AnalysisBasedWarnings.cpp revision 9e7617220135a6f6226cf09cb242cc1b905aedb4 
1//=- AnalysisBasedWarnings.cpp - Sema warnings based on libAnalysis -*- C++ -*-=//
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 defines analysis_warnings::[Policy,Executor].
11// Together they are used by Sema to issue warnings based on inexpensive
12// static analysis algorithms in libAnalysis.
13//
14//===----------------------------------------------------------------------===//
15
16#include "clang/Sema/AnalysisBasedWarnings.h"
17#include "clang/Sema/SemaInternal.h"
18#include "clang/Sema/ScopeInfo.h"
19#include "clang/Basic/SourceManager.h"
20#include "clang/Basic/SourceLocation.h"
21#include "clang/Lex/Preprocessor.h"
22#include "clang/AST/DeclObjC.h"
23#include "clang/AST/DeclCXX.h"
24#include "clang/AST/ExprObjC.h"
25#include "clang/AST/ExprCXX.h"
26#include "clang/AST/StmtObjC.h"
27#include "clang/AST/StmtCXX.h"
28#include "clang/AST/EvaluatedExprVisitor.h"
29#include "clang/AST/StmtVisitor.h"
30#include "clang/Analysis/AnalysisContext.h"
31#include "clang/Analysis/CFG.h"
32#include "clang/Analysis/Analyses/ReachableCode.h"
33#include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h"
34#include "clang/Analysis/Analyses/ThreadSafety.h"
35#include "clang/Analysis/CFGStmtMap.h"
36#include "clang/Analysis/Analyses/UninitializedValues.h"
37#include "llvm/ADT/BitVector.h"
38#include "llvm/ADT/FoldingSet.h"
39#include "llvm/ADT/ImmutableMap.h"
40#include "llvm/ADT/PostOrderIterator.h"
41#include "llvm/ADT/SmallVector.h"
42#include "llvm/ADT/StringRef.h"
43#include "llvm/Support/Casting.h"
44#include <algorithm>
45#include <vector>
46
47using namespace clang;
48
49//===----------------------------------------------------------------------===//
50// Unreachable code analysis.
51//===----------------------------------------------------------------------===//
52
53namespace {
54  class UnreachableCodeHandler : public reachable_code::Callback {
55    Sema &S;
56  public:
57    UnreachableCodeHandler(Sema &s) : S(s) {}
58
59    void HandleUnreachable(SourceLocation L, SourceRange R1, SourceRange R2) {
60      S.Diag(L, diag::warn_unreachable) << R1 << R2;
61    }
62  };
63}
64
65/// CheckUnreachable - Check for unreachable code.
66static void CheckUnreachable(Sema &S, AnalysisContext &AC) {
67  UnreachableCodeHandler UC(S);
68  reachable_code::FindUnreachableCode(AC, UC);
69}
70
71//===----------------------------------------------------------------------===//
72// Check for missing return value.
73//===----------------------------------------------------------------------===//
74
75enum ControlFlowKind {
76  UnknownFallThrough,
77  NeverFallThrough,
78  MaybeFallThrough,
79  AlwaysFallThrough,
80  NeverFallThroughOrReturn
81};
82
83/// CheckFallThrough - Check that we don't fall off the end of a
84/// Statement that should return a value.
85///
86/// \returns AlwaysFallThrough iff we always fall off the end of the statement,
87/// MaybeFallThrough iff we might or might not fall off the end,
88/// NeverFallThroughOrReturn iff we never fall off the end of the statement or
89/// return.  We assume NeverFallThrough iff we never fall off the end of the
90/// statement but we may return.  We assume that functions not marked noreturn
91/// will return.
92static ControlFlowKind CheckFallThrough(AnalysisContext &AC) {
93  CFG *cfg = AC.getCFG();
94  if (cfg == 0) return UnknownFallThrough;
95
96  // The CFG leaves in dead things, and we don't want the dead code paths to
97  // confuse us, so we mark all live things first.
98  llvm::BitVector live(cfg->getNumBlockIDs());
99  unsigned count = reachable_code::ScanReachableFromBlock(&cfg->getEntry(),
100                                                          live);
101
102  bool AddEHEdges = AC.getAddEHEdges();
103  if (!AddEHEdges && count != cfg->getNumBlockIDs())
104    // When there are things remaining dead, and we didn't add EH edges
105    // from CallExprs to the catch clauses, we have to go back and
106    // mark them as live.
107    for (CFG::iterator I = cfg->begin(), E = cfg->end(); I != E; ++I) {
108      CFGBlock &b = **I;
109      if (!live[b.getBlockID()]) {
110        if (b.pred_begin() == b.pred_end()) {
111          if (b.getTerminator() && isa<CXXTryStmt>(b.getTerminator()))
112            // When not adding EH edges from calls, catch clauses
113            // can otherwise seem dead.  Avoid noting them as dead.
114            count += reachable_code::ScanReachableFromBlock(&b, live);
115          continue;
116        }
117      }
118    }
119
120  // Now we know what is live, we check the live precessors of the exit block
121  // and look for fall through paths, being careful to ignore normal returns,
122  // and exceptional paths.
