| //===--- JumpDiagnostics.cpp - Protected scope jump analysis ------*- C++ -*-=// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the JumpScopeChecker class, which is used to diagnose |
| // jumps that enter a protected scope in an invalid way. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/Sema/SemaInternal.h" |
| #include "clang/AST/DeclCXX.h" |
| #include "clang/AST/Expr.h" |
| #include "clang/AST/ExprCXX.h" |
| #include "clang/AST/StmtCXX.h" |
| #include "clang/AST/StmtObjC.h" |
| #include "llvm/ADT/BitVector.h" |
| using namespace clang; |
| |
| namespace { |
| |
| /// JumpScopeChecker - This object is used by Sema to diagnose invalid jumps |
| /// into VLA and other protected scopes. For example, this rejects: |
| /// goto L; |
| /// int a[n]; |
| /// L: |
| /// |
| class JumpScopeChecker { |
| Sema &S; |
| |
| /// Permissive - True when recovering from errors, in which case precautions |
| /// are taken to handle incomplete scope information. |
| const bool Permissive; |
| |
| /// GotoScope - This is a record that we use to keep track of all of the |
| /// scopes that are introduced by VLAs and other things that scope jumps like |
| /// gotos. This scope tree has nothing to do with the source scope tree, |
| /// because you can have multiple VLA scopes per compound statement, and most |
| /// compound statements don't introduce any scopes. |
| struct GotoScope { |
| /// ParentScope - The index in ScopeMap of the parent scope. This is 0 for |
| /// the parent scope is the function body. |
| unsigned ParentScope; |
| |
| /// InDiag - The note to emit if there is a jump into this scope. |
| unsigned InDiag; |
| |
| /// OutDiag - The note to emit if there is an indirect jump out |
| /// of this scope. Direct jumps always clean up their current scope |
| /// in an orderly way. |
| unsigned OutDiag; |
| |
| /// Loc - Location to emit the diagnostic. |
| SourceLocation Loc; |
| |
| GotoScope(unsigned parentScope, unsigned InDiag, unsigned OutDiag, |
| SourceLocation L) |
| : ParentScope(parentScope), InDiag(InDiag), OutDiag(OutDiag), Loc(L) {} |
| }; |
| |
| SmallVector<GotoScope, 48> Scopes; |
| llvm::DenseMap<Stmt*, unsigned> LabelAndGotoScopes; |
| SmallVector<Stmt*, 16> Jumps; |
| |
| SmallVector<IndirectGotoStmt*, 4> IndirectJumps; |
| SmallVector<LabelDecl*, 4> IndirectJumpTargets; |
| public: |
| JumpScopeChecker(Stmt *Body, Sema &S); |
| private: |
| void BuildScopeInformation(Decl *D, unsigned &ParentScope); |
| void BuildScopeInformation(VarDecl *D, const BlockDecl *BDecl, |
| unsigned &ParentScope); |
| void BuildScopeInformation(Stmt *S, unsigned &origParentScope); |
| |
| void VerifyJumps(); |
| void VerifyIndirectJumps(); |
| void NoteJumpIntoScopes(ArrayRef<unsigned> ToScopes); |
| void DiagnoseIndirectJump(IndirectGotoStmt *IG, unsigned IGScope, |
| LabelDecl *Target, unsigned TargetScope); |
| void CheckJump(Stmt *From, Stmt *To, SourceLocation DiagLoc, |
| unsigned JumpDiag, unsigned JumpDiagWarning, |
| unsigned JumpDiagCXX98Compat); |
| void CheckGotoStmt(GotoStmt *GS); |
| |
| unsigned GetDeepestCommonScope(unsigned A, unsigned B); |
| }; |
| } // end anonymous namespace |
| |
| #define CHECK_PERMISSIVE(x) (assert(Permissive || !(x)), (Permissive && (x))) |
| |
| JumpScopeChecker::JumpScopeChecker(Stmt *Body, Sema &s) |
| : S(s), Permissive(s.hasAnyUnrecoverableErrorsInThisFunction()) { |
| // Add a scope entry for function scope. |
| Scopes.push_back(GotoScope(~0U, ~0U, ~0U, SourceLocation())); |
| |
| // Build information for the top level compound statement, so that we have a |
| // defined scope record for every "goto" and label. |
| unsigned BodyParentScope = 0; |
| BuildScopeInformation(Body, BodyParentScope); |
| |
| // Check that all jumps we saw are kosher. |
| VerifyJumps(); |
| VerifyIndirectJumps(); |
| } |
| |
| /// GetDeepestCommonScope - Finds the innermost scope enclosing the |
| /// two scopes. |
| unsigned JumpScopeChecker::GetDeepestCommonScope(unsigned A, unsigned B) { |
| while (A != B) { |
| // Inner scopes are created after outer scopes and therefore have |
| // higher indices. |
| if (A < B) { |
| assert(Scopes[B].ParentScope < B); |
| B = Scopes[B].ParentScope; |
| } else { |
| assert(Scopes[A].ParentScope < A); |
| A = Scopes[A].ParentScope; |
