlockExpr>(stackE)) { // local block.
3065    Diag(diagLoc, diag::err_ret_local_block) << diagRange;
3066  } else if (isa<AddrLabelExpr>(stackE)) { // address of label.
3067    Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
3068  } else { // local temporary.
3069    Diag(diagLoc, lhsType->isReferenceType() ? diag::warn_ret_local_temp_ref
3070                                             : diag::warn_ret_local_temp_addr)
3071     << diagRange;
3072  }
3073
3074  // Display the "trail" of reference variables that we followed until we
3075  // found the problematic expression using notes.
3076  for (unsigned i = 0, e = refVars.size(); i != e; ++i) {
3077    VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl());
3078    // If this var binds to another reference var, show the range of the next
3079    // var, otherwise the var binds to the problematic expression, in which case
3080    // show the range of the expression.
3081    SourceRange range = (i < e-1) ? refVars[i+1]->getSourceRange()
3082                                  : stackE->getSourceRange();
3083    Diag(VD->getLocation(), diag::note_ref_var_local_bind)
3084      << VD->getDeclName() << range;
3085  }
3086}
3087
3088/// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
3089///  check if the expression in a return statement evaluates to an address
3090///  to a location on the stack, a local block, an address of a label, or a
3091///  reference to local temporary. The recursion is used to traverse the
3092///  AST of the return expression, with recursion backtracking when we
3093///  encounter a subexpression that (1) clearly does not lead to one of the
3094///  above problematic expressions (2) is something we cannot determine leads to
3095///  a problematic expression based on such local checking.
3096///
3097///  Both EvalAddr and EvalVal follow through reference variables to evaluate
3098///  the expression that they point to. Such variables are added to the
3099///  'refVars' vector so that we know what the reference variable "trail" was.
3100///
3101///  EvalAddr processes expressions that are pointers that are used as
3102///  references (and not L-values).  EvalVal handles all other values.
3103///  At the base case of the recursion is a check for the above problematic
3104///  expressions.
3105///
3106///  This implementation handles:
3107///
3108///   * pointer-to-pointer casts
3109///   * implicit conversions from array references to pointers
3110///   * taking the address of fields
3111///   * arbitrary interplay between "&" and "*" operators
3112///   * pointer arithmetic from an address of a stack variable
3113///   * taking the address of an array element where the array is on the stack
3114static Expr *EvalAddr(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3115                      Decl *ParentDecl) {
3116  if (E->isTypeDependent())
3117      return NULL;
3118
3119  // We should only be called for evaluating pointer expressions.
3120  assert((E->getType()->isAnyPointerType() ||
3121          E->getType()->isBlockPointerType() ||
3122          E->getType()->isObjCQualifiedIdType()) &&
3123         "EvalAddr only works on pointers");
3124
3125  E = E->IgnoreParens();
3126
3127  // Our "symbolic interpreter" is just a dispatch off the currently
3128  // viewed AST node.  We then recursively traverse the AST by calling
3129  // EvalAddr and EvalVal appropriately.
3130  switch (E->getStmtClass()) {
3131  case Stmt::DeclRefExprClass: {
3132    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3133
3134    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
3135      // If this is a reference variable, follow through to the expression that
3136      // it points to.
3137      if (V->hasLocalStorage() &&
3138          V->getType()->isReferenceType() && V->hasInit()) {
3139        // Add the reference variable to the "trail".
3140        refVars.push_back(DR);
3141        return EvalAddr(V->getInit(), refVars, ParentDecl);
3142      }
3143
3144    return NULL;
3145  }
3146
3147  case Stmt::UnaryOperatorClass: {
3148    // The only unary operator that make sense to handle here
3149    // is AddrOf.  All others don't make sense as pointers.
3150    UnaryOperator *U = cast<UnaryOperator>(E);
3151
3152    if (U->getOpcode() == UO_AddrOf)
3153      return EvalVal(U->getSubExpr(), refVars, ParentDecl);
3154    else
3155      return NULL;
3156  }
3157
3158  case Stmt::BinaryOperatorClass: {
3159    // Handle pointer arithmetic.  All other binary operators are not valid
3160    // in this context.
3161    BinaryOperator *B = cast<BinaryOperator>(E);
3162    BinaryOperatorKind op = B->getOpcode();
3163
3164    if (op != BO_Add && op != BO_Sub)
3165      return NULL;
3166
3167    Expr *Base = B->getLHS();
3168
3169    // Determine which argument is the real pointer base.  It could be
3170    // the RHS argument instead of the LHS.
3171    if (!Base->getType()->isPointerType()) Base = B->getRHS();
3172
3173    assert (Base->getType()->isPointerType());
3174    return EvalAddr(Base, refVars, ParentDecl);
3175  }
3176
3177  // For conditional operators we need to see if either the LHS or RHS are
3178  // valid DeclRefExpr*s.  If one of them is valid, we return it.
3179  case Stmt::ConditionalOperatorClass: {
3180    ConditionalOperator *C = cast<ConditionalOperator>(E);
3181
3182    // Handle the GNU extension for missing LHS.
3183    if (Expr *lhsExpr = C->getLHS()) {
3184    // In C++, we can have a throw-expression, which has 'void' type.
3185      if (!lhsExpr->getType()->isVoidType())
3186        if (Expr* LHS = EvalAddr(lhsExpr, refVars, ParentDecl))
3187          return LHS;
3188    }
3189
3190    // In C++, we can have a throw-expression, which has 'void' type.
3191    if (C->getRHS()->getType()->isVoidType())
3192      return NULL;
3193
3194    return EvalAddr(C->getRHS(), refVars, ParentDecl);
3195  }
3196
3197  case Stmt::BlockExprClass:
3198    if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures())
3199      return E; // local block.
3200    return NULL;
3201
3202  case Stmt::AddrLabelExprClass:
3203    return E; // address of label.
3204
3205  case Stmt::ExprWithCleanupsClass:
3206    return EvalAddr(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,
3207                    ParentDecl);
3208
3209  // For casts, we need to handle conversions from arrays to
3210  // pointer values, and pointer-to-pointer conversions.
3211  case Stmt::ImplicitCastExprClass:
3212  case Stmt::CStyleCastExprClass:
3213  case Stmt::CXXFunctionalCastExprClass:
3214  case Stmt::ObjCBridgedCastExprClass:
3215  case Stmt::CXXStaticCastExprClass:
3216  case Stmt::CXXDynamicCastExprClass:
3217  case Stmt::CXXConstCastExprClass:
3218  case Stmt::CXXReinterpretCastExprClass: {
3219    Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
3220    switch (cast<CastExpr>(E)->getCastKind()) {
3221    case CK_BitCast:
3222    case CK_LValueToRValue:
3223    case CK_NoOp:
3224    case CK_BaseToDerived:
3225    case CK_DerivedToBase:
3226    case CK_UncheckedDerivedToBase:
3227    case CK_Dynamic:
3228    case CK_CPointerToObjCPointerCast:
3229    case CK_BlockPointerToObjCPointerCast:
3230    case CK_AnyPointerToBlockPointerCast:
3231      return EvalAddr(SubExpr, refVars, ParentDecl);
3232
3233    case CK_ArrayToPointerDecay:
3234      return EvalVal(SubExpr, refVars, ParentDecl);
3235
3236    default:
3237      return 0;
3238    }
3239  }
3240
3241  case Stmt::MaterializeTemporaryExprClass:
3242    if (Expr *Result = EvalAddr(
3243                         cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3244                                refVars, ParentDecl))
3245      return Result;
3246
3247    return E;
3248
3249  // Everything else: we simply don't reason about them.
3250  default:
3251    return NULL;
3252  }
3253}
3254
3255
3256///  EvalVal - This function is complements EvalAddr in the mutual recursion.
3257///   See the comments for EvalAddr for more details.
3258static Expr *EvalVal(Expr *E, SmallVectorImpl<DeclRefExpr *> &refVars,
3259                     Decl *ParentDecl) {
3260do {
3261  // We should only be called for evaluating non-pointer expressions, or
3262  // expressions with a pointer type that are not used as references but instead
3263  // are l-values (e.g., DeclRefExpr with a pointer type).
3264
3265  // Our "symbolic interpreter" is just a dispatch off the currently
3266  // viewed AST node.  We then recursively traverse the AST by calling
3267  // EvalAddr and EvalVal appropriately.
3268
3269  E = E->IgnoreParens();
3270  switch (E->getStmtClass()) {
3271  case Stmt::ImplicitCastExprClass: {
3272    ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E);
3273    if (IE->getValueKind() == VK_LValue) {
3274      E = IE->getSubExpr();
3275      continue;
3276    }
3277    return NULL;
3278  }
3279
3280  case Stmt::ExprWithCleanupsClass:
3281    return EvalVal(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,ParentDecl);
3282
3283  case Stmt::DeclRefExprClass: {
3284    // When we hit a DeclRefExpr we are looking at code that refers to a
3285    // variable's name. If it's not a reference variable we check if it has
3286    // local storage within the function, and if so, return the expression.
3287    DeclRefExpr *DR = cast<DeclRefExpr>(E);
3288
3289    if (VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) {
3290      // Check if it refers to itself, e.g. "int& i = i;".
3291      if (V == ParentDecl)
3292        return DR;
3293
3294      if (V->hasLocalStorage()) {
3295        if (!V->getType()->isReferenceType())
3296          return DR;
3297
3298        // Reference variable, follow through to the expression that
3299        // it points to.
3300        if (V->hasInit()) {
3301          // Add the reference variable to the "trail".
3302          refVars.push_back(DR);
3303          return EvalVal(V->getInit(), refVars, V);
3304        }
3305      }
3306    }
3307
3308    return NULL;
3309  }
3310
3311  case Stmt::UnaryOperatorClass: {
3312    // The only unary operator that make sense to handle here
3313    // is Deref.  All others don't resolve to a "name."  This includes
3314    // handling all sorts of rvalues passed to a unary operator.