123  bool HasLiveReturn = false;
124  bool HasFakeEdge = false;
125  bool HasPlainEdge = false;
126  bool HasAbnormalEdge = false;
127
128  // Ignore default cases that aren't likely to be reachable because all
129  // enums in a switch(X) have explicit case statements.
130  CFGBlock::FilterOptions FO;
131  FO.IgnoreDefaultsWithCoveredEnums = 1;
132
133  for (CFGBlock::filtered_pred_iterator
134	 I = cfg->getExit().filtered_pred_start_end(FO); I.hasMore(); ++I) {
135    const CFGBlock& B = **I;
136    if (!live[B.getBlockID()])
137      continue;
138
139    // Skip blocks which contain an element marked as no-return. They don't
140    // represent actually viable edges into the exit block, so mark them as
141    // abnormal.
142    if (B.hasNoReturnElement()) {
143      HasAbnormalEdge = true;
144      continue;
145    }
146
147    // Destructors can appear after the 'return' in the CFG.  This is
148    // normal.  We need to look pass the destructors for the return
149    // statement (if it exists).
150    CFGBlock::const_reverse_iterator ri = B.rbegin(), re = B.rend();
151
152    for ( ; ri != re ; ++ri)
153      if (isa<CFGStmt>(*ri))
154        break;
155
156    // No more CFGElements in the block?
157    if (ri == re) {
158      if (B.getTerminator() && isa<CXXTryStmt>(B.getTerminator())) {
159        HasAbnormalEdge = true;
160        continue;
161      }
162      // A labeled empty statement, or the entry block...
163      HasPlainEdge = true;
164      continue;
165    }
166
167    CFGStmt CS = cast<CFGStmt>(*ri);
168    const Stmt *S = CS.getStmt();
169    if (isa<ReturnStmt>(S)) {
170      HasLiveReturn = true;
171      continue;
172    }
173    if (isa<ObjCAtThrowStmt>(S)) {
174      HasFakeEdge = true;
175      continue;
176    }
177    if (isa<CXXThrowExpr>(S)) {
178      HasFakeEdge = true;
179      continue;
180    }
181    if (const AsmStmt *AS = dyn_cast<AsmStmt>(S)) {
182      if (AS->isMSAsm()) {
183        HasFakeEdge = true;
184        HasLiveReturn = true;
185        continue;
186      }
187    }
188    if (isa<CXXTryStmt>(S)) {
189      HasAbnormalEdge = true;
190      continue;
191    }
192    if (std::find(B.succ_begin(), B.succ_end(), &cfg->getExit())
193        == B.succ_end()) {
194      HasAbnormalEdge = true;
195      continue;
196    }
197
198    HasPlainEdge = true;
199  }
200  if (!HasPlainEdge) {
201    if (HasLiveReturn)
202      return NeverFallThrough;
203    return NeverFallThroughOrReturn;
204  }
205  if (HasAbnormalEdge || HasFakeEdge || HasLiveReturn)
206    return MaybeFallThrough;
207  // This says AlwaysFallThrough for calls to functions that are not marked
208  // noreturn, that don't return.  If people would like this warning to be more
209  // accurate, such functions should be marked as noreturn.
210  return AlwaysFallThrough;
211}
212
213namespace {
214
215struct CheckFallThroughDiagnostics {
216  unsigned diag_MaybeFallThrough_HasNoReturn;
217  unsigned diag_MaybeFallThrough_ReturnsNonVoid;
218  unsigned diag_AlwaysFallThrough_HasNoReturn;
219  unsigned diag_AlwaysFallThrough_ReturnsNonVoid;
220  unsigned diag_NeverFallThroughOrReturn;
221  bool funMode;
222  SourceLocation FuncLoc;
223
224  static CheckFallThroughDiagnostics MakeForFunction(const Decl *Func) {
225    CheckFallThroughDiagnostics D;
226    D.FuncLoc = Func->getLocation();
227    D.diag_MaybeFallThrough_HasNoReturn =
228      diag::warn_falloff_noreturn_function;
229    D.diag_MaybeFallThrough_ReturnsNonVoid =
230      diag::warn_maybe_falloff_nonvoid_function;
231    D.diag_AlwaysFallThrough_HasNoReturn =
232      diag::warn_falloff_noreturn_function;
233    D.diag_AlwaysFallThrough_ReturnsNonVoid =
234      diag::warn_falloff_nonvoid_function;
235
236    // Don't suggest that virtual functions be marked "noreturn", since they
237    // might be overridden by non-noreturn functions.
