SemaStmt.cpp revision a7cf23a72b0846fc5aacf3f38bb8c8f9e76784cf 
1//===--- SemaStmt.cpp - Semantic Analysis for Statements ------------------===//
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 semantic analysis for statements.
11//
12//===----------------------------------------------------------------------===//
13
14#include "Sema.h"
15#include "clang/AST/APValue.h"
16#include "clang/AST/ASTContext.h"
17#include "clang/AST/DeclObjC.h"
18#include "clang/AST/ExprObjC.h"
19#include "clang/AST/StmtObjC.h"
20#include "clang/AST/StmtCXX.h"
21#include "clang/Basic/TargetInfo.h"
22#include "llvm/ADT/STLExtras.h"
23#include "llvm/ADT/SmallVector.h"
24using namespace clang;
25
26Sema::OwningStmtResult Sema::ActOnExprStmt(FullExprArg expr) {
27  Expr *E = expr->takeAs<Expr>();
28  assert(E && "ActOnExprStmt(): missing expression");
29  if (E->getType()->isObjCInterfaceType()) {
30    if (LangOpts.ObjCNonFragileABI)
31      Diag(E->getLocEnd(), diag::err_indirection_requires_nonfragile_object)
32             << E->getType();
33    else
34      Diag(E->getLocEnd(), diag::err_direct_interface_unsupported)
35             << E->getType();
36    return StmtError();
37  }
38  // C99 6.8.3p2: The expression in an expression statement is evaluated as a
39  // void expression for its side effects.  Conversion to void allows any
40  // operand, even incomplete types.
41
42  // Same thing in for stmt first clause (when expr) and third clause.
43  return Owned(static_cast<Stmt*>(E));
44}
45
46
47Sema::OwningStmtResult Sema::ActOnNullStmt(SourceLocation SemiLoc) {
48  return Owned(new (Context) NullStmt(SemiLoc));
49}
50
51Sema::OwningStmtResult Sema::ActOnDeclStmt(DeclGroupPtrTy dg,
52                                           SourceLocation StartLoc,
53                                           SourceLocation EndLoc) {
54  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
55
56  // If we have an invalid decl, just return an error.
57  if (DG.isNull()) return StmtError();
58
59  return Owned(new (Context) DeclStmt(DG, StartLoc, EndLoc));
60}
61
62void Sema::ActOnForEachDeclStmt(DeclGroupPtrTy dg) {
63  DeclGroupRef DG = dg.getAsVal<DeclGroupRef>();
64
65  // If we have an invalid decl, just return.
66  if (DG.isNull() || !DG.isSingleDecl()) return;
67  // suppress any potential 'unused variable' warning.
68  DG.getSingleDecl()->setUsed();
69}
70
71void Sema::DiagnoseUnusedExprResult(const Stmt *S) {
72  const Expr *E = dyn_cast_or_null<Expr>(S);
73  if (!E)
74    return;
75
76  // Ignore expressions that have void type.
77  if (E->getType()->isVoidType())
78    return;
79
80  SourceLocation Loc;
81  SourceRange R1, R2;
82  if (!E->isUnusedResultAWarning(Loc, R1, R2, Context))
83    return;
84
85  // Okay, we have an unused result.  Depending on what the base expression is,
86  // we might want to make a more specific diagnostic.  Check for one of these
87  // cases now.
88  unsigned DiagID = diag::warn_unused_expr;
89  E = E->IgnoreParens();
90  if (isa<ObjCImplicitSetterGetterRefExpr>(E))
91    DiagID = diag::warn_unused_property_expr;
92
93  if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
94    // If the callee has attribute pure, const, or warn_unused_result, warn with
95    // a more specific message to make it clear what is happening.
96    if (const FunctionDecl *FD = CE->getDirectCallee()) {
97      if (FD->getAttr<WarnUnusedResultAttr>()) {
98        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "warn_unused_result";
99        return;
100      }
101      if (FD->getAttr<PureAttr>()) {
102        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "pure";
103        return;
104      }
105      if (FD->getAttr<ConstAttr>()) {
106        Diag(Loc, diag::warn_unused_call) << R1 << R2 << "const";
107        return;
108      }
109    }
110  }
111
112  Diag(Loc, DiagID) << R1 << R2;
113}
114
115Action::OwningStmtResult
116Sema::ActOnCompoundStmt(SourceLocation L, SourceLocation R,
117                        MultiStmtArg elts, bool isStmtExpr) {
118  unsigned NumElts = elts.size();
119  Stmt **Elts = reinterpret_cast<Stmt**>(elts.release());
120  // If we're in C89 mode, check that we don't have any decls after stmts.  If
121  // so, emit an extension diagnostic.
122  if (!getLangOptions().C99 && !getLangOptions().CPlusPlus) {
123    // Note that __extension__ can be around a decl.
124    unsigned i = 0;
125    // Skip over all declarations.
126    for (; i != NumElts && isa<DeclStmt>(Elts[i]); ++i)
127      /*empty*/;
128
129    // We found the end of the list or a statement.  Scan for another declstmt.
130    for (; i != NumElts && !isa<DeclStmt>(Elts[i]); ++i)
131      /*empty*/;
132
133    if (i != NumElts) {
134      Decl *D = *cast<DeclStmt>(Elts[i])->decl_begin();
135      Diag(D->getLocation(), diag::ext_mixed_decls_code);
136    }
137  }
138  // Warn about unused expressions in statements.
139  for (unsigned i = 0; i != NumElts; ++i) {
140    // Ignore statements that are last in a statement expression.
141    if (isStmtExpr && i == NumElts - 1)
142      continue;
143
144    DiagnoseUnusedExprResult(Elts[i]);
145  }
146
147  return Owned(new (Context) CompoundStmt(Context, Elts, NumElts, L, R));
148}
149
150Action::OwningStmtResult
151Sema::ActOnCaseStmt(SourceLocation CaseLoc, ExprArg lhsval,
152                    SourceLocation DotDotDotLoc, ExprArg rhsval,
153                    SourceLocation ColonLoc) {
154  assert((lhsval.get() != 0) && "missing expression in case statement");
155
156  // C99 6.8.4.2p3: The expression shall be an integer constant.
157  // However, GCC allows any evaluatable integer expression.
158  Expr *LHSVal = static_cast<Expr*>(lhsval.get());
159  if (!LHSVal->isTypeDependent() && !LHSVal->isValueDependent() &&
160      VerifyIntegerConstantExpression(LHSVal))
161    return StmtError();
162
163  // GCC extension: The expression shall be an integer constant.
164
165  Expr *RHSVal = static_cast<Expr*>(rhsval.get());
166  if (RHSVal && !RHSVal->isTypeDependent() && !RHSVal->isValueDependent() &&
167      VerifyIntegerConstantExpression(RHSVal)) {
168    RHSVal = 0;  // Recover by just forgetting about it.
169    rhsval = 0;
170  }
171
172  if (getSwitchStack().empty()) {
173    Diag(CaseLoc, diag::err_case_not_in_switch);
174    return StmtError();
175  }
176
177  // Only now release the smart pointers.
178  lhsval.release();
179  rhsval.release();
180  CaseStmt *CS = new (Context) CaseStmt(LHSVal, RHSVal, CaseLoc, DotDotDotLoc,
181                                        ColonLoc);
182  getSwitchStack().back()->addSwitchCase(CS);
183  return Owned(CS);
184}
185
186/// ActOnCaseStmtBody - This installs a statement as the body of a case.