| } |
| } |
| return A; |
| } |
| |
| typedef std::pair<unsigned,unsigned> ScopePair; |
| |
| /// GetDiagForGotoScopeDecl - If this decl induces a new goto scope, return a |
| /// diagnostic that should be emitted if control goes over it. If not, return 0. |
| static ScopePair GetDiagForGotoScopeDecl(Sema &S, const Decl *D) { |
| if (const VarDecl *VD = dyn_cast<VarDecl>(D)) { |
| unsigned InDiag = 0; |
| unsigned OutDiag = 0; |
| |
| if (VD->getType()->isVariablyModifiedType()) |
| InDiag = diag::note_protected_by_vla; |
| |
| if (VD->hasAttr<BlocksAttr>()) |
| return ScopePair(diag::note_protected_by___block, |
| diag::note_exits___block); |
| |
| if (VD->hasAttr<CleanupAttr>()) |
| return ScopePair(diag::note_protected_by_cleanup, |
| diag::note_exits_cleanup); |
| |
| if (VD->hasLocalStorage()) { |
| switch (VD->getType().isDestructedType()) { |
| case QualType::DK_objc_strong_lifetime: |
| return ScopePair(diag::note_protected_by_objc_strong_init, |
| diag::note_exits_objc_strong); |
| |
| case QualType::DK_objc_weak_lifetime: |
| return ScopePair(diag::note_protected_by_objc_weak_init, |
| diag::note_exits_objc_weak); |
| |
| case QualType::DK_nontrivial_c_struct: |
| return ScopePair(diag::note_protected_by_non_trivial_c_struct_init, |
| diag::note_exits_dtor); |
| |
| case QualType::DK_cxx_destructor: |
| OutDiag = diag::note_exits_dtor; |
| break; |
| |
| case QualType::DK_none: |
| break; |
| } |
| } |
| |
| const Expr *Init = VD->getInit(); |
| if (S.Context.getLangOpts().CPlusPlus && VD->hasLocalStorage() && Init) { |
| // C++11 [stmt.dcl]p3: |
| // A program that jumps from a point where a variable with automatic |
| // storage duration is not in scope to a point where it is in scope |
| // is ill-formed unless the variable has scalar type, class type with |
| // a trivial default constructor and a trivial destructor, a |
| // cv-qualified version of one of these types, or an array of one of |
| // the preceding types and is declared without an initializer. |
| |
| // C++03 [stmt.dcl.p3: |
| // A program that jumps from a point where a local variable |
| // with automatic storage duration is not in scope to a point |
| // where it is in scope is ill-formed unless the variable has |
| // POD type and is declared without an initializer. |
| |
| InDiag = diag::note_protected_by_variable_init; |
| |
| // For a variable of (array of) class type declared without an |
| // initializer, we will have call-style initialization and the initializer |
| // will be the CXXConstructExpr with no intervening nodes. |
| if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(Init)) { |
| const CXXConstructorDecl *Ctor = CCE->getConstructor(); |
| if (Ctor->isTrivial() && Ctor->isDefaultConstructor() && |
| VD->getInitStyle() == VarDecl::CallInit) { |
| if (OutDiag) |
| InDiag = diag::note_protected_by_variable_nontriv_destructor; |
| else if (!Ctor->getParent()->isPOD()) |
| InDiag = diag::note_protected_by_variable_non_pod; |
| else |
| InDiag = 0; |
| } |
| } |
| } |
| |
| return ScopePair(InDiag, OutDiag); |
| } |
| |
| if (const TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(D)) { |
| if (TD->getUnderlyingType()->isVariablyModifiedType()) |
| return ScopePair(isa<TypedefDecl>(TD) |
| ? diag::note_protected_by_vla_typedef |
| : diag::note_protected_by_vla_type_alias, |
| 0); |
| } |
| |
| return ScopePair(0U, 0U); |
| } |
| |
| /// Build scope information for a declaration that is part of a DeclStmt. |
| void JumpScopeChecker::BuildScopeInformation(Decl *D, unsigned &ParentScope) { |
| // If this decl causes a new scope, push and switch to it. |
| std::pair<unsigned,unsigned> Diags = GetDiagForGotoScopeDecl(S, D); |
| if (Diags.first || Diags.second) { |
| Scopes.push_back(GotoScope(ParentScope, Diags.first, Diags.second, |
| D->getLocation())); |
| ParentScope = Scopes.size()-1; |
| } |
| |
| // If the decl has an initializer, walk it with the potentially new |
| // scope we just installed. |
| if (VarDecl *VD = dyn_cast<VarDecl>(D)) |
| if (Expr *Init = VD->getInit()) |
| BuildScopeInformation(Init, ParentScope); |
| } |
| |
| /// Build scope information for a captured block literal variables. |
| void JumpScopeChecker::BuildScopeInformation(VarDecl *D, |
| const BlockDecl *BDecl, |
