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 return ScopePair(diag::note_protected_by_objc_strong_init,
151 diag::note_exits_objc_strong);
153 case QualType::DK_objc_weak_lifetime:
154 return ScopePair(diag::note_protected_by_objc_weak_init,
155 diag::note_exits_objc_weak);
157 case QualType::DK_cxx_destructor:
158 OutDiag = diag::note_exits_dtor;
161 case QualType::DK_none:
166 const Expr *Init = VD->getInit();
167 if (S.Context.getLangOpts().CPlusPlus && VD->hasLocalStorage() && Init) {
168 // C++11 [stmt.dcl]p3:
169 // A program that jumps from a point where a variable with automatic
170 // storage duration is not in scope to a point where it is in scope
171 // is ill-formed unless the variable has scalar type, class type with
172 // a trivial default constructor and a trivial destructor, a
173 // cv-qualified version of one of these types, or an array of one of
174 // the preceding types and is declared without an initializer.
176 // C++03 [stmt.dcl.p3:
177 // A program that jumps from a point where a local variable
178 // with automatic storage duration is not in scope to a point
179 // where it is in scope is ill-formed unless the variable has
180 // POD type and is declared without an initializer.
182 InDiag = diag::note_protected_by_variable_init;
184 // For a variable of (array of) class type declared without an
185 // initializer, we will have call-style initialization and the initializer
186 // will be the CXXConstructExpr with no intervening nodes.
187 if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(Init)) {
188 const CXXConstructorDecl *Ctor = CCE->getConstructor();
189 if (Ctor->isTrivial() && Ctor->isDefaultConstructor() &&
190 VD->getInitStyle() == VarDecl::CallInit) {
192 InDiag = diag::note_protected_by_variable_nontriv_destructor;
193 else if (!Ctor->getParent()->isPOD())
194 InDiag = diag::note_protected_by_variable_non_pod;
201 return ScopePair(InDiag, OutDiag);
204 if (const TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(D)) {
205 if (TD->getUnderlyingType()->isVariablyModifiedType())
206 return ScopePair(isa<TypedefDecl>(TD)
207 ? diag::note_protected_by_vla_typedef
208 : diag::note_protected_by_vla_type_alias,
212 return ScopePair(0U, 0U);
215 /// \brief Build scope information for a declaration that is part of a DeclStmt.
216 void JumpScopeChecker::BuildScopeInformation(Decl *D, unsigned &ParentScope) {
217 // If this decl causes a new scope, push and switch to it.
218 std::pair<unsigned,unsigned> Diags = GetDiagForGotoScopeDecl(S, D);
219 if (Diags.first || Diags.second) {
220 Scopes.push_back(GotoScope(ParentScope, Diags.first, Diags.second,
222 ParentScope = Scopes.size()-1;
225 // If the decl has an initializer, walk it with the potentially new
226 // scope we just installed.
227 if (VarDecl *VD = dyn_cast<VarDecl>(D))
228 if (Expr *Init = VD->getInit())
229 BuildScopeInformation(Init, ParentScope);
232 /// \brief Build scope information for a captured block literal variables.
233 void JumpScopeChecker::BuildScopeInformation(VarDecl *D,
234 const BlockDecl *BDecl,
235 unsigned &ParentScope) {
236 // exclude captured __block variables; there's no destructor
237 // associated with the block literal for them.
