1 //=- AnalysisBasedWarnings.cpp - Sema warnings based on libAnalysis -*- C++ -*-=//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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.
14 //===----------------------------------------------------------------------===//
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"
47 using namespace clang;
49 //===----------------------------------------------------------------------===//
50 // Unreachable code analysis.
51 //===----------------------------------------------------------------------===//
54 class UnreachableCodeHandler : public reachable_code::Callback {
57 UnreachableCodeHandler(Sema &s) : S(s) {}
59 void HandleUnreachable(SourceLocation L, SourceRange R1, SourceRange R2) {
60 S.Diag(L, diag::warn_unreachable) << R1 << R2;
65 /// CheckUnreachable - Check for unreachable code.
66 static void CheckUnreachable(Sema &S, AnalysisDeclContext &AC) {
67 UnreachableCodeHandler UC(S);
68 reachable_code::FindUnreachableCode(AC, UC);
71 //===----------------------------------------------------------------------===//
72 // Check for missing return value.
73 //===----------------------------------------------------------------------===//
75 enum ControlFlowKind {
80 NeverFallThroughOrReturn
83 /// CheckFallThrough - Check that we don't fall off the end of a
84 /// Statement that should return a value.
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
92 static ControlFlowKind CheckFallThrough(AnalysisDeclContext &AC) {
93 CFG *cfg = AC.getCFG();
94 if (cfg == 0) return UnknownFallThrough;
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(),
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) {
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);
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;
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;
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()])
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
142 if (B.hasNoReturnElement()) {
143 HasAbnormalEdge = true;
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();
152 for ( ; ri != re ; ++ri)
153 if (isa<CFGStmt>(*ri))
156 // No more CFGElements in the block?
158 if (B.getTerminator() && isa<CXXTryStmt>(B.getTerminator())) {
159 HasAbnormalEdge = true;
162 // A labeled empty statement, or the entry block...
167 CFGStmt CS = cast<CFGStmt>(*ri);
168 const Stmt *S = CS.getStmt();
169 if (isa<ReturnStmt>(S)) {
170 HasLiveReturn = true;
173 if (isa<ObjCAtThrowStmt>(S)) {
177 if (isa<CXXThrowExpr>(S)) {
181 if (const AsmStmt *AS = dyn_cast<AsmStmt>(S)) {
184 HasLiveReturn = true;
188 if (isa<CXXTryStmt>(S)) {
189 HasAbnormalEdge = true;
192 if (std::find(B.succ_begin(), B.succ_end(), &cfg->getExit())
194 HasAbnormalEdge = true;
202 return NeverFallThrough;
203 return NeverFallThroughOrReturn;
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;
215 struct 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 enum { Function, Block, Lambda } funMode;
222 SourceLocation FuncLoc;
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;
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();
242 // Don't suggest that template instantiations be marked "noreturn"
243 bool isTemplateInstantiation = false;
244 if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(Func))
245 isTemplateInstantiation = Function->isTemplateInstantiation();
247 if (!isVirtualMethod && !isTemplateInstantiation)
248 D.diag_NeverFallThroughOrReturn =
249 diag::warn_suggest_noreturn_function;
251 D.diag_NeverFallThroughOrReturn = 0;
253 D.funMode = Function;
257 static CheckFallThroughDiagnostics MakeForBlock() {
258 CheckFallThroughDiagnostics D;
259 D.diag_MaybeFallThrough_HasNoReturn =
260 diag::err_noreturn_block_has_return_expr;
261 D.diag_MaybeFallThrough_ReturnsNonVoid =
262 diag::err_maybe_falloff_nonvoid_block;
263 D.diag_AlwaysFallThrough_HasNoReturn =
264 diag::err_noreturn_block_has_return_expr;
265 D.diag_AlwaysFallThrough_ReturnsNonVoid =
266 diag::err_falloff_nonvoid_block;