| unsigned &ParentScope) { |
| // exclude captured __block variables; there's no destructor |
| // associated with the block literal for them. |
| if (D->hasAttr<BlocksAttr>()) |
| return; |
| QualType T = D->getType(); |
| QualType::DestructionKind destructKind = T.isDestructedType(); |
| if (destructKind != QualType::DK_none) { |
| std::pair<unsigned,unsigned> Diags; |
| switch (destructKind) { |
| case QualType::DK_cxx_destructor: |
| Diags = ScopePair(diag::note_enters_block_captures_cxx_obj, |
| diag::note_exits_block_captures_cxx_obj); |
| break; |
| case QualType::DK_objc_strong_lifetime: |
| Diags = ScopePair(diag::note_enters_block_captures_strong, |
| diag::note_exits_block_captures_strong); |
| break; |
| case QualType::DK_objc_weak_lifetime: |
| Diags = ScopePair(diag::note_enters_block_captures_weak, |
| diag::note_exits_block_captures_weak); |
| break; |
| case QualType::DK_nontrivial_c_struct: |
| Diags = ScopePair(diag::note_enters_block_captures_non_trivial_c_struct, |
| diag::note_exits_block_captures_non_trivial_c_struct); |
| break; |
| case QualType::DK_none: |
| llvm_unreachable("non-lifetime captured variable"); |
| } |
| SourceLocation Loc = D->getLocation(); |
| if (Loc.isInvalid()) |
| Loc = BDecl->getLocation(); |
| Scopes.push_back(GotoScope(ParentScope, |
| Diags.first, Diags.second, Loc)); |
| ParentScope = Scopes.size()-1; |
| } |
| } |
| |
| /// BuildScopeInformation - The statements from CI to CE are known to form a |
| /// coherent VLA scope with a specified parent node. Walk through the |
| /// statements, adding any labels or gotos to LabelAndGotoScopes and recursively |
| /// walking the AST as needed. |
| void JumpScopeChecker::BuildScopeInformation(Stmt *S, |
| unsigned &origParentScope) { |
| // If this is a statement, rather than an expression, scopes within it don't |
| // propagate out into the enclosing scope. Otherwise we have to worry |
| // about block literals, which have the lifetime of their enclosing statement. |
| unsigned independentParentScope = origParentScope; |
| unsigned &ParentScope = ((isa<Expr>(S) && !isa<StmtExpr>(S)) |
| ? origParentScope : independentParentScope); |
| |
| unsigned StmtsToSkip = 0u; |
| |
| // If we found a label, remember that it is in ParentScope scope. |
| switch (S->getStmtClass()) { |
| case Stmt::AddrLabelExprClass: |
| IndirectJumpTargets.push_back(cast<AddrLabelExpr>(S)->getLabel()); |
| break; |
| |
| case Stmt::ObjCForCollectionStmtClass: { |
| auto *CS = cast<ObjCForCollectionStmt>(S); |
| unsigned Diag = diag::note_protected_by_objc_fast_enumeration; |
| unsigned NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, Diag, 0, S->getLocStart())); |
| BuildScopeInformation(CS->getBody(), NewParentScope); |
| return; |
| } |
| |
| case Stmt::IndirectGotoStmtClass: |
| // "goto *&&lbl;" is a special case which we treat as equivalent |
| // to a normal goto. In addition, we don't calculate scope in the |
| // operand (to avoid recording the address-of-label use), which |
| // works only because of the restricted set of expressions which |
| // we detect as constant targets. |
| if (cast<IndirectGotoStmt>(S)->getConstantTarget()) { |
| LabelAndGotoScopes[S] = ParentScope; |
| Jumps.push_back(S); |
| return; |
| } |
| |
| LabelAndGotoScopes[S] = ParentScope; |
| IndirectJumps.push_back(cast<IndirectGotoStmt>(S)); |
| break; |
| |
| case Stmt::SwitchStmtClass: |
| // Evaluate the C++17 init stmt and condition variable |
| // before entering the scope of the switch statement. |
| if (Stmt *Init = cast<SwitchStmt>(S)->getInit()) { |
| BuildScopeInformation(Init, ParentScope); |
| ++StmtsToSkip; |
| } |
| if (VarDecl *Var = cast<SwitchStmt>(S)->getConditionVariable()) { |
| BuildScopeInformation(Var, ParentScope); |
| ++StmtsToSkip; |
| } |
| LLVM_FALLTHROUGH; |
| |
| case Stmt::GotoStmtClass: |
| // Remember both what scope a goto is in as well as the fact that we have |
| // it. This makes the second scan not have to walk the AST again. |
| LabelAndGotoScopes[S] = ParentScope; |
| Jumps.push_back(S); |
| break; |
| |
| case Stmt::IfStmtClass: { |
| IfStmt *IS = cast<IfStmt>(S); |
| if (!(IS->isConstexpr() || IS->isObjCAvailabilityCheck())) |
| break; |
| |
| unsigned Diag = IS->isConstexpr() ? diag::note_protected_by_constexpr_if |