238 if (D->hasAttr<BlocksAttr>())
240 QualType T = D->getType();
241 QualType::DestructionKind destructKind = T.isDestructedType();
242 if (destructKind != QualType::DK_none) {
243 std::pair<unsigned,unsigned> Diags;
244 switch (destructKind) {
245 case QualType::DK_cxx_destructor:
246 Diags = ScopePair(diag::note_enters_block_captures_cxx_obj,
247 diag::note_exits_block_captures_cxx_obj);
249 case QualType::DK_objc_strong_lifetime:
250 Diags = ScopePair(diag::note_enters_block_captures_strong,
251 diag::note_exits_block_captures_strong);
253 case QualType::DK_objc_weak_lifetime:
254 Diags = ScopePair(diag::note_enters_block_captures_weak,
255 diag::note_exits_block_captures_weak);
257 case QualType::DK_none:
258 llvm_unreachable("non-lifetime captured variable");
260 SourceLocation Loc = D->getLocation();
262 Loc = BDecl->getLocation();
263 Scopes.push_back(GotoScope(ParentScope,
264 Diags.first, Diags.second, Loc));
265 ParentScope = Scopes.size()-1;
269 /// BuildScopeInformation - The statements from CI to CE are known to form a
270 /// coherent VLA scope with a specified parent node. Walk through the
271 /// statements, adding any labels or gotos to LabelAndGotoScopes and recursively
272 /// walking the AST as needed.
273 void JumpScopeChecker::BuildScopeInformation(Stmt *S,
274 unsigned &origParentScope) {
275 // If this is a statement, rather than an expression, scopes within it don't
276 // propagate out into the enclosing scope. Otherwise we have to worry
277 // about block literals, which have the lifetime of their enclosing statement.
278 unsigned independentParentScope = origParentScope;
279 unsigned &ParentScope = ((isa<Expr>(S) && !isa<StmtExpr>(S))
280 ? origParentScope : independentParentScope);
282 unsigned StmtsToSkip = 0u;
284 // If we found a label, remember that it is in ParentScope scope.
285 switch (S->getStmtClass()) {
286 case Stmt::AddrLabelExprClass:
287 IndirectJumpTargets.push_back(cast<AddrLabelExpr>(S)->getLabel());
290 case Stmt::IndirectGotoStmtClass:
291 // "goto *&&lbl;" is a special case which we treat as equivalent
292 // to a normal goto. In addition, we don't calculate scope in the
293 // operand (to avoid recording the address-of-label use), which
294 // works only because of the restricted set of expressions which
295 // we detect as constant targets.
296 if (cast<IndirectGotoStmt>(S)->getConstantTarget()) {
297 LabelAndGotoScopes[S] = ParentScope;
302 LabelAndGotoScopes[S] = ParentScope;
303 IndirectJumps.push_back(cast<IndirectGotoStmt>(S));
306 case Stmt::SwitchStmtClass:
307 // Evaluate the C++17 init stmt and condition variable
308 // before entering the scope of the switch statement.
309 if (Stmt *Init = cast<SwitchStmt>(S)->getInit()) {
310 BuildScopeInformation(Init, ParentScope);
313 if (VarDecl *Var = cast<SwitchStmt>(S)->getConditionVariable()) {
314 BuildScopeInformation(Var, ParentScope);
319 case Stmt::GotoStmtClass:
320 // Remember both what scope a goto is in as well as the fact that we have
321 // it. This makes the second scan not have to walk the AST again.
322 LabelAndGotoScopes[S] = ParentScope;
326 case Stmt::IfStmtClass: {
327 IfStmt *IS = cast<IfStmt>(S);
328 if (!IS->isConstexpr())
331 if (VarDecl *Var = IS->getConditionVariable())
332 BuildScopeInformation(Var, ParentScope);
334 // Cannot jump into the middle of the condition.
335 unsigned NewParentScope = Scopes.size();
336 Scopes.push_back(GotoScope(ParentScope,
337 diag::note_protected_by_constexpr_if, 0,
339 BuildScopeInformation(IS->getCond(), NewParentScope);
341 // Jumps into either arm of an 'if constexpr' are not allowed.