3315    UnaryOperator *U = cast<UnaryOperator>(E);
3316
3317    if (U->getOpcode() == UO_Deref)
3318      return EvalAddr(U->getSubExpr(), refVars, ParentDecl);
3319
3320    return NULL;
3321  }
3322
3323  case Stmt::ArraySubscriptExprClass: {
3324    // Array subscripts are potential references to data on the stack.  We
3325    // retrieve the DeclRefExpr* for the array variable if it indeed
3326    // has local storage.
3327    return EvalAddr(cast<ArraySubscriptExpr>(E)->getBase(), refVars,ParentDecl);
3328  }
3329
3330  case Stmt::ConditionalOperatorClass: {
3331    // For conditional operators we need to see if either the LHS or RHS are
3332    // non-NULL Expr's.  If one is non-NULL, we return it.
3333    ConditionalOperator *C = cast<ConditionalOperator>(E);
3334
3335    // Handle the GNU extension for missing LHS.
3336    if (Expr *lhsExpr = C->getLHS())
3337      if (Expr *LHS = EvalVal(lhsExpr, refVars, ParentDecl))
3338        return LHS;
3339
3340    return EvalVal(C->getRHS(), refVars, ParentDecl);
3341  }
3342
3343  // Accesses to members are potential references to data on the stack.
3344  case Stmt::MemberExprClass: {
3345    MemberExpr *M = cast<MemberExpr>(E);
3346
3347    // Check for indirect access.  We only want direct field accesses.
3348    if (M->isArrow())
3349      return NULL;
3350
3351    // Check whether the member type is itself a reference, in which case
3352    // we're not going to refer to the member, but to what the member refers to.
3353    if (M->getMemberDecl()->getType()->isReferenceType())
3354      return NULL;
3355
3356    return EvalVal(M->getBase(), refVars, ParentDecl);
3357  }
3358
3359  case Stmt::MaterializeTemporaryExprClass:
3360    if (Expr *Result = EvalVal(
3361                          cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
3362                               refVars, ParentDecl))
3363      return Result;
3364
3365    return E;
3366
3367  default:
3368    // Check that we don't return or take the address of a reference to a
3369    // temporary. This is only useful in C++.
3370    if (!E->isTypeDependent() && E->isRValue())
3371      return E;
3372
3373    // Everything else: we simply don't reason about them.
3374    return NULL;
3375  }
3376} while (true);
3377}
3378
3379//===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
3380
3381/// Check for comparisons of floating point operands using != and ==.
3382/// Issue a warning if these are no self-comparisons, as they are not likely
3383/// to do what the programmer intended.
3384void Sema::CheckFloatComparison(SourceLocation Loc, Expr* LHS, Expr *RHS) {
3385  bool EmitWarning = true;
3386
3387  Expr* LeftExprSansParen = LHS->IgnoreParenImpCasts();
3388  Expr* RightExprSansParen = RHS->IgnoreParenImpCasts();
3389
3390  // Special case: check for x == x (which is OK).
3391  // Do not emit warnings for such cases.
3392  if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
3393    if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
3394      if (DRL->getDecl() == DRR->getDecl())
3395        EmitWarning = false;
3396
3397
3398  // Special case: check for comparisons against literals that can be exactly
3399  //  represented by APFloat.  In such cases, do not emit a warning.  This
3400  //  is a heuristic: often comparison against such literals are used to
3401  //  detect if a value in a variable has not changed.  This clearly can
3402  //  lead to false negatives.
3403  if (EmitWarning) {
3404    if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
3405      if (FLL->isExact())
3406        EmitWarning = false;
3407    } else
3408      if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen)){
3409        if (FLR->isExact())
3410          EmitWarning = false;
3411    }
3412  }
3413
3414  // Check for comparisons with builtin types.
3415  if (EmitWarning)
3416    if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
3417      if (CL->isBuiltinCall())
3418        EmitWarning = false;
3419
3420  if (EmitWarning)
3421    if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
3422      if (CR->isBuiltinCall())
3423        EmitWarning = false;
3424
3425  // Emit the diagnostic.
3426  if (EmitWarning)
3427    Diag(Loc, diag::warn_floatingpoint_eq)
3428      << LHS->getSourceRange() << RHS->getSourceRange();
3429}
3430
3431//===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
3432//===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
3433
3434namespace {
3435
3436/// Structure recording the 'active' range of an integer-valued
3437/// expression.
3438struct IntRange {
3439  /// The number of bits active in the int.
3440  unsigned Width;
3441
3442  /// True if the int is known not to have negative values.
3443  bool NonNegative;
3444
3445  IntRange(unsigned Width, bool NonNegative)
3446    : Width(Width), NonNegative(NonNegative)
3447  {}
3448
3449  /// Returns the range of the bool type.
3450  static IntRange forBoolType() {
3451    return IntRange(1, true);
3452  }
3453
3454  /// Returns the range of an opaque value of the given integral type.
3455  static IntRange forValueOfType(ASTContext &C, QualType T) {
3456    return forValueOfCanonicalType(C,
3457                          T->getCanonicalTypeInternal().getTypePtr());
3458  }
3459
3460  /// Returns the range of an opaque value of a canonical integral type.
3461  static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) {
3462    assert(T->isCanonicalUnqualified());
3463
3464    if (const VectorType *VT = dyn_cast<VectorType>(T))
3465      T = VT->getElementType().getTypePtr();
3466    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
3467      T = CT->getElementType().getTypePtr();
3468
3469    // For enum types, use the known bit width of the enumerators.
3470    if (const EnumType *ET = dyn_cast<EnumType>(T)) {
3471      EnumDecl *Enum = ET->getDecl();
3472      if (!Enum->isCompleteDefinition())
3473        return IntRange(C.getIntWidth(QualType(T, 0)), false);
3474
3475      unsigned NumPositive = Enum->getNumPositiveBits();
3476      unsigned NumNegative = Enum->getNumNegativeBits();
3477
3478      return IntRange(std::max(NumPositive, NumNegative), NumNegative == 0);
3479    }
3480
3481    const BuiltinType *BT = cast<BuiltinType>(T);
3482    assert(BT->isInteger());
3483
3484    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
3485  }
3486
3487  /// Returns the "target" range of a canonical integral type, i.e.
3488  /// the range of values expressible in the type.
3489  ///
3490  /// This matches forValueOfCanonicalType except that enums have the
3491  /// full range of their type, not the range of their enumerators.
3492  static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) {
3493    assert(T->isCanonicalUnqualified());
3494
3495    if (const VectorType *VT = dyn_cast<VectorType>(T))
3496      T = VT->getElementType().getTypePtr();
3497    if (const ComplexType *CT = dyn_cast<ComplexType>(T))
3498      T = CT->getElementType().getTypePtr();
3499    if (const EnumType *ET = dyn_cast<EnumType>(T))
3500      T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr();
3501
3502    const BuiltinType *BT = cast<BuiltinType>(T);
3503    assert(BT->isInteger());
3504
3505    return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
3506  }
3507
3508  /// Returns the supremum of two ranges: i.e. their conservative merge.
3509  static IntRange join(IntRange L, IntRange R) {
3510    return IntRange(std::max(L.Width, R.Width),
3511                    L.NonNegative && R.NonNegative);
3512  }
3513
3514  /// Returns the infinum of two ranges: i.e. their aggressive merge.
3515  static IntRange meet(IntRange L, IntRange R) {
3516    return IntRange(std::min(L.Width, R.Width),
3517                    L.NonNegative || R.NonNegative);
3518  }
3519};
3520
3521static IntRange GetValueRange(ASTContext &C, llvm::APSInt &value,
3522                              unsigned MaxWidth) {
3523  if (value.isSigned() && value.isNegative())
3524    return IntRange(value.getMinSignedBits(), false);
3525
3526  if (value.getBitWidth() > MaxWidth)
3527    value = value.trunc(MaxWidth);
3528
3529  // isNonNegative() just checks the sign bit without considering
3530  // signedness.
3531  return IntRange(value.getActiveBits(), true);
3532}
3533
3534static IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
3535                              unsigned MaxWidth) {
3536  if (result.isInt())
3537    return GetValueRange(C, result.getInt(), MaxWidth);
3538
3539  if (result.isVector()) {
3540    IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
3541    for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
3542      IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
3543      R = IntRange::join(R, El);
3544    }
3545    return R;
3546  }
3547
3548  if (result.isComplexInt()) {
3549    IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
3550    IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
3551    return IntRange::join(R, I);
3552  }
3553
3554  // This can happen with lossless casts to intptr_t of "based" lvalues.
3555  // Assume it might use arbitrary bits.
3556  // FIXME: The only reason we need to pass the type in here is to get
3557  // the sign right on this one case.  It would be nice if APValue
3558  // preserved this.
3559  assert(result.isLValue() || result.isAddrLabelDiff());
3560  return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
3561}
3562
3563/// Pseudo-evaluate the given integer expression, estimating the
3564/// range of values it might take.
3565///
3566/// \param MaxWidth - the width to which the value will be truncated
3567static IntRange GetExprRange(ASTContext &C, Expr *E, unsigned MaxWidth) {
3568  E = E->IgnoreParens();
3569
3570  // Try a full evaluation first.
3571  Expr::EvalResult result;
3572  if (E->EvaluateAsRValue(result, C))
3573    return GetValueRange(C, result.Val, E->getType(), MaxWidth);
3574
3575  // I think we only want to look through implicit casts here; if the
3576  // user has an explicit widening cast, we should treat the value as
3577  // being of the new, wider type.
3578  if (ImplicitCastExpr *CE = dyn_cast<ImplicitCastExpr>(E)) {
3579    if (CE->getCastKind() == CK_NoOp || CE->getCastKind() == CK_LValueToRValue)
3580      return GetExprRange(C, CE->getSubExpr(), MaxWidth);
3581
3582    IntRange OutputTypeRange = IntRange::forValueOfType(C, CE->getType());
3583
3584    bool isIntegerCast = (CE->getCastKind() == CK_IntegralCast);
3585
3586    // Assume that non-integer casts can span the full range of the type.