| : diag::note_protected_by_if_available; |
| |
| if (VarDecl *Var = IS->getConditionVariable()) |
| BuildScopeInformation(Var, ParentScope); |
| |
| // Cannot jump into the middle of the condition. |
| unsigned NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, Diag, 0, IS->getLocStart())); |
| BuildScopeInformation(IS->getCond(), NewParentScope); |
| |
| // Jumps into either arm of an 'if constexpr' are not allowed. |
| NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, Diag, 0, IS->getLocStart())); |
| BuildScopeInformation(IS->getThen(), NewParentScope); |
| if (Stmt *Else = IS->getElse()) { |
| NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, Diag, 0, IS->getLocStart())); |
| BuildScopeInformation(Else, NewParentScope); |
| } |
| return; |
| } |
| |
| case Stmt::CXXTryStmtClass: { |
| CXXTryStmt *TS = cast<CXXTryStmt>(S); |
| { |
| unsigned NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, |
| diag::note_protected_by_cxx_try, |
| diag::note_exits_cxx_try, |
| TS->getSourceRange().getBegin())); |
| if (Stmt *TryBlock = TS->getTryBlock()) |
| BuildScopeInformation(TryBlock, NewParentScope); |
| } |
| |
| // Jump from the catch into the try is not allowed either. |
| for (unsigned I = 0, E = TS->getNumHandlers(); I != E; ++I) { |
| CXXCatchStmt *CS = TS->getHandler(I); |
| unsigned NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, |
| diag::note_protected_by_cxx_catch, |
| diag::note_exits_cxx_catch, |
| CS->getSourceRange().getBegin())); |
| BuildScopeInformation(CS->getHandlerBlock(), NewParentScope); |
| } |
| return; |
| } |
| |
| case Stmt::SEHTryStmtClass: { |
| SEHTryStmt *TS = cast<SEHTryStmt>(S); |
| { |
| unsigned NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, |
| diag::note_protected_by_seh_try, |
| diag::note_exits_seh_try, |
| TS->getSourceRange().getBegin())); |
| if (Stmt *TryBlock = TS->getTryBlock()) |
| BuildScopeInformation(TryBlock, NewParentScope); |
| } |
| |
| // Jump from __except or __finally into the __try are not allowed either. |
| if (SEHExceptStmt *Except = TS->getExceptHandler()) { |
| unsigned NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, |
| diag::note_protected_by_seh_except, |
| diag::note_exits_seh_except, |
| Except->getSourceRange().getBegin())); |
| BuildScopeInformation(Except->getBlock(), NewParentScope); |
| } else if (SEHFinallyStmt *Finally = TS->getFinallyHandler()) { |
| unsigned NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, |
| diag::note_protected_by_seh_finally, |
| diag::note_exits_seh_finally, |
| Finally->getSourceRange().getBegin())); |
| BuildScopeInformation(Finally->getBlock(), NewParentScope); |
| } |
| |
| return; |
| } |
| |
| case Stmt::DeclStmtClass: { |
| // If this is a declstmt with a VLA definition, it defines a scope from here |
| // to the end of the containing context. |
| DeclStmt *DS = cast<DeclStmt>(S); |
| // The decl statement creates a scope if any of the decls in it are VLAs |
| // or have the cleanup attribute. |
| for (auto *I : DS->decls()) |
| BuildScopeInformation(I, origParentScope); |
| return; |
| } |
| |
| case Stmt::ObjCAtTryStmtClass: { |
| // Disallow jumps into any part of an @try statement by pushing a scope and |
| // walking all sub-stmts in that scope. |
| ObjCAtTryStmt *AT = cast<ObjCAtTryStmt>(S); |
| // Recursively walk the AST for the @try part. |
| { |
| unsigned NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, |
| diag::note_protected_by_objc_try, |
| diag::note_exits_objc_try, |
| AT->getAtTryLoc())); |
| if (Stmt *TryPart = AT->getTryBody()) |
| BuildScopeInformation(TryPart, NewParentScope); |
| } |
| |
| // Jump from the catch to the finally or try is not valid. |
| for (unsigned I = 0, N = AT->getNumCatchStmts(); I != N; ++I) { |
| ObjCAtCatchStmt *AC = AT->getCatchStmt(I); |
| unsigned NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, |
| diag::note_protected_by_objc_catch, |
| diag::note_exits_objc_catch, |
| AC->getAtCatchLoc())); |
| // @catches are nested and it isn't |
| BuildScopeInformation(AC->getCatchBody(), NewParentScope); |
| } |
| |
| // Jump from the finally to the try or catch is not valid. |
| if (ObjCAtFinallyStmt *AF = AT->getFinallyStmt()) { |