342 NewParentScope = Scopes.size();
343 Scopes.push_back(GotoScope(ParentScope,
344 diag::note_protected_by_constexpr_if, 0,
346 BuildScopeInformation(IS->getThen(), NewParentScope);
347 if (Stmt *Else = IS->getElse()) {
348 NewParentScope = Scopes.size();
349 Scopes.push_back(GotoScope(ParentScope,
350 diag::note_protected_by_constexpr_if, 0,
352 BuildScopeInformation(Else, NewParentScope);
357 case Stmt::CXXTryStmtClass: {
358 CXXTryStmt *TS = cast<CXXTryStmt>(S);
360 unsigned NewParentScope = Scopes.size();
361 Scopes.push_back(GotoScope(ParentScope,
362 diag::note_protected_by_cxx_try,
363 diag::note_exits_cxx_try,
364 TS->getSourceRange().getBegin()));
365 if (Stmt *TryBlock = TS->getTryBlock())
366 BuildScopeInformation(TryBlock, NewParentScope);
369 // Jump from the catch into the try is not allowed either.
370 for (unsigned I = 0, E = TS->getNumHandlers(); I != E; ++I) {
371 CXXCatchStmt *CS = TS->getHandler(I);
372 unsigned NewParentScope = Scopes.size();
373 Scopes.push_back(GotoScope(ParentScope,
374 diag::note_protected_by_cxx_catch,
375 diag::note_exits_cxx_catch,
376 CS->getSourceRange().getBegin()));
377 BuildScopeInformation(CS->getHandlerBlock(), NewParentScope);
382 case Stmt::SEHTryStmtClass: {
383 SEHTryStmt *TS = cast<SEHTryStmt>(S);
385 unsigned NewParentScope = Scopes.size();
386 Scopes.push_back(GotoScope(ParentScope,
387 diag::note_protected_by_seh_try,
388 diag::note_exits_seh_try,
389 TS->getSourceRange().getBegin()));
390 if (Stmt *TryBlock = TS->getTryBlock())
391 BuildScopeInformation(TryBlock, NewParentScope);
394 // Jump from __except or __finally into the __try are not allowed either.
395 if (SEHExceptStmt *Except = TS->getExceptHandler()) {
396 unsigned NewParentScope = Scopes.size();
397 Scopes.push_back(GotoScope(ParentScope,
398 diag::note_protected_by_seh_except,
399 diag::note_exits_seh_except,
400 Except->getSourceRange().getBegin()));
401 BuildScopeInformation(Except->getBlock(), NewParentScope);
402 } else if (SEHFinallyStmt *Finally = TS->getFinallyHandler()) {
403 unsigned NewParentScope = Scopes.size();
404 Scopes.push_back(GotoScope(ParentScope,
405 diag::note_protected_by_seh_finally,
406 diag::note_exits_seh_finally,
407 Finally->getSourceRange().getBegin()));
408 BuildScopeInformation(Finally->getBlock(), NewParentScope);
414 case Stmt::DeclStmtClass: {
415 // If this is a declstmt with a VLA definition, it defines a scope from here
416 // to the end of the containing context.
417 DeclStmt *DS = cast<DeclStmt>(S);
418 // The decl statement creates a scope if any of the decls in it are VLAs
419 // or have the cleanup attribute.
420 for (auto *I : DS->decls())
421 BuildScopeInformation(I, origParentScope);
425 case Stmt::ObjCAtTryStmtClass: {
426 // Disallow jumps into any part of an @try statement by pushing a scope and
427 // walking all sub-stmts in that scope.
428 ObjCAtTryStmt *AT = cast<ObjCAtTryStmt>(S);
429 // Recursively walk the AST for the @try part.
431 unsigned NewParentScope = Scopes.size();
432 Scopes.push_back(GotoScope(ParentScope,
433 diag::note_protected_by_objc_try,
434 diag::note_exits_objc_try,
436 if (Stmt *TryPart = AT->getTryBody())
437 BuildScopeInformation(TryPart, NewParentScope);
440 // Jump from the catch to the finally or try is not valid.