3587    if (!isIntegerCast)
3588      return OutputTypeRange;
3589
3590    IntRange SubRange
3591      = GetExprRange(C, CE->getSubExpr(),
3592                     std::min(MaxWidth, OutputTypeRange.Width));
3593
3594    // Bail out if the subexpr's range is as wide as the cast type.
3595    if (SubRange.Width >= OutputTypeRange.Width)
3596      return OutputTypeRange;
3597
3598    // Otherwise, we take the smaller width, and we're non-negative if
3599    // either the output type or the subexpr is.
3600    return IntRange(SubRange.Width,
3601                    SubRange.NonNegative || OutputTypeRange.NonNegative);
3602  }
3603
3604  if (ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
3605    // If we can fold the condition, just take that operand.
3606    bool CondResult;
3607    if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
3608      return GetExprRange(C, CondResult ? CO->getTrueExpr()
3609                                        : CO->getFalseExpr(),
3610                          MaxWidth);
3611
3612    // Otherwise, conservatively merge.
3613    IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
3614    IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
3615    return IntRange::join(L, R);
3616  }
3617
3618  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
3619    switch (BO->getOpcode()) {
3620
3621    // Boolean-valued operations are single-bit and positive.
3622    case BO_LAnd:
3623    case BO_LOr:
3624    case BO_LT:
3625    case BO_GT:
3626    case BO_LE:
3627    case BO_GE:
3628    case BO_EQ:
3629    case BO_NE:
3630      return IntRange::forBoolType();
3631
3632    // The type of the assignments is the type of the LHS, so the RHS
3633    // is not necessarily the same type.
3634    case BO_MulAssign:
3635    case BO_DivAssign:
3636    case BO_RemAssign:
3637    case BO_AddAssign:
3638    case BO_SubAssign:
3639    case BO_XorAssign:
3640    case BO_OrAssign:
3641      // TODO: bitfields?
3642      return IntRange::forValueOfType(C, E->getType());
3643
3644    // Simple assignments just pass through the RHS, which will have
3645    // been coerced to the LHS type.
3646    case BO_Assign:
3647      // TODO: bitfields?
3648      return GetExprRange(C, BO->getRHS(), MaxWidth);
3649
3650    // Operations with opaque sources are black-listed.
3651    case BO_PtrMemD:
3652    case BO_PtrMemI:
3653      return IntRange::forValueOfType(C, E->getType());
3654
3655    // Bitwise-and uses the *infinum* of the two source ranges.
3656    case BO_And:
3657    case BO_AndAssign:
3658      return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
3659                            GetExprRange(C, BO->getRHS(), MaxWidth));
3660
3661    // Left shift gets black-listed based on a judgement call.
3662    case BO_Shl:
3663      // ...except that we want to treat '1 << (blah)' as logically
3664      // positive.  It's an important idiom.
3665      if (IntegerLiteral *I
3666            = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) {
3667        if (I->getValue() == 1) {
3668          IntRange R = IntRange::forValueOfType(C, E->getType());
3669          return IntRange(R.Width, /*NonNegative*/ true);
3670        }
3671      }
3672      // fallthrough
3673
3674    case BO_ShlAssign:
3675      return IntRange::forValueOfType(C, E->getType());
3676
3677    // Right shift by a constant can narrow its left argument.
3678    case BO_Shr:
3679    case BO_ShrAssign: {
3680      IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
3681
3682      // If the shift amount is a positive constant, drop the width by
3683      // that much.
3684      llvm::APSInt shift;
3685      if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
3686          shift.isNonNegative()) {
3687        unsigned zext = shift.getZExtValue();
3688        if (zext >= L.Width)
3689          L.Width = (L.NonNegative ? 0 : 1);
3690        else
3691          L.Width -= zext;
3692      }
3693
3694      return L;
3695    }
3696
3697    // Comma acts as its right operand.
3698    case BO_Comma:
3699      return GetExprRange(C, BO->getRHS(), MaxWidth);
3700
3701    // Black-list pointer subtractions.
3702    case BO_Sub:
3703      if (BO->getLHS()->getType()->isPointerType())
3704        return IntRange::forValueOfType(C, E->getType());
3705      break;
3706
3707    // The width of a division result is mostly determined by the size
3708    // of the LHS.
3709    case BO_Div: {
3710      // Don't 'pre-truncate' the operands.
3711      unsigned opWidth = C.getIntWidth(E->getType());
3712      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
3713
3714      // If the divisor is constant, use that.
3715      llvm::APSInt divisor;
3716      if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) {
3717        unsigned log2 = divisor.logBase2(); // floor(log_2(divisor))
3718        if (log2 >= L.Width)
3719          L.Width = (L.NonNegative ? 0 : 1);
3720        else
3721          L.Width = std::min(L.Width - log2, MaxWidth);
3722        return L;
3723      }
3724
3725      // Otherwise, just use the LHS's width.
3726      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
3727      return IntRange(L.Width, L.NonNegative && R.NonNegative);
3728    }
3729
3730    // The result of a remainder can't be larger than the result of
3731    // either side.
3732    case BO_Rem: {
3733      // Don't 'pre-truncate' the operands.
3734      unsigned opWidth = C.getIntWidth(E->getType());
3735      IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
3736      IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
3737
3738      IntRange meet = IntRange::meet(L, R);
3739      meet.Width = std::min(meet.Width, MaxWidth);
3740      return meet;
3741    }
3742
3743    // The default behavior is okay for these.
3744    case BO_Mul:
3745    case BO_Add:
3746    case BO_Xor:
3747    case BO_Or:
3748      break;
3749    }
3750
3751    // The default case is to treat the operation as if it were closed
3752    // on the narrowest type that encompasses both operands.
3753    IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
3754    IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
3755    return IntRange::join(L, R);
3756  }
3757
3758  if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
3759    switch (UO->getOpcode()) {
3760    // Boolean-valued operations are white-listed.
3761    case UO_LNot:
3762      return IntRange::forBoolType();
3763
3764    // Operations with opaque sources are black-listed.
3765    case UO_Deref:
3766    case UO_AddrOf: // should be impossible
3767      return IntRange::forValueOfType(C, E->getType());
3768
3769    default:
3770      return GetExprRange(C, UO->getSubExpr(), MaxWidth);
3771    }
3772  }
3773
3774  if (dyn_cast<OffsetOfExpr>(E)) {
3775    IntRange::forValueOfType(C, E->getType());
3776  }
3777
3778  if (FieldDecl *BitField = E->getBitField())
3779    return IntRange(BitField->getBitWidthValue(C),
3780                    BitField->getType()->isUnsignedIntegerOrEnumerationType());
3781
3782  return IntRange::forValueOfType(C, E->getType());
3783}
3784
3785static IntRange GetExprRange(ASTContext &C, Expr *E) {
3786  return GetExprRange(C, E, C.getIntWidth(E->getType()));
3787}
3788
3789/// Checks whether the given value, which currently has the given
3790/// source semantics, has the same value when coerced through the
3791/// target semantics.
3792static bool IsSameFloatAfterCast(const llvm::APFloat &value,
3793                                 const llvm::fltSemantics &Src,
3794                                 const llvm::fltSemantics &Tgt) {
3795  llvm::APFloat truncated = value;
3796
3797  bool ignored;
3798  truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
3799  truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
3800
3801  return truncated.bitwiseIsEqual(value);
3802}
3803
3804/// Checks whether the given value, which currently has the given
3805/// source semantics, has the same value when coerced through the
3806/// target semantics.
3807///
3808/// The value might be a vector of floats (or a complex number).
3809static bool IsSameFloatAfterCast(const APValue &value,
3810                                 const llvm::fltSemantics &Src,
3811                                 const llvm::fltSemantics &Tgt) {
3812  if (value.isFloat())
3813    return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
3814
3815  if (value.isVector()) {
3816    for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
3817      if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
3818        return false;
3819    return true;
3820  }
3821
3822  assert(value.isComplexFloat());
3823  return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
3824          IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
3825}
3826
3827static void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
3828
3829static bool IsZero(Sema &S, Expr *E) {
3830  // Suppress cases where we are comparing against an enum constant.
3831  if (const DeclRefExpr *DR =
3832      dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
3833    if (isa<EnumConstantDecl>(DR->getDecl()))
3834      return false;
3835
3836  // Suppress cases where the '0' value is expanded from a macro.
3837  if (E->getLocStart().isMacroID())
3838    return false;
3839
3840  llvm::APSInt Value;
3841  return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
3842}
3843
3844static bool HasEnumType(Expr *E) {
3845  // Strip off implicit integral promotions.
3846  while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
3847    if (ICE->getCastKind() != CK_IntegralCast &&
3848        ICE->getCastKind() != CK_NoOp)
3849      break;
3850    E = ICE->getSubExpr();
3851  }
3852
3853  return E->getType()->isEnumeralType();
3854}
3855
3856static void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
3857  BinaryOperatorKind op = E->getOpcode();
3858  if (E->isValueDependent())
3859    return;
3860
3861  if (op == BO_LT && IsZero(S, E->getRHS())) {
3862    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
3863      << "< 0" << "false" << HasEnumType(E->getLHS())
3864      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3865  } else if (op == BO_GE && IsZero(S, E->getRHS())) {
3866    S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
3867      << ">= 0" << "true" << HasEnumType(E->getLHS())
3868      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3869  } else if (op == BO_GT && IsZero(S, E->getLHS())) {
3870    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
3871      << "0 >" << "false" << HasEnumType(E->getRHS())
3872      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3873  } else if (op == BO_LE && IsZero(S, E->getLHS())) {
3874    S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
3875      << "0 <=" << "true" << HasEnumType(E->getRHS())
3876      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
3877  }
3878}
3879
3880/// Analyze the operands of the given comparison.  Implements the
3881/// fallback case from AnalyzeComparison.