267 D.diag_NeverFallThroughOrReturn =
268 diag::warn_suggest_noreturn_block;
273 static CheckFallThroughDiagnostics MakeForLambda() {
274 CheckFallThroughDiagnostics D;
275 D.diag_MaybeFallThrough_HasNoReturn =
276 diag::err_noreturn_lambda_has_return_expr;
277 D.diag_MaybeFallThrough_ReturnsNonVoid =
278 diag::warn_maybe_falloff_nonvoid_lambda;
279 D.diag_AlwaysFallThrough_HasNoReturn =
280 diag::err_noreturn_lambda_has_return_expr;
281 D.diag_AlwaysFallThrough_ReturnsNonVoid =
282 diag::warn_falloff_nonvoid_lambda;
283 D.diag_NeverFallThroughOrReturn = 0;
288 bool checkDiagnostics(DiagnosticsEngine &D, bool ReturnsVoid,
289 bool HasNoReturn) const {
290 if (funMode == Function) {
291 return (ReturnsVoid ||
292 D.getDiagnosticLevel(diag::warn_maybe_falloff_nonvoid_function,
293 FuncLoc) == DiagnosticsEngine::Ignored)
295 D.getDiagnosticLevel(diag::warn_noreturn_function_has_return_expr,
296 FuncLoc) == DiagnosticsEngine::Ignored)
298 D.getDiagnosticLevel(diag::warn_suggest_noreturn_block, FuncLoc)
299 == DiagnosticsEngine::Ignored);
302 // For blocks / lambdas.
303 return ReturnsVoid && !HasNoReturn
304 && ((funMode == Lambda) ||
305 D.getDiagnosticLevel(diag::warn_suggest_noreturn_block, FuncLoc)
306 == DiagnosticsEngine::Ignored);
312 /// CheckFallThroughForFunctionDef - Check that we don't fall off the end of a
313 /// function that should return a value. Check that we don't fall off the end
314 /// of a noreturn function. We assume that functions and blocks not marked
315 /// noreturn will return.
316 static void CheckFallThroughForBody(Sema &S, const Decl *D, const Stmt *Body,
317 const BlockExpr *blkExpr,
318 const CheckFallThroughDiagnostics& CD,
319 AnalysisDeclContext &AC) {
321 bool ReturnsVoid = false;
322 bool HasNoReturn = false;
324 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
325 ReturnsVoid = FD->getResultType()->isVoidType();
326 HasNoReturn = FD->hasAttr<NoReturnAttr>() ||
327 FD->getType()->getAs<FunctionType>()->getNoReturnAttr();
329 else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
330 ReturnsVoid = MD->getResultType()->isVoidType();
331 HasNoReturn = MD->hasAttr<NoReturnAttr>();
333 else if (isa<BlockDecl>(D)) {
334 QualType BlockTy = blkExpr->getType();
335 if (const FunctionType *FT =
336 BlockTy->getPointeeType()->getAs<FunctionType>()) {
337 if (FT->getResultType()->isVoidType())
339 if (FT->getNoReturnAttr())
344 DiagnosticsEngine &Diags = S.getDiagnostics();
346 // Short circuit for compilation speed.
347 if (CD.checkDiagnostics(Diags, ReturnsVoid, HasNoReturn))
350 // FIXME: Function try block
351 if (const CompoundStmt *Compound = dyn_cast<CompoundStmt>(Body)) {
352 switch (CheckFallThrough(AC)) {
353 case UnknownFallThrough:
356 case MaybeFallThrough:
358 S.Diag(Compound->getRBracLoc(),
359 CD.diag_MaybeFallThrough_HasNoReturn);
360 else if (!ReturnsVoid)
361 S.Diag(Compound->getRBracLoc(),
362 CD.diag_MaybeFallThrough_ReturnsNonVoid);
364 case AlwaysFallThrough:
366 S.Diag(Compound->getRBracLoc(),
367 CD.diag_AlwaysFallThrough_HasNoReturn);
368 else if (!ReturnsVoid)
369 S.Diag(Compound->getRBracLoc(),
370 CD.diag_AlwaysFallThrough_ReturnsNonVoid);
372 case NeverFallThroughOrReturn:
373 if (ReturnsVoid && !HasNoReturn && CD.diag_NeverFallThroughOrReturn) {
374 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
375 S.Diag(Compound->getLBracLoc(), CD.diag_NeverFallThroughOrReturn)
377 } else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
378 S.Diag(Compound->getLBracLoc(), CD.diag_NeverFallThroughOrReturn)
381 S.Diag(Compound->getLBracLoc(), CD.diag_NeverFallThroughOrReturn);
385 case NeverFallThrough:
391 //===----------------------------------------------------------------------===//
393 //===----------------------------------------------------------------------===//
396 /// ContainsReference - A visitor class to search for references to
397 /// a particular declaration (the needle) within any evaluated component of an
398 /// expression (recursively).