441 for (unsigned I = 0, N = AT->getNumCatchStmts(); I != N; ++I) {
442 ObjCAtCatchStmt *AC = AT->getCatchStmt(I);
443 unsigned NewParentScope = Scopes.size();
444 Scopes.push_back(GotoScope(ParentScope,
445 diag::note_protected_by_objc_catch,
446 diag::note_exits_objc_catch,
447 AC->getAtCatchLoc()));
448 // @catches are nested and it isn't
449 BuildScopeInformation(AC->getCatchBody(), NewParentScope);
452 // Jump from the finally to the try or catch is not valid.
453 if (ObjCAtFinallyStmt *AF = AT->getFinallyStmt()) {
454 unsigned NewParentScope = Scopes.size();
455 Scopes.push_back(GotoScope(ParentScope,
456 diag::note_protected_by_objc_finally,
457 diag::note_exits_objc_finally,
458 AF->getAtFinallyLoc()));
459 BuildScopeInformation(AF, NewParentScope);
465 case Stmt::ObjCAtSynchronizedStmtClass: {
466 // Disallow jumps into the protected statement of an @synchronized, but
467 // allow jumps into the object expression it protects.
468 ObjCAtSynchronizedStmt *AS = cast<ObjCAtSynchronizedStmt>(S);
469 // Recursively walk the AST for the @synchronized object expr, it is
470 // evaluated in the normal scope.
471 BuildScopeInformation(AS->getSynchExpr(), ParentScope);
473 // Recursively walk the AST for the @synchronized part, protected by a new
475 unsigned NewParentScope = Scopes.size();
476 Scopes.push_back(GotoScope(ParentScope,
477 diag::note_protected_by_objc_synchronized,
478 diag::note_exits_objc_synchronized,
479 AS->getAtSynchronizedLoc()));
480 BuildScopeInformation(AS->getSynchBody(), NewParentScope);
484 case Stmt::ObjCAutoreleasePoolStmtClass: {
485 // Disallow jumps into the protected statement of an @autoreleasepool.
486 ObjCAutoreleasePoolStmt *AS = cast<ObjCAutoreleasePoolStmt>(S);
487 // Recursively walk the AST for the @autoreleasepool part, protected by a
489 unsigned NewParentScope = Scopes.size();
490 Scopes.push_back(GotoScope(ParentScope,
491 diag::note_protected_by_objc_autoreleasepool,
492 diag::note_exits_objc_autoreleasepool,
494 BuildScopeInformation(AS->getSubStmt(), NewParentScope);
498 case Stmt::ExprWithCleanupsClass: {
499 // Disallow jumps past full-expressions that use blocks with
500 // non-trivial cleanups of their captures. This is theoretically
501 // implementable but a lot of work which we haven't felt up to doing.
502 ExprWithCleanups *EWC = cast<ExprWithCleanups>(S);
503 for (unsigned i = 0, e = EWC->getNumObjects(); i != e; ++i) {
504 const BlockDecl *BDecl = EWC->getObject(i);
505 for (const auto &CI : BDecl->captures()) {
506 VarDecl *variable = CI.getVariable();
507 BuildScopeInformation(variable, BDecl, origParentScope);
513 case Stmt::MaterializeTemporaryExprClass: {
514 // Disallow jumps out of scopes containing temporaries lifetime-extended to
515 // automatic storage duration.
516 MaterializeTemporaryExpr *MTE = cast<MaterializeTemporaryExpr>(S);
517 if (MTE->getStorageDuration() == SD_Automatic) {
518 SmallVector<const Expr *, 4> CommaLHS;
519 SmallVector<SubobjectAdjustment, 4> Adjustments;
520 const Expr *ExtendedObject =
521 MTE->GetTemporaryExpr()->skipRValueSubobjectAdjustments(
522 CommaLHS, Adjustments);
523 if (ExtendedObject->getType().isDestructedType()) {
524 Scopes.push_back(GotoScope(ParentScope, 0,
525 diag::note_exits_temporary_dtor,
526 ExtendedObject->getExprLoc()));
527 origParentScope = Scopes.size()-1;
533 case Stmt::CaseStmtClass:
534 case Stmt::DefaultStmtClass:
535 case Stmt::LabelStmtClass:
536 LabelAndGotoScopes[S] = ParentScope;
543 for (Stmt *SubStmt : S->children()) {
551 // Cases, labels, and defaults aren't "scope parents". It's also
552 // important to handle these iteratively instead of recursively in
553 // order to avoid blowing out the stack.