3882static void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
3883  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
3884  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
3885}
3886
3887/// \brief Implements -Wsign-compare.
3888///
3889/// \param E the binary operator to check for warnings
3890static void AnalyzeComparison(Sema &S, BinaryOperator *E) {
3891  // The type the comparison is being performed in.
3892  QualType T = E->getLHS()->getType();
3893  assert(S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType())
3894         && "comparison with mismatched types");
3895
3896  // We don't do anything special if this isn't an unsigned integral
3897  // comparison:  we're only interested in integral comparisons, and
3898  // signed comparisons only happen in cases we don't care to warn about.
3899  //
3900  // We also don't care about value-dependent expressions or expressions
3901  // whose result is a constant.
3902  if (!T->hasUnsignedIntegerRepresentation()
3903      || E->isValueDependent() || E->isIntegerConstantExpr(S.Context))
3904    return AnalyzeImpConvsInComparison(S, E);
3905
3906  Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
3907  Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
3908
3909  // Check to see if one of the (unmodified) operands is of different
3910  // signedness.
3911  Expr *signedOperand, *unsignedOperand;
3912  if (LHS->getType()->hasSignedIntegerRepresentation()) {
3913    assert(!RHS->getType()->hasSignedIntegerRepresentation() &&
3914           "unsigned comparison between two signed integer expressions?");
3915    signedOperand = LHS;
3916    unsignedOperand = RHS;
3917  } else if (RHS->getType()->hasSignedIntegerRepresentation()) {
3918    signedOperand = RHS;
3919    unsignedOperand = LHS;
3920  } else {
3921    CheckTrivialUnsignedComparison(S, E);
3922    return AnalyzeImpConvsInComparison(S, E);
3923  }
3924
3925  // Otherwise, calculate the effective range of the signed operand.
3926  IntRange signedRange = GetExprRange(S.Context, signedOperand);
3927
3928  // Go ahead and analyze implicit conversions in the operands.  Note
3929  // that we skip the implicit conversions on both sides.
3930  AnalyzeImplicitConversions(S, LHS, E->getOperatorLoc());
3931  AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc());
3932
3933  // If the signed range is non-negative, -Wsign-compare won't fire,
3934  // but we should still check for comparisons which are always true
3935  // or false.
3936  if (signedRange.NonNegative)
3937    return CheckTrivialUnsignedComparison(S, E);
3938
3939  // For (in)equality comparisons, if the unsigned operand is a
3940  // constant which cannot collide with a overflowed signed operand,
3941  // then reinterpreting the signed operand as unsigned will not
3942  // change the result of the comparison.
3943  if (E->isEqualityOp()) {
3944    unsigned comparisonWidth = S.Context.getIntWidth(T);
3945    IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand);
3946
3947    // We should never be unable to prove that the unsigned operand is
3948    // non-negative.
3949    assert(unsignedRange.NonNegative && "unsigned range includes negative?");
3950
3951    if (unsignedRange.Width < comparisonWidth)
3952      return;
3953  }
3954
3955  S.Diag(E->getOperatorLoc(), diag::warn_mixed_sign_comparison)
3956    << LHS->getType() << RHS->getType()
3957    << LHS->getSourceRange() << RHS->getSourceRange();
3958}
3959
3960/// Analyzes an attempt to assign the given value to a bitfield.
3961///
3962/// Returns true if there was something fishy about the attempt.
3963static bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
3964                                      SourceLocation InitLoc) {
3965  assert(Bitfield->isBitField());
3966  if (Bitfield->isInvalidDecl())
3967    return false;
3968
3969  // White-list bool bitfields.
3970  if (Bitfield->getType()->isBooleanType())
3971    return false;
3972
3973  // Ignore value- or type-dependent expressions.
3974  if (Bitfield->getBitWidth()->isValueDependent() ||
3975      Bitfield->getBitWidth()->isTypeDependent() ||
3976      Init->isValueDependent() ||
3977      Init->isTypeDependent())
3978    return false;
3979
3980  Expr *OriginalInit = Init->IgnoreParenImpCasts();
3981
3982  llvm::APSInt Value;
3983  if (!OriginalInit->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects))
3984    return false;
3985
3986  unsigned OriginalWidth = Value.getBitWidth();
3987  unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
3988
3989  if (OriginalWidth <= FieldWidth)
3990    return false;
3991
3992  // Compute the value which the bitfield will contain.
3993  llvm::APSInt TruncatedValue = Value.trunc(FieldWidth);
3994  TruncatedValue.setIsSigned(Bitfield->getType()->isSignedIntegerType());
3995
3996  // Check whether the stored value is equal to the original value.
3997  TruncatedValue = TruncatedValue.extend(OriginalWidth);
3998  if (Value == TruncatedValue)
3999    return false;
4000
4001  // Special-case bitfields of width 1: booleans are naturally 0/1, and
4002  // therefore don't strictly fit into a signed bitfield of width 1.
4003  if (FieldWidth == 1 && Value == 1)
4004    return false;
4005
4006  std::string PrettyValue = Value.toString(10);
4007  std::string PrettyTrunc = TruncatedValue.toString(10);
4008
4009  S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
4010    << PrettyValue << PrettyTrunc << OriginalInit->getType()
4011    << Init->getSourceRange();
4012
4013  return true;
4014}
4015
4016/// Analyze the given simple or compound assignment for warning-worthy
4017/// operations.
4018static void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
4019  // Just recurse on the LHS.
4020  AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
4021
4022  // We want to recurse on the RHS as normal unless we're assigning to
4023  // a bitfield.
4024  if (FieldDecl *Bitfield = E->getLHS()->getBitField()) {
4025    if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
4026                                  E->getOperatorLoc())) {
4027      // Recurse, ignoring any implicit conversions on the RHS.
4028      return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
4029                                        E->getOperatorLoc());
4030    }
4031  }
4032
4033  AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
4034}
4035
4036/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
4037static void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T,
4038                            SourceLocation CContext, unsigned diag,
4039                            bool pruneControlFlow = false) {
4040  if (pruneControlFlow) {
4041    S.DiagRuntimeBehavior(E->getExprLoc(), E,
4042                          S.PDiag(diag)
4043                            << SourceType << T << E->getSourceRange()
4044                            << SourceRange(CContext));
4045    return;
4046  }
4047  S.Diag(E->getExprLoc(), diag)
4048    << SourceType << T << E->getSourceRange() << SourceRange(CContext);
4049}
4050
4051/// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
4052static void DiagnoseImpCast(Sema &S, Expr *E, QualType T,
4053                            SourceLocation CContext, unsigned diag,
4054                            bool pruneControlFlow = false) {
4055  DiagnoseImpCast(S, E, E->getType(), T, CContext, diag, pruneControlFlow);
4056}
4057
4058/// Diagnose an implicit cast from a literal expression. Does not warn when the
4059/// cast wouldn't lose information.
4060void DiagnoseFloatingLiteralImpCast(Sema &S, FloatingLiteral *FL, QualType T,
4061                                    SourceLocation CContext) {
4062  // Try to convert the literal exactly to an integer. If we can, don't warn.
4063  bool isExact = false;
4064  const llvm::APFloat &Value = FL->getValue();
4065  llvm::APSInt IntegerValue(S.Context.getIntWidth(T),
4066                            T->hasUnsignedIntegerRepresentation());
4067  if (Value.convertToInteger(IntegerValue,
4068                             llvm::APFloat::rmTowardZero, &isExact)
4069      == llvm::APFloat::opOK && isExact)
4070    return;
4071
4072  S.Diag(FL->getExprLoc(), diag::warn_impcast_literal_float_to_integer)
4073    << FL->getType() << T << FL->getSourceRange() << SourceRange(CContext);
4074}
4075
4076std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) {
4077  if (!Range.Width) return "0";
4078
4079  llvm::APSInt ValueInRange = Value;
4080  ValueInRange.setIsSigned(!Range.NonNegative);
4081  ValueInRange = ValueInRange.trunc(Range.Width);
4082  return ValueInRange.toString(10);
4083}
4084
4085void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
4086                             SourceLocation CC, bool *ICContext = 0) {
4087  if (E->isTypeDependent() || E->isValueDependent()) return;
4088
4089  const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
4090  const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
4091  if (Source == Target) return;
4092  if (Target->isDependentType()) return;
4093
4094  // If the conversion context location is invalid don't complain. We also
4095  // don't want to emit a warning if the issue occurs from the expansion of
4096  // a system macro. The problem is that 'getSpellingLoc()' is slow, so we
4097  // delay this check as long as possible. Once we detect we are in that
4098  // scenario, we just return.
4099  if (CC.isInvalid())
4100    return;
4101
4102  // Diagnose implicit casts to bool.
4103  if (Target->isSpecificBuiltinType(BuiltinType::Bool)) {
4104    if (isa<StringLiteral>(E))
4105      // Warn on string literal to bool.  Checks for string literals in logical
4106      // expressions, for instances, assert(0 && "error here"), is prevented
4107      // by a check in AnalyzeImplicitConversions().
4108      return DiagnoseImpCast(S, E, T, CC,
4109                             diag::warn_impcast_string_literal_to_bool);
4110    if (Source->isFunctionType()) {
4111      // Warn on function to bool. Checks free functions and static member
4112      // functions. Weakly imported functions are excluded from the check,
4113      // since it's common to test their value to check whether the linker
4114      // found a definition for them.