399 class ContainsReference : public EvaluatedExprVisitor<ContainsReference> {
401 const DeclRefExpr *Needle;
404 ContainsReference(ASTContext &Context, const DeclRefExpr *Needle)
405 : EvaluatedExprVisitor<ContainsReference>(Context),
406 FoundReference(false), Needle(Needle) {}
408 void VisitExpr(Expr *E) {
409 // Stop evaluating if we already have a reference.
413 EvaluatedExprVisitor<ContainsReference>::VisitExpr(E);
416 void VisitDeclRefExpr(DeclRefExpr *E) {
418 FoundReference = true;
420 EvaluatedExprVisitor<ContainsReference>::VisitDeclRefExpr(E);
423 bool doesContainReference() const { return FoundReference; }
427 static bool SuggestInitializationFixit(Sema &S, const VarDecl *VD) {
428 QualType VariableTy = VD->getType().getCanonicalType();
429 if (VariableTy->isBlockPointerType() &&
430 !VD->hasAttr<BlocksAttr>()) {
431 S.Diag(VD->getLocation(), diag::note_block_var_fixit_add_initialization) << VD->getDeclName()
432 << FixItHint::CreateInsertion(VD->getLocation(), "__block ");
436 // Don't issue a fixit if there is already an initializer.
440 // Suggest possible initialization (if any).
441 const char *Init = S.getFixItZeroInitializerForType(VariableTy);
444 SourceLocation Loc = S.PP.getLocForEndOfToken(VD->getLocEnd());
446 S.Diag(Loc, diag::note_var_fixit_add_initialization) << VD->getDeclName()
447 << FixItHint::CreateInsertion(Loc, Init);
451 /// DiagnoseUninitializedUse -- Helper function for diagnosing uses of an
452 /// uninitialized variable. This manages the different forms of diagnostic
453 /// emitted for particular types of uses. Returns true if the use was diagnosed
454 /// as a warning. If a pariticular use is one we omit warnings for, returns
456 static bool DiagnoseUninitializedUse(Sema &S, const VarDecl *VD,
457 const Expr *E, bool isAlwaysUninit,
458 bool alwaysReportSelfInit = false) {
459 bool isSelfInit = false;
461 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
462 if (isAlwaysUninit) {
463 // Inspect the initializer of the variable declaration which is
464 // being referenced prior to its initialization. We emit
465 // specialized diagnostics for self-initialization, and we
466 // specifically avoid warning about self references which take the
471 // This is used to indicate to GCC that 'x' is intentionally left
472 // uninitialized. Proven code paths which access 'x' in
473 // an uninitialized state after this will still warn.
475 // TODO: Should we suppress maybe-uninitialized warnings for
476 // variables initialized in this way?
477 if (const Expr *Initializer = VD->getInit()) {
478 if (!alwaysReportSelfInit && DRE == Initializer->IgnoreParenImpCasts())
481 ContainsReference CR(S.Context, DRE);
482 CR.Visit(const_cast<Expr*>(Initializer));
483 isSelfInit = CR.doesContainReference();
486 S.Diag(DRE->getLocStart(),
487 diag::warn_uninit_self_reference_in_init)
488 << VD->getDeclName() << VD->getLocation() << DRE->getSourceRange();
490 S.Diag(DRE->getLocStart(), diag::warn_uninit_var)
491 << VD->getDeclName() << DRE->getSourceRange();
494 S.Diag(DRE->getLocStart(), diag::warn_maybe_uninit_var)
495 << VD->getDeclName() << DRE->getSourceRange();
498 const BlockExpr *BE = cast<BlockExpr>(E);
499 if (VD->getType()->isBlockPointerType() &&
500 !VD->hasAttr<BlocksAttr>())
501 S.Diag(BE->getLocStart(), diag::warn_uninit_byref_blockvar_captured_by_block)
502 << VD->getDeclName();
504 S.Diag(BE->getLocStart(),
505 isAlwaysUninit ? diag::warn_uninit_var_captured_by_block
506 : diag::warn_maybe_uninit_var_captured_by_block)
507 << VD->getDeclName();
510 // Report where the variable was declared when the use wasn't within
511 // the initializer of that declaration & we didn't already suggest
512 // an initialization fixit.