556 if (CaseStmt *CS = dyn_cast<CaseStmt>(SubStmt))
557 Next = CS->getSubStmt();
558 else if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SubStmt))
559 Next = DS->getSubStmt();
560 else if (LabelStmt *LS = dyn_cast<LabelStmt>(SubStmt))
561 Next = LS->getSubStmt();
565 LabelAndGotoScopes[SubStmt] = ParentScope;
569 // Recursively walk the AST.
570 BuildScopeInformation(SubStmt, ParentScope);
574 /// VerifyJumps - Verify each element of the Jumps array to see if they are
575 /// valid, emitting diagnostics if not.
576 void JumpScopeChecker::VerifyJumps() {
577 while (!Jumps.empty()) {
578 Stmt *Jump = Jumps.pop_back_val();
581 if (GotoStmt *GS = dyn_cast<GotoStmt>(Jump)) {
582 // The label may not have a statement if it's coming from inline MS ASM.
583 if (GS->getLabel()->getStmt()) {
584 CheckJump(GS, GS->getLabel()->getStmt(), GS->getGotoLoc(),
585 diag::err_goto_into_protected_scope,
586 diag::ext_goto_into_protected_scope,
587 diag::warn_cxx98_compat_goto_into_protected_scope);
593 // We only get indirect gotos here when they have a constant target.
594 if (IndirectGotoStmt *IGS = dyn_cast<IndirectGotoStmt>(Jump)) {
595 LabelDecl *Target = IGS->getConstantTarget();
596 CheckJump(IGS, Target->getStmt(), IGS->getGotoLoc(),
597 diag::err_goto_into_protected_scope,
598 diag::ext_goto_into_protected_scope,
599 diag::warn_cxx98_compat_goto_into_protected_scope);
603 SwitchStmt *SS = cast<SwitchStmt>(Jump);
604 for (SwitchCase *SC = SS->getSwitchCaseList(); SC;
605 SC = SC->getNextSwitchCase()) {
606 if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(SC)))
609 if (CaseStmt *CS = dyn_cast<CaseStmt>(SC))
610 Loc = CS->getLocStart();
611 else if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC))
612 Loc = DS->getLocStart();
614 Loc = SC->getLocStart();
615 CheckJump(SS, SC, Loc, diag::err_switch_into_protected_scope, 0,
616 diag::warn_cxx98_compat_switch_into_protected_scope);
621 /// VerifyIndirectJumps - Verify whether any possible indirect jump
622 /// might cross a protection boundary. Unlike direct jumps, indirect
623 /// jumps count cleanups as protection boundaries: since there's no
624 /// way to know where the jump is going, we can't implicitly run the
625 /// right cleanups the way we can with direct jumps.
627 /// Thus, an indirect jump is "trivial" if it bypasses no
628 /// initializations and no teardowns. More formally, an indirect jump
629 /// from A to B is trivial if the path out from A to DCA(A,B) is
630 /// trivial and the path in from DCA(A,B) to B is trivial, where
631 /// DCA(A,B) is the deepest common ancestor of A and B.
632 /// Jump-triviality is transitive but asymmetric.
634 /// A path in is trivial if none of the entered scopes have an InDiag.
635 /// A path out is trivial is none of the exited scopes have an OutDiag.
637 /// Under these definitions, this function checks that the indirect
638 /// jump between A and B is trivial for every indirect goto statement A
639 /// and every label B whose address was taken in the function.