238    bool isVirtualMethod = false;
239    if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Func))
240      isVirtualMethod = Method->isVirtual();
241
242    // Don't suggest that template instantiations be marked "noreturn"
243    bool isTemplateInstantiation = false;
244    if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(Func)) {
245      switch (Function->getTemplateSpecializationKind()) {
246      case TSK_Undeclared:
247      case TSK_ExplicitSpecialization:
248        break;
249
250      case TSK_ImplicitInstantiation:
251      case TSK_ExplicitInstantiationDeclaration:
252      case TSK_ExplicitInstantiationDefinition:
253        isTemplateInstantiation = true;
254        break;
255      }
256    }
257
258    if (!isVirtualMethod && !isTemplateInstantiation)
259      D.diag_NeverFallThroughOrReturn =
260        diag::warn_suggest_noreturn_function;
261    else
262      D.diag_NeverFallThroughOrReturn = 0;
263
264    D.funMode = true;
265    return D;
266  }
267
268  static CheckFallThroughDiagnostics MakeForBlock() {
269    CheckFallThroughDiagnostics D;
270    D.diag_MaybeFallThrough_HasNoReturn =
271      diag::err_noreturn_block_has_return_expr;
272    D.diag_MaybeFallThrough_ReturnsNonVoid =
273      diag::err_maybe_falloff_nonvoid_block;
274    D.diag_AlwaysFallThrough_HasNoReturn =
275      diag::err_noreturn_block_has_return_expr;
276    D.diag_AlwaysFallThrough_ReturnsNonVoid =
277      diag::err_falloff_nonvoid_block;
278    D.diag_NeverFallThroughOrReturn =
279      diag::warn_suggest_noreturn_block;
280    D.funMode = false;
281    return D;
282  }
283
284  bool checkDiagnostics(DiagnosticsEngine &D, bool ReturnsVoid,
285                        bool HasNoReturn) const {
286    if (funMode) {
287      return (ReturnsVoid ||
288              D.getDiagnosticLevel(diag::warn_maybe_falloff_nonvoid_function,
289                                   FuncLoc) == DiagnosticsEngine::Ignored)
290        && (!HasNoReturn ||
291            D.getDiagnosticLevel(diag::warn_noreturn_function_has_return_expr,
292                                 FuncLoc) == DiagnosticsEngine::Ignored)
293        && (!ReturnsVoid ||
294            D.getDiagnosticLevel(diag::warn_suggest_noreturn_block, FuncLoc)
295              == DiagnosticsEngine::Ignored);
296    }
297
298    // For blocks.
299    return  ReturnsVoid && !HasNoReturn
300            && (!ReturnsVoid ||
301                D.getDiagnosticLevel(diag::warn_suggest_noreturn_block, FuncLoc)
302                  == DiagnosticsEngine::Ignored);
303  }
304};
305
306}
307
308/// CheckFallThroughForFunctionDef - Check that we don't fall off the end of a
309/// function that should return a value.  Check that we don't fall off the end
310/// of a noreturn function.  We assume that functions and blocks not marked
311/// noreturn will return.
312static void CheckFallThroughForBody(Sema &S, const Decl *D, const Stmt *Body,
313                                    const BlockExpr *blkExpr,
314                                    const CheckFallThroughDiagnostics& CD,
315                                    AnalysisContext &AC) {
316
317  bool ReturnsVoid = false;
318  bool HasNoReturn = false;
319
320  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
321    ReturnsVoid = FD->getResultType()->isVoidType();
322    HasNoReturn = FD->hasAttr<NoReturnAttr>() ||
323       FD->getType()->getAs<FunctionType>()->getNoReturnAttr();
324  }
325  else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
326    ReturnsVoid = MD->getResultType()->isVoidType();
327    HasNoReturn = MD->hasAttr<NoReturnAttr>();
328  }
329  else if (isa<BlockDecl>(D)) {
330    QualType BlockTy = blkExpr->getType();
331    if (const FunctionType *FT =
332          BlockTy->getPointeeType()->getAs<FunctionType>()) {
333      if (FT->getResultType()->isVoidType())
334        ReturnsVoid = true;
335      if (FT->getNoReturnAttr())
336        HasNoReturn = true;
337    }
338  }
339
340  DiagnosticsEngine &Diags = S.getDiagnostics();
341
342  // Short circuit for compilation speed.
343  if (CD.checkDiagnostics(Diags, ReturnsVoid, HasNoReturn))
344      return;
345
346  // FIXME: Function try block
347  if (const CompoundStmt *Compound = dyn_cast<CompoundStmt>(Body)) {
348    switch (CheckFallThrough(AC)) {
349      case UnknownFallThrough:
350        break;
351
352      case MaybeFallThrough:
353        if (HasNoReturn)
354          S.Diag(Compound->getRBracLoc(),
355                 CD.diag_MaybeFallThrough_HasNoReturn);
356        else if (!ReturnsVoid)
357          S.Diag(Compound->getRBracLoc(),
358                 CD.diag_MaybeFallThrough_ReturnsNonVoid);
359        break;
360      case AlwaysFallThrough:
361        if (HasNoReturn)
362          S.Diag(Compound->getRBracLoc(),
363                 CD.diag_AlwaysFallThrough_HasNoReturn);
364        else if (!ReturnsVoid)
365          S.Diag(Compound->getRBracLoc(),
366                 CD.diag_AlwaysFallThrough_ReturnsNonVoid);
367        break;
368      case NeverFallThroughOrReturn:
369        if (ReturnsVoid && !HasNoReturn && CD.diag_NeverFallThroughOrReturn) {
370          if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
371            S.Diag(Compound->getLBracLoc(), CD.diag_NeverFallThroughOrReturn)
372              << 0 << FD;
373          } else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
374            S.Diag(Compound->getLBracLoc(), CD.diag_NeverFallThroughOrReturn)
375              << 1 << MD;
376          } else {
377            S.Diag(Compound->getLBracLoc(), CD.diag_NeverFallThroughOrReturn);
378          }
379        }
380        break;
381      case NeverFallThrough:
382        break;
383    }
384  }
385}
386
387//===----------------------------------------------------------------------===//
388// -Wuninitialized
389//===----------------------------------------------------------------------===//
390
391namespace {
392/// ContainsReference - A visitor class to search for references to
393/// a particular declaration (the needle) within any evaluated component of an
394/// expression (recursively).
