1 //===--- JumpDiagnostics.cpp - Protected scope jump analysis ------*- 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 implements the JumpScopeChecker class, which is used to diagnose
11 // jumps that enter a protected scope in an invalid way.
13 //===----------------------------------------------------------------------===//
15 #include "clang/Sema/SemaInternal.h"
16 #include "clang/AST/DeclCXX.h"
17 #include "clang/AST/Expr.h"
18 #include "clang/AST/ExprCXX.h"
19 #include "clang/AST/StmtCXX.h"
20 #include "clang/AST/StmtObjC.h"
21 #include "llvm/ADT/BitVector.h"
22 using namespace clang;
26 /// JumpScopeChecker - This object is used by Sema to diagnose invalid jumps
27 /// into VLA and other protected scopes. For example, this rejects:
32 class JumpScopeChecker {
35 /// Permissive - True when recovering from errors, in which case precautions
36 /// are taken to handle incomplete scope information.
37 const bool Permissive;
39 /// GotoScope - This is a record that we use to keep track of all of the
40 /// scopes that are introduced by VLAs and other things that scope jumps like
41 /// gotos. This scope tree has nothing to do with the source scope tree,
42 /// because you can have multiple VLA scopes per compound statement, and most
43 /// compound statements don't introduce any scopes.
45 /// ParentScope - The index in ScopeMap of the parent scope. This is 0 for
46 /// the parent scope is the function body.
49 /// InDiag - The note to emit if there is a jump into this scope.
52 /// OutDiag - The note to emit if there is an indirect jump out
53 /// of this scope. Direct jumps always clean up their current scope
54 /// in an orderly way.
57 /// Loc - Location to emit the diagnostic.
60 GotoScope(unsigned parentScope, unsigned InDiag, unsigned OutDiag,
62 : ParentScope(parentScope), InDiag(InDiag), OutDiag(OutDiag), Loc(L) {}
65 SmallVector<GotoScope, 48> Scopes;
66 llvm::DenseMap<Stmt*, unsigned> LabelAndGotoScopes;
67 SmallVector<Stmt*, 16> Jumps;
69 SmallVector<IndirectGotoStmt*, 4> IndirectJumps;
70 SmallVector<LabelDecl*, 4> IndirectJumpTargets;
72 JumpScopeChecker(Stmt *Body, Sema &S);
74 void BuildScopeInformation(Decl *D, unsigned &ParentScope);
75 void BuildScopeInformation(VarDecl *D, const BlockDecl *BDecl,
76 unsigned &ParentScope);
77 void BuildScopeInformation(Stmt *S, unsigned &origParentScope);
80 void VerifyIndirectJumps();
81 void NoteJumpIntoScopes(ArrayRef<unsigned> ToScopes);
82 void DiagnoseIndirectJump(IndirectGotoStmt *IG, unsigned IGScope,
83 LabelDecl *Target, unsigned TargetScope);
84 void CheckJump(Stmt *From, Stmt *To, SourceLocation DiagLoc,
85 unsigned JumpDiag, unsigned JumpDiagWarning,
86 unsigned JumpDiagCXX98Compat);
87 void CheckGotoStmt(GotoStmt *GS);
89 unsigned GetDeepestCommonScope(unsigned A, unsigned B);
91 } // end anonymous namespace
93 #define CHECK_PERMISSIVE(x) (assert(Permissive || !(x)), (Permissive && (x)))
95 JumpScopeChecker::JumpScopeChecker(Stmt *Body, Sema &s)
96 : S(s), Permissive(s.hasAnyUnrecoverableErrorsInThisFunction()) {
97 // Add a scope entry for function scope.
98 Scopes.push_back(GotoScope(~0U, ~0U, ~0U, SourceLocation()));
100 // Build information for the top level compound statement, so that we have a
101 // defined scope record for every "goto" and label.
102 unsigned BodyParentScope = 0;
103 BuildScopeInformation(Body, BodyParentScope);
105 // Check that all jumps we saw are kosher.
107 VerifyIndirectJumps();
110 /// GetDeepestCommonScope - Finds the innermost scope enclosing the
112 unsigned JumpScopeChecker::GetDeepestCommonScope(unsigned A, unsigned B) {
114 // Inner scopes are created after outer scopes and therefore have
117 assert(Scopes[B].ParentScope < B);
118 B = Scopes[B].ParentScope;
120 assert(Scopes[A].ParentScope < A);
121 A = Scopes[A].ParentScope;
127 typedef std::pair<unsigned,unsigned> ScopePair;
129 /// GetDiagForGotoScopeDecl - If this decl induces a new goto scope, return a
130 /// diagnostic that should be emitted if control goes over it. If not, return 0.