187void Sema::ActOnCaseStmtBody(StmtTy *caseStmt, StmtArg subStmt) {
188  CaseStmt *CS = static_cast<CaseStmt*>(caseStmt);
189  Stmt *SubStmt = subStmt.takeAs<Stmt>();
190  CS->setSubStmt(SubStmt);
191}
192
193Action::OwningStmtResult
194Sema::ActOnDefaultStmt(SourceLocation DefaultLoc, SourceLocation ColonLoc,
195                       StmtArg subStmt, Scope *CurScope) {
196  Stmt *SubStmt = subStmt.takeAs<Stmt>();
197
198  if (getSwitchStack().empty()) {
199    Diag(DefaultLoc, diag::err_default_not_in_switch);
200    return Owned(SubStmt);
201  }
202
203  DefaultStmt *DS = new (Context) DefaultStmt(DefaultLoc, ColonLoc, SubStmt);
204  getSwitchStack().back()->addSwitchCase(DS);
205  return Owned(DS);
206}
207
208Action::OwningStmtResult
209Sema::ActOnLabelStmt(SourceLocation IdentLoc, IdentifierInfo *II,
210                     SourceLocation ColonLoc, StmtArg subStmt) {
211  Stmt *SubStmt = subStmt.takeAs<Stmt>();
212  // Look up the record for this label identifier.
213  LabelStmt *&LabelDecl = getLabelMap()[II];
214
215  // If not forward referenced or defined already, just create a new LabelStmt.
216  if (LabelDecl == 0)
217    return Owned(LabelDecl = new (Context) LabelStmt(IdentLoc, II, SubStmt));
218
219  assert(LabelDecl->getID() == II && "Label mismatch!");
220
221  // Otherwise, this label was either forward reference or multiply defined.  If
222  // multiply defined, reject it now.
223  if (LabelDecl->getSubStmt()) {
224    Diag(IdentLoc, diag::err_redefinition_of_label) << LabelDecl->getID();
225    Diag(LabelDecl->getIdentLoc(), diag::note_previous_definition);
226    return Owned(SubStmt);
227  }
228
229  // Otherwise, this label was forward declared, and we just found its real
230  // definition.  Fill in the forward definition and return it.
231  LabelDecl->setIdentLoc(IdentLoc);
232  LabelDecl->setSubStmt(SubStmt);
233  return Owned(LabelDecl);
234}
235
236Action::OwningStmtResult
237Sema::ActOnIfStmt(SourceLocation IfLoc, FullExprArg CondVal,
238                  StmtArg ThenVal, SourceLocation ElseLoc,
239                  StmtArg ElseVal) {
240  OwningExprResult CondResult(CondVal.release());
241
242  Expr *condExpr = CondResult.takeAs<Expr>();
243
244  assert(condExpr && "ActOnIfStmt(): missing expression");
245  if (CheckBooleanCondition(condExpr, IfLoc)) {
246    CondResult = condExpr;
247    return StmtError();
248  }
249
250  Stmt *thenStmt = ThenVal.takeAs<Stmt>();
251  DiagnoseUnusedExprResult(thenStmt);
252
253  // Warn if the if block has a null body without an else value.
254  // this helps prevent bugs due to typos, such as
255  // if (condition);
256  //   do_stuff();
257  if (!ElseVal.get()) {
258    if (NullStmt* stmt = dyn_cast<NullStmt>(thenStmt))
259      Diag(stmt->getSemiLoc(), diag::warn_empty_if_body);
260  }
261
262  Stmt *elseStmt = ElseVal.takeAs<Stmt>();
263  DiagnoseUnusedExprResult(elseStmt);
264
265  CondResult.release();
266  return Owned(new (Context) IfStmt(IfLoc, condExpr, thenStmt,
267                                    ElseLoc, elseStmt));
268}
269
270Action::OwningStmtResult
271Sema::ActOnStartOfSwitchStmt(ExprArg cond) {
272  Expr *Cond = cond.takeAs<Expr>();
273
274  if (getLangOptions().CPlusPlus) {
275    // C++ 6.4.2.p2:
276    // The condition shall be of integral type, enumeration type, or of a class
277    // type for which a single conversion function to integral or enumeration
278    // type exists (12.3). If the condition is of class type, the condition is
279    // converted by calling that conversion function, and the result of the
280    // conversion is used in place of the original condition for the remainder
281    // of this section. Integral promotions are performed.
282    if (!Cond->isTypeDependent()) {
283      QualType Ty = Cond->getType();
284
285      // FIXME: Handle class types.
286
287      // If the type is wrong a diagnostic will be emitted later at
288      // ActOnFinishSwitchStmt.
289      if (Ty->isIntegralType() || Ty->isEnumeralType()) {
290        // Integral promotions are performed.
291        // FIXME: Integral promotions for C++ are not complete.
292        UsualUnaryConversions(Cond);
293      }
294    }
295  } else {
296    // C99 6.8.4.2p5 - Integer promotions are performed on the controlling expr.
297    UsualUnaryConversions(Cond);
298  }
299
300  SwitchStmt *SS = new (Context) SwitchStmt(Cond);
301  getSwitchStack().push_back(SS);
302  return Owned(SS);
303}
304
305/// ConvertIntegerToTypeWarnOnOverflow - Convert the specified APInt to have
306/// the specified width and sign.  If an overflow occurs, detect it and emit
307/// the specified diagnostic.
308void Sema::ConvertIntegerToTypeWarnOnOverflow(llvm::APSInt &Val,
309                                              unsigned NewWidth, bool NewSign,
310                                              SourceLocation Loc,
311                                              unsigned DiagID) {
312  // Perform a conversion to the promoted condition type if needed.
313  if (NewWidth > Val.getBitWidth()) {
314    // If this is an extension, just do it.
315    llvm::APSInt OldVal(Val);
316    Val.extend(NewWidth);
317
318    // If the input was signed and negative and the output is unsigned,
319    // warn.
320    if (!NewSign && OldVal.isSigned() && OldVal.isNegative())
321      Diag(Loc, DiagID) << OldVal.toString(10) << Val.toString(10);
322
323    Val.setIsSigned(NewSign);
324  } else if (NewWidth < Val.getBitWidth()) {
325    // If this is a truncation, check for overflow.
326    llvm::APSInt ConvVal(Val);
327    ConvVal.trunc(NewWidth);
328    ConvVal.setIsSigned(NewSign);
329    ConvVal.extend(Val.getBitWidth());
330    ConvVal.setIsSigned(Val.isSigned());
331    if (ConvVal != Val)
332      Diag(Loc, DiagID) << Val.toString(10) << ConvVal.toString(10);
333
334    // Regardless of whether a diagnostic was emitted, really do the
335    // truncation.
336    Val.trunc(NewWidth);
337    Val.setIsSigned(NewSign);
338  } else if (NewSign != Val.isSigned()) {
339    // Convert the sign to match the sign of the condition.  This can cause
340    // overflow as well: unsigned(INTMIN)
341    llvm::APSInt OldVal(Val);
342    Val.setIsSigned(NewSign);
343
344    if (Val.isNegative())  // Sign bit changes meaning.
345      Diag(Loc, DiagID) << OldVal.toString(10) << Val.toString(10);
346  }
347}
348
349namespace {
350  struct CaseCompareFunctor {
351    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
352                    const llvm::APSInt &RHS) {
353      return LHS.first < RHS;
354    }
355    bool operator()(const std::pair<llvm::APSInt, CaseStmt*> &LHS,
356                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
357      return LHS.first < RHS.first;
358    }
359    bool operator()(const llvm::APSInt &LHS,
360                    const std::pair<llvm::APSInt, CaseStmt*> &RHS) {
361      return LHS < RHS.first;
362    }
363  };
364}
365
366/// CmpCaseVals - Comparison predicate for sorting case values.