4115      ValueDecl *D = 0;
4116      if (DeclRefExpr* R = dyn_cast<DeclRefExpr>(E)) {
4117        D = R->getDecl();
4118      } else if (MemberExpr *M = dyn_cast<MemberExpr>(E)) {
4119        D = M->getMemberDecl();
4120      }
4121
4122      if (D && !D->isWeak()) {
4123        if (FunctionDecl* F = dyn_cast<FunctionDecl>(D)) {
4124          S.Diag(E->getExprLoc(), diag::warn_impcast_function_to_bool)
4125            << F << E->getSourceRange() << SourceRange(CC);
4126          S.Diag(E->getExprLoc(), diag::note_function_to_bool_silence)
4127            << FixItHint::CreateInsertion(E->getExprLoc(), "&");
4128          QualType ReturnType;
4129          UnresolvedSet<4> NonTemplateOverloads;
4130          S.isExprCallable(*E, ReturnType, NonTemplateOverloads);
4131          if (!ReturnType.isNull()
4132              && ReturnType->isSpecificBuiltinType(BuiltinType::Bool))
4133            S.Diag(E->getExprLoc(), diag::note_function_to_bool_call)
4134              << FixItHint::CreateInsertion(
4135                 S.getPreprocessor().getLocForEndOfToken(E->getLocEnd()), "()");
4136          return;
4137        }
4138      }
4139    }
4140    return; // Other casts to bool are not checked.
4141  }
4142
4143  // Strip vector types.
4144  if (isa<VectorType>(Source)) {
4145    if (!isa<VectorType>(Target)) {
4146      if (S.SourceMgr.isInSystemMacro(CC))
4147        return;
4148      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar);
4149    }
4150
4151    // If the vector cast is cast between two vectors of the same size, it is
4152    // a bitcast, not a conversion.
4153    if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target))
4154      return;
4155
4156    Source = cast<VectorType>(Source)->getElementType().getTypePtr();
4157    Target = cast<VectorType>(Target)->getElementType().getTypePtr();
4158  }
4159
4160  // Strip complex types.
4161  if (isa<ComplexType>(Source)) {
4162    if (!isa<ComplexType>(Target)) {
4163      if (S.SourceMgr.isInSystemMacro(CC))
4164        return;
4165
4166      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar);
4167    }
4168
4169    Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
4170    Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
4171  }
4172
4173  const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
4174  const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
4175
4176  // If the source is floating point...
4177  if (SourceBT && SourceBT->isFloatingPoint()) {
4178    // ...and the target is floating point...
4179    if (TargetBT && TargetBT->isFloatingPoint()) {
4180      // ...then warn if we're dropping FP rank.
4181
4182      // Builtin FP kinds are ordered by increasing FP rank.
4183      if (SourceBT->getKind() > TargetBT->getKind()) {
4184        // Don't warn about float constants that are precisely
4185        // representable in the target type.
4186        Expr::EvalResult result;
4187        if (E->EvaluateAsRValue(result, S.Context)) {
4188          // Value might be a float, a float vector, or a float complex.
4189          if (IsSameFloatAfterCast(result.Val,
4190                   S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
4191                   S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
4192            return;
4193        }
4194
4195        if (S.SourceMgr.isInSystemMacro(CC))
4196          return;
4197
4198        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision);
4199      }
4200      return;
4201    }
4202
4203    // If the target is integral, always warn.
4204    if ((TargetBT && TargetBT->isInteger())) {
4205      if (S.SourceMgr.isInSystemMacro(CC))
4206        return;
4207
4208      Expr *InnerE = E->IgnoreParenImpCasts();
4209      // We also want to warn on, e.g., "int i = -1.234"
4210      if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE))
4211        if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus)
4212          InnerE = UOp->getSubExpr()->IgnoreParenImpCasts();
4213
4214      if (FloatingLiteral *FL = dyn_cast<FloatingLiteral>(InnerE)) {
4215        DiagnoseFloatingLiteralImpCast(S, FL, T, CC);
4216      } else {
4217        DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_integer);
4218      }
4219    }
4220
4221    return;
4222  }
4223
4224  if (!Source->isIntegerType() || !Target->isIntegerType())
4225    return;
4226
4227  if ((E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull)
4228           == Expr::NPCK_GNUNull) && Target->isIntegerType()) {
4229    SourceLocation Loc = E->getSourceRange().getBegin();
4230    if (Loc.isMacroID())
4231      Loc = S.SourceMgr.getImmediateExpansionRange(Loc).first;
4232    S.Diag(Loc, diag::warn_impcast_null_pointer_to_integer)
4233        << T << clang::SourceRange(CC)
4234        << FixItHint::CreateReplacement(Loc, S.getFixItZeroLiteralForType(T));
4235    return;
4236  }
4237
4238  IntRange SourceRange = GetExprRange(S.Context, E);
4239  IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
4240
4241  if (SourceRange.Width > TargetRange.Width) {
4242    // If the source is a constant, use a default-on diagnostic.
4243    // TODO: this should happen for bitfield stores, too.
4244    llvm::APSInt Value(32);
4245    if (E->isIntegerConstantExpr(Value, S.Context)) {
4246      if (S.SourceMgr.isInSystemMacro(CC))
4247        return;
4248
4249      std::string PrettySourceValue = Value.toString(10);
4250      std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
4251
4252      S.DiagRuntimeBehavior(E->getExprLoc(), E,
4253        S.PDiag(diag::warn_impcast_integer_precision_constant)
4254            << PrettySourceValue << PrettyTargetValue
4255            << E->getType() << T << E->getSourceRange()
4256            << clang::SourceRange(CC));
4257      return;
4258    }
4259
4260    // People want to build with -Wshorten-64-to-32 and not -Wconversion.
4261    if (S.SourceMgr.isInSystemMacro(CC))
4262      return;
4263
4264    if (TargetRange.Width == 32 && S.Context.getIntWidth(E->getType()) == 64)
4265      return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32,
4266                             /* pruneControlFlow */ true);
4267    return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
4268  }
4269
4270  if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
4271      (!TargetRange.NonNegative && SourceRange.NonNegative &&
4272       SourceRange.Width == TargetRange.Width)) {
4273
4274    if (S.SourceMgr.isInSystemMacro(CC))
4275      return;
4276
4277    unsigned DiagID = diag::warn_impcast_integer_sign;
4278
4279    // Traditionally, gcc has warned about this under -Wsign-compare.
4280    // We also want to warn about it in -Wconversion.
4281    // So if -Wconversion is off, use a completely identical diagnostic
4282    // in the sign-compare group.
4283    // The conditional-checking code will
4284    if (ICContext) {
4285      DiagID = diag::warn_impcast_integer_sign_conditional;
4286      *ICContext = true;
4287    }
4288
4289    return DiagnoseImpCast(S, E, T, CC, DiagID);
4290  }
4291
4292  // Diagnose conversions between different enumeration types.
4293  // In C, we pretend that the type of an EnumConstantDecl is its enumeration
4294  // type, to give us better diagnostics.
4295  QualType SourceType = E->getType();
4296  if (!S.getLangOpts().CPlusPlus) {
4297    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
4298      if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
4299        EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
4300        SourceType = S.Context.getTypeDeclType(Enum);
4301        Source = S.Context.getCanonicalType(SourceType).getTypePtr();
4302      }
4303  }
4304
4305  if (const EnumType *SourceEnum = Source->getAs<EnumType>())
4306    if (const EnumType *TargetEnum = Target->getAs<EnumType>())
4307      if ((SourceEnum->getDecl()->getIdentifier() ||
4308           SourceEnum->getDecl()->getTypedefNameForAnonDecl()) &&
4309          (TargetEnum->getDecl()->getIdentifier() ||
4310           TargetEnum->getDecl()->getTypedefNameForAnonDecl()) &&
4311          SourceEnum != TargetEnum) {
4312        if (S.SourceMgr.isInSystemMacro(CC))
4313          return;
4314
4315        return DiagnoseImpCast(S, E, SourceType, T, CC,
4316                               diag::warn_impcast_different_enum_types);
4317      }
4318
4319  return;
4320}
4321
4322void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T);
4323
4324void CheckConditionalOperand(Sema &S, Expr *E, QualType T,
4325                             SourceLocation CC, bool &ICContext) {
4326  E = E->IgnoreParenImpCasts();
4327
4328  if (isa<ConditionalOperator>(E))
4329    return CheckConditionalOperator(S, cast<ConditionalOperator>(E), T);
4330
4331  AnalyzeImplicitConversions(S, E, CC);
4332  if (E->getType() != T)
4333    return CheckImplicitConversion(S, E, T, CC, &ICContext);
4334  return;
4335}
4336
4337void CheckConditionalOperator(Sema &S, ConditionalOperator *E, QualType T) {
4338  SourceLocation CC = E->getQuestionLoc();
4339
4340  AnalyzeImplicitConversions(S, E->getCond(), CC);
4341
4342  bool Suspicious = false;
4343  CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
4344  CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
4345
4346  // If -Wconversion would have warned about either of the candidates
4347  // for a signedness conversion to the context type...
4348  if (!Suspicious) return;
4349
4350  // ...but it's currently ignored...
4351  if (S.Diags.getDiagnosticLevel(diag::warn_impcast_integer_sign_conditional,
4352                                 CC))
4353    return;
4354
4355  // ...then check whether it would have warned about either of the
4356  // candidates for a signedness conversion to the condition type.
4357  if (E->getType() == T) return;
4358
4359  Suspicious = false;
4360  CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(),
4361                          E->getType(), CC, &Suspicious);
4362  if (!Suspicious)
4363    CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(),
4364                            E->getType(), CC, &Suspicious);
4365}
4366
4367/// AnalyzeImplicitConversions - Find and report any interesting
4368/// implicit conversions in the given expression.  There are a couple
4369/// of competing diagnostics here, -Wconversion and -Wsign-compare.
4370void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) {
4371  QualType T = OrigE->getType();
4372  Expr *E = OrigE->IgnoreParenImpCasts();
4373
4374  if (E->isTypeDependent() || E->isValueDependent())
4375    return;
4376
4377  // For conditional operators, we analyze the arguments as if they
4378  // were being fed directly into the output.