395class ContainsReference : public EvaluatedExprVisitor<ContainsReference> {
396  bool FoundReference;
397  const DeclRefExpr *Needle;
398
399public:
400  ContainsReference(ASTContext &Context, const DeclRefExpr *Needle)
401    : EvaluatedExprVisitor<ContainsReference>(Context),
402      FoundReference(false), Needle(Needle) {}
403
404  void VisitExpr(Expr *E) {
405    // Stop evaluating if we already have a reference.
406    if (FoundReference)
407      return;
408
409    EvaluatedExprVisitor<ContainsReference>::VisitExpr(E);
410  }
411
412  void VisitDeclRefExpr(DeclRefExpr *E) {
413    if (E == Needle)
414      FoundReference = true;
415    else
416      EvaluatedExprVisitor<ContainsReference>::VisitDeclRefExpr(E);
417  }
418
419  bool doesContainReference() const { return FoundReference; }
420};
421}
422
423static bool SuggestInitializationFixit(Sema &S, const VarDecl *VD) {
424  // Don't issue a fixit if there is already an initializer.
425  if (VD->getInit())
426    return false;
427
428  // Suggest possible initialization (if any).
429  const char *initialization = 0;
430  QualType VariableTy = VD->getType().getCanonicalType();
431
432  if (VariableTy->isObjCObjectPointerType() ||
433      VariableTy->isBlockPointerType()) {
434    // Check if 'nil' is defined.
435    if (S.PP.getMacroInfo(&S.getASTContext().Idents.get("nil")))
436      initialization = " = nil";
437    else
438      initialization = " = 0";
439  }
440  else if (VariableTy->isRealFloatingType())
441    initialization = " = 0.0";
442  else if (VariableTy->isBooleanType() && S.Context.getLangOptions().CPlusPlus)
443    initialization = " = false";
444  else if (VariableTy->isEnumeralType())
445    return false;
446  else if (VariableTy->isPointerType() || VariableTy->isMemberPointerType()) {
447    if (S.Context.getLangOptions().CPlusPlus0x)
448      initialization = " = nullptr";
449    // Check if 'NULL' is defined.
450    else if (S.PP.getMacroInfo(&S.getASTContext().Idents.get("NULL")))
451      initialization = " = NULL";
452    else
453      initialization = " = 0";
454  }
455  else if (VariableTy->isScalarType())
456    initialization = " = 0";
457
458  if (initialization) {
459    SourceLocation loc = S.PP.getLocForEndOfToken(VD->getLocEnd());
460    S.Diag(loc, diag::note_var_fixit_add_initialization) << VD->getDeclName()
461      << FixItHint::CreateInsertion(loc, initialization);
462    return true;
463  }
464  return false;
465}
466
467/// DiagnoseUninitializedUse -- Helper function for diagnosing uses of an
468/// uninitialized variable. This manages the different forms of diagnostic
469/// emitted for particular types of uses. Returns true if the use was diagnosed
470/// as a warning. If a pariticular use is one we omit warnings for, returns
471/// false.
472static bool DiagnoseUninitializedUse(Sema &S, const VarDecl *VD,
473                                     const Expr *E, bool isAlwaysUninit,
474                                     bool alwaysReportSelfInit = false) {
475  bool isSelfInit = false;
476
477  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
478    if (isAlwaysUninit) {
479      // Inspect the initializer of the variable declaration which is
480      // being referenced prior to its initialization. We emit
481      // specialized diagnostics for self-initialization, and we
482      // specifically avoid warning about self references which take the
483      // form of:
484      //
485      //   int x = x;
486      //
487      // This is used to indicate to GCC that 'x' is intentionally left
488      // uninitialized. Proven code paths which access 'x' in
489      // an uninitialized state after this will still warn.
490      //
491      // TODO: Should we suppress maybe-uninitialized warnings for
492      // variables initialized in this way?
493      if (const Expr *Initializer = VD->getInit()) {
494        if (!alwaysReportSelfInit && DRE == Initializer->IgnoreParenImpCasts())
495          return false;
496
497        ContainsReference CR(S.Context, DRE);
498        CR.Visit(const_cast<Expr*>(Initializer));
499        isSelfInit = CR.doesContainReference();
500      }
501      if (isSelfInit) {
502        S.Diag(DRE->getLocStart(),
503               diag::warn_uninit_self_reference_in_init)
504        << VD->getDeclName() << VD->getLocation() << DRE->getSourceRange();
505      } else {
506        S.Diag(DRE->getLocStart(), diag::warn_uninit_var)
507          << VD->getDeclName() << DRE->getSourceRange();
508      }
509    } else {
510      S.Diag(DRE->getLocStart(), diag::warn_maybe_uninit_var)
511        << VD->getDeclName() << DRE->getSourceRange();
512    }
513  } else {
514    const BlockExpr *BE = cast<BlockExpr>(E);
515    S.Diag(BE->getLocStart(),
516           isAlwaysUninit ? diag::warn_uninit_var_captured_by_block
517                          : diag::warn_maybe_uninit_var_captured_by_block)
518      << VD->getDeclName();
519  }
520
521  // Report where the variable was declared when the use wasn't within
522  // the initializer of that declaration & we didn't already suggest
523  // an initialization fixit.