367///
368static bool CmpCaseVals(const std::pair<llvm::APSInt, CaseStmt*>& lhs,
369                        const std::pair<llvm::APSInt, CaseStmt*>& rhs) {
370  if (lhs.first < rhs.first)
371    return true;
372
373  if (lhs.first == rhs.first &&
374      lhs.second->getCaseLoc().getRawEncoding()
375       < rhs.second->getCaseLoc().getRawEncoding())
376    return true;
377  return false;
378}
379
380/// GetTypeBeforeIntegralPromotion - Returns the pre-promotion type of
381/// potentially integral-promoted expression @p expr.
382static QualType GetTypeBeforeIntegralPromotion(const Expr* expr) {
383  const ImplicitCastExpr *ImplicitCast =
384      dyn_cast_or_null<ImplicitCastExpr>(expr);
385  if (ImplicitCast != NULL) {
386    const Expr *ExprBeforePromotion = ImplicitCast->getSubExpr();
387    QualType TypeBeforePromotion = ExprBeforePromotion->getType();
388    if (TypeBeforePromotion->isIntegralType()) {
389      return TypeBeforePromotion;
390    }
391  }
392  return expr->getType();
393}
394
395Action::OwningStmtResult
396Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, StmtArg Switch,
397                            StmtArg Body) {
398  Stmt *BodyStmt = Body.takeAs<Stmt>();
399
400  SwitchStmt *SS = getSwitchStack().back();
401  assert(SS == (SwitchStmt*)Switch.get() && "switch stack missing push/pop!");
402
403  SS->setBody(BodyStmt, SwitchLoc);
404  getSwitchStack().pop_back();
405
406  Expr *CondExpr = SS->getCond();
407  QualType CondType = CondExpr->getType();
408
409  // C++ 6.4.2.p2:
410  // Integral promotions are performed (on the switch condition).
411  //
412  // A case value unrepresentable by the original switch condition
413  // type (before the promotion) doesn't make sense, even when it can
414  // be represented by the promoted type.  Therefore we need to find
415  // the pre-promotion type of the switch condition.
416  QualType CondTypeBeforePromotion =
417      GetTypeBeforeIntegralPromotion(CondExpr);
418
419  if (!CondExpr->isTypeDependent()) {
420    if (!CondType->isIntegerType()) { // C99 6.8.4.2p1
421      Diag(SwitchLoc, diag::err_typecheck_statement_requires_integer)
422          << CondType << CondExpr->getSourceRange();
423      return StmtError();
424    }
425
426    if (CondTypeBeforePromotion->isBooleanType()) {
427      // switch(bool_expr) {...} is often a programmer error, e.g.
428      //   switch(n && mask) { ... }  // Doh - should be "n & mask".
429      // One can always use an if statement instead of switch(bool_expr).
430      Diag(SwitchLoc, diag::warn_bool_switch_condition)
431          << CondExpr->getSourceRange();
432    }
433  }
434
435  // Get the bitwidth of the switched-on value before promotions.  We must
436  // convert the integer case values to this width before comparison.
437  bool HasDependentValue
438    = CondExpr->isTypeDependent() || CondExpr->isValueDependent();
439  unsigned CondWidth
440    = HasDependentValue? 0
441      : static_cast<unsigned>(Context.getTypeSize(CondTypeBeforePromotion));
442  bool CondIsSigned = CondTypeBeforePromotion->isSignedIntegerType();
443
444  // Accumulate all of the case values in a vector so that we can sort them
445  // and detect duplicates.  This vector contains the APInt for the case after
446  // it has been converted to the condition type.
447  typedef llvm::SmallVector<std::pair<llvm::APSInt, CaseStmt*>, 64> CaseValsTy;
448  CaseValsTy CaseVals;
449
450  // Keep track of any GNU case ranges we see.  The APSInt is the low value.
451  std::vector<std::pair<llvm::APSInt, CaseStmt*> > CaseRanges;
452
453  DefaultStmt *TheDefaultStmt = 0;
454
455  bool CaseListIsErroneous = false;
456
457  for (SwitchCase *SC = SS->getSwitchCaseList(); SC && !HasDependentValue;
458       SC = SC->getNextSwitchCase()) {
459
460    if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) {
461      if (TheDefaultStmt) {
462        Diag(DS->getDefaultLoc(), diag::err_multiple_default_labels_defined);
463        Diag(TheDefaultStmt->getDefaultLoc(), diag::note_duplicate_case_prev);
464
465        // FIXME: Remove the default statement from the switch block so that
466        // we'll return a valid AST.  This requires recursing down the AST and
467        // finding it, not something we are set up to do right now.  For now,
468        // just lop the entire switch stmt out of the AST.
469        CaseListIsErroneous = true;
470      }
471      TheDefaultStmt = DS;
472
473    } else {
474      CaseStmt *CS = cast<CaseStmt>(SC);
475
476      // We already verified that the expression has a i-c-e value (C99
477      // 6.8.4.2p3) - get that value now.
478      Expr *Lo = CS->getLHS();
479
480      if (Lo->isTypeDependent() || Lo->isValueDependent()) {
481        HasDependentValue = true;
482        break;
483      }
484
485      llvm::APSInt LoVal = Lo->EvaluateAsInt(Context);
486
487      // Convert the value to the same width/sign as the condition.
488      ConvertIntegerToTypeWarnOnOverflow(LoVal, CondWidth, CondIsSigned,
489                                         CS->getLHS()->getLocStart(),
490                                         diag::warn_case_value_overflow);
491
492      // If the LHS is not the same type as the condition, insert an implicit
493      // cast.
494      ImpCastExprToType(Lo, CondType, CastExpr::CK_IntegralCast);
495      CS->setLHS(Lo);
496
497      // If this is a case range, remember it in CaseRanges, otherwise CaseVals.
498      if (CS->getRHS()) {
499        if (CS->getRHS()->isTypeDependent() ||
500            CS->getRHS()->isValueDependent()) {
501          HasDependentValue = true;
502          break;
503        }
504        CaseRanges.push_back(std::make_pair(LoVal, CS));
505      } else
506        CaseVals.push_back(std::make_pair(LoVal, CS));
507    }
508  }
509
510  if (!HasDependentValue) {
511    // Sort all the scalar case values so we can easily detect duplicates.
512    std::stable_sort(CaseVals.begin(), CaseVals.end(), CmpCaseVals);
513
514    if (!CaseVals.empty()) {
515      for (unsigned i = 0, e = CaseVals.size()-1; i != e; ++i) {
516        if (CaseVals[i].first == CaseVals[i+1].first) {
517          // If we have a duplicate, report it.
518          Diag(CaseVals[i+1].second->getLHS()->getLocStart(),
519               diag::err_duplicate_case) << CaseVals[i].first.toString(10);
520          Diag(CaseVals[i].second->getLHS()->getLocStart(),
521               diag::note_duplicate_case_prev);
522          // FIXME: We really want to remove the bogus case stmt from the
523          // substmt, but we have no way to do this right now.
524          CaseListIsErroneous = true;
525        }
526      }
527    }
528
529    // Detect duplicate case ranges, which usually don't exist at all in
530    // the first place.