640 void JumpScopeChecker::VerifyIndirectJumps() {
641 if (IndirectJumps.empty()) return;
643 // If there aren't any address-of-label expressions in this function,
644 // complain about the first indirect goto.
645 if (IndirectJumpTargets.empty()) {
646 S.Diag(IndirectJumps[0]->getGotoLoc(),
647 diag::err_indirect_goto_without_addrlabel);
651 // Collect a single representative of every scope containing an
652 // indirect goto. For most code bases, this substantially cuts
653 // down on the number of jump sites we'll have to consider later.
654 typedef std::pair<unsigned, IndirectGotoStmt*> JumpScope;
655 SmallVector<JumpScope, 32> JumpScopes;
657 llvm::DenseMap<unsigned, IndirectGotoStmt*> JumpScopesMap;
658 for (SmallVectorImpl<IndirectGotoStmt*>::iterator
659 I = IndirectJumps.begin(), E = IndirectJumps.end(); I != E; ++I) {
660 IndirectGotoStmt *IG = *I;
661 if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(IG)))
663 unsigned IGScope = LabelAndGotoScopes[IG];
664 IndirectGotoStmt *&Entry = JumpScopesMap[IGScope];
665 if (!Entry) Entry = IG;
667 JumpScopes.reserve(JumpScopesMap.size());
668 for (llvm::DenseMap<unsigned, IndirectGotoStmt*>::iterator
669 I = JumpScopesMap.begin(), E = JumpScopesMap.end(); I != E; ++I)
670 JumpScopes.push_back(*I);
673 // Collect a single representative of every scope containing a
674 // label whose address was taken somewhere in the function.
675 // For most code bases, there will be only one such scope.
676 llvm::DenseMap<unsigned, LabelDecl*> TargetScopes;
677 for (SmallVectorImpl<LabelDecl*>::iterator
678 I = IndirectJumpTargets.begin(), E = IndirectJumpTargets.end();
680 LabelDecl *TheLabel = *I;
681 if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(TheLabel->getStmt())))
683 unsigned LabelScope = LabelAndGotoScopes[TheLabel->getStmt()];
684 LabelDecl *&Target = TargetScopes[LabelScope];
685 if (!Target) Target = TheLabel;
688 // For each target scope, make sure it's trivially reachable from
689 // every scope containing a jump site.
691 // A path between scopes always consists of exitting zero or more
692 // scopes, then entering zero or more scopes. We build a set of
693 // of scopes S from which the target scope can be trivially
694 // entered, then verify that every jump scope can be trivially
695 // exitted to reach a scope in S.
696 llvm::BitVector Reachable(Scopes.size(), false);
697 for (llvm::DenseMap<unsigned,LabelDecl*>::iterator
698 TI = TargetScopes.begin(), TE = TargetScopes.end(); TI != TE; ++TI) {
699 unsigned TargetScope = TI->first;
700 LabelDecl *TargetLabel = TI->second;
704 // Mark all the enclosing scopes from which you can safely jump
705 // into the target scope. 'Min' will end up being the index of
706 // the shallowest such scope.
707 unsigned Min = TargetScope;
711 // Don't go beyond the outermost scope.
714 // Stop if we can't trivially enter the current scope.
715 if (Scopes[Min].InDiag) break;
717 Min = Scopes[Min].ParentScope;
720 // Walk through all the jump sites, checking that they can trivially
721 // reach this label scope.
722 for (SmallVectorImpl<JumpScope>::iterator
723 I = JumpScopes.begin(), E = JumpScopes.end(); I != E; ++I) {
724 unsigned Scope = I->first;
726 // Walk out the "scope chain" for this scope, looking for a scope
727 // we've marked reachable. For well-formed code this amortizes
728 // to O(JumpScopes.size() / Scopes.size()): we only iterate
729 // when we see something unmarked, and in well-formed code we
730 // mark everything we iterate past.