4379  if (isa<ConditionalOperator>(E)) {
4380    ConditionalOperator *CO = cast<ConditionalOperator>(E);
4381    CheckConditionalOperator(S, CO, T);
4382    return;
4383  }
4384
4385  // Go ahead and check any implicit conversions we might have skipped.
4386  // The non-canonical typecheck is just an optimization;
4387  // CheckImplicitConversion will filter out dead implicit conversions.
4388  if (E->getType() != T)
4389    CheckImplicitConversion(S, E, T, CC);
4390
4391  // Now continue drilling into this expression.
4392
4393  // Skip past explicit casts.
4394  if (isa<ExplicitCastExpr>(E)) {
4395    E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts();
4396    return AnalyzeImplicitConversions(S, E, CC);
4397  }
4398
4399  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
4400    // Do a somewhat different check with comparison operators.
4401    if (BO->isComparisonOp())
4402      return AnalyzeComparison(S, BO);
4403
4404    // And with simple assignments.
4405    if (BO->getOpcode() == BO_Assign)
4406      return AnalyzeAssignment(S, BO);
4407  }
4408
4409  // These break the otherwise-useful invariant below.  Fortunately,
4410  // we don't really need to recurse into them, because any internal
4411  // expressions should have been analyzed already when they were
4412  // built into statements.
4413  if (isa<StmtExpr>(E)) return;
4414
4415  // Don't descend into unevaluated contexts.
4416  if (isa<UnaryExprOrTypeTraitExpr>(E)) return;
4417
4418  // Now just recurse over the expression's children.
4419  CC = E->getExprLoc();
4420  BinaryOperator *BO = dyn_cast<BinaryOperator>(E);
4421  bool IsLogicalOperator = BO && BO->isLogicalOp();
4422  for (Stmt::child_range I = E->children(); I; ++I) {
4423    Expr *ChildExpr = dyn_cast_or_null<Expr>(*I);
4424    if (!ChildExpr)
4425      continue;
4426
4427    if (IsLogicalOperator &&
4428        isa<StringLiteral>(ChildExpr->IgnoreParenImpCasts()))
4429      // Ignore checking string literals that are in logical operators.
4430      continue;
4431    AnalyzeImplicitConversions(S, ChildExpr, CC);
4432  }
4433}
4434
4435} // end anonymous namespace
4436
4437/// Diagnoses "dangerous" implicit conversions within the given
4438/// expression (which is a full expression).  Implements -Wconversion
4439/// and -Wsign-compare.
4440///
4441/// \param CC the "context" location of the implicit conversion, i.e.
4442///   the most location of the syntactic entity requiring the implicit
4443///   conversion
4444void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
4445  // Don't diagnose in unevaluated contexts.
4446  if (ExprEvalContexts.back().Context == Sema::Unevaluated)
4447    return;
4448
4449  // Don't diagnose for value- or type-dependent expressions.
4450  if (E->isTypeDependent() || E->isValueDependent())
4451    return;
4452
4453  // Check for array bounds violations in cases where the check isn't triggered
4454  // elsewhere for other Expr types (like BinaryOperators), e.g. when an
4455  // ArraySubscriptExpr is on the RHS of a variable initialization.
4456  CheckArrayAccess(E);
4457
4458  // This is not the right CC for (e.g.) a variable initialization.
4459  AnalyzeImplicitConversions(*this, E, CC);
4460}
4461
4462void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
4463                                       FieldDecl *BitField,
4464                                       Expr *Init) {
4465  (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
4466}
4467
4468/// CheckParmsForFunctionDef - Check that the parameters of the given
4469/// function are appropriate for the definition of a function. This
4470/// takes care of any checks that cannot be performed on the
4471/// declaration itself, e.g., that the types of each of the function
4472/// parameters are complete.
4473bool Sema::CheckParmsForFunctionDef(ParmVarDecl **P, ParmVarDecl **PEnd,
4474                                    bool CheckParameterNames) {
4475  bool HasInvalidParm = false;
4476  for (; P != PEnd; ++P) {
4477    ParmVarDecl *Param = *P;
4478
4479    // C99 6.7.5.3p4: the parameters in a parameter type list in a
4480    // function declarator that is part of a function definition of
4481    // that function shall not have incomplete type.
4482    //
4483    // This is also C++ [dcl.fct]p6.
4484    if (!Param->isInvalidDecl() &&
4485        RequireCompleteType(Param->getLocation(), Param->getType(),
4486                               diag::err_typecheck_decl_incomplete_type)) {
4487      Param->setInvalidDecl();
4488      HasInvalidParm = true;
4489    }
4490
4491    // C99 6.9.1p5: If the declarator includes a parameter type list, the
4492    // declaration of each parameter shall include an identifier.
4493    if (CheckParameterNames &&
4494        Param->getIdentifier() == 0 &&
4495        !Param->isImplicit() &&
4496        !getLangOpts().CPlusPlus)
4497      Diag(Param->getLocation(), diag::err_parameter_name_omitted);
4498
4499    // C99 6.7.5.3p12:
4500    //   If the function declarator is not part of a definition of that
4501    //   function, parameters may have incomplete type and may use the [*]
4502    //   notation in their sequences of declarator specifiers to specify
4503    //   variable length array types.
4504    QualType PType = Param->getOriginalType();
4505    if (const ArrayType *AT = Context.getAsArrayType(PType)) {
4506      if (AT->getSizeModifier() == ArrayType::Star) {
4507        // FIXME: This diagnosic should point the the '[*]' if source-location
4508        // information is added for it.
4509        Diag(Param->getLocation(), diag::err_array_star_in_function_definition);
4510      }
4511    }
4512  }
4513
4514  return HasInvalidParm;
4515}
4516
4517/// CheckCastAlign - Implements -Wcast-align, which warns when a
4518/// pointer cast increases the alignment requirements.
4519void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
4520  // This is actually a lot of work to potentially be doing on every
4521  // cast; don't do it if we're ignoring -Wcast_align (as is the default).
4522  if (getDiagnostics().getDiagnosticLevel(diag::warn_cast_align,
4523                                          TRange.getBegin())
4524        == DiagnosticsEngine::Ignored)
4525    return;
4526
4527  // Ignore dependent types.
4528  if (T->isDependentType() || Op->getType()->isDependentType())
4529    return;
4530
4531  // Require that the destination be a pointer type.
4532  const PointerType *DestPtr = T->getAs<PointerType>();
4533  if (!DestPtr) return;
4534
4535  // If the destination has alignment 1, we're done.
4536  QualType DestPointee = DestPtr->getPointeeType();
4537  if (DestPointee->isIncompleteType()) return;
4538  CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee);
4539  if (DestAlign.isOne()) return;
4540
4541  // Require that the source be a pointer type.
4542  const PointerType *SrcPtr = Op->getType()->getAs<PointerType>();
4543  if (!SrcPtr) return;
4544  QualType SrcPointee = SrcPtr->getPointeeType();
4545
4546  // Whitelist casts from cv void*.  We already implicitly
4547  // whitelisted casts to cv void*, since they have alignment 1.
4548  // Also whitelist casts involving incomplete types, which implicitly
4549  // includes 'void'.
4550  if (SrcPointee->isIncompleteType()) return;
4551
4552  CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee);
4553  if (SrcAlign >= DestAlign) return;
4554
4555  Diag(TRange.getBegin(), diag::warn_cast_align)
4556    << Op->getType() << T
4557    << static_cast<unsigned>(SrcAlign.getQuantity())
4558    << static_cast<unsigned>(DestAlign.getQuantity())
4559    << TRange << Op->getSourceRange();
4560}
4561
4562static const Type* getElementType(const Expr *BaseExpr) {
4563  const Type* EltType = BaseExpr->getType().getTypePtr();
4564  if (EltType->isAnyPointerType())
4565    return EltType->getPointeeType().getTypePtr();
4566  else if (EltType->isArrayType())
4567    return EltType->getBaseElementTypeUnsafe();
4568  return EltType;
4569}
4570
4571/// \brief Check whether this array fits the idiom of a size-one tail padded
4572/// array member of a struct.
4573///
4574/// We avoid emitting out-of-bounds access warnings for such arrays as they are
4575/// commonly used to emulate flexible arrays in C89 code.
4576static bool IsTailPaddedMemberArray(Sema &S, llvm::APInt Size,
4577                                    const NamedDecl *ND) {
4578  if (Size != 1 || !ND) return false;
4579
4580  const FieldDecl *FD = dyn_cast<FieldDecl>(ND);
4581  if (!FD) return false;
4582
4583  // Don't consider sizes resulting from macro expansions or template argument
4584  // substitution to form C89 tail-padded arrays.
4585  ConstantArrayTypeLoc TL =
4586    cast<ConstantArrayTypeLoc>(FD->getTypeSourceInfo()->getTypeLoc());
4587  const Expr *SizeExpr = dyn_cast<IntegerLiteral>(TL.getSizeExpr());
4588  if (!SizeExpr || SizeExpr->getExprLoc().isMacroID())
4589    return false;
4590
4591  const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext());
4592  if (!RD) return false;
4593  if (RD->isUnion()) return false;
4594  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
4595    if (!CRD->isStandardLayout()) return false;
4596  }
4597
4598  // See if this is the last field decl in the record.