513 if (!isSelfInit && !SuggestInitializationFixit(S, VD))
514 S.Diag(VD->getLocStart(), diag::note_uninit_var_def)
515 << VD->getDeclName();
520 typedef std::pair<const Expr*, bool> UninitUse;
524 bool operator()(const UninitUse &a, const UninitUse &b) {
525 SourceLocation aLoc = a.first->getLocStart();
526 SourceLocation bLoc = b.first->getLocStart();
527 return aLoc.getRawEncoding() < bLoc.getRawEncoding();
531 class UninitValsDiagReporter : public UninitVariablesHandler {
533 typedef SmallVector<UninitUse, 2> UsesVec;
534 typedef llvm::DenseMap<const VarDecl *, std::pair<UsesVec*, bool> > UsesMap;
538 UninitValsDiagReporter(Sema &S) : S(S), uses(0) {}
539 ~UninitValsDiagReporter() {
543 std::pair<UsesVec*, bool> &getUses(const VarDecl *vd) {
545 uses = new UsesMap();
547 UsesMap::mapped_type &V = (*uses)[vd];
548 UsesVec *&vec = V.first;
555 void handleUseOfUninitVariable(const Expr *ex, const VarDecl *vd,
556 bool isAlwaysUninit) {
557 getUses(vd).first->push_back(std::make_pair(ex, isAlwaysUninit));
560 void handleSelfInit(const VarDecl *vd) {
561 getUses(vd).second = true;
564 void flushDiagnostics() {
568 for (UsesMap::iterator i = uses->begin(), e = uses->end(); i != e; ++i) {
569 const VarDecl *vd = i->first;
570 const UsesMap::mapped_type &V = i->second;
572 UsesVec *vec = V.first;
573 bool hasSelfInit = V.second;
575 // Specially handle the case where we have uses of an uninitialized
576 // variable, but the root cause is an idiomatic self-init. We want
577 // to report the diagnostic at the self-init since that is the root cause.
578 if (!vec->empty() && hasSelfInit && hasAlwaysUninitializedUse(vec))
579 DiagnoseUninitializedUse(S, vd, vd->getInit()->IgnoreParenCasts(),
580 /* isAlwaysUninit */ true,
581 /* alwaysReportSelfInit */ true);
583 // Sort the uses by their SourceLocations. While not strictly
584 // guaranteed to produce them in line/column order, this will provide
585 // a stable ordering.
586 std::sort(vec->begin(), vec->end(), SLocSort());
588 for (UsesVec::iterator vi = vec->begin(), ve = vec->end(); vi != ve;
590 if (DiagnoseUninitializedUse(S, vd, vi->first,
591 /*isAlwaysUninit=*/vi->second))
592 // Skip further diagnostics for this variable. We try to warn only
593 // on the first point at which a variable is used uninitialized.
598 // Release the uses vector.
605 static bool hasAlwaysUninitializedUse(const UsesVec* vec) {
606 for (UsesVec::const_iterator i = vec->begin(), e = vec->end(); i != e; ++i) {
617 //===----------------------------------------------------------------------===//
619 //===----------------------------------------------------------------------===//
621 namespace thread_safety {
622 typedef llvm::SmallVector<PartialDiagnosticAt, 1> OptionalNotes;
623 typedef std::pair<PartialDiagnosticAt, OptionalNotes> DelayedDiag;
624 typedef std::list<DelayedDiag> DiagList;
626 struct SortDiagBySourceLocation {
628 SortDiagBySourceLocation(SourceManager &SM) : SM(SM) {}
630 bool operator()(const DelayedDiag &left, const DelayedDiag &right) {
631 // Although this call will be slow, this is only called when outputting
632 // multiple warnings.