731 bool IsReachable = false;
733 if (Reachable.test(Scope)) {
734 // If we find something reachable, mark all the scopes we just
735 // walked through as reachable.
736 for (unsigned S = I->first; S != Scope; S = Scopes[S].ParentScope)
742 // Don't walk out if we've reached the top-level scope or we've
743 // gotten shallower than the shallowest reachable scope.
744 if (Scope == 0 || Scope < Min) break;
746 // Don't walk out through an out-diagnostic.
747 if (Scopes[Scope].OutDiag) break;
749 Scope = Scopes[Scope].ParentScope;
752 // Only diagnose if we didn't find something.
753 if (IsReachable) continue;
755 DiagnoseIndirectJump(I->second, I->first, TargetLabel, TargetScope);
760 /// Return true if a particular error+note combination must be downgraded to a
761 /// warning in Microsoft mode.
762 static bool IsMicrosoftJumpWarning(unsigned JumpDiag, unsigned InDiagNote) {
763 return (JumpDiag == diag::err_goto_into_protected_scope &&
764 (InDiagNote == diag::note_protected_by_variable_init ||
765 InDiagNote == diag::note_protected_by_variable_nontriv_destructor));
768 /// Return true if a particular note should be downgraded to a compatibility
769 /// warning in C++11 mode.
770 static bool IsCXX98CompatWarning(Sema &S, unsigned InDiagNote) {
771 return S.getLangOpts().CPlusPlus11 &&
772 InDiagNote == diag::note_protected_by_variable_non_pod;
775 /// Produce primary diagnostic for an indirect jump statement.
776 static void DiagnoseIndirectJumpStmt(Sema &S, IndirectGotoStmt *Jump,
777 LabelDecl *Target, bool &Diagnosed) {
780 S.Diag(Jump->getGotoLoc(), diag::err_indirect_goto_in_protected_scope);
781 S.Diag(Target->getStmt()->getIdentLoc(), diag::note_indirect_goto_target);
785 /// Produce note diagnostics for a jump into a protected scope.
786 void JumpScopeChecker::NoteJumpIntoScopes(ArrayRef<unsigned> ToScopes) {
787 if (CHECK_PERMISSIVE(ToScopes.empty()))
789 for (unsigned I = 0, E = ToScopes.size(); I != E; ++I)
790 if (Scopes[ToScopes[I]].InDiag)
791 S.Diag(Scopes[ToScopes[I]].Loc, Scopes[ToScopes[I]].InDiag);
794 /// Diagnose an indirect jump which is known to cross scopes.
795 void JumpScopeChecker::DiagnoseIndirectJump(IndirectGotoStmt *Jump,
798 unsigned TargetScope) {
799 if (CHECK_PERMISSIVE(JumpScope == TargetScope))
802 unsigned Common = GetDeepestCommonScope(JumpScope, TargetScope);
803 bool Diagnosed = false;
805 // Walk out the scope chain until we reach the common ancestor.
806 for (unsigned I = JumpScope; I != Common; I = Scopes[I].ParentScope)
807 if (Scopes[I].OutDiag) {
808 DiagnoseIndirectJumpStmt(S, Jump, Target, Diagnosed);
809 S.Diag(Scopes[I].Loc, Scopes[I].OutDiag);
812 SmallVector<unsigned, 10> ToScopesCXX98Compat;
814 // Now walk into the scopes containing the label whose address was taken.
815 for (unsigned I = TargetScope; I != Common; I = Scopes[I].ParentScope)
816 if (IsCXX98CompatWarning(S, Scopes[I].InDiag))
817 ToScopesCXX98Compat.push_back(I);
818 else if (Scopes[I].InDiag) {
819 DiagnoseIndirectJumpStmt(S, Jump, Target, Diagnosed);
820 S.Diag(Scopes[I].Loc, Scopes[I].InDiag);
823 // Diagnose this jump if it would be ill-formed in C++98.