| unsigned NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, |
| diag::note_protected_by_objc_finally, |
| diag::note_exits_objc_finally, |
| AF->getAtFinallyLoc())); |
| BuildScopeInformation(AF, NewParentScope); |
| } |
| |
| return; |
| } |
| |
| case Stmt::ObjCAtSynchronizedStmtClass: { |
| // Disallow jumps into the protected statement of an @synchronized, but |
| // allow jumps into the object expression it protects. |
| ObjCAtSynchronizedStmt *AS = cast<ObjCAtSynchronizedStmt>(S); |
| // Recursively walk the AST for the @synchronized object expr, it is |
| // evaluated in the normal scope. |
| BuildScopeInformation(AS->getSynchExpr(), ParentScope); |
| |
| // Recursively walk the AST for the @synchronized part, protected by a new |
| // scope. |
| unsigned NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, |
| diag::note_protected_by_objc_synchronized, |
| diag::note_exits_objc_synchronized, |
| AS->getAtSynchronizedLoc())); |
| BuildScopeInformation(AS->getSynchBody(), NewParentScope); |
| return; |
| } |
| |
| case Stmt::ObjCAutoreleasePoolStmtClass: { |
| // Disallow jumps into the protected statement of an @autoreleasepool. |
| ObjCAutoreleasePoolStmt *AS = cast<ObjCAutoreleasePoolStmt>(S); |
| // Recursively walk the AST for the @autoreleasepool part, protected by a |
| // new scope. |
| unsigned NewParentScope = Scopes.size(); |
| Scopes.push_back(GotoScope(ParentScope, |
| diag::note_protected_by_objc_autoreleasepool, |
| diag::note_exits_objc_autoreleasepool, |
| AS->getAtLoc())); |
| BuildScopeInformation(AS->getSubStmt(), NewParentScope); |
| return; |
| } |
| |
| case Stmt::ExprWithCleanupsClass: { |
| // Disallow jumps past full-expressions that use blocks with |
| // non-trivial cleanups of their captures. This is theoretically |
| // implementable but a lot of work which we haven't felt up to doing. |
| ExprWithCleanups *EWC = cast<ExprWithCleanups>(S); |
| for (unsigned i = 0, e = EWC->getNumObjects(); i != e; ++i) { |
| const BlockDecl *BDecl = EWC->getObject(i); |
| for (const auto &CI : BDecl->captures()) { |
| VarDecl *variable = CI.getVariable(); |
| BuildScopeInformation(variable, BDecl, origParentScope); |
| } |
| } |
| break; |
| } |
| |
| case Stmt::MaterializeTemporaryExprClass: { |
| // Disallow jumps out of scopes containing temporaries lifetime-extended to |
| // automatic storage duration. |
| MaterializeTemporaryExpr *MTE = cast<MaterializeTemporaryExpr>(S); |
| if (MTE->getStorageDuration() == SD_Automatic) { |
| SmallVector<const Expr *, 4> CommaLHS; |
| SmallVector<SubobjectAdjustment, 4> Adjustments; |
| const Expr *ExtendedObject = |
| MTE->GetTemporaryExpr()->skipRValueSubobjectAdjustments( |
| CommaLHS, Adjustments); |
| if (ExtendedObject->getType().isDestructedType()) { |
| Scopes.push_back(GotoScope(ParentScope, 0, |
| diag::note_exits_temporary_dtor, |
| ExtendedObject->getExprLoc())); |
| origParentScope = Scopes.size()-1; |
| } |
| } |
| break; |
| } |
| |
| case Stmt::CaseStmtClass: |
| case Stmt::DefaultStmtClass: |
| case Stmt::LabelStmtClass: |
| LabelAndGotoScopes[S] = ParentScope; |
| break; |
| |
| default: |
| break; |
| } |
| |
| for (Stmt *SubStmt : S->children()) { |
| if (!SubStmt) |
| continue; |
| if (StmtsToSkip) { |
| --StmtsToSkip; |
| continue; |
| } |
| |
| // Cases, labels, and defaults aren't "scope parents". It's also |
| // important to handle these iteratively instead of recursively in |
| // order to avoid blowing out the stack. |
| while (true) { |
| Stmt *Next; |
| if (SwitchCase *SC = dyn_cast<SwitchCase>(SubStmt)) |
| Next = SC->getSubStmt(); |
| else if (LabelStmt *LS = dyn_cast<LabelStmt>(SubStmt)) |
| Next = LS->getSubStmt(); |
| else |
| break; |
| |
| LabelAndGotoScopes[SubStmt] = ParentScope; |
| SubStmt = Next; |
| } |
| |
| // Recursively walk the AST. |
| BuildScopeInformation(SubStmt, ParentScope); |
| } |
| } |
| |
| /// VerifyJumps - Verify each element of the Jumps array to see if they are |
| /// valid, emitting diagnostics if not. |
| void JumpScopeChecker::VerifyJumps() { |
| while (!Jumps.empty()) { |
| Stmt *Jump = Jumps.pop_back_val(); |
| |
| // With a goto, |
| if (GotoStmt *GS = dyn_cast<GotoStmt>(Jump)) { |
| // The label may not have a statement if it's coming from inline MS ASM. |
| if (GS->getLabel()->getStmt()) { |