131 static ScopePair GetDiagForGotoScopeDecl(Sema &S, const Decl *D) {
132 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
134 unsigned OutDiag = 0;
136 if (VD->getType()->isVariablyModifiedType())
137 InDiag = diag::note_protected_by_vla;
139 if (VD->hasAttr<BlocksAttr>())
140 return ScopePair(diag::note_protected_by___block,
141 diag::note_exits___block);
143 if (VD->hasAttr<CleanupAttr>())
144 return ScopePair(diag::note_protected_by_cleanup,
145 diag::note_exits_cleanup);
147 if (VD->hasLocalStorage()) {
148 switch (VD->getType().isDestructedType()) {
149 case QualType::DK_objc_strong_lifetime:
150 case QualType::DK_objc_weak_lifetime:
151 return ScopePair(diag::note_protected_by_objc_ownership,
152 diag::note_exits_objc_ownership);
154 case QualType::DK_cxx_destructor:
155 OutDiag = diag::note_exits_dtor;
158 case QualType::DK_none:
163 const Expr *Init = VD->getInit();
164 if (S.Context.getLangOpts().CPlusPlus && VD->hasLocalStorage() && Init) {
165 // C++11 [stmt.dcl]p3:
166 // A program that jumps from a point where a variable with automatic
167 // storage duration is not in scope to a point where it is in scope
168 // is ill-formed unless the variable has scalar type, class type with
169 // a trivial default constructor and a trivial destructor, a
170 // cv-qualified version of one of these types, or an array of one of
171 // the preceding types and is declared without an initializer.
173 // C++03 [stmt.dcl.p3:
174 // A program that jumps from a point where a local variable
175 // with automatic storage duration is not in scope to a point
176 // where it is in scope is ill-formed unless the variable has
177 // POD type and is declared without an initializer.
179 InDiag = diag::note_protected_by_variable_init;
181 // For a variable of (array of) class type declared without an
182 // initializer, we will have call-style initialization and the initializer
183 // will be the CXXConstructExpr with no intervening nodes.
184 if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(Init)) {
185 const CXXConstructorDecl *Ctor = CCE->getConstructor();
186 if (Ctor->isTrivial() && Ctor->isDefaultConstructor() &&
187 VD->getInitStyle() == VarDecl::CallInit) {
189 InDiag = diag::note_protected_by_variable_nontriv_destructor;
190 else if (!Ctor->getParent()->isPOD())
191 InDiag = diag::note_protected_by_variable_non_pod;
198 return ScopePair(InDiag, OutDiag);
201 if (const TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(D)) {
202 if (TD->getUnderlyingType()->isVariablyModifiedType())
203 return ScopePair(isa<TypedefDecl>(TD)
204 ? diag::note_protected_by_vla_typedef
205 : diag::note_protected_by_vla_type_alias,
209 return ScopePair(0U, 0U);
212 /// \brief Build scope information for a declaration that is part of a DeclStmt.
213 void JumpScopeChecker::BuildScopeInformation(Decl *D, unsigned &ParentScope) {
214 // If this decl causes a new scope, push and switch to it.
215 std::pair<unsigned,unsigned> Diags = GetDiagForGotoScopeDecl(S, D);
216 if (Diags.first || Diags.second) {
217 Scopes.push_back(GotoScope(ParentScope, Diags.first, Diags.second,
219 ParentScope = Scopes.size()-1;
222 // If the decl has an initializer, walk it with the potentially new
223 // scope we just installed.
224 if (VarDecl *VD = dyn_cast<VarDecl>(D))
225 if (Expr *Init = VD->getInit())
226 BuildScopeInformation(Init, ParentScope);
229 /// \brief Build scope information for a captured block literal variables.
230 void JumpScopeChecker::BuildScopeInformation(VarDecl *D,
231 const BlockDecl *BDecl,
232 unsigned &ParentScope) {
233 // exclude captured __block variables; there's no destructor
234 // associated with the block literal for them.