524  if (!isSelfInit && !SuggestInitializationFixit(S, VD))
525    S.Diag(VD->getLocStart(), diag::note_uninit_var_def)
526      << VD->getDeclName();
527
528  return true;
529}
530
531typedef std::pair<const Expr*, bool> UninitUse;
532
533namespace {
534struct SLocSort {
535  bool operator()(const UninitUse &a, const UninitUse &b) {
536    SourceLocation aLoc = a.first->getLocStart();
537    SourceLocation bLoc = b.first->getLocStart();
538    return aLoc.getRawEncoding() < bLoc.getRawEncoding();
539  }
540};
541
542class UninitValsDiagReporter : public UninitVariablesHandler {
543  Sema &S;
544  typedef SmallVector<UninitUse, 2> UsesVec;
545  typedef llvm::DenseMap<const VarDecl *, std::pair<UsesVec*, bool> > UsesMap;
546  UsesMap *uses;
547
548public:
549  UninitValsDiagReporter(Sema &S) : S(S), uses(0) {}
550  ~UninitValsDiagReporter() {
551    flushDiagnostics();
552  }
553
554  std::pair<UsesVec*, bool> &getUses(const VarDecl *vd) {
555    if (!uses)
556      uses = new UsesMap();
557
558    UsesMap::mapped_type &V = (*uses)[vd];
559    UsesVec *&vec = V.first;
560    if (!vec)
561      vec = new UsesVec();
562
563    return V;
564  }
565
566  void handleUseOfUninitVariable(const Expr *ex, const VarDecl *vd,
567                                 bool isAlwaysUninit) {
568    getUses(vd).first->push_back(std::make_pair(ex, isAlwaysUninit));
569  }
570
571  void handleSelfInit(const VarDecl *vd) {
572    getUses(vd).second = true;
573  }
574
575  void flushDiagnostics() {
576    if (!uses)
577      return;
578
579    for (UsesMap::iterator i = uses->begin(), e = uses->end(); i != e; ++i) {
580      const VarDecl *vd = i->first;
581      const UsesMap::mapped_type &V = i->second;
582
583      UsesVec *vec = V.first;
584      bool hasSelfInit = V.second;
585
586      // Specially handle the case where we have uses of an uninitialized
587      // variable, but the root cause is an idiomatic self-init.  We want
588      // to report the diagnostic at the self-init since that is the root cause.
589      if (!vec->empty() && hasSelfInit)
590        DiagnoseUninitializedUse(S, vd, vd->getInit()->IgnoreParenCasts(),
591                                 true, /* alwaysReportSelfInit */ true);
592      else {
593        // Sort the uses by their SourceLocations.  While not strictly
594        // guaranteed to produce them in line/column order, this will provide
595        // a stable ordering.
596        std::sort(vec->begin(), vec->end(), SLocSort());
597
598        for (UsesVec::iterator vi = vec->begin(), ve = vec->end(); vi != ve;
599             ++vi) {
600          if (DiagnoseUninitializedUse(S, vd, vi->first,
601                                        /*isAlwaysUninit=*/vi->second))
602            // Skip further diagnostics for this variable. We try to warn only
603            // on the first point at which a variable is used uninitialized.
604            break;
605        }
606      }
607
608      // Release the uses vector.
609      delete vec;
610    }
611    delete uses;
612  }
613};
614}
615
616
617//===----------------------------------------------------------------------===//
618// -Wthread-safety
619//===----------------------------------------------------------------------===//
620namespace clang {
621namespace thread_safety {
622typedef std::pair<SourceLocation, PartialDiagnostic> DelayedDiag;
623typedef llvm::SmallVector<DelayedDiag, 4> DiagList;
624
625struct SortDiagBySourceLocation {
626  Sema &S;
627  SortDiagBySourceLocation(Sema &S) : S(S) {}
628
629  bool operator()(const DelayedDiag &left, const DelayedDiag &right) {
630    // Although this call will be slow, this is only called when outputting
631    // multiple warnings.
632    return S.getSourceManager().isBeforeInTranslationUnit(left.first,
633                                                          right.first);
634  }
635};
636
637class ThreadSafetyReporter : public clang::thread_safety::ThreadSafetyHandler {
638  Sema &S;
639  DiagList Warnings;
640
641  // Helper functions
642  void warnLockMismatch(unsigned DiagID, Name LockName, SourceLocation Loc) {
643    PartialDiagnostic Warning = S.PDiag(DiagID) << LockName;
644    Warnings.push_back(DelayedDiag(Loc, Warning));
645  }
646
647 public:
648  ThreadSafetyReporter(Sema &S) : S(S) {}
649
650  /// \brief Emit all buffered diagnostics in order of sourcelocation.