4599  const Decl *D = FD;
4600  while ((D = D->getNextDeclInContext()))
4601    if (isa<FieldDecl>(D))
4602      return false;
4603  return true;
4604}
4605
4606void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
4607                            const ArraySubscriptExpr *ASE,
4608                            bool AllowOnePastEnd, bool IndexNegated) {
4609  IndexExpr = IndexExpr->IgnoreParenImpCasts();
4610  if (IndexExpr->isValueDependent())
4611    return;
4612
4613  const Type *EffectiveType = getElementType(BaseExpr);
4614  BaseExpr = BaseExpr->IgnoreParenCasts();
4615  const ConstantArrayType *ArrayTy =
4616    Context.getAsConstantArrayType(BaseExpr->getType());
4617  if (!ArrayTy)
4618    return;
4619
4620  llvm::APSInt index;
4621  if (!IndexExpr->EvaluateAsInt(index, Context))
4622    return;
4623  if (IndexNegated)
4624    index = -index;
4625
4626  const NamedDecl *ND = NULL;
4627  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
4628    ND = dyn_cast<NamedDecl>(DRE->getDecl());
4629  if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
4630    ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
4631
4632  if (index.isUnsigned() || !index.isNegative()) {
4633    llvm::APInt size = ArrayTy->getSize();
4634    if (!size.isStrictlyPositive())
4635      return;
4636
4637    const Type* BaseType = getElementType(BaseExpr);
4638    if (BaseType != EffectiveType) {
4639      // Make sure we're comparing apples to apples when comparing index to size
4640      uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType);
4641      uint64_t array_typesize = Context.getTypeSize(BaseType);
4642      // Handle ptrarith_typesize being zero, such as when casting to void*
4643      if (!ptrarith_typesize) ptrarith_typesize = 1;
4644      if (ptrarith_typesize != array_typesize) {
4645        // There's a cast to a different size type involved
4646        uint64_t ratio = array_typesize / ptrarith_typesize;
4647        // TODO: Be smarter about handling cases where array_typesize is not a
4648        // multiple of ptrarith_typesize
4649        if (ptrarith_typesize * ratio == array_typesize)
4650          size *= llvm::APInt(size.getBitWidth(), ratio);
4651      }
4652    }
4653
4654    if (size.getBitWidth() > index.getBitWidth())
4655      index = index.zext(size.getBitWidth());
4656    else if (size.getBitWidth() < index.getBitWidth())
4657      size = size.zext(index.getBitWidth());
4658
4659    // For array subscripting the index must be less than size, but for pointer
4660    // arithmetic also allow the index (offset) to be equal to size since
4661    // computing the next address after the end of the array is legal and
4662    // commonly done e.g. in C++ iterators and range-based for loops.
4663    if (AllowOnePastEnd ? index.ule(size) : index.ult(size))
4664      return;
4665
4666    // Also don't warn for arrays of size 1 which are members of some
4667    // structure. These are often used to approximate flexible arrays in C89
4668    // code.
4669    if (IsTailPaddedMemberArray(*this, size, ND))
4670      return;
4671
4672    // Suppress the warning if the subscript expression (as identified by the
4673    // ']' location) and the index expression are both from macro expansions
4674    // within a system header.
4675    if (ASE) {
4676      SourceLocation RBracketLoc = SourceMgr.getSpellingLoc(
4677          ASE->getRBracketLoc());
4678      if (SourceMgr.isInSystemHeader(RBracketLoc)) {
4679        SourceLocation IndexLoc = SourceMgr.getSpellingLoc(
4680            IndexExpr->getLocStart());
4681        if (SourceMgr.isFromSameFile(RBracketLoc, IndexLoc))
4682          return;
4683      }
4684    }
4685
4686    unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds;
4687    if (ASE)
4688      DiagID = diag::warn_array_index_exceeds_bounds;
4689
4690    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
4691                        PDiag(DiagID) << index.toString(10, true)
4692                          << size.toString(10, true)
4693                          << (unsigned)size.getLimitedValue(~0U)
4694                          << IndexExpr->getSourceRange());
4695  } else {
4696    unsigned DiagID = diag::warn_array_index_precedes_bounds;
4697    if (!ASE) {
4698      DiagID = diag::warn_ptr_arith_precedes_bounds;
4699      if (index.isNegative()) index = -index;
4700    }
4701
4702    DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
4703                        PDiag(DiagID) << index.toString(10, true)
4704                          << IndexExpr->getSourceRange());
4705  }
4706
4707  if (!ND) {
4708    // Try harder to find a NamedDecl to point at in the note.
4709    while (const ArraySubscriptExpr *ASE =
4710           dyn_cast<ArraySubscriptExpr>(BaseExpr))
4711      BaseExpr = ASE->getBase()->IgnoreParenCasts();
4712    if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
4713      ND = dyn_cast<NamedDecl>(DRE->getDecl());
4714    if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
4715      ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
4716  }
4717
4718  if (ND)
4719    DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
4720                        PDiag(diag::note_array_index_out_of_bounds)
4721                          << ND->getDeclName());
4722}
4723
4724void Sema::CheckArrayAccess(const Expr *expr) {
4725  int AllowOnePastEnd = 0;
4726  while (expr) {
4727    expr = expr->IgnoreParenImpCasts();
4728    switch (expr->getStmtClass()) {
4729      case Stmt::ArraySubscriptExprClass: {
4730        const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr);
4731        CheckArrayAccess(ASE->getBase(), ASE->getIdx(), ASE,
4732                         AllowOnePastEnd > 0);
4733        return;
4734      }
4735      case Stmt::UnaryOperatorClass: {
4736        // Only unwrap the * and & unary operators
4737        const UnaryOperator *UO = cast<UnaryOperator>(expr);
4738        expr = UO->getSubExpr();
4739        switch (UO->getOpcode()) {
4740          case UO_AddrOf:
4741            AllowOnePastEnd++;
4742            break;
4743          case UO_Deref:
4744            AllowOnePastEnd--;
4745            break;
4746          default:
4747            return;
4748        }
4749        break;
4750      }
4751      case Stmt::ConditionalOperatorClass: {
4752        const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
4753        if (const Expr *lhs = cond->getLHS())
4754          CheckArrayAccess(lhs);
4755        if (const Expr *rhs = cond->getRHS())
4756          CheckArrayAccess(rhs);
4757        return;
4758      }
4759      default:
4760        return;
4761    }
4762  }
4763}
4764
4765//===--- CHECK: Objective-C retain cycles ----------------------------------//
4766
4767namespace {
4768  struct RetainCycleOwner {
4769    RetainCycleOwner() : Variable(0), Indirect(false) {}
4770    VarDecl *Variable;
4771    SourceRange Range;
4772    SourceLocation Loc;
4773    bool Indirect;
4774
4775    void setLocsFrom(Expr *e) {
4776      Loc = e->getExprLoc();
4777      Range = e->getSourceRange();
4778    }
4779  };
4780}
4781
4782/// Consider whether capturing the given variable can possibly lead to
4783/// a retain cycle.
4784static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
4785  // In ARC, it's captured strongly iff the variable has __strong
4786  // lifetime.  In MRR, it's captured strongly if the variable is
4787  // __block and has an appropriate type.
4788  if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
4789    return false;
4790
4791  owner.Variable = var;
4792  owner.setLocsFrom(ref);
4793  return true;
4794}
4795
4796static bool findRetainCycleOwner(Sema &S, Expr *e, RetainCycleOwner &owner) {
4797  while (true) {
4798    e = e->IgnoreParens();
4799    if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
4800      switch (cast->getCastKind()) {
4801      case CK_BitCast:
4802      case CK_LValueBitCast:
4803      case CK_LValueToRValue:
4804      case CK_ARCReclaimReturnedObject:
4805        e = cast->getSubExpr();
4806        continue;
4807
4808      default:
4809        return false;
4810      }
4811    }
4812
4813    if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
4814      ObjCIvarDecl *ivar = ref->getDecl();
4815      if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
4816        return false;
4817
4818      // Try to find a retain cycle in the base.
4819      if (!findRetainCycleOwner(S, ref->getBase(), owner))
4820        return false;
4821
4822      if (ref->isFreeIvar()) owner.setLocsFrom(ref);
4823      owner.Indirect = true;
4824      return true;
4825    }
4826
4827    if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
4828      VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
4829      if (!var) return false;
4830      return considerVariable(var, ref, owner);
4831    }
4832
4833    if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
4834      if (member->isArrow()) return false;
4835
4836      // Don't count this as an indirect ownership.
4837      e = member->getBase();
4838      continue;
4839    }
4840
4841    if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
4842      // Only pay attention to pseudo-objects on property references.
4843      ObjCPropertyRefExpr *pre
4844        = dyn_cast<ObjCPropertyRefExpr>(pseudo->getSyntacticForm()
4845                                              ->IgnoreParens());
4846      if (!pre) return false;
4847      if (pre->isImplicitProperty()) return false;
4848      ObjCPropertyDecl *property = pre->getExplicitProperty();
4849      if (!property->isRetaining() &&
4850          !(property->getPropertyIvarDecl() &&
4851            property->getPropertyIvarDecl()->getType()
4852              .getObjCLifetime() == Qualifiers::OCL_Strong))
4853          return false;
4854
4855      owner.Indirect = true;
4856      if (pre->isSuperReceiver()) {
4857        owner.Variable = S.getCurMethodDecl()->getSelfDecl();
4858        if (!owner.Variable)
4859          return false;
4860        owner.Loc = pre->getLocation();
4861        owner.Range = pre->getSourceRange();
4862        return true;
4863      }
4864      e = const_cast<Expr*>(cast<OpaqueValueExpr>(pre->getBase())
4865                              ->getSourceExpr());
4866      continue;
4867    }
4868
4869    // Array ivars?
4870
4871    return false;
4872  }
4873}
4874
4875namespace {
4876  struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
4877    FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
4878      : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
4879        Variable(variable), Capturer(0) {}
4880
4881    VarDecl *Variable;
4882    Expr *Capturer;
4883
4884    void VisitDeclRefExpr(DeclRefExpr *ref) {
4885      if (ref->getDecl() == Variable && !Capturer)
4886        Capturer = ref;
4887    }
4888
4889    void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
4890      if (Capturer) return;
4891      Visit(ref->getBase());
4892      if (Capturer && ref->isFreeIvar())
4893        Capturer = ref;
4894    }
4895
4896    void VisitBlockExpr(BlockExpr *block) {
4897      // Look inside nested blocks
4898      if (block->getBlockDecl()->capturesVariable(Variable))
4899        Visit(block->getBlockDecl()->getBody());
4900    }
4901  };
4902}
4903
4904/// Check whether the given argument is a block which captures a
4905/// variable.