| CheckJump(GS, GS->getLabel()->getStmt(), GS->getGotoLoc(), |
| diag::err_goto_into_protected_scope, |
| diag::ext_goto_into_protected_scope, |
| diag::warn_cxx98_compat_goto_into_protected_scope); |
| } |
| CheckGotoStmt(GS); |
| continue; |
| } |
| |
| // We only get indirect gotos here when they have a constant target. |
| if (IndirectGotoStmt *IGS = dyn_cast<IndirectGotoStmt>(Jump)) { |
| LabelDecl *Target = IGS->getConstantTarget(); |
| CheckJump(IGS, Target->getStmt(), IGS->getGotoLoc(), |
| diag::err_goto_into_protected_scope, |
| diag::ext_goto_into_protected_scope, |
| diag::warn_cxx98_compat_goto_into_protected_scope); |
| continue; |
| } |
| |
| SwitchStmt *SS = cast<SwitchStmt>(Jump); |
| for (SwitchCase *SC = SS->getSwitchCaseList(); SC; |
| SC = SC->getNextSwitchCase()) { |
| if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(SC))) |
| continue; |
| SourceLocation Loc; |
| if (CaseStmt *CS = dyn_cast<CaseStmt>(SC)) |
| Loc = CS->getLocStart(); |
| else if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SC)) |
| Loc = DS->getLocStart(); |
| else |
| Loc = SC->getLocStart(); |
| CheckJump(SS, SC, Loc, diag::err_switch_into_protected_scope, 0, |
| diag::warn_cxx98_compat_switch_into_protected_scope); |
| } |
| } |
| } |
| |
| /// VerifyIndirectJumps - Verify whether any possible indirect jump |
| /// might cross a protection boundary. Unlike direct jumps, indirect |
| /// jumps count cleanups as protection boundaries: since there's no |
| /// way to know where the jump is going, we can't implicitly run the |
| /// right cleanups the way we can with direct jumps. |
| /// |
| /// Thus, an indirect jump is "trivial" if it bypasses no |
| /// initializations and no teardowns. More formally, an indirect jump |
| /// from A to B is trivial if the path out from A to DCA(A,B) is |
| /// trivial and the path in from DCA(A,B) to B is trivial, where |
| /// DCA(A,B) is the deepest common ancestor of A and B. |
| /// Jump-triviality is transitive but asymmetric. |
| /// |
| /// A path in is trivial if none of the entered scopes have an InDiag. |
| /// A path out is trivial is none of the exited scopes have an OutDiag. |
| /// |
| /// Under these definitions, this function checks that the indirect |
| /// jump between A and B is trivial for every indirect goto statement A |
| /// and every label B whose address was taken in the function. |
| void JumpScopeChecker::VerifyIndirectJumps() { |
| if (IndirectJumps.empty()) return; |
| |
| // If there aren't any address-of-label expressions in this function, |
| // complain about the first indirect goto. |
| if (IndirectJumpTargets.empty()) { |
| S.Diag(IndirectJumps[0]->getGotoLoc(), |
| diag::err_indirect_goto_without_addrlabel); |
| return; |
| } |
| |
| // Collect a single representative of every scope containing an |
| // indirect goto. For most code bases, this substantially cuts |
| // down on the number of jump sites we'll have to consider later. |
| typedef std::pair<unsigned, IndirectGotoStmt*> JumpScope; |
| SmallVector<JumpScope, 32> JumpScopes; |
| { |
| llvm::DenseMap<unsigned, IndirectGotoStmt*> JumpScopesMap; |
| for (SmallVectorImpl<IndirectGotoStmt*>::iterator |
| I = IndirectJumps.begin(), E = IndirectJumps.end(); I != E; ++I) { |
| IndirectGotoStmt *IG = *I; |
| if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(IG))) |
| continue; |
| unsigned IGScope = LabelAndGotoScopes[IG]; |
| IndirectGotoStmt *&Entry = JumpScopesMap[IGScope]; |
| if (!Entry) Entry = IG; |
| } |
| JumpScopes.reserve(JumpScopesMap.size()); |
| for (llvm::DenseMap<unsigned, IndirectGotoStmt*>::iterator |
| I = JumpScopesMap.begin(), E = JumpScopesMap.end(); I != E; ++I) |
| JumpScopes.push_back(*I); |
| } |
| |
| // Collect a single representative of every scope containing a |
| // label whose address was taken somewhere in the function. |
| // For most code bases, there will be only one such scope. |
| llvm::DenseMap<unsigned, LabelDecl*> TargetScopes; |
| for (SmallVectorImpl<LabelDecl*>::iterator |
| I = IndirectJumpTargets.begin(), E = IndirectJumpTargets.end(); |
| I != E; ++I) { |
| LabelDecl *TheLabel = *I; |
| if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(TheLabel->getStmt()))) |
| continue; |