235 if (D->hasAttr<BlocksAttr>())
237 QualType T = D->getType();
238 QualType::DestructionKind destructKind = T.isDestructedType();
239 if (destructKind != QualType::DK_none) {
240 std::pair<unsigned,unsigned> Diags;
241 switch (destructKind) {
242 case QualType::DK_cxx_destructor:
243 Diags = ScopePair(diag::note_enters_block_captures_cxx_obj,
244 diag::note_exits_block_captures_cxx_obj);
246 case QualType::DK_objc_strong_lifetime:
247 Diags = ScopePair(diag::note_enters_block_captures_strong,
248 diag::note_exits_block_captures_strong);
250 case QualType::DK_objc_weak_lifetime:
251 Diags = ScopePair(diag::note_enters_block_captures_weak,
252 diag::note_exits_block_captures_weak);
254 case QualType::DK_none:
255 llvm_unreachable("non-lifetime captured variable");
257 SourceLocation Loc = D->getLocation();
259 Loc = BDecl->getLocation();
260 Scopes.push_back(GotoScope(ParentScope,
261 Diags.first, Diags.second, Loc));
262 ParentScope = Scopes.size()-1;
266 /// BuildScopeInformation - The statements from CI to CE are known to form a
267 /// coherent VLA scope with a specified parent node. Walk through the
268 /// statements, adding any labels or gotos to LabelAndGotoScopes and recursively
269 /// walking the AST as needed.
270 void JumpScopeChecker::BuildScopeInformation(Stmt *S, unsigned &origParentScope) {
271 // If this is a statement, rather than an expression, scopes within it don't
272 // propagate out into the enclosing scope. Otherwise we have to worry
273 // about block literals, which have the lifetime of their enclosing statement.
274 unsigned independentParentScope = origParentScope;
275 unsigned &ParentScope = ((isa<Expr>(S) && !isa<StmtExpr>(S))
276 ? origParentScope : independentParentScope);
278 bool SkipFirstSubStmt = false;
280 // If we found a label, remember that it is in ParentScope scope.
281 switch (S->getStmtClass()) {
282 case Stmt::AddrLabelExprClass:
283 IndirectJumpTargets.push_back(cast<AddrLabelExpr>(S)->getLabel());
286 case Stmt::IndirectGotoStmtClass:
287 // "goto *&&lbl;" is a special case which we treat as equivalent
288 // to a normal goto. In addition, we don't calculate scope in the
289 // operand (to avoid recording the address-of-label use), which
290 // works only because of the restricted set of expressions which
291 // we detect as constant targets.
292 if (cast<IndirectGotoStmt>(S)->getConstantTarget()) {
293 LabelAndGotoScopes[S] = ParentScope;
298 LabelAndGotoScopes[S] = ParentScope;
299 IndirectJumps.push_back(cast<IndirectGotoStmt>(S));
302 case Stmt::SwitchStmtClass:
303 // Evaluate the condition variable before entering the scope of the switch
305 if (VarDecl *Var = cast<SwitchStmt>(S)->getConditionVariable()) {
306 BuildScopeInformation(Var, ParentScope);
307 SkipFirstSubStmt = true;
311 case Stmt::GotoStmtClass:
312 // Remember both what scope a goto is in as well as the fact that we have
313 // it. This makes the second scan not have to walk the AST again.
314 LabelAndGotoScopes[S] = ParentScope;
318 case Stmt::CXXTryStmtClass: {
319 CXXTryStmt *TS = cast<CXXTryStmt>(S);
320 unsigned newParentScope;
321 Scopes.push_back(GotoScope(ParentScope,
322 diag::note_protected_by_cxx_try,
323 diag::note_exits_cxx_try,
324 TS->getSourceRange().getBegin()));
325 if (Stmt *TryBlock = TS->getTryBlock())
326 BuildScopeInformation(TryBlock, (newParentScope = Scopes.size()-1));
328 // Jump from the catch into the try is not allowed either.