651  /// We need to output diagnostics produced while iterating through
652  /// the lockset in deterministic order, so this function orders diagnostics
653  /// and outputs them.
654  void emitDiagnostics() {
655    SortDiagBySourceLocation SortDiagBySL(S);
656    sort(Warnings.begin(), Warnings.end(), SortDiagBySL);
657    for (DiagList::iterator I = Warnings.begin(), E = Warnings.end();
658         I != E; ++I)
659      S.Diag(I->first, I->second);
660  }
661
662  void handleInvalidLockExp(SourceLocation Loc) {
663    PartialDiagnostic Warning = S.PDiag(diag::warn_cannot_resolve_lock) << Loc;
664    Warnings.push_back(DelayedDiag(Loc, Warning));
665  }
666  void handleUnmatchedUnlock(Name LockName, SourceLocation Loc) {
667    warnLockMismatch(diag::warn_unlock_but_no_lock, LockName, Loc);
668  }
669
670  void handleDoubleLock(Name LockName, SourceLocation Loc) {
671    warnLockMismatch(diag::warn_double_lock, LockName, Loc);
672  }
673
674  void handleMutexHeldEndOfScope(Name LockName, SourceLocation Loc,
675                                 LockErrorKind LEK){
676    unsigned DiagID = 0;
677    switch (LEK) {
678      case LEK_LockedSomePredecessors:
679        DiagID = diag::warn_lock_at_end_of_scope;
680        break;
681      case LEK_LockedSomeLoopIterations:
682        DiagID = diag::warn_expecting_lock_held_on_loop;
683        break;
684      case LEK_LockedAtEndOfFunction:
685        DiagID = diag::warn_no_unlock;
686        break;
687    }
688    warnLockMismatch(DiagID, LockName, Loc);
689  }
690
691
692  void handleExclusiveAndShared(Name LockName, SourceLocation Loc1,
693                                SourceLocation Loc2) {
694    PartialDiagnostic Warning =
695      S.PDiag(diag::warn_lock_exclusive_and_shared) << LockName;
696    PartialDiagnostic Note =
697      S.PDiag(diag::note_lock_exclusive_and_shared) << LockName;
698    Warnings.push_back(DelayedDiag(Loc1, Warning));
699    Warnings.push_back(DelayedDiag(Loc2, Note));
700  }
701
702  void handleNoMutexHeld(const NamedDecl *D, ProtectedOperationKind POK,
703                         AccessKind AK, SourceLocation Loc) {
704    assert((POK == POK_VarAccess || POK == POK_VarDereference)
705             && "Only works for variables");
706    unsigned DiagID = POK == POK_VarAccess?
707                        diag::warn_variable_requires_any_lock:
708                        diag::warn_var_deref_requires_any_lock;
709    PartialDiagnostic Warning = S.PDiag(DiagID)
710      << D->getName() << getLockKindFromAccessKind(AK);
711    Warnings.push_back(DelayedDiag(Loc, Warning));
712  }
713
714  void handleMutexNotHeld(const NamedDecl *D, ProtectedOperationKind POK,
715                          Name LockName, LockKind LK, SourceLocation Loc) {
716    unsigned DiagID = 0;
717    switch (POK) {
718      case POK_VarAccess:
719        DiagID = diag::warn_variable_requires_lock;
720        break;
721      case POK_VarDereference:
722        DiagID = diag::warn_var_deref_requires_lock;
723        break;
724      case POK_FunctionCall:
725        DiagID = diag::warn_fun_requires_lock;
726        break;
727    }
728    PartialDiagnostic Warning = S.PDiag(DiagID)
729      << D->getName() << LockName << LK;
730    Warnings.push_back(DelayedDiag(Loc, Warning));
731  }
732
733  void handleFunExcludesLock(Name FunName, Name LockName, SourceLocation Loc) {
734    PartialDiagnostic Warning =
735      S.PDiag(diag::warn_fun_excludes_mutex) << FunName << LockName;
736    Warnings.push_back(DelayedDiag(Loc, Warning));
737  }
738};
739}
740}
741
742//===----------------------------------------------------------------------===//
743// AnalysisBasedWarnings - Worker object used by Sema to execute analysis-based
744//  warnings on a function, method, or block.