531    if (!CaseRanges.empty()) {
532      // Sort all the case ranges by their low value so we can easily detect
533      // overlaps between ranges.
534      std::stable_sort(CaseRanges.begin(), CaseRanges.end());
535
536      // Scan the ranges, computing the high values and removing empty ranges.
537      std::vector<llvm::APSInt> HiVals;
538      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
539        CaseStmt *CR = CaseRanges[i].second;
540        Expr *Hi = CR->getRHS();
541        llvm::APSInt HiVal = Hi->EvaluateAsInt(Context);
542
543        // Convert the value to the same width/sign as the condition.
544        ConvertIntegerToTypeWarnOnOverflow(HiVal, CondWidth, CondIsSigned,
545                                           CR->getRHS()->getLocStart(),
546                                           diag::warn_case_value_overflow);
547
548        // If the LHS is not the same type as the condition, insert an implicit
549        // cast.
550        ImpCastExprToType(Hi, CondType, CastExpr::CK_IntegralCast);
551        CR->setRHS(Hi);
552
553        // If the low value is bigger than the high value, the case is empty.
554        if (CaseRanges[i].first > HiVal) {
555          Diag(CR->getLHS()->getLocStart(), diag::warn_case_empty_range)
556            << SourceRange(CR->getLHS()->getLocStart(),
557                           CR->getRHS()->getLocEnd());
558          CaseRanges.erase(CaseRanges.begin()+i);
559          --i, --e;
560          continue;
561        }
562        HiVals.push_back(HiVal);
563      }
564
565      // Rescan the ranges, looking for overlap with singleton values and other
566      // ranges.  Since the range list is sorted, we only need to compare case
567      // ranges with their neighbors.
568      for (unsigned i = 0, e = CaseRanges.size(); i != e; ++i) {
569        llvm::APSInt &CRLo = CaseRanges[i].first;
570        llvm::APSInt &CRHi = HiVals[i];
571        CaseStmt *CR = CaseRanges[i].second;
572
573        // Check to see whether the case range overlaps with any
574        // singleton cases.
575        CaseStmt *OverlapStmt = 0;
576        llvm::APSInt OverlapVal(32);
577
578        // Find the smallest value >= the lower bound.  If I is in the
579        // case range, then we have overlap.
580        CaseValsTy::iterator I = std::lower_bound(CaseVals.begin(),
581                                                  CaseVals.end(), CRLo,
582                                                  CaseCompareFunctor());
583        if (I != CaseVals.end() && I->first < CRHi) {
584          OverlapVal  = I->first;   // Found overlap with scalar.
585          OverlapStmt = I->second;
586        }
587
588        // Find the smallest value bigger than the upper bound.
589        I = std::upper_bound(I, CaseVals.end(), CRHi, CaseCompareFunctor());
590        if (I != CaseVals.begin() && (I-1)->first >= CRLo) {
591          OverlapVal  = (I-1)->first;      // Found overlap with scalar.
592          OverlapStmt = (I-1)->second;
593        }
594
595        // Check to see if this case stmt overlaps with the subsequent
596        // case range.
597        if (i && CRLo <= HiVals[i-1]) {
598          OverlapVal  = HiVals[i-1];       // Found overlap with range.
599          OverlapStmt = CaseRanges[i-1].second;
600        }
601
602        if (OverlapStmt) {
603          // If we have a duplicate, report it.
604          Diag(CR->getLHS()->getLocStart(), diag::err_duplicate_case)
605            << OverlapVal.toString(10);
606          Diag(OverlapStmt->getLHS()->getLocStart(),
607               diag::note_duplicate_case_prev);
608          // FIXME: We really want to remove the bogus case stmt from the
609          // substmt, but we have no way to do this right now.
610          CaseListIsErroneous = true;
611        }
612      }
613    }
614  }
615
616  // FIXME: If the case list was broken is some way, we don't have a good system
617  // to patch it up.  Instead, just return the whole substmt as broken.
618  if (CaseListIsErroneous)
619    return StmtError();
620
621  Switch.release();
622  return Owned(SS);
623}
624
625Action::OwningStmtResult
626Sema::ActOnWhileStmt(SourceLocation WhileLoc, FullExprArg Cond, StmtArg Body) {
627  ExprArg CondArg(Cond.release());
628  Expr *condExpr = CondArg.takeAs<Expr>();
629  assert(condExpr && "ActOnWhileStmt(): missing expression");
630
631  if (CheckBooleanCondition(condExpr, WhileLoc)) {
632    CondArg = condExpr;
633    return StmtError();
634  }
635
636  Stmt *bodyStmt = Body.takeAs<Stmt>();
637  DiagnoseUnusedExprResult(bodyStmt);
638
639  CondArg.release();
640  return Owned(new (Context) WhileStmt(condExpr, bodyStmt, WhileLoc));
641}
642
643Action::OwningStmtResult
644Sema::ActOnDoStmt(SourceLocation DoLoc, StmtArg Body,
645                  SourceLocation WhileLoc, SourceLocation CondLParen,
646                  ExprArg Cond, SourceLocation CondRParen) {
647  Expr *condExpr = Cond.takeAs<Expr>();
648  assert(condExpr && "ActOnDoStmt(): missing expression");
649
650  if (CheckBooleanCondition(condExpr, DoLoc)) {
651    Cond = condExpr;
652    return StmtError();
653  }
654
655  Stmt *bodyStmt = Body.takeAs<Stmt>();
656  DiagnoseUnusedExprResult(bodyStmt);
657
658  Cond.release();
659  return Owned(new (Context) DoStmt(bodyStmt, condExpr, DoLoc,
660                                    WhileLoc, CondRParen));
661}
662
663Action::OwningStmtResult
664Sema::ActOnForStmt(SourceLocation ForLoc, SourceLocation LParenLoc,
665                   StmtArg first, ExprArg second, ExprArg third,
666                   SourceLocation RParenLoc, StmtArg body) {
667  Stmt *First  = static_cast<Stmt*>(first.get());
668  Expr *Second = second.takeAs<Expr>();
669  Expr *Third  = static_cast<Expr*>(third.get());
670  Stmt *Body  = static_cast<Stmt*>(body.get());
671
672  if (!getLangOptions().CPlusPlus) {
673    if (DeclStmt *DS = dyn_cast_or_null<DeclStmt>(First)) {
674      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
675      // declare identifiers for objects having storage class 'auto' or
676      // 'register'.
677      for (DeclStmt::decl_iterator DI=DS->decl_begin(), DE=DS->decl_end();
678           DI!=DE; ++DI) {
679        VarDecl *VD = dyn_cast<VarDecl>(*DI);
680        if (VD && VD->isBlockVarDecl() && !VD->hasLocalStorage())
681          VD = 0;
682        if (VD == 0)
683          Diag((*DI)->getLocation(), diag::err_non_variable_decl_in_for);
684        // FIXME: mark decl erroneous!
