summaryrefslogtreecommitdiff
path: root/clang/lib/Sema/JumpDiagnostics.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'clang/lib/Sema/JumpDiagnostics.cpp')
-rw-r--r--clang/lib/Sema/JumpDiagnostics.cpp770
1 files changed, 770 insertions, 0 deletions
diff --git a/clang/lib/Sema/JumpDiagnostics.cpp b/clang/lib/Sema/JumpDiagnostics.cpp
new file mode 100644
index 0000000..ab786c6
--- /dev/null
+++ b/clang/lib/Sema/JumpDiagnostics.cpp
@@ -0,0 +1,770 @@
+//===--- 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/StmtObjC.h"
+#include "clang/AST/StmtCXX.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;
+
+ /// 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);
+
+ unsigned GetDeepestCommonScope(unsigned A, unsigned B);
+};
+} // end anonymous namespace
+
+
+JumpScopeChecker::JumpScopeChecker(Stmt *Body, Sema &s) : S(s) {
+ // 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(ASTContext &Context, const Decl *D) {
+ if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
+ unsigned InDiag = 0, 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 (Context.getLangOpts().ObjCAutoRefCount && VD->hasLocalStorage()) {
+ switch (VD->getType().getObjCLifetime()) {
+ case Qualifiers::OCL_None:
+ case Qualifiers::OCL_ExplicitNone:
+ case Qualifiers::OCL_Autoreleasing:
+ break;
+
+ case Qualifiers::OCL_Strong:
+ case Qualifiers::OCL_Weak:
+ return ScopePair(diag::note_protected_by_objc_ownership,
+ diag::note_exits_objc_ownership);
+ }
+ }
+
+ if (Context.getLangOpts().CPlusPlus && VD->hasLocalStorage()) {
+ // 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.
+
+ if (const Expr *init = VD->getInit()) {
+ // We actually give variables of record type (or array thereof)
+ // an initializer even if that initializer only calls a trivial
+ // ctor. Detect that case.
+ // FIXME: With generalized initializer lists, this may
+ // classify "X x{};" as having no initializer.
+ unsigned inDiagToUse = diag::note_protected_by_variable_init;
+
+ const CXXRecordDecl *record = 0;
+
+ if (const CXXConstructExpr *cce = dyn_cast<CXXConstructExpr>(init)) {
+ const CXXConstructorDecl *ctor = cce->getConstructor();
+ record = ctor->getParent();
+
+ if (ctor->isTrivial() && ctor->isDefaultConstructor()) {
+ if (!record->hasTrivialDestructor())
+ inDiagToUse = diag::note_protected_by_variable_nontriv_destructor;
+ else if (!record->isPOD())
+ inDiagToUse = diag::note_protected_by_variable_non_pod;
+ else
+ inDiagToUse = 0;
+ }
+ } else if (VD->getType()->isArrayType()) {
+ record = VD->getType()->getBaseElementTypeUnsafe()
+ ->getAsCXXRecordDecl();
+ }
+
+ if (inDiagToUse)
+ InDiag = inDiagToUse;
+
+ // Also object to indirect jumps which leave scopes with dtors.
+ if (record && !record->hasTrivialDestructor())
+ OutDiag = diag::note_exits_dtor;
+ }
+ }
+
+ return ScopePair(InDiag, OutDiag);
+ }
+
+ if (const TypedefDecl *TD = dyn_cast<TypedefDecl>(D)) {
+ if (TD->getUnderlyingType()->isVariablyModifiedType())
+ return ScopePair(diag::note_protected_by_vla_typedef, 0);
+ }
+
+ if (const TypeAliasDecl *TD = dyn_cast<TypeAliasDecl>(D)) {
+ if (TD->getUnderlyingType()->isVariablyModifiedType())
+ return ScopePair(diag::note_protected_by_vla_type_alias, 0);
+ }
+
+ return ScopePair(0U, 0U);
+}
+
+/// \brief 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.Context, 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);
+}
+
+/// \brief 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_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);
+
+ bool SkipFirstSubStmt = false;
+
+ // 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::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 condition variable before entering the scope of the switch
+ // statement.