824 if (!Diagnosed && !ToScopesCXX98Compat.empty()) {
825 S.Diag(Jump->getGotoLoc(),
826 diag::warn_cxx98_compat_indirect_goto_in_protected_scope);
827 S.Diag(Target->getStmt()->getIdentLoc(), diag::note_indirect_goto_target);
828 NoteJumpIntoScopes(ToScopesCXX98Compat);
832 /// CheckJump - Validate that the specified jump statement is valid: that it is
833 /// jumping within or out of its current scope, not into a deeper one.
834 void JumpScopeChecker::CheckJump(Stmt *From, Stmt *To, SourceLocation DiagLoc,
835 unsigned JumpDiagError, unsigned JumpDiagWarning,
836 unsigned JumpDiagCXX98Compat) {
837 if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(From)))
839 if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(To)))
842 unsigned FromScope = LabelAndGotoScopes[From];
843 unsigned ToScope = LabelAndGotoScopes[To];
845 // Common case: exactly the same scope, which is fine.
846 if (FromScope == ToScope) return;
848 // Warn on gotos out of __finally blocks.
849 if (isa<GotoStmt>(From) || isa<IndirectGotoStmt>(From)) {
850 // If FromScope > ToScope, FromScope is more nested and the jump goes to a
851 // less nested scope. Check if it crosses a __finally along the way.
852 for (unsigned I = FromScope; I > ToScope; I = Scopes[I].ParentScope) {
853 if (Scopes[I].InDiag == diag::note_protected_by_seh_finally) {
854 S.Diag(From->getLocStart(), diag::warn_jump_out_of_seh_finally);
860 unsigned CommonScope = GetDeepestCommonScope(FromScope, ToScope);
862 // It's okay to jump out from a nested scope.
863 if (CommonScope == ToScope) return;
865 // Pull out (and reverse) any scopes we might need to diagnose skipping.
866 SmallVector<unsigned, 10> ToScopesCXX98Compat;
867 SmallVector<unsigned, 10> ToScopesError;
868 SmallVector<unsigned, 10> ToScopesWarning;
869 for (unsigned I = ToScope; I != CommonScope; I = Scopes[I].ParentScope) {
870 if (S.getLangOpts().MSVCCompat && JumpDiagWarning != 0 &&
871 IsMicrosoftJumpWarning(JumpDiagError, Scopes[I].InDiag))
872 ToScopesWarning.push_back(I);
873 else if (IsCXX98CompatWarning(S, Scopes[I].InDiag))
874 ToScopesCXX98Compat.push_back(I);
875 else if (Scopes[I].InDiag)
876 ToScopesError.push_back(I);
880 if (!ToScopesWarning.empty()) {
881 S.Diag(DiagLoc, JumpDiagWarning);
882 NoteJumpIntoScopes(ToScopesWarning);
886 if (!ToScopesError.empty()) {
887 S.Diag(DiagLoc, JumpDiagError);
888 NoteJumpIntoScopes(ToScopesError);
891 // Handle -Wc++98-compat warnings if the jump is well-formed.
892 if (ToScopesError.empty() && !ToScopesCXX98Compat.empty()) {
893 S.Diag(DiagLoc, JumpDiagCXX98Compat);
894 NoteJumpIntoScopes(ToScopesCXX98Compat);
898 void JumpScopeChecker::CheckGotoStmt(GotoStmt *GS) {
899 if (GS->getLabel()->isMSAsmLabel()) {
900 S.Diag(GS->getGotoLoc(), diag::err_goto_ms_asm_label)
901 << GS->getLabel()->getIdentifier();
902 S.Diag(GS->getLabel()->getLocation(), diag::note_goto_ms_asm_label)
903 << GS->getLabel()->getIdentifier();
907 void Sema::DiagnoseInvalidJumps(Stmt *Body) {
908 (void)JumpScopeChecker(Body, *this);