685      }
686    }
687  }
688  if (Second && CheckBooleanCondition(Second, ForLoc)) {
689    second = Second;
690    return StmtError();
691  }
692
693  DiagnoseUnusedExprResult(First);
694  DiagnoseUnusedExprResult(Third);
695  DiagnoseUnusedExprResult(Body);
696
697  first.release();
698  third.release();
699  body.release();
700  return Owned(new (Context) ForStmt(First, Second, Third, Body, ForLoc,
701                                     LParenLoc, RParenLoc));
702}
703
704Action::OwningStmtResult
705Sema::ActOnObjCForCollectionStmt(SourceLocation ForLoc,
706                                 SourceLocation LParenLoc,
707                                 StmtArg first, ExprArg second,
708                                 SourceLocation RParenLoc, StmtArg body) {
709  Stmt *First  = static_cast<Stmt*>(first.get());
710  Expr *Second = static_cast<Expr*>(second.get());
711  Stmt *Body  = static_cast<Stmt*>(body.get());
712  if (First) {
713    QualType FirstType;
714    if (DeclStmt *DS = dyn_cast<DeclStmt>(First)) {
715      if (!DS->isSingleDecl())
716        return StmtError(Diag((*DS->decl_begin())->getLocation(),
717                         diag::err_toomany_element_decls));
718
719      Decl *D = DS->getSingleDecl();
720      FirstType = cast<ValueDecl>(D)->getType();
721      // C99 6.8.5p3: The declaration part of a 'for' statement shall only
722      // declare identifiers for objects having storage class 'auto' or
723      // 'register'.
724      VarDecl *VD = cast<VarDecl>(D);
725      if (VD->isBlockVarDecl() && !VD->hasLocalStorage())
726        return StmtError(Diag(VD->getLocation(),
727                              diag::err_non_variable_decl_in_for));
728    } else {
729      if (cast<Expr>(First)->isLvalue(Context) != Expr::LV_Valid)
730        return StmtError(Diag(First->getLocStart(),
731                   diag::err_selector_element_not_lvalue)
732          << First->getSourceRange());
733
734      FirstType = static_cast<Expr*>(First)->getType();
735    }
736    if (!FirstType->isObjCObjectPointerType() &&
737        !FirstType->isBlockPointerType())
738        Diag(ForLoc, diag::err_selector_element_type)
739          << FirstType << First->getSourceRange();
740  }
741  if (Second) {
742    DefaultFunctionArrayConversion(Second);
743    QualType SecondType = Second->getType();
744    if (!SecondType->isObjCObjectPointerType())
745      Diag(ForLoc, diag::err_collection_expr_type)
746        << SecondType << Second->getSourceRange();
747  }
748  first.release();
749  second.release();
750  body.release();
751  return Owned(new (Context) ObjCForCollectionStmt(First, Second, Body,
752                                                   ForLoc, RParenLoc));
753}
754
755Action::OwningStmtResult
756Sema::ActOnGotoStmt(SourceLocation GotoLoc, SourceLocation LabelLoc,
757                    IdentifierInfo *LabelII) {
758  // If we are in a block, reject all gotos for now.
759  if (CurBlock)
760    return StmtError(Diag(GotoLoc, diag::err_goto_in_block));
761
762  // Look up the record for this label identifier.
763  LabelStmt *&LabelDecl = getLabelMap()[LabelII];
764
765  // If we haven't seen this label yet, create a forward reference.
766  if (LabelDecl == 0)
767    LabelDecl = new (Context) LabelStmt(LabelLoc, LabelII, 0);
768
769  return Owned(new (Context) GotoStmt(LabelDecl, GotoLoc, LabelLoc));
770}
771
772Action::OwningStmtResult
773Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
774                            ExprArg DestExp) {
775  // Convert operand to void*
776  Expr* E = DestExp.takeAs<Expr>();
777  if (!E->isTypeDependent()) {
778    QualType ETy = E->getType();
779    AssignConvertType ConvTy =
780      CheckSingleAssignmentConstraints(Context.VoidPtrTy, E);
781    if (DiagnoseAssignmentResult(ConvTy, StarLoc, Context.VoidPtrTy, ETy,
782                                 E, "passing"))
783      return StmtError();
784  }
785  return Owned(new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E));
786}
787
788Action::OwningStmtResult
789Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
790  Scope *S = CurScope->getContinueParent();
791  if (!S) {
792    // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
793    return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
794  }
795
796  return Owned(new (Context) ContinueStmt(ContinueLoc));
797}
798
799Action::OwningStmtResult
800Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
801  Scope *S = CurScope->getBreakParent();
802  if (!S) {
803    // C99 6.8.6.3p1: A break shall appear only in or as a switch/loop body.
804    return StmtError(Diag(BreakLoc, diag::err_break_not_in_loop_or_switch));
805  }
806
807  return Owned(new (Context) BreakStmt(BreakLoc));
808}
809
810/// ActOnBlockReturnStmt - Utility routine to figure out block's return type.
811///
812Action::OwningStmtResult
813Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
814  // If this is the first return we've seen in the block, infer the type of
815  // the block from it.
816  if (CurBlock->ReturnType.isNull()) {
817    if (RetValExp) {
818      // Don't call UsualUnaryConversions(), since we don't want to do
819      // integer promotions here.
820      DefaultFunctionArrayConversion(RetValExp);
821      CurBlock->ReturnType = RetValExp->getType();
822      if (BlockDeclRefExpr *CDRE = dyn_cast<BlockDeclRefExpr>(RetValExp)) {
823        // We have to remove a 'const' added to copied-in variable which was
824        // part of the implementation spec. and not the actual qualifier for
825        // the variable.
826        if (CDRE->isConstQualAdded())
827           CurBlock->ReturnType.removeConst();
828      }
829    } else
830      CurBlock->ReturnType = Context.VoidTy;
831  }
832  QualType FnRetType = CurBlock->ReturnType;
833
834  if (CurBlock->TheDecl->hasAttr<NoReturnAttr>()) {
835    Diag(ReturnLoc, diag::err_noreturn_block_has_return_expr)
836      << getCurFunctionOrMethodDecl()->getDeclName();
837    return StmtError();
838  }
839
840  // Otherwise, verify that this result type matches the previous one.  We are
841  // pickier with blocks than for normal functions because we don't have GCC
842  // compatibility to worry about here.
843  if (CurBlock->ReturnType->isVoidType()) {
844    if (RetValExp) {
845      Diag(ReturnLoc, diag::err_return_block_has_expr);
846      RetValExp->Destroy(Context);
847      RetValExp = 0;
848    }
849    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
850  }
851
852  if (!RetValExp)
853    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
854
855  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
856    // we have a non-void block with an expression, continue checking
857    QualType RetValType = RetValExp->getType();
858
859    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
860    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
861    // function return.
862
863    // In C++ the return statement is handled via a copy initialization.
864    // the C version of which boils down to CheckSingleAssignmentConstraints.
865    // FIXME: Leaks RetValExp.
866    if (PerformCopyInitialization(RetValExp, FnRetType, "returning"))
867      return StmtError();
868
869    if (RetValExp) CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
870  }
871
872  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
873}
874
875/// IsReturnCopyElidable - Whether returning @p RetExpr from a function that
876/// returns a @p RetType fulfills the criteria for copy elision (C++0x 12.8p15).
877static bool IsReturnCopyElidable(ASTContext &Ctx, QualType RetType,
878                                 Expr *RetExpr) {
879  QualType ExprType = RetExpr->getType();
880  // - in a return statement in a function with ...
881  // ... a class return type ...
882  if (!RetType->isRecordType())
883    return false;
884  // ... the same cv-unqualified type as the function return type ...
885  if (!Ctx.hasSameUnqualifiedType(RetType, ExprType))
886    return false;
887  // ... the expression is the name of a non-volatile automatic object ...
888  // We ignore parentheses here.
889  // FIXME: Is this compliant?