+ if (VarDecl *Var = cast<SwitchStmt>(S)->getConditionVariable()) {
+ BuildScopeInformation(Var, ParentScope);
+ SkipFirstSubStmt = true;
+ }
+ // Fall through
+
+ 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;
+
+ default:
+ break;
+ }
+
+ for (Stmt::child_range CI = S->children(); CI; ++CI) {
+ if (SkipFirstSubStmt) {
+ SkipFirstSubStmt = false;
+ continue;
+ }
+
+ Stmt *SubStmt = *CI;
+ if (SubStmt == 0) 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 (CaseStmt *CS = dyn_cast<CaseStmt>(SubStmt))
+ Next = CS->getSubStmt();
+ else if (DefaultStmt *DS = dyn_cast<DefaultStmt>(SubStmt))
+ Next = DS->getSubStmt();
+ else if (LabelStmt *LS = dyn_cast<LabelStmt>(SubStmt))
+ Next = LS->getSubStmt();
+ else
+ break;
+
+ LabelAndGotoScopes[SubStmt] = ParentScope;
+ SubStmt = Next;
+ }
+
+ // If this is a declstmt with a VLA definition, it defines a scope from here
+ // to the end of the containing context.
+ if (DeclStmt *DS = dyn_cast<DeclStmt>(SubStmt)) {
+ // The decl statement creates a scope if any of the decls in it are VLAs
+ // or have the cleanup attribute.
+ for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end();
+ I != E; ++I)
+ BuildScopeInformation(*I, ParentScope);
+ continue;
+ }
+ // Disallow jumps into any part of an @try statement by pushing a scope and
+ // walking all sub-stmts in that scope.
+ if (ObjCAtTryStmt *AT = dyn_cast<ObjCAtTryStmt>(SubStmt)) {
+ unsigned newParentScope;
+ // Recursively walk the AST for the @try part.
+ 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 = Scopes.size()-1));
+
+ // 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);
+ 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 = Scopes.size()-1));
+ }
+
+ // Jump from the finally to the try or catch is not valid.
+ if (ObjCAtFinallyStmt *AF = AT->getFinallyStmt()) {
+ Scopes.push_back(GotoScope(ParentScope,
+ diag::note_protected_by_objc_finally,
+ diag::note_exits_objc_finally,
+ AF->getAtFinallyLoc()));
+ BuildScopeInformation(AF, (newParentScope = Scopes.size()-1));
+ }
+
+ continue;
+ }
+
+ unsigned newParentScope;
+ // Disallow jumps into the protected statement of an @synchronized, but
+ // allow jumps into the object expression it protects.
+ if (ObjCAtSynchronizedStmt *AS = dyn_cast<ObjCAtSynchronizedStmt>(SubStmt)){
+ // 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.
+ Scopes.push_back(GotoScope(ParentScope,
+ diag::note_protected_by_objc_synchronized,
+ diag::note_exits_objc_synchronized,
+ AS->getAtSynchronizedLoc()));
+ BuildScopeInformation(AS->getSynchBody(),
+ (newParentScope = Scopes.size()-1));
+ continue;
+ }
+
+ // Disallow jumps into any part of a C++ try statement. This is pretty
+ // much the same as for Obj-C.
+ if (CXXTryStmt *TS = dyn_cast<CXXTryStmt>(SubStmt)) {
+ 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 = Scopes.size()-1));
+
+ // 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);
+ Scopes.push_back(GotoScope(ParentScope,
+ diag::note_protected_by_cxx_catch,
+ diag::note_exits_cxx_catch,
+ CS->getSourceRange().getBegin()));
+ BuildScopeInformation(CS->getHandlerBlock(),
+ (newParentScope = Scopes.size()-1));
+ }
+
+ continue;
+ }
+
+ // Disallow jumps into the protected statement of an @autoreleasepool.
+ if (ObjCAutoreleasePoolStmt *AS = dyn_cast<ObjCAutoreleasePoolStmt>(