329 for (unsigned I = 0, E = TS->getNumHandlers(); I != E; ++I) {
330 CXXCatchStmt *CS = TS->getHandler(I);
331 Scopes.push_back(GotoScope(ParentScope,
332 diag::note_protected_by_cxx_catch,
333 diag::note_exits_cxx_catch,
334 CS->getSourceRange().getBegin()));
335 BuildScopeInformation(CS->getHandlerBlock(),
336 (newParentScope = Scopes.size()-1));
341 case Stmt::SEHTryStmtClass: {
342 SEHTryStmt *TS = cast<SEHTryStmt>(S);
343 unsigned newParentScope;
344 Scopes.push_back(GotoScope(ParentScope,
345 diag::note_protected_by_seh_try,
346 diag::note_exits_seh_try,
347 TS->getSourceRange().getBegin()));
348 if (Stmt *TryBlock = TS->getTryBlock())
349 BuildScopeInformation(TryBlock, (newParentScope = Scopes.size()-1));
351 // Jump from __except or __finally into the __try are not allowed either.
352 if (SEHExceptStmt *Except = TS->getExceptHandler()) {
353 Scopes.push_back(GotoScope(ParentScope,
354 diag::note_protected_by_seh_except,
355 diag::note_exits_seh_except,
356 Except->getSourceRange().getBegin()));
357 BuildScopeInformation(Except->getBlock(),
358 (newParentScope = Scopes.size()-1));
359 } else if (SEHFinallyStmt *Finally = TS->getFinallyHandler()) {
360 Scopes.push_back(GotoScope(ParentScope,
361 diag::note_protected_by_seh_finally,
362 diag::note_exits_seh_finally,
363 Finally->getSourceRange().getBegin()));
364 BuildScopeInformation(Finally->getBlock(),
365 (newParentScope = Scopes.size()-1));
375 for (Stmt::child_range CI = S->children(); CI; ++CI) {
376 if (SkipFirstSubStmt) {
377 SkipFirstSubStmt = false;
382 if (!SubStmt) continue;
384 // Cases, labels, and defaults aren't "scope parents". It's also
385 // important to handle these iteratively instead of recursively in
386 // order to avoid blowing out the stack.
389 if (CaseStmt *CS = dyn_cast<CaseStmt>(SubStmt))
390 Next = CS->getSubStmt();
391 else if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SubStmt))
392 Next = DS->getSubStmt();
393 else if (LabelStmt *LS = dyn_cast<LabelStmt>(SubStmt))
394 Next = LS->getSubStmt();
398 LabelAndGotoScopes[SubStmt] = ParentScope;
402 // If this is a declstmt with a VLA definition, it defines a scope from here
403 // to the end of the containing context.
404 if (DeclStmt *DS = dyn_cast<DeclStmt>(SubStmt)) {
405 // The decl statement creates a scope if any of the decls in it are VLAs
406 // or have the cleanup attribute.
407 for (auto *I : DS->decls())
408 BuildScopeInformation(I, ParentScope);
411 // Disallow jumps into any part of an @try statement by pushing a scope and
412 // walking all sub-stmts in that scope.
413 if (ObjCAtTryStmt *AT = dyn_cast<ObjCAtTryStmt>(SubStmt)) {
414 unsigned newParentScope;
415 // Recursively walk the AST for the @try part.
416 Scopes.push_back(GotoScope(ParentScope,
417 diag::note_protected_by_objc_try,
418 diag::note_exits_objc_try,
420 if (Stmt *TryPart = AT->getTryBody())
421 BuildScopeInformation(TryPart, (newParentScope = Scopes.size()-1));
423 // Jump from the catch to the finally or try is not valid.
424 for (unsigned I = 0, N = AT->getNumCatchStmts(); I != N; ++I) {
425 ObjCAtCatchStmt *AC = AT->getCatchStmt(I);
426 Scopes.push_back(GotoScope(ParentScope,
427 diag::note_protected_by_objc_catch,
428 diag::note_exits_objc_catch,
429 AC->getAtCatchLoc()));
430 // @catches are nested and it isn't
431 BuildScopeInformation(AC->getCatchBody(),
432 (newParentScope = Scopes.size()-1));
435 // Jump from the finally to the try or catch is not valid.
436 if (ObjCAtFinallyStmt *AF = AT->getFinallyStmt()) {
437 Scopes.push_back(GotoScope(ParentScope,
438 diag::note_protected_by_objc_finally,
439 diag::note_exits_objc_finally,
440 AF->getAtFinallyLoc()));
441 BuildScopeInformation(AF, (newParentScope = Scopes.size()-1));
447 unsigned newParentScope;
448 // Disallow jumps into the protected statement of an @synchronized, but
449 // allow jumps into the object expression it protects.