745//===----------------------------------------------------------------------===//
746
747clang::sema::AnalysisBasedWarnings::Policy::Policy() {
748  enableCheckFallThrough = 1;
749  enableCheckUnreachable = 0;
750  enableThreadSafetyAnalysis = 0;
751}
752
753clang::sema::AnalysisBasedWarnings::AnalysisBasedWarnings(Sema &s)
754  : S(s),
755    NumFunctionsAnalyzed(0),
756    NumFunctionsWithBadCFGs(0),
757    NumCFGBlocks(0),
758    MaxCFGBlocksPerFunction(0),
759    NumUninitAnalysisFunctions(0),
760    NumUninitAnalysisVariables(0),
761    MaxUninitAnalysisVariablesPerFunction(0),
762    NumUninitAnalysisBlockVisits(0),
763    MaxUninitAnalysisBlockVisitsPerFunction(0) {
764  DiagnosticsEngine &D = S.getDiagnostics();
765  DefaultPolicy.enableCheckUnreachable = (unsigned)
766    (D.getDiagnosticLevel(diag::warn_unreachable, SourceLocation()) !=
767        DiagnosticsEngine::Ignored);
768  DefaultPolicy.enableThreadSafetyAnalysis = (unsigned)
769    (D.getDiagnosticLevel(diag::warn_double_lock, SourceLocation()) !=
770     DiagnosticsEngine::Ignored);
771
772}
773
774static void flushDiagnostics(Sema &S, sema::FunctionScopeInfo *fscope) {
775  for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
776       i = fscope->PossiblyUnreachableDiags.begin(),
777       e = fscope->PossiblyUnreachableDiags.end();
778       i != e; ++i) {
779    const sema::PossiblyUnreachableDiag &D = *i;
780    S.Diag(D.Loc, D.PD);
781  }
782}
783
784void clang::sema::
785AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
786                                     sema::FunctionScopeInfo *fscope,
787                                     const Decl *D, const BlockExpr *blkExpr) {
788
789  // We avoid doing analysis-based warnings when there are errors for
790  // two reasons:
791  // (1) The CFGs often can't be constructed (if the body is invalid), so
792  //     don't bother trying.
793  // (2) The code already has problems; running the analysis just takes more
794  //     time.
795  DiagnosticsEngine &Diags = S.getDiagnostics();
796
797  // Do not do any analysis for declarations in system headers if we are
798  // going to just ignore them.
799  if (Diags.getSuppressSystemWarnings() &&
800      S.SourceMgr.isInSystemHeader(D->getLocation()))
801    return;
802
803  // For code in dependent contexts, we'll do this at instantiation time.
804  if (cast<DeclContext>(D)->isDependentContext())
805    return;
806
807  if (Diags.hasErrorOccurred() || Diags.hasFatalErrorOccurred()) {
808    // Flush out any possibly unreachable diagnostics.
809    flushDiagnostics(S, fscope);
810    return;
811  }
812
813  const Stmt *Body = D->getBody();
814  assert(Body);
815
816  AnalysisContext AC(D, 0);
817
818  // Don't generate EH edges for CallExprs as we'd like to avoid the n^2
819  // explosion for destrutors that can result and the compile time hit.
820  AC.getCFGBuildOptions().PruneTriviallyFalseEdges = true;
821  AC.getCFGBuildOptions().AddEHEdges = false;
822  AC.getCFGBuildOptions().AddInitializers = true;
823  AC.getCFGBuildOptions().AddImplicitDtors = true;
824
825  // Force that certain expressions appear as CFGElements in the CFG.  This
826  // is used to speed up various analyses.
827  // FIXME: This isn't the right factoring.  This is here for initial
828  // prototyping, but we need a way for analyses to say what expressions they
829  // expect to always be CFGElements and then fill in the BuildOptions
830  // appropriately.  This is essentially a layering violation.
831  if (P.enableCheckUnreachable) {
832    // Unreachable code analysis requires a linearized CFG.
833    AC.getCFGBuildOptions().setAllAlwaysAdd();
834  }
835  else {
836    AC.getCFGBuildOptions()
837      .setAlwaysAdd(Stmt::BinaryOperatorClass)
838      .setAlwaysAdd(Stmt::BlockExprClass)
839      .setAlwaysAdd(Stmt::CStyleCastExprClass)
840      .setAlwaysAdd(Stmt::DeclRefExprClass)
841      .setAlwaysAdd(Stmt::ImplicitCastExprClass)
842      .setAlwaysAdd(Stmt::UnaryOperatorClass);
843  }
844
845  // Construct the analysis context with the specified CFG build options.
846
847  // Emit delayed diagnostics.
848  if (!fscope->PossiblyUnreachableDiags.empty()) {
849    bool analyzed = false;
850
851    // Register the expressions with the CFGBuilder.
852    for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
853         i = fscope->PossiblyUnreachableDiags.begin(),
854         e = fscope->PossiblyUnreachableDiags.end();
855         i != e; ++i) {
856      if (const Stmt *stmt = i->stmt)
857        AC.registerForcedBlockExpression(stmt);
858    }
859
860    if (AC.getCFG()) {
861      analyzed = true;
862      for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
863            i = fscope->PossiblyUnreachableDiags.begin(),
864            e = fscope->PossiblyUnreachableDiags.end();
865            i != e; ++i)
866      {
867        const sema::PossiblyUnreachableDiag &D = *i;
868        bool processed = false;
869        if (const Stmt *stmt = i->stmt) {
870          const CFGBlock *block = AC.getBlockForRegisteredExpression(stmt);
871          assert(block);
872          if (CFGReverseBlockReachabilityAnalysis *cra = AC.getCFGReachablityAnalysis()) {
873            // Can this block be reached from the entrance?
874            if (cra->isReachable(&AC.getCFG()->getEntry(), block))
875              S.Diag(D.Loc, D.PD);
876            processed = true;
877          }
878        }
879        if (!processed) {
880          // Emit the warning anyway if we cannot map to a basic block.