4906static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
4907  assert(owner.Variable && owner.Loc.isValid());
4908
4909  e = e->IgnoreParenCasts();
4910  BlockExpr *block = dyn_cast<BlockExpr>(e);
4911  if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
4912    return 0;
4913
4914  FindCaptureVisitor visitor(S.Context, owner.Variable);
4915  visitor.Visit(block->getBlockDecl()->getBody());
4916  return visitor.Capturer;
4917}
4918
4919static void diagnoseRetainCycle(Sema &S, Expr *capturer,
4920                                RetainCycleOwner &owner) {
4921  assert(capturer);
4922  assert(owner.Variable && owner.Loc.isValid());
4923
4924  S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
4925    << owner.Variable << capturer->getSourceRange();
4926  S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
4927    << owner.Indirect << owner.Range;
4928}
4929
4930/// Check for a keyword selector that starts with the word 'add' or
4931/// 'set'.
4932static bool isSetterLikeSelector(Selector sel) {
4933  if (sel.isUnarySelector()) return false;
4934
4935  StringRef str = sel.getNameForSlot(0);
4936  while (!str.empty() && str.front() == '_') str = str.substr(1);
4937  if (str.startswith("set"))
4938    str = str.substr(3);
4939  else if (str.startswith("add")) {
4940    // Specially whitelist 'addOperationWithBlock:'.
4941    if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock"))
4942      return false;
4943    str = str.substr(3);
4944  }
4945  else
4946    return false;
4947
4948  if (str.empty()) return true;
4949  return !islower(str.front());
4950}
4951
4952/// Check a message send to see if it's likely to cause a retain cycle.
4953void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
4954  // Only check instance methods whose selector looks like a setter.
4955  if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
4956    return;
4957
4958  // Try to find a variable that the receiver is strongly owned by.
4959  RetainCycleOwner owner;
4960  if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
4961    if (!findRetainCycleOwner(*this, msg->getInstanceReceiver(), owner))
4962      return;
4963  } else {
4964    assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
4965    owner.Variable = getCurMethodDecl()->getSelfDecl();
4966    owner.Loc = msg->getSuperLoc();
4967    owner.Range = msg->getSuperLoc();
4968  }
4969
4970  // Check whether the receiver is captured by any of the arguments.
4971  for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
4972    if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
4973      return diagnoseRetainCycle(*this, capturer, owner);
4974}
4975
4976/// Check a property assign to see if it's likely to cause a retain cycle.
4977void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
4978  RetainCycleOwner owner;
4979  if (!findRetainCycleOwner(*this, receiver, owner))
4980    return;
4981
4982  if (Expr *capturer = findCapturingExpr(*this, argument, owner))
4983    diagnoseRetainCycle(*this, capturer, owner);
4984}
4985
4986bool Sema::checkUnsafeAssigns(SourceLocation Loc,
4987                              QualType LHS, Expr *RHS) {
4988  Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
4989  if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
4990    return false;
4991  // strip off any implicit cast added to get to the one arc-specific
4992  while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
4993    if (cast->getCastKind() == CK_ARCConsumeObject) {
4994      Diag(Loc, diag::warn_arc_retained_assign)
4995        << (LT == Qualifiers::OCL_ExplicitNone)
4996        << RHS->getSourceRange();
4997      return true;
4998    }
4999    RHS = cast->getSubExpr();
5000  }
5001  return false;
5002}
5003
5004void Sema::checkUnsafeExprAssigns(SourceLocation Loc,
5005                              Expr *LHS, Expr *RHS) {
5006  QualType LHSType;
5007  // PropertyRef on LHS type need be directly obtained from
5008  // its declaration as it has a PsuedoType.
5009  ObjCPropertyRefExpr *PRE
5010    = dyn_cast<ObjCPropertyRefExpr>(LHS->IgnoreParens());
5011  if (PRE && !PRE->isImplicitProperty()) {
5012    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
5013    if (PD)
5014      LHSType = PD->getType();
5015  }
5016
5017  if (LHSType.isNull())
5018    LHSType = LHS->getType();
5019  if (checkUnsafeAssigns(Loc, LHSType, RHS))
5020    return;
5021  Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime();
5022  // FIXME. Check for other life times.
5023  if (LT != Qualifiers::OCL_None)
5024    return;
5025
5026  if (PRE) {
5027    if (PRE->isImplicitProperty())
5028      return;
5029    const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
5030    if (!PD)
5031      return;
5032
5033    unsigned Attributes = PD->getPropertyAttributes();
5034    if (Attributes & ObjCPropertyDecl::OBJC_PR_assign) {
5035      // when 'assign' attribute was not explicitly specified
5036      // by user, ignore it and rely on property type itself
5037      // for lifetime info.
5038      unsigned AsWrittenAttr = PD->getPropertyAttributesAsWritten();
5039      if (!(AsWrittenAttr & ObjCPropertyDecl::OBJC_PR_assign) &&
5040          LHSType->isObjCRetainableType())
5041        return;
5042
5043      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
5044        if (cast->getCastKind() == CK_ARCConsumeObject) {
5045          Diag(Loc, diag::warn_arc_retained_property_assign)
5046          << RHS->getSourceRange();
5047          return;
5048        }
5049        RHS = cast->getSubExpr();
5050      }
5051    }
5052  }
5053}
5054
5055//===--- CHECK: Empty statement body (-Wempty-body) ---------------------===//
5056
5057namespace {
5058bool ShouldDiagnoseEmptyStmtBody(const SourceManager &SourceMgr,
5059                                 SourceLocation StmtLoc,
5060                                 const NullStmt *Body) {
5061  // Do not warn if the body is a macro that expands to nothing, e.g:
5062  //
5063  // #define CALL(x)
5064  // if (condition)
5065  //   CALL(0);
5066  //
5067  if (Body->hasLeadingEmptyMacro())
5068    return false;
5069
5070  // Get line numbers of statement and body.
5071  bool StmtLineInvalid;
5072  unsigned StmtLine = SourceMgr.getSpellingLineNumber(StmtLoc,
5073                                                      &StmtLineInvalid);
5074  if (StmtLineInvalid)
5075    return false;
5076
5077  bool BodyLineInvalid;
5078  unsigned BodyLine = SourceMgr.getSpellingLineNumber(Body->getSemiLoc(),
5079                                                      &BodyLineInvalid);
5080  if (BodyLineInvalid)
5081    return false;
5082
5083  // Warn if null statement and body are on the same line.
5084  if (StmtLine != BodyLine)
5085    return false;
5086
5087  return true;
5088}
5089} // Unnamed namespace
5090
5091void Sema::DiagnoseEmptyStmtBody(SourceLocation StmtLoc,
5092                                 const Stmt *Body,
5093                                 unsigned DiagID) {
5094  // Since this is a syntactic check, don't emit diagnostic for template
5095  // instantiations, this just adds noise.
5096  if (CurrentInstantiationScope)
5097    return;
5098
5099  // The body should be a null statement.
5100  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
5101  if (!NBody)
5102    return;
5103
5104  // Do the usual checks.
5105  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
5106    return;
5107
5108  Diag(NBody->getSemiLoc(), DiagID);
5109  Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
5110}
5111
5112void Sema::DiagnoseEmptyLoopBody(const Stmt *S,
5113                                 const Stmt *PossibleBody) {
5114  assert(!CurrentInstantiationScope); // Ensured by caller
5115
5116  SourceLocation StmtLoc;
5117  const Stmt *Body;
5118  unsigned DiagID;
5119  if (const ForStmt *FS = dyn_cast<ForStmt>(S)) {
5120    StmtLoc = FS->getRParenLoc();
5121    Body = FS->getBody();
5122    DiagID = diag::warn_empty_for_body;
5123  } else if (const WhileStmt *WS = dyn_cast<WhileStmt>(S)) {
5124    StmtLoc = WS->getCond()->getSourceRange().getEnd();
5125    Body = WS->getBody();
5126    DiagID = diag::warn_empty_while_body;
5127  } else
5128    return; // Neither `for' nor `while'.
5129
5130  // The body should be a null statement.
5131  const NullStmt *NBody = dyn_cast<NullStmt>(Body);
5132  if (!NBody)
5133    return;
5134
5135  // Skip expensive checks if diagnostic is disabled.
5136  if (Diags.getDiagnosticLevel(DiagID, NBody->getSemiLoc()) ==
5137          DiagnosticsEngine::Ignored)
5138    return;
5139
5140  // Do the usual checks.
5141  if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
5142    return;
5143
5144  // `for(...);' and `while(...);' are popular idioms, so in order to keep
5145  // noise level low, emit diagnostics only if for/while is followed by a
5146  // CompoundStmt, e.g.:
5147  //    for (int i = 0; i < n; i++);
5148  //    {
5149  //      a(i);
5150  //    }
5151  // or if for/while is followed by a statement with more indentation
5152  // than for/while itself:
5153  //    for (int i = 0; i < n; i++);
5154  //      a(i);
5155  bool ProbableTypo = isa<CompoundStmt>(PossibleBody);
5156  if (!ProbableTypo) {
5157    bool BodyColInvalid;
5158    unsigned BodyCol = SourceMgr.getPresumedColumnNumber(
5159                             PossibleBody->getLocStart(),
5160                             &BodyColInvalid);
5161    if (BodyColInvalid)
5162      return;
5163
5164    bool StmtColInvalid;
5165    unsigned StmtCol = SourceMgr.getPresumedColumnNumber(
5166                             S->getLocStart(),
5167                             &StmtColInvalid);
5168    if (StmtColInvalid)
5169      return;
5170
5171    if (BodyCol > StmtCol)
5172      ProbableTypo = true;
5173  }
5174
5175  if (ProbableTypo) {
5176    Diag(NBody->getSemiLoc(), DiagID);
5177    Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
5178  }
5179}
5180