450 if (ObjCAtSynchronizedStmt *AS =
451 dyn_cast<ObjCAtSynchronizedStmt>(SubStmt)) {
452 // Recursively walk the AST for the @synchronized object expr, it is
453 // evaluated in the normal scope.
454 BuildScopeInformation(AS->getSynchExpr(), ParentScope);
456 // Recursively walk the AST for the @synchronized part, protected by a new
458 Scopes.push_back(GotoScope(ParentScope,
459 diag::note_protected_by_objc_synchronized,
460 diag::note_exits_objc_synchronized,
461 AS->getAtSynchronizedLoc()));
462 BuildScopeInformation(AS->getSynchBody(),
463 (newParentScope = Scopes.size()-1));
467 // Disallow jumps into the protected statement of an @autoreleasepool.
468 if (ObjCAutoreleasePoolStmt *AS =
469 dyn_cast<ObjCAutoreleasePoolStmt>(SubStmt)) {
470 // Recursively walk the AST for the @autoreleasepool part, protected by a
472 Scopes.push_back(GotoScope(ParentScope,
473 diag::note_protected_by_objc_autoreleasepool,
474 diag::note_exits_objc_autoreleasepool,
476 BuildScopeInformation(AS->getSubStmt(),
477 (newParentScope = Scopes.size() - 1));
481 // Disallow jumps past full-expressions that use blocks with
482 // non-trivial cleanups of their captures. This is theoretically
483 // implementable but a lot of work which we haven't felt up to doing.
484 if (ExprWithCleanups *EWC = dyn_cast<ExprWithCleanups>(SubStmt)) {
485 for (unsigned i = 0, e = EWC->getNumObjects(); i != e; ++i) {
486 const BlockDecl *BDecl = EWC->getObject(i);
487 for (const auto &CI : BDecl->captures()) {
488 VarDecl *variable = CI.getVariable();
489 BuildScopeInformation(variable, BDecl, ParentScope);
494 // Disallow jumps out of scopes containing temporaries lifetime-extended to
495 // automatic storage duration.
496 if (MaterializeTemporaryExpr *MTE =
497 dyn_cast<MaterializeTemporaryExpr>(SubStmt)) {
498 if (MTE->getStorageDuration() == SD_Automatic) {
499 SmallVector<const Expr *, 4> CommaLHS;
500 SmallVector<SubobjectAdjustment, 4> Adjustments;
501 const Expr *ExtendedObject =
502 MTE->GetTemporaryExpr()->skipRValueSubobjectAdjustments(
503 CommaLHS, Adjustments);
504 if (ExtendedObject->getType().isDestructedType()) {
505 Scopes.push_back(GotoScope(ParentScope, 0,
506 diag::note_exits_temporary_dtor,
507 ExtendedObject->getExprLoc()));
508 ParentScope = Scopes.size()-1;
513 // Recursively walk the AST.
514 BuildScopeInformation(SubStmt, ParentScope);
518 /// VerifyJumps - Verify each element of the Jumps array to see if they are
519 /// valid, emitting diagnostics if not.
520 void JumpScopeChecker::VerifyJumps() {
521 while (!Jumps.empty()) {
522 Stmt *Jump = Jumps.pop_back_val();
525 if (GotoStmt *GS = dyn_cast<GotoStmt>(Jump)) {
526 // The label may not have a statement if it's coming from inline MS ASM.
527 if (GS->getLabel()->getStmt()) {
528 CheckJump(GS, GS->getLabel()->getStmt(), GS->getGotoLoc(),
529 diag::err_goto_into_protected_scope,
530 diag::ext_goto_into_protected_scope,
531 diag::warn_cxx98_compat_goto_into_protected_scope);
537 // We only get indirect gotos here when they have a constant target.