633 return SM.isBeforeInTranslationUnit(left.first.first, right.first.first);
638 class ThreadSafetyReporter : public clang::thread_safety::ThreadSafetyHandler {
641 SourceLocation FunLocation, FunEndLocation;
644 void warnLockMismatch(unsigned DiagID, Name LockName, SourceLocation Loc) {
645 // Gracefully handle rare cases when the analysis can't get a more
646 // precise source location.
649 PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID) << LockName);
650 Warnings.push_back(DelayedDiag(Warning, OptionalNotes()));
654 ThreadSafetyReporter(Sema &S, SourceLocation FL, SourceLocation FEL)
655 : S(S), FunLocation(FL), FunEndLocation(FEL) {}
657 /// \brief Emit all buffered diagnostics in order of sourcelocation.
658 /// We need to output diagnostics produced while iterating through
659 /// the lockset in deterministic order, so this function orders diagnostics
660 /// and outputs them.
661 void emitDiagnostics() {
662 Warnings.sort(SortDiagBySourceLocation(S.getSourceManager()));
663 for (DiagList::iterator I = Warnings.begin(), E = Warnings.end();
665 S.Diag(I->first.first, I->first.second);
666 const OptionalNotes &Notes = I->second;
667 for (unsigned NoteI = 0, NoteN = Notes.size(); NoteI != NoteN; ++NoteI)
668 S.Diag(Notes[NoteI].first, Notes[NoteI].second);
672 void handleInvalidLockExp(SourceLocation Loc) {
673 PartialDiagnosticAt Warning(Loc,
674 S.PDiag(diag::warn_cannot_resolve_lock) << Loc);
675 Warnings.push_back(DelayedDiag(Warning, OptionalNotes()));
677 void handleUnmatchedUnlock(Name LockName, SourceLocation Loc) {
678 warnLockMismatch(diag::warn_unlock_but_no_lock, LockName, Loc);
681 void handleDoubleLock(Name LockName, SourceLocation Loc) {
682 warnLockMismatch(diag::warn_double_lock, LockName, Loc);
685 void handleMutexHeldEndOfScope(Name LockName, SourceLocation LocLocked,
686 SourceLocation LocEndOfScope,
690 case LEK_LockedSomePredecessors:
691 DiagID = diag::warn_lock_some_predecessors;
693 case LEK_LockedSomeLoopIterations:
694 DiagID = diag::warn_expecting_lock_held_on_loop;
696 case LEK_LockedAtEndOfFunction:
697 DiagID = diag::warn_no_unlock;
700 if (LocEndOfScope.isInvalid())
701 LocEndOfScope = FunEndLocation;
703 PartialDiagnosticAt Warning(LocEndOfScope, S.PDiag(DiagID) << LockName);
704 PartialDiagnosticAt Note(LocLocked, S.PDiag(diag::note_locked_here));
705 Warnings.push_back(DelayedDiag(Warning, OptionalNotes(1, Note)));
709 void handleExclusiveAndShared(Name LockName, SourceLocation Loc1,
710 SourceLocation Loc2) {
711 PartialDiagnosticAt Warning(
712 Loc1, S.PDiag(diag::warn_lock_exclusive_and_shared) << LockName);
713 PartialDiagnosticAt Note(
714 Loc2, S.PDiag(diag::note_lock_exclusive_and_shared) << LockName);
715 Warnings.push_back(DelayedDiag(Warning, OptionalNotes(1, Note)));
718 void handleNoMutexHeld(const NamedDecl *D, ProtectedOperationKind POK,
719 AccessKind AK, SourceLocation Loc) {
720 assert((POK == POK_VarAccess || POK == POK_VarDereference)
721 && "Only works for variables");
722 unsigned DiagID = POK == POK_VarAccess?