881          S.Diag(D.Loc, D.PD);
882        }
883      }
884    }
885
886    if (!analyzed)
887      flushDiagnostics(S, fscope);
888  }
889
890
891  // Warning: check missing 'return'
892  if (P.enableCheckFallThrough) {
893    const CheckFallThroughDiagnostics &CD =
894      (isa<BlockDecl>(D) ? CheckFallThroughDiagnostics::MakeForBlock()
895                         : CheckFallThroughDiagnostics::MakeForFunction(D));
896    CheckFallThroughForBody(S, D, Body, blkExpr, CD, AC);
897  }
898
899  // Warning: check for unreachable code
900  if (P.enableCheckUnreachable)
901    CheckUnreachable(S, AC);
902
903  // Check for thread safety violations
904  if (P.enableThreadSafetyAnalysis) {
905    thread_safety::ThreadSafetyReporter Reporter(S);
906    thread_safety::runThreadSafetyAnalysis(AC, Reporter);
907    Reporter.emitDiagnostics();
908  }
909
910  if (Diags.getDiagnosticLevel(diag::warn_uninit_var, D->getLocStart())
911      != DiagnosticsEngine::Ignored ||
912      Diags.getDiagnosticLevel(diag::warn_maybe_uninit_var, D->getLocStart())
913      != DiagnosticsEngine::Ignored) {
914    if (CFG *cfg = AC.getCFG()) {
915      UninitValsDiagReporter reporter(S);
916      UninitVariablesAnalysisStats stats;
917      std::memset(&stats, 0, sizeof(UninitVariablesAnalysisStats));
918      runUninitializedVariablesAnalysis(*cast<DeclContext>(D), *cfg, AC,
919                                        reporter, stats);
920
921      if (S.CollectStats && stats.NumVariablesAnalyzed > 0) {
922        ++NumUninitAnalysisFunctions;
923        NumUninitAnalysisVariables += stats.NumVariablesAnalyzed;
924        NumUninitAnalysisBlockVisits += stats.NumBlockVisits;
925        MaxUninitAnalysisVariablesPerFunction =
926            std::max(MaxUninitAnalysisVariablesPerFunction,
927                     stats.NumVariablesAnalyzed);
928        MaxUninitAnalysisBlockVisitsPerFunction =
929            std::max(MaxUninitAnalysisBlockVisitsPerFunction,
930                     stats.NumBlockVisits);
931      }
932    }
933  }
934
935  // Collect statistics about the CFG if it was built.
936  if (S.CollectStats && AC.isCFGBuilt()) {
937    ++NumFunctionsAnalyzed;
938    if (CFG *cfg = AC.getCFG()) {
939      // If we successfully built a CFG for this context, record some more
940      // detail information about it.
941      NumCFGBlocks += cfg->getNumBlockIDs();
942      MaxCFGBlocksPerFunction = std::max(MaxCFGBlocksPerFunction,
943                                         cfg->getNumBlockIDs());
944    } else {
945      ++NumFunctionsWithBadCFGs;
946    }
947  }
948}
949
950void clang::sema::AnalysisBasedWarnings::PrintStats() const {
951  llvm::errs() << "\n*** Analysis Based Warnings Stats:\n";
952
953  unsigned NumCFGsBuilt = NumFunctionsAnalyzed - NumFunctionsWithBadCFGs;
954  unsigned AvgCFGBlocksPerFunction =
955      !NumCFGsBuilt ? 0 : NumCFGBlocks/NumCFGsBuilt;
956  llvm::errs() << NumFunctionsAnalyzed << " functions analyzed ("
957               << NumFunctionsWithBadCFGs << " w/o CFGs).\n"
958               << "  " << NumCFGBlocks << " CFG blocks built.\n"
959               << "  " << AvgCFGBlocksPerFunction
960               << " average CFG blocks per function.\n"
961               << "  " << MaxCFGBlocksPerFunction
962               << " max CFG blocks per function.\n";
963
964  unsigned AvgUninitVariablesPerFunction = !NumUninitAnalysisFunctions ? 0
965      : NumUninitAnalysisVariables/NumUninitAnalysisFunctions;
966  unsigned AvgUninitBlockVisitsPerFunction = !NumUninitAnalysisFunctions ? 0
967      : NumUninitAnalysisBlockVisits/NumUninitAnalysisFunctions;
968  llvm::errs() << NumUninitAnalysisFunctions
969               << " functions analyzed for uninitialiazed variables\n"
970               << "  " << NumUninitAnalysisVariables << " variables analyzed.\n"
971               << "  " << AvgUninitVariablesPerFunction
972               << " average variables per function.\n"
973               << "  " << MaxUninitAnalysisVariablesPerFunction
974               << " max variables per function.\n"
975               << "  " << NumUninitAnalysisBlockVisits << " block visits.\n"
976               << "  " << AvgUninitBlockVisitsPerFunction
977               << " average block visits per function.\n"
978               << "  " << MaxUninitAnalysisBlockVisitsPerFunction
979               << " max block visits per function.\n";
980}
981