538 if (IndirectGotoStmt *IGS = dyn_cast<IndirectGotoStmt>(Jump)) {
539 LabelDecl *Target = IGS->getConstantTarget();
540 CheckJump(IGS, Target->getStmt(), IGS->getGotoLoc(),
541 diag::err_goto_into_protected_scope,
542 diag::ext_goto_into_protected_scope,
543 diag::warn_cxx98_compat_goto_into_protected_scope);
547 SwitchStmt *SS = cast<SwitchStmt>(Jump);
548 for (SwitchCase *SC = SS->getSwitchCaseList(); SC;
549 SC = SC->getNextSwitchCase()) {
550 if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(SC)))
553 if (CaseStmt *CS = dyn_cast<CaseStmt>(SC))
554 Loc = CS->getLocStart();
555 else if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC))
556 Loc = DS->getLocStart();
558 Loc = SC->getLocStart();
559 CheckJump(SS, SC, Loc, diag::err_switch_into_protected_scope, 0,
560 diag::warn_cxx98_compat_switch_into_protected_scope);
565 /// VerifyIndirectJumps - Verify whether any possible indirect jump
566 /// might cross a protection boundary. Unlike direct jumps, indirect
567 /// jumps count cleanups as protection boundaries: since there's no
568 /// way to know where the jump is going, we can't implicitly run the
569 /// right cleanups the way we can with direct jumps.
571 /// Thus, an indirect jump is "trivial" if it bypasses no
572 /// initializations and no teardowns. More formally, an indirect jump
573 /// from A to B is trivial if the path out from A to DCA(A,B) is
574 /// trivial and the path in from DCA(A,B) to B is trivial, where
575 /// DCA(A,B) is the deepest common ancestor of A and B.
576 /// Jump-triviality is transitive but asymmetric.
578 /// A path in is trivial if none of the entered scopes have an InDiag.
579 /// A path out is trivial is none of the exited scopes have an OutDiag.
581 /// Under these definitions, this function checks that the indirect
582 /// jump between A and B is trivial for every indirect goto statement A
583 /// and every label B whose address was taken in the function.
584 void JumpScopeChecker::VerifyIndirectJumps() {
585 if (IndirectJumps.empty()) return;
587 // If there aren't any address-of-label expressions in this function,
588 // complain about the first indirect goto.
589 if (IndirectJumpTargets.empty()) {
590 S.Diag(IndirectJumps[0]->getGotoLoc(),
591 diag::err_indirect_goto_without_addrlabel);
595 // Collect a single representative of every scope containing an
596 // indirect goto. For most code bases, this substantially cuts
597 // down on the number of jump sites we'll have to consider later.
598 typedef std::pair<unsigned, IndirectGotoStmt*> JumpScope;
599 SmallVector<JumpScope, 32> JumpScopes;
601 llvm::DenseMap<unsigned, IndirectGotoStmt*> JumpScopesMap;
602 for (SmallVectorImpl<IndirectGotoStmt*>::iterator
603 I = IndirectJumps.begin(), E = IndirectJumps.end(); I != E; ++I) {
604 IndirectGotoStmt *IG = *I;
605 if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(IG)))
607 unsigned IGScope = LabelAndGotoScopes[IG];
608 IndirectGotoStmt *&Entry = JumpScopesMap[IGScope];
609 if (!Entry) Entry = IG;
611 JumpScopes.reserve(JumpScopesMap.size());
612 for (llvm::DenseMap<unsigned, IndirectGotoStmt*>::iterator
613 I = JumpScopesMap.begin(), E = JumpScopesMap.end(); I != E; ++I)
614 JumpScopes.push_back(*I);
617 // Collect a single representative of every scope containing a
618 // label whose address was taken somewhere in the function.
619 // For most code bases, there will be only one such scope.
620 llvm::DenseMap<unsigned, LabelDecl*> TargetScopes;
621 for (SmallVectorImpl<LabelDecl*>::iterator
622 I = IndirectJumpTargets.begin(), E = IndirectJumpTargets.end();
624 LabelDecl *TheLabel = *I;
625 if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(TheLabel->getStmt())))
627 unsigned LabelScope = LabelAndGotoScopes[TheLabel->getStmt()];
628 LabelDecl *&Target = TargetScopes[LabelScope];
629 if (!Target) Target = TheLabel;
632 // For each target scope, make sure it's trivially reachable from
633 // every scope containing a jump site.
635 // A path between scopes always consists of exitting zero or more
636 // scopes, then entering zero or more scopes. We build a set of
637 // of scopes S from which the target scope can be trivially
638 // entered, then verify that every jump scope can be trivially
639 // exitted to reach a scope in S.
640 llvm::BitVector Reachable(Scopes.size(), false);
641 for (llvm::DenseMap<unsigned,LabelDecl*>::iterator
642 TI = TargetScopes.begin(), TE = TargetScopes.end(); TI != TE; ++TI) {
643 unsigned TargetScope = TI->first;
644 LabelDecl *TargetLabel = TI->second;
648 // Mark all the enclosing scopes from which you can safely jump
649 // into the target scope. 'Min' will end up being the index of
650 // the shallowest such scope.