723 diag::warn_variable_requires_any_lock:
724 diag::warn_var_deref_requires_any_lock;
725 PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID)
726 << D->getName() << getLockKindFromAccessKind(AK));
727 Warnings.push_back(DelayedDiag(Warning, OptionalNotes()));
730 void handleMutexNotHeld(const NamedDecl *D, ProtectedOperationKind POK,
731 Name LockName, LockKind LK, SourceLocation Loc) {
735 DiagID = diag::warn_variable_requires_lock;
737 case POK_VarDereference:
738 DiagID = diag::warn_var_deref_requires_lock;
740 case POK_FunctionCall:
741 DiagID = diag::warn_fun_requires_lock;
744 PartialDiagnosticAt Warning(Loc, S.PDiag(DiagID)
745 << D->getName() << LockName << LK);
746 Warnings.push_back(DelayedDiag(Warning, OptionalNotes()));
749 void handleFunExcludesLock(Name FunName, Name LockName, SourceLocation Loc) {
750 PartialDiagnosticAt Warning(Loc,
751 S.PDiag(diag::warn_fun_excludes_mutex) << FunName << LockName);
752 Warnings.push_back(DelayedDiag(Warning, OptionalNotes()));
759 //===----------------------------------------------------------------------===//
760 // AnalysisBasedWarnings - Worker object used by Sema to execute analysis-based
761 // warnings on a function, method, or block.
762 //===----------------------------------------------------------------------===//
764 clang::sema::AnalysisBasedWarnings::Policy::Policy() {
765 enableCheckFallThrough = 1;
766 enableCheckUnreachable = 0;
767 enableThreadSafetyAnalysis = 0;
770 clang::sema::AnalysisBasedWarnings::AnalysisBasedWarnings(Sema &s)
772 NumFunctionsAnalyzed(0),
773 NumFunctionsWithBadCFGs(0),
775 MaxCFGBlocksPerFunction(0),
776 NumUninitAnalysisFunctions(0),
777 NumUninitAnalysisVariables(0),
778 MaxUninitAnalysisVariablesPerFunction(0),
779 NumUninitAnalysisBlockVisits(0),
780 MaxUninitAnalysisBlockVisitsPerFunction(0) {
781 DiagnosticsEngine &D = S.getDiagnostics();
782 DefaultPolicy.enableCheckUnreachable = (unsigned)
783 (D.getDiagnosticLevel(diag::warn_unreachable, SourceLocation()) !=
784 DiagnosticsEngine::Ignored);
785 DefaultPolicy.enableThreadSafetyAnalysis = (unsigned)
786 (D.getDiagnosticLevel(diag::warn_double_lock, SourceLocation()) !=
787 DiagnosticsEngine::Ignored);
791 static void flushDiagnostics(Sema &S, sema::FunctionScopeInfo *fscope) {
792 for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
793 i = fscope->PossiblyUnreachableDiags.begin(),
794 e = fscope->PossiblyUnreachableDiags.end();
796 const sema::PossiblyUnreachableDiag &D = *i;
802 AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
803 sema::FunctionScopeInfo *fscope,
804 const Decl *D, const BlockExpr *blkExpr) {
806 // We avoid doing analysis-based warnings when there are errors for
808 // (1) The CFGs often can't be constructed (if the body is invalid), so
809 // don't bother trying.
810 // (2) The code already has problems; running the analysis just takes more
812 DiagnosticsEngine &Diags = S.getDiagnostics();
814 // Do not do any analysis for declarations in system headers if we are
815 // going to just ignore them.
816 if (Diags.getSuppressSystemWarnings() &&
817 S.SourceMgr.isInSystemHeader(D->getLocation()))
820 // For code in dependent contexts, we'll do this at instantiation time.
821 if (cast<DeclContext>(D)->isDependentContext())
824 if (Diags.hasErrorOccurred() || Diags.hasFatalErrorOccurred()) {
825 // Flush out any possibly unreachable diagnostics.
826 flushDiagnostics(S, fscope);
830 const Stmt *Body = D->getBody();
833 AnalysisDeclContext AC(/* AnalysisDeclContextManager */ 0, D, 0);
835 // Don't generate EH edges for CallExprs as we'd like to avoid the n^2
836 // explosion for destrutors that can result and the compile time hit.