890  const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(RetExpr->IgnoreParens());
891  if (!DR)
892    return false;
893  const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl());
894  if (!VD)
895    return false;
896  return VD->hasLocalStorage() && !VD->getType()->isReferenceType()
897    && !VD->getType().isVolatileQualified();
898}
899
900Action::OwningStmtResult
901Sema::ActOnReturnStmt(SourceLocation ReturnLoc, ExprArg rex) {
902  Expr *RetValExp = rex.takeAs<Expr>();
903  if (CurBlock)
904    return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
905
906  QualType FnRetType;
907  if (const FunctionDecl *FD = getCurFunctionDecl()) {
908    FnRetType = FD->getResultType();
909    if (FD->hasAttr<NoReturnAttr>())
910      Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
911        << getCurFunctionOrMethodDecl()->getDeclName();
912  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
913    FnRetType = MD->getResultType();
914  else // If we don't have a function/method context, bail.
915    return StmtError();
916
917  if (FnRetType->isVoidType()) {
918    if (RetValExp && !RetValExp->isTypeDependent()) {
919      // C99 6.8.6.4p1 (ext_ since GCC warns)
920      unsigned D = diag::ext_return_has_expr;
921      if (RetValExp->getType()->isVoidType())
922        D = diag::ext_return_has_void_expr;
923
924      // return (some void expression); is legal in C++.
925      if (D != diag::ext_return_has_void_expr ||
926          !getLangOptions().CPlusPlus) {
927        NamedDecl *CurDecl = getCurFunctionOrMethodDecl();
928        Diag(ReturnLoc, D)
929          << CurDecl->getDeclName() << isa<ObjCMethodDecl>(CurDecl)
930          << RetValExp->getSourceRange();
931      }
932
933      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp, true);
934    }
935    return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
936  }
937
938  if (!RetValExp && !FnRetType->isDependentType()) {
939    unsigned DiagID = diag::warn_return_missing_expr;  // C90 6.6.6.4p4
940    // C99 6.8.6.4p1 (ext_ since GCC warns)
941    if (getLangOptions().C99) DiagID = diag::ext_return_missing_expr;
942
943    if (FunctionDecl *FD = getCurFunctionDecl())
944      Diag(ReturnLoc, DiagID) << FD->getIdentifier() << 0/*fn*/;
945    else
946      Diag(ReturnLoc, DiagID) << getCurMethodDecl()->getDeclName() << 1/*meth*/;
947    return Owned(new (Context) ReturnStmt(ReturnLoc, (Expr*)0));
948  }
949
950  if (!FnRetType->isDependentType() && !RetValExp->isTypeDependent()) {
951    // we have a non-void function with an expression, continue checking
952
953    // C99 6.8.6.4p3(136): The return statement is not an assignment. The
954    // overlap restriction of subclause 6.5.16.1 does not apply to the case of
955    // function return.
956
957    // C++0x 12.8p15: When certain criteria are met, an implementation is
958    //   allowed to omit the copy construction of a class object, [...]
959    //   - in a return statement in a function with a class return type, when
960    //     the expression is the name of a non-volatile automatic object with
961    //     the same cv-unqualified type as the function return type, the copy
962    //     operation can be omitted [...]
963    // C++0x 12.8p16: When the criteria for elision of a copy operation are met
964    //   and the object to be copied is designated by an lvalue, overload
965    //   resolution to select the constructor for the copy is first performed
966    //   as if the object were designated by an rvalue.
967    // Note that we only compute Elidable if we're in C++0x, since we don't
968    // care otherwise.
969    bool Elidable = getLangOptions().CPlusPlus0x ?
970                      IsReturnCopyElidable(Context, FnRetType, RetValExp) :
971                      false;
972
973    // In C++ the return statement is handled via a copy initialization.
974    // the C version of which boils down to CheckSingleAssignmentConstraints.
975    // FIXME: Leaks RetValExp on error.
976    if (PerformCopyInitialization(RetValExp, FnRetType, "returning", Elidable)){
977      // We should still clean up our temporaries, even when we're failing!
978      RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp, true);
979      return StmtError();
980    }
981
982    if (RetValExp) CheckReturnStackAddr(RetValExp, FnRetType, ReturnLoc);
983  }
984
985  if (RetValExp)
986    RetValExp = MaybeCreateCXXExprWithTemporaries(RetValExp, true);
987  return Owned(new (Context) ReturnStmt(ReturnLoc, RetValExp));
988}
989
990/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
991/// ignore "noop" casts in places where an lvalue is required by an inline asm.
992/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
993/// provide a strong guidance to not use it.
994///
995/// This method checks to see if the argument is an acceptable l-value and
996/// returns false if it is a case we can handle.
997static bool CheckAsmLValue(const Expr *E, Sema &S) {
998  if (E->isLvalue(S.Context) == Expr::LV_Valid)
999    return false;  // Cool, this is an lvalue.
1000
1001  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
1002  // are supposed to allow.
1003  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
1004  if (E != E2 && E2->isLvalue(S.Context) == Expr::LV_Valid) {
1005    if (!S.getLangOptions().HeinousExtensions)
1006      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
1007        << E->getSourceRange();
1008    else
1009      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
1010        << E->getSourceRange();
1011    // Accept, even if we emitted an error diagnostic.
1012    return false;
1013  }
1014
1015  // None of the above, just randomly invalid non-lvalue.
1016  return true;
1017}
1018
1019
1020Sema::OwningStmtResult Sema::ActOnAsmStmt(SourceLocation AsmLoc,
1021                                          bool IsSimple,
1022                                          bool IsVolatile,
1023                                          unsigned NumOutputs,
1024                                          unsigned NumInputs,
1025                                          std::string *Names,
1026                                          MultiExprArg constraints,
1027                                          MultiExprArg exprs,
1028                                          ExprArg asmString,
1029                                          MultiExprArg clobbers,
1030                                          SourceLocation RParenLoc) {
1031  unsigned NumClobbers = clobbers.size();
1032  StringLiteral **Constraints =
1033    reinterpret_cast<StringLiteral**>(constraints.get());
1034  Expr **Exprs = reinterpret_cast<Expr **>(exprs.get());
1035  StringLiteral *AsmString = cast<StringLiteral>((Expr *)asmString.get());
1036  StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.get());
1037
1038  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1039
1040  // The parser verifies that there is a string literal here.
1041  if (AsmString->isWide())
1042    return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
1043      << AsmString->getSourceRange());
1044
1045  for (unsigned i = 0; i != NumOutputs; i++) {
1046    StringLiteral *Literal = Constraints[i];
1047    if (Literal->isWide())
1048      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1049        << Literal->getSourceRange());
1050
1051    TargetInfo::ConstraintInfo Info(Literal->getStrData(),
1052                                    Literal->getByteLength(),
1053                                    Names[i]);
1054    if (!Context.Target.validateOutputConstraint(Info))
1055      return StmtError(Diag(Literal->getLocStart(),
1056                            diag::err_asm_invalid_output_constraint)
1057                       << Info.getConstraintStr());
1058
1059    // Check that the output exprs are valid lvalues.
1060    Expr *OutputExpr = Exprs[i];
1061    if (CheckAsmLValue(OutputExpr, *this)) {
1062      return StmtError(Diag(OutputExpr->getLocStart(),
1063                  diag::err_asm_invalid_lvalue_in_output)
1064        << OutputExpr->getSourceRange());
1065    }
1066
1067    OutputConstraintInfos.push_back(Info);
1068  }
1069
1070  llvm::SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1071
1072  for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
1073    StringLiteral *Literal = Constraints[i];
1074    if (Literal->isWide())
1075      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1076        << Literal->getSourceRange());
1077
1078    TargetInfo::ConstraintInfo Info(Literal->getStrData(),
1079                                    Literal->getByteLength(),
1080                                    Names[i]);
1081    if (!Context.Target.validateInputConstraint(OutputConstraintInfos.data(),
1082                                                NumOutputs, Info)) {
1083      return StmtError(Diag(Literal->getLocStart(),
1084                            diag::err_asm_invalid_input_constraint)
1085                       << Info.getConstraintStr());
1086    }
1087
1088    Expr *InputExpr = Exprs[i];
1089
1090    // Only allow void types for memory constraints.