651 unsigned Min = TargetScope;
655 // Don't go beyond the outermost scope.
658 // Stop if we can't trivially enter the current scope.
659 if (Scopes[Min].InDiag) break;
661 Min = Scopes[Min].ParentScope;
664 // Walk through all the jump sites, checking that they can trivially
665 // reach this label scope.
666 for (SmallVectorImpl<JumpScope>::iterator
667 I = JumpScopes.begin(), E = JumpScopes.end(); I != E; ++I) {
668 unsigned Scope = I->first;
670 // Walk out the "scope chain" for this scope, looking for a scope
671 // we've marked reachable. For well-formed code this amortizes
672 // to O(JumpScopes.size() / Scopes.size()): we only iterate
673 // when we see something unmarked, and in well-formed code we
674 // mark everything we iterate past.
675 bool IsReachable = false;
677 if (Reachable.test(Scope)) {
678 // If we find something reachable, mark all the scopes we just
679 // walked through as reachable.
680 for (unsigned S = I->first; S != Scope; S = Scopes[S].ParentScope)
686 // Don't walk out if we've reached the top-level scope or we've
687 // gotten shallower than the shallowest reachable scope.
688 if (Scope == 0 || Scope < Min) break;
690 // Don't walk out through an out-diagnostic.
691 if (Scopes[Scope].OutDiag) break;
693 Scope = Scopes[Scope].ParentScope;
696 // Only diagnose if we didn't find something.
697 if (IsReachable) continue;
699 DiagnoseIndirectJump(I->second, I->first, TargetLabel, TargetScope);
704 /// Return true if a particular error+note combination must be downgraded to a
705 /// warning in Microsoft mode.
706 static bool IsMicrosoftJumpWarning(unsigned JumpDiag, unsigned InDiagNote) {
707 return (JumpDiag == diag::err_goto_into_protected_scope &&
708 (InDiagNote == diag::note_protected_by_variable_init ||
709 InDiagNote == diag::note_protected_by_variable_nontriv_destructor));
712 /// Return true if a particular note should be downgraded to a compatibility
713 /// warning in C++11 mode.
714 static bool IsCXX98CompatWarning(Sema &S, unsigned InDiagNote) {
715 return S.getLangOpts().CPlusPlus11 &&
716 InDiagNote == diag::note_protected_by_variable_non_pod;
719 /// Produce primary diagnostic for an indirect jump statement.
720 static void DiagnoseIndirectJumpStmt(Sema &S, IndirectGotoStmt *Jump,
721 LabelDecl *Target, bool &Diagnosed) {
724 S.Diag(Jump->getGotoLoc(), diag::err_indirect_goto_in_protected_scope);
725 S.Diag(Target->getStmt()->getIdentLoc(), diag::note_indirect_goto_target);
729 /// Produce note diagnostics for a jump into a protected scope.
730 void JumpScopeChecker::NoteJumpIntoScopes(ArrayRef<unsigned> ToScopes) {
731 if (CHECK_PERMISSIVE(ToScopes.empty()))
733 for (unsigned I = 0, E = ToScopes.size(); I != E; ++I)
734 if (Scopes[ToScopes[I]].InDiag)
735 S.Diag(Scopes[ToScopes[I]].Loc, Scopes[ToScopes[I]].InDiag);
738 /// Diagnose an indirect jump which is known to cross scopes.
739 void JumpScopeChecker::DiagnoseIndirectJump(IndirectGotoStmt *Jump,
742 unsigned TargetScope) {
743 if (CHECK_PERMISSIVE(JumpScope == TargetScope))
746 unsigned Common = GetDeepestCommonScope(JumpScope, TargetScope);
747 bool Diagnosed = false;
749 // Walk out the scope chain until we reach the common ancestor.
750 for (unsigned I = JumpScope; I != Common; I = Scopes[I].ParentScope)
751 if (Scopes[I].OutDiag) {
752 DiagnoseIndirectJumpStmt(S, Jump, Target, Diagnosed);
753 S.Diag(Scopes[I].Loc, Scopes[I].OutDiag);
756 SmallVector<unsigned, 10> ToScopesCXX98Compat;
758 // Now walk into the scopes containing the label whose address was taken.