837 AC.getCFGBuildOptions().PruneTriviallyFalseEdges = true;
838 AC.getCFGBuildOptions().AddEHEdges = false;
839 AC.getCFGBuildOptions().AddInitializers = true;
840 AC.getCFGBuildOptions().AddImplicitDtors = true;
842 // Force that certain expressions appear as CFGElements in the CFG. This
843 // is used to speed up various analyses.
844 // FIXME: This isn't the right factoring. This is here for initial
845 // prototyping, but we need a way for analyses to say what expressions they
846 // expect to always be CFGElements and then fill in the BuildOptions
847 // appropriately. This is essentially a layering violation.
848 if (P.enableCheckUnreachable || P.enableThreadSafetyAnalysis) {
849 // Unreachable code analysis and thread safety require a linearized CFG.
850 AC.getCFGBuildOptions().setAllAlwaysAdd();
853 AC.getCFGBuildOptions()
854 .setAlwaysAdd(Stmt::BinaryOperatorClass)
855 .setAlwaysAdd(Stmt::BlockExprClass)
856 .setAlwaysAdd(Stmt::CStyleCastExprClass)
857 .setAlwaysAdd(Stmt::DeclRefExprClass)
858 .setAlwaysAdd(Stmt::ImplicitCastExprClass)
859 .setAlwaysAdd(Stmt::UnaryOperatorClass);
862 // Construct the analysis context with the specified CFG build options.
864 // Emit delayed diagnostics.
865 if (!fscope->PossiblyUnreachableDiags.empty()) {
866 bool analyzed = false;
868 // Register the expressions with the CFGBuilder.
869 for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
870 i = fscope->PossiblyUnreachableDiags.begin(),
871 e = fscope->PossiblyUnreachableDiags.end();
873 if (const Stmt *stmt = i->stmt)
874 AC.registerForcedBlockExpression(stmt);
879 for (SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
880 i = fscope->PossiblyUnreachableDiags.begin(),
881 e = fscope->PossiblyUnreachableDiags.end();
884 const sema::PossiblyUnreachableDiag &D = *i;
885 bool processed = false;
886 if (const Stmt *stmt = i->stmt) {
887 const CFGBlock *block = AC.getBlockForRegisteredExpression(stmt);
888 CFGReverseBlockReachabilityAnalysis *cra =
889 AC.getCFGReachablityAnalysis();
890 // FIXME: We should be able to assert that block is non-null, but
891 // the CFG analysis can skip potentially-evaluated expressions in
892 // edge cases; see test/Sema/vla-2.c.
894 // Can this block be reached from the entrance?
895 if (cra->isReachable(&AC.getCFG()->getEntry(), block))
901 // Emit the warning anyway if we cannot map to a basic block.
908 flushDiagnostics(S, fscope);
912 // Warning: check missing 'return'
913 if (P.enableCheckFallThrough) {
914 const CheckFallThroughDiagnostics &CD =
915 (isa<BlockDecl>(D) ? CheckFallThroughDiagnostics::MakeForBlock()
916 : (isa<CXXMethodDecl>(D) &&
917 cast<CXXMethodDecl>(D)->getOverloadedOperator() == OO_Call &&
918 cast<CXXMethodDecl>(D)->getParent()->isLambda())
919 ? CheckFallThroughDiagnostics::MakeForLambda()
920 : CheckFallThroughDiagnostics::MakeForFunction(D));
921 CheckFallThroughForBody(S, D, Body, blkExpr, CD, AC);
924 // Warning: check for unreachable code
925 if (P.enableCheckUnreachable) {
926 // Only check for unreachable code on non-template instantiations.
927 // Different template instantiations can effectively change the control-flow
928 // and it is very difficult to prove that a snippet of code in a template
929 // is unreachable for all instantiations.