| unsigned LabelScope = LabelAndGotoScopes[TheLabel->getStmt()]; |
| LabelDecl *&Target = TargetScopes[LabelScope]; |
| if (!Target) Target = TheLabel; |
| } |
| |
| // For each target scope, make sure it's trivially reachable from |
| // every scope containing a jump site. |
| // |
| // A path between scopes always consists of exitting zero or more |
| // scopes, then entering zero or more scopes. We build a set of |
| // of scopes S from which the target scope can be trivially |
| // entered, then verify that every jump scope can be trivially |
| // exitted to reach a scope in S. |
| llvm::BitVector Reachable(Scopes.size(), false); |
| for (llvm::DenseMap<unsigned,LabelDecl*>::iterator |
| TI = TargetScopes.begin(), TE = TargetScopes.end(); TI != TE; ++TI) { |
| unsigned TargetScope = TI->first; |
| LabelDecl *TargetLabel = TI->second; |
| |
| Reachable.reset(); |
| |
| // Mark all the enclosing scopes from which you can safely jump |
| // into the target scope. 'Min' will end up being the index of |
| // the shallowest such scope. |
| unsigned Min = TargetScope; |
| while (true) { |
| Reachable.set(Min); |
| |
| // Don't go beyond the outermost scope. |
| if (Min == 0) break; |
| |
| // Stop if we can't trivially enter the current scope. |
| if (Scopes[Min].InDiag) break; |
| |
| Min = Scopes[Min].ParentScope; |
| } |
| |
| // Walk through all the jump sites, checking that they can trivially |
| // reach this label scope. |
| for (SmallVectorImpl<JumpScope>::iterator |
| I = JumpScopes.begin(), E = JumpScopes.end(); I != E; ++I) { |
| unsigned Scope = I->first; |
| |
| // Walk out the "scope chain" for this scope, looking for a scope |
| // we've marked reachable. For well-formed code this amortizes |
| // to O(JumpScopes.size() / Scopes.size()): we only iterate |
| // when we see something unmarked, and in well-formed code we |
| // mark everything we iterate past. |
| bool IsReachable = false; |
| while (true) { |
| if (Reachable.test(Scope)) { |
| // If we find something reachable, mark all the scopes we just |
| // walked through as reachable. |
| for (unsigned S = I->first; S != Scope; S = Scopes[S].ParentScope) |
| Reachable.set(S); |
| IsReachable = true; |
| break; |
| } |
| |
| // Don't walk out if we've reached the top-level scope or we've |
| // gotten shallower than the shallowest reachable scope. |
| if (Scope == 0 || Scope < Min) break; |
| |
| // Don't walk out through an out-diagnostic. |
| if (Scopes[Scope].OutDiag) break; |
| |
| Scope = Scopes[Scope].ParentScope; |
| } |
| |
| // Only diagnose if we didn't find something. |
| if (IsReachable) continue; |
| |
| DiagnoseIndirectJump(I->second, I->first, TargetLabel, TargetScope); |
| } |
| } |
| } |
| |
| /// Return true if a particular error+note combination must be downgraded to a |
| /// warning in Microsoft mode. |
| static bool IsMicrosoftJumpWarning(unsigned JumpDiag, unsigned InDiagNote) { |
| return (JumpDiag == diag::err_goto_into_protected_scope && |
| (InDiagNote == diag::note_protected_by_variable_init || |
| InDiagNote == diag::note_protected_by_variable_nontriv_destructor)); |
| } |
| |
| /// Return true if a particular note should be downgraded to a compatibility |
| /// warning in C++11 mode. |
| static bool IsCXX98CompatWarning(Sema &S, unsigned InDiagNote) { |
| return S.getLangOpts().CPlusPlus11 && |
| InDiagNote == diag::note_protected_by_variable_non_pod; |
| } |
| |
| /// Produce primary diagnostic for an indirect jump statement. |
| static void DiagnoseIndirectJumpStmt(Sema &S, IndirectGotoStmt *Jump, |
| LabelDecl *Target, bool &Diagnosed) { |
| if (Diagnosed) |
| return; |
| S.Diag(Jump->getGotoLoc(), diag::err_indirect_goto_in_protected_scope); |
| S.Diag(Target->getStmt()->getIdentLoc(), diag::note_indirect_goto_target); |
| Diagnosed = true; |
| } |
| |
| /// Produce note diagnostics for a jump into a protected scope. |
| void JumpScopeChecker::NoteJumpIntoScopes(ArrayRef<unsigned> ToScopes) { |
| if (CHECK_PERMISSIVE(ToScopes.empty())) |
| return; |
| for (unsigned I = 0, E = ToScopes.size(); I != E; ++I) |
| if (Scopes[ToScopes[I]].InDiag) |
| S.Diag(Scopes[ToScopes[I]].Loc, Scopes[ToScopes[I]].InDiag); |
| } |
| |
| /// Diagnose an indirect jump which is known to cross scopes. |
| void JumpScopeChecker::DiagnoseIndirectJump(IndirectGotoStmt *Jump, |