759 for (unsigned I = TargetScope; I != Common; I = Scopes[I].ParentScope)
760 if (IsCXX98CompatWarning(S, Scopes[I].InDiag))
761 ToScopesCXX98Compat.push_back(I);
762 else if (Scopes[I].InDiag) {
763 DiagnoseIndirectJumpStmt(S, Jump, Target, Diagnosed);
764 S.Diag(Scopes[I].Loc, Scopes[I].InDiag);
767 // Diagnose this jump if it would be ill-formed in C++98.
768 if (!Diagnosed && !ToScopesCXX98Compat.empty()) {
769 S.Diag(Jump->getGotoLoc(),
770 diag::warn_cxx98_compat_indirect_goto_in_protected_scope);
771 S.Diag(Target->getStmt()->getIdentLoc(), diag::note_indirect_goto_target);
772 NoteJumpIntoScopes(ToScopesCXX98Compat);
776 /// CheckJump - Validate that the specified jump statement is valid: that it is
777 /// jumping within or out of its current scope, not into a deeper one.
778 void JumpScopeChecker::CheckJump(Stmt *From, Stmt *To, SourceLocation DiagLoc,
779 unsigned JumpDiagError, unsigned JumpDiagWarning,
780 unsigned JumpDiagCXX98Compat) {
781 if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(From)))
783 if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(To)))
786 unsigned FromScope = LabelAndGotoScopes[From];
787 unsigned ToScope = LabelAndGotoScopes[To];
789 // Common case: exactly the same scope, which is fine.
790 if (FromScope == ToScope) return;
792 // Warn on gotos out of __finally blocks.
793 if (isa<GotoStmt>(From) || isa<IndirectGotoStmt>(From)) {
794 // If FromScope > ToScope, FromScope is more nested and the jump goes to a
795 // less nested scope. Check if it crosses a __finally along the way.
796 for (unsigned I = FromScope; I > ToScope; I = Scopes[I].ParentScope) {
797 if (Scopes[I].InDiag == diag::note_protected_by_seh_finally) {
798 S.Diag(From->getLocStart(), diag::warn_jump_out_of_seh_finally);
804 unsigned CommonScope = GetDeepestCommonScope(FromScope, ToScope);
806 // It's okay to jump out from a nested scope.
807 if (CommonScope == ToScope) return;
809 // Pull out (and reverse) any scopes we might need to diagnose skipping.
810 SmallVector<unsigned, 10> ToScopesCXX98Compat;
811 SmallVector<unsigned, 10> ToScopesError;
812 SmallVector<unsigned, 10> ToScopesWarning;
813 for (unsigned I = ToScope; I != CommonScope; I = Scopes[I].ParentScope) {
814 if (S.getLangOpts().MSVCCompat && JumpDiagWarning != 0 &&
815 IsMicrosoftJumpWarning(JumpDiagError, Scopes[I].InDiag))
816 ToScopesWarning.push_back(I);
817 else if (IsCXX98CompatWarning(S, Scopes[I].InDiag))
818 ToScopesCXX98Compat.push_back(I);
819 else if (Scopes[I].InDiag)
820 ToScopesError.push_back(I);
824 if (!ToScopesWarning.empty()) {
825 S.Diag(DiagLoc, JumpDiagWarning);
826 NoteJumpIntoScopes(ToScopesWarning);
830 if (!ToScopesError.empty()) {
831 S.Diag(DiagLoc, JumpDiagError);
832 NoteJumpIntoScopes(ToScopesError);
835 // Handle -Wc++98-compat warnings if the jump is well-formed.
836 if (ToScopesError.empty() && !ToScopesCXX98Compat.empty()) {
837 S.Diag(DiagLoc, JumpDiagCXX98Compat);
838 NoteJumpIntoScopes(ToScopesCXX98Compat);
842 void JumpScopeChecker::CheckGotoStmt(GotoStmt *GS) {
843 if (GS->getLabel()->isMSAsmLabel()) {
844 S.Diag(GS->getGotoLoc(), diag::err_goto_ms_asm_label)
845 << GS->getLabel()->getIdentifier();
846 S.Diag(GS->getLabel()->getLocation(), diag::note_goto_ms_asm_label)
847 << GS->getLabel()->getIdentifier();
851 void Sema::DiagnoseInvalidJumps(Stmt *Body) {
852 (void)JumpScopeChecker(Body, *this);