1091    if (Info.allowsMemory() && !Info.allowsRegister()) {
1092      if (CheckAsmLValue(InputExpr, *this))
1093        return StmtError(Diag(InputExpr->getLocStart(),
1094                              diag::err_asm_invalid_lvalue_in_input)
1095                         << Info.getConstraintStr()
1096                         << InputExpr->getSourceRange());
1097    }
1098
1099    if (Info.allowsRegister()) {
1100      if (InputExpr->getType()->isVoidType()) {
1101        return StmtError(Diag(InputExpr->getLocStart(),
1102                              diag::err_asm_invalid_type_in_input)
1103          << InputExpr->getType() << Info.getConstraintStr()
1104          << InputExpr->getSourceRange());
1105      }
1106    }
1107
1108    DefaultFunctionArrayConversion(Exprs[i]);
1109
1110    InputConstraintInfos.push_back(Info);
1111  }
1112
1113  // Check that the clobbers are valid.
1114  for (unsigned i = 0; i != NumClobbers; i++) {
1115    StringLiteral *Literal = Clobbers[i];
1116    if (Literal->isWide())
1117      return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
1118        << Literal->getSourceRange());
1119
1120    std::string Clobber(Literal->getStrData(),
1121                        Literal->getStrData() +
1122                        Literal->getByteLength());
1123
1124    if (!Context.Target.isValidGCCRegisterName(Clobber.c_str()))
1125      return StmtError(Diag(Literal->getLocStart(),
1126                  diag::err_asm_unknown_register_name) << Clobber);
1127  }
1128
1129  constraints.release();
1130  exprs.release();
1131  asmString.release();
1132  clobbers.release();
1133  AsmStmt *NS =
1134    new (Context) AsmStmt(AsmLoc, IsSimple, IsVolatile, NumOutputs, NumInputs,
1135                          Names, Constraints, Exprs, AsmString, NumClobbers,
1136                          Clobbers, RParenLoc);
1137  // Validate the asm string, ensuring it makes sense given the operands we
1138  // have.
1139  llvm::SmallVector<AsmStmt::AsmStringPiece, 8> Pieces;
1140  unsigned DiagOffs;
1141  if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
1142    Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
1143           << AsmString->getSourceRange();
1144    DeleteStmt(NS);
1145    return StmtError();
1146  }
1147
1148  // Validate tied input operands for type mismatches.
1149  for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
1150    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1151
1152    // If this is a tied constraint, verify that the output and input have
1153    // either exactly the same type, or that they are int/ptr operands with the
1154    // same size (int/long, int*/long, are ok etc).
1155    if (!Info.hasTiedOperand()) continue;
1156
1157    unsigned TiedTo = Info.getTiedOperand();
1158    Expr *OutputExpr = Exprs[TiedTo];
1159    Expr *InputExpr = Exprs[i+NumOutputs];
1160    QualType InTy = InputExpr->getType();
1161    QualType OutTy = OutputExpr->getType();
1162    if (Context.hasSameType(InTy, OutTy))
1163      continue;  // All types can be tied to themselves.
1164
1165    // Int/ptr operands have some special cases that we allow.
1166    if ((OutTy->isIntegerType() || OutTy->isPointerType()) &&
1167        (InTy->isIntegerType() || InTy->isPointerType())) {
1168
1169      // They are ok if they are the same size.  Tying void* to int is ok if
1170      // they are the same size, for example.  This also allows tying void* to
1171      // int*.
1172      uint64_t OutSize = Context.getTypeSize(OutTy);
1173      uint64_t InSize = Context.getTypeSize(InTy);
1174      if (OutSize == InSize)
1175        continue;
1176
1177      // If the smaller input/output operand is not mentioned in the asm string,
1178      // then we can promote it and the asm string won't notice.  Check this
1179      // case now.
1180      bool SmallerValueMentioned = false;
1181      for (unsigned p = 0, e = Pieces.size(); p != e; ++p) {
1182        AsmStmt::AsmStringPiece &Piece = Pieces[p];
1183        if (!Piece.isOperand()) continue;
1184
1185        // If this is a reference to the input and if the input was the smaller
1186        // one, then we have to reject this asm.
1187        if (Piece.getOperandNo() == i+NumOutputs) {
1188          if (InSize < OutSize) {
1189            SmallerValueMentioned = true;
1190            break;
1191          }
1192        }
1193
1194        // If this is a reference to the input and if the input was the smaller
1195        // one, then we have to reject this asm.
1196        if (Piece.getOperandNo() == TiedTo) {
1197          if (InSize > OutSize) {
1198            SmallerValueMentioned = true;
1199            break;
1200          }
1201        }
1202      }
1203
1204      // If the smaller value wasn't mentioned in the asm string, and if the
1205      // output was a register, just extend the shorter one to the size of the
1206      // larger one.
1207      if (!SmallerValueMentioned &&
1208          OutputConstraintInfos[TiedTo].allowsRegister())
1209        continue;
1210    }
1211
1212    Diag(InputExpr->getLocStart(),
1213         diag::err_asm_tying_incompatible_types)
1214      << InTy << OutTy << OutputExpr->getSourceRange()
1215      << InputExpr->getSourceRange();
1216    DeleteStmt(NS);
1217    return StmtError();
1218  }
1219
1220  return Owned(NS);
1221}
1222
1223Action::OwningStmtResult
1224Sema::ActOnObjCAtCatchStmt(SourceLocation AtLoc,
1225                           SourceLocation RParen, DeclPtrTy Parm,
1226                           StmtArg Body, StmtArg catchList) {
1227  Stmt *CatchList = catchList.takeAs<Stmt>();
1228  ParmVarDecl *PVD = cast_or_null<ParmVarDecl>(Parm.getAs<Decl>());
1229
1230  // PVD == 0 implies @catch(...).
1231  if (PVD) {
1232    // If we already know the decl is invalid, reject it.
1233    if (PVD->isInvalidDecl())
1234      return StmtError();
1235
1236    if (!PVD->getType()->isObjCObjectPointerType())
1237      return StmtError(Diag(PVD->getLocation(),
1238                       diag::err_catch_param_not_objc_type));
1239    if (PVD->getType()->isObjCQualifiedIdType())
1240      return StmtError(Diag(PVD->getLocation(),
1241                       diag::err_illegal_qualifiers_on_catch_parm));
1242  }
1243
1244  ObjCAtCatchStmt *CS = new (Context) ObjCAtCatchStmt(AtLoc, RParen,
1245    PVD, Body.takeAs<Stmt>(), CatchList);
1246  return Owned(CatchList ? CatchList : CS);
1247}
1248
1249Action::OwningStmtResult
1250Sema::ActOnObjCAtFinallyStmt(SourceLocation AtLoc, StmtArg Body) {
1251  return Owned(new (Context) ObjCAtFinallyStmt(AtLoc,
1252                                           static_cast<Stmt*>(Body.release())));
1253}
1254
1255Action::OwningStmtResult
1256Sema::ActOnObjCAtTryStmt(SourceLocation AtLoc,
1257                         StmtArg Try, StmtArg Catch, StmtArg Finally) {
1258  CurFunctionNeedsScopeChecking = true;
1259  return Owned(new (Context) ObjCAtTryStmt(AtLoc, Try.takeAs<Stmt>(),
1260                                           Catch.takeAs<Stmt>(),
1261                                           Finally.takeAs<Stmt>()));
1262}
1263
1264Action::OwningStmtResult
1265Sema::ActOnObjCAtThrowStmt(SourceLocation AtLoc, ExprArg expr,Scope *CurScope) {
1266  Expr *ThrowExpr = expr.takeAs<Expr>();
1267  if (!ThrowExpr) {
1268    // @throw without an expression designates a rethrow (which much occur
1269    // in the context of an @catch clause).