| unsigned JumpScope, |
| LabelDecl *Target, |
| unsigned TargetScope) { |
| if (CHECK_PERMISSIVE(JumpScope == TargetScope)) |
| return; |
| |
| unsigned Common = GetDeepestCommonScope(JumpScope, TargetScope); |
| bool Diagnosed = false; |
| |
| // Walk out the scope chain until we reach the common ancestor. |
| for (unsigned I = JumpScope; I != Common; I = Scopes[I].ParentScope) |
| if (Scopes[I].OutDiag) { |
| DiagnoseIndirectJumpStmt(S, Jump, Target, Diagnosed); |
| S.Diag(Scopes[I].Loc, Scopes[I].OutDiag); |
| } |
| |
| SmallVector<unsigned, 10> ToScopesCXX98Compat; |
| |
| // Now walk into the scopes containing the label whose address was taken. |
| for (unsigned I = TargetScope; I != Common; I = Scopes[I].ParentScope) |
| if (IsCXX98CompatWarning(S, Scopes[I].InDiag)) |
| ToScopesCXX98Compat.push_back(I); |
| else if (Scopes[I].InDiag) { |
| DiagnoseIndirectJumpStmt(S, Jump, Target, Diagnosed); |
| S.Diag(Scopes[I].Loc, Scopes[I].InDiag); |
| } |
| |
| // Diagnose this jump if it would be ill-formed in C++98. |
| if (!Diagnosed && !ToScopesCXX98Compat.empty()) { |
| S.Diag(Jump->getGotoLoc(), |
| diag::warn_cxx98_compat_indirect_goto_in_protected_scope); |
| S.Diag(Target->getStmt()->getIdentLoc(), diag::note_indirect_goto_target); |
| NoteJumpIntoScopes(ToScopesCXX98Compat); |
| } |
| } |
| |
| /// CheckJump - Validate that the specified jump statement is valid: that it is |
| /// jumping within or out of its current scope, not into a deeper one. |
| void JumpScopeChecker::CheckJump(Stmt *From, Stmt *To, SourceLocation DiagLoc, |
| unsigned JumpDiagError, unsigned JumpDiagWarning, |
| unsigned JumpDiagCXX98Compat) { |
| if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(From))) |
| return; |
| if (CHECK_PERMISSIVE(!LabelAndGotoScopes.count(To))) |
| return; |
| |
| unsigned FromScope = LabelAndGotoScopes[From]; |
| unsigned ToScope = LabelAndGotoScopes[To]; |
| |
| // Common case: exactly the same scope, which is fine. |
| if (FromScope == ToScope) return; |
| |
| // Warn on gotos out of __finally blocks. |
| if (isa<GotoStmt>(From) || isa<IndirectGotoStmt>(From)) { |
| // If FromScope > ToScope, FromScope is more nested and the jump goes to a |
| // less nested scope. Check if it crosses a __finally along the way. |
| for (unsigned I = FromScope; I > ToScope; I = Scopes[I].ParentScope) { |
| if (Scopes[I].InDiag == diag::note_protected_by_seh_finally) { |
| S.Diag(From->getLocStart(), diag::warn_jump_out_of_seh_finally); |
| break; |
| } |
| } |
| } |
| |
| unsigned CommonScope = GetDeepestCommonScope(FromScope, ToScope); |
| |
| // It's okay to jump out from a nested scope. |
| if (CommonScope == ToScope) return; |
| |
| // Pull out (and reverse) any scopes we might need to diagnose skipping. |
| SmallVector<unsigned, 10> ToScopesCXX98Compat; |
| SmallVector<unsigned, 10> ToScopesError; |
| SmallVector<unsigned, 10> ToScopesWarning; |
| for (unsigned I = ToScope; I != CommonScope; I = Scopes[I].ParentScope) { |
| if (S.getLangOpts().MSVCCompat && JumpDiagWarning != 0 && |
| IsMicrosoftJumpWarning(JumpDiagError, Scopes[I].InDiag)) |
| ToScopesWarning.push_back(I); |
| else if (IsCXX98CompatWarning(S, Scopes[I].InDiag)) |
| ToScopesCXX98Compat.push_back(I); |
| else if (Scopes[I].InDiag) |
| ToScopesError.push_back(I); |
| } |
| |
| // Handle warnings. |
| if (!ToScopesWarning.empty()) { |
| S.Diag(DiagLoc, JumpDiagWarning); |
| NoteJumpIntoScopes(ToScopesWarning); |
| } |
| |
| // Handle errors. |
| if (!ToScopesError.empty()) { |
| S.Diag(DiagLoc, JumpDiagError); |
| NoteJumpIntoScopes(ToScopesError); |
| } |
| |
| // Handle -Wc++98-compat warnings if the jump is well-formed. |
| if (ToScopesError.empty() && !ToScopesCXX98Compat.empty()) { |
| S.Diag(DiagLoc, JumpDiagCXX98Compat); |
| NoteJumpIntoScopes(ToScopesCXX98Compat); |
| } |
| } |
| |
| void JumpScopeChecker::CheckGotoStmt(GotoStmt *GS) { |
| if (GS->getLabel()->isMSAsmLabel()) { |
| S.Diag(GS->getGotoLoc(), diag::err_goto_ms_asm_label) |
| << GS->getLabel()->getIdentifier(); |
| S.Diag(GS->getLabel()->getLocation(), diag::note_goto_ms_asm_label) |
| << GS->getLabel()->getIdentifier(); |
| } |
| } |
| |
| void Sema::DiagnoseInvalidJumps(Stmt *Body) { |
| (void)JumpScopeChecker(Body, *this); |
| } |