930 bool isTemplateInstantiation = false;
931 if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D))
932 isTemplateInstantiation = Function->isTemplateInstantiation();
933 if (!isTemplateInstantiation)
934 CheckUnreachable(S, AC);
937 // Check for thread safety violations
938 if (P.enableThreadSafetyAnalysis) {
939 SourceLocation FL = AC.getDecl()->getLocation();
940 SourceLocation FEL = AC.getDecl()->getLocEnd();
941 thread_safety::ThreadSafetyReporter Reporter(S, FL, FEL);
942 thread_safety::runThreadSafetyAnalysis(AC, Reporter);
943 Reporter.emitDiagnostics();
946 if (Diags.getDiagnosticLevel(diag::warn_uninit_var, D->getLocStart())
947 != DiagnosticsEngine::Ignored ||
948 Diags.getDiagnosticLevel(diag::warn_maybe_uninit_var, D->getLocStart())
949 != DiagnosticsEngine::Ignored) {
950 if (CFG *cfg = AC.getCFG()) {
951 UninitValsDiagReporter reporter(S);
952 UninitVariablesAnalysisStats stats;
953 std::memset(&stats, 0, sizeof(UninitVariablesAnalysisStats));
954 runUninitializedVariablesAnalysis(*cast<DeclContext>(D), *cfg, AC,
957 if (S.CollectStats && stats.NumVariablesAnalyzed > 0) {
958 ++NumUninitAnalysisFunctions;
959 NumUninitAnalysisVariables += stats.NumVariablesAnalyzed;
960 NumUninitAnalysisBlockVisits += stats.NumBlockVisits;
961 MaxUninitAnalysisVariablesPerFunction =
962 std::max(MaxUninitAnalysisVariablesPerFunction,
963 stats.NumVariablesAnalyzed);
964 MaxUninitAnalysisBlockVisitsPerFunction =
965 std::max(MaxUninitAnalysisBlockVisitsPerFunction,
966 stats.NumBlockVisits);
971 // Collect statistics about the CFG if it was built.
972 if (S.CollectStats && AC.isCFGBuilt()) {
973 ++NumFunctionsAnalyzed;
974 if (CFG *cfg = AC.getCFG()) {
975 // If we successfully built a CFG for this context, record some more
976 // detail information about it.
977 NumCFGBlocks += cfg->getNumBlockIDs();
978 MaxCFGBlocksPerFunction = std::max(MaxCFGBlocksPerFunction,
979 cfg->getNumBlockIDs());
981 ++NumFunctionsWithBadCFGs;
986 void clang::sema::AnalysisBasedWarnings::PrintStats() const {
987 llvm::errs() << "\n*** Analysis Based Warnings Stats:\n";
989 unsigned NumCFGsBuilt = NumFunctionsAnalyzed - NumFunctionsWithBadCFGs;
990 unsigned AvgCFGBlocksPerFunction =
991 !NumCFGsBuilt ? 0 : NumCFGBlocks/NumCFGsBuilt;
992 llvm::errs() << NumFunctionsAnalyzed << " functions analyzed ("
993 << NumFunctionsWithBadCFGs << " w/o CFGs).\n"
994 << " " << NumCFGBlocks << " CFG blocks built.\n"
995 << " " << AvgCFGBlocksPerFunction
996 << " average CFG blocks per function.\n"
997 << " " << MaxCFGBlocksPerFunction
998 << " max CFG blocks per function.\n";
1000 unsigned AvgUninitVariablesPerFunction = !NumUninitAnalysisFunctions ? 0
1001 : NumUninitAnalysisVariables/NumUninitAnalysisFunctions;
1002 unsigned AvgUninitBlockVisitsPerFunction = !NumUninitAnalysisFunctions ? 0
1003 : NumUninitAnalysisBlockVisits/NumUninitAnalysisFunctions;
1004 llvm::errs() << NumUninitAnalysisFunctions
1005 << " functions analyzed for uninitialiazed variables\n"
1006 << " " << NumUninitAnalysisVariables << " variables analyzed.\n"
1007 << " " << AvgUninitVariablesPerFunction
1008 << " average variables per function.\n"
1009 << " " << MaxUninitAnalysisVariablesPerFunction
1010 << " max variables per function.\n"
1011 << " " << NumUninitAnalysisBlockVisits << " block visits.\n"
1012 << " " << AvgUninitBlockVisitsPerFunction
1013 << " average block visits per function.\n"
1014 << " " << MaxUninitAnalysisBlockVisitsPerFunction
1015 << " max block visits per function.\n";