1270    Scope *AtCatchParent = CurScope;
1271    while (AtCatchParent && !AtCatchParent->isAtCatchScope())
1272      AtCatchParent = AtCatchParent->getParent();
1273    if (!AtCatchParent)
1274      return StmtError(Diag(AtLoc, diag::error_rethrow_used_outside_catch));
1275  } else {
1276    QualType ThrowType = ThrowExpr->getType();
1277    // Make sure the expression type is an ObjC pointer or "void *".
1278    if (!ThrowType->isObjCObjectPointerType()) {
1279      const PointerType *PT = ThrowType->getAs<PointerType>();
1280      if (!PT || !PT->getPointeeType()->isVoidType())
1281        return StmtError(Diag(AtLoc, diag::error_objc_throw_expects_object)
1282                        << ThrowExpr->getType() << ThrowExpr->getSourceRange());
1283    }
1284  }
1285  return Owned(new (Context) ObjCAtThrowStmt(AtLoc, ThrowExpr));
1286}
1287
1288Action::OwningStmtResult
1289Sema::ActOnObjCAtSynchronizedStmt(SourceLocation AtLoc, ExprArg SynchExpr,
1290                                  StmtArg SynchBody) {
1291  CurFunctionNeedsScopeChecking = true;
1292
1293  // Make sure the expression type is an ObjC pointer or "void *".
1294  Expr *SyncExpr = static_cast<Expr*>(SynchExpr.get());
1295  if (!SyncExpr->getType()->isObjCObjectPointerType()) {
1296    const PointerType *PT = SyncExpr->getType()->getAs<PointerType>();
1297    if (!PT || !PT->getPointeeType()->isVoidType())
1298      return StmtError(Diag(AtLoc, diag::error_objc_synchronized_expects_object)
1299                       << SyncExpr->getType() << SyncExpr->getSourceRange());
1300  }
1301
1302  return Owned(new (Context) ObjCAtSynchronizedStmt(AtLoc,
1303                                                    SynchExpr.takeAs<Stmt>(),
1304                                                    SynchBody.takeAs<Stmt>()));
1305}
1306
1307/// ActOnCXXCatchBlock - Takes an exception declaration and a handler block
1308/// and creates a proper catch handler from them.
1309Action::OwningStmtResult
1310Sema::ActOnCXXCatchBlock(SourceLocation CatchLoc, DeclPtrTy ExDecl,
1311                         StmtArg HandlerBlock) {
1312  // There's nothing to test that ActOnExceptionDecl didn't already test.
1313  return Owned(new (Context) CXXCatchStmt(CatchLoc,
1314                                  cast_or_null<VarDecl>(ExDecl.getAs<Decl>()),
1315                                          HandlerBlock.takeAs<Stmt>()));
1316}
1317
1318class TypeWithHandler {
1319  QualType t;
1320  CXXCatchStmt *stmt;
1321public:
1322  TypeWithHandler(const QualType &type, CXXCatchStmt *statement)
1323  : t(type), stmt(statement) {}
1324
1325  // An arbitrary order is fine as long as it places identical
1326  // types next to each other.
1327  bool operator<(const TypeWithHandler &y) const {
1328    if (t.getAsOpaquePtr() < y.t.getAsOpaquePtr())
1329      return true;
1330    if (t.getAsOpaquePtr() > y.t.getAsOpaquePtr())
1331      return false;
1332    else
1333      return getTypeSpecStartLoc() < y.getTypeSpecStartLoc();
1334  }
1335
1336  bool operator==(const TypeWithHandler& other) const {
1337    return t == other.t;
1338  }
1339
1340  QualType getQualType() const { return t; }
1341  CXXCatchStmt *getCatchStmt() const { return stmt; }
1342  SourceLocation getTypeSpecStartLoc() const {
1343    return stmt->getExceptionDecl()->getTypeSpecStartLoc();
1344  }
1345};
1346
1347/// ActOnCXXTryBlock - Takes a try compound-statement and a number of
1348/// handlers and creates a try statement from them.
1349Action::OwningStmtResult
1350Sema::ActOnCXXTryBlock(SourceLocation TryLoc, StmtArg TryBlock,
1351                       MultiStmtArg RawHandlers) {
1352  unsigned NumHandlers = RawHandlers.size();
1353  assert(NumHandlers > 0 &&
1354         "The parser shouldn't call this if there are no handlers.");
1355  Stmt **Handlers = reinterpret_cast<Stmt**>(RawHandlers.get());
1356
1357  llvm::SmallVector<TypeWithHandler, 8> TypesWithHandlers;
1358
1359  for (unsigned i = 0; i < NumHandlers; ++i) {
1360    CXXCatchStmt *Handler = llvm::cast<CXXCatchStmt>(Handlers[i]);
1361    if (!Handler->getExceptionDecl()) {
1362      if (i < NumHandlers - 1)
1363        return StmtError(Diag(Handler->getLocStart(),
1364                              diag::err_early_catch_all));
1365
1366      continue;
1367    }
1368
1369    const QualType CaughtType = Handler->getCaughtType();
1370    const QualType CanonicalCaughtType = Context.getCanonicalType(CaughtType);
1371    TypesWithHandlers.push_back(TypeWithHandler(CanonicalCaughtType, Handler));
1372  }
1373
1374  // Detect handlers for the same type as an earlier one.
1375  if (NumHandlers > 1) {
1376    llvm::array_pod_sort(TypesWithHandlers.begin(), TypesWithHandlers.end());
1377
1378    TypeWithHandler prev = TypesWithHandlers[0];
1379    for (unsigned i = 1; i < TypesWithHandlers.size(); ++i) {
1380      TypeWithHandler curr = TypesWithHandlers[i];
1381
1382      if (curr == prev) {
1383        Diag(curr.getTypeSpecStartLoc(),
1384             diag::warn_exception_caught_by_earlier_handler)
1385          << curr.getCatchStmt()->getCaughtType().getAsString();
1386        Diag(prev.getTypeSpecStartLoc(),
1387             diag::note_previous_exception_handler)
1388          << prev.getCatchStmt()->getCaughtType().getAsString();
1389      }
1390
1391      prev = curr;
1392    }
1393  }
1394
1395  // FIXME: We should detect handlers that cannot catch anything because an
1396  // earlier handler catches a superclass. Need to find a method that is not
1397  // quadratic for this.
1398  // Neither of these are explicitly forbidden, but every compiler detects them
1399  // and warns.
1400
1401  CurFunctionNeedsScopeChecking = true;
1402  RawHandlers.release();
1403  return Owned(new (Context) CXXTryStmt(TryLoc,
1404                                        static_cast<Stmt*>(TryBlock.release()),
1405                                        Handlers, NumHandlers));
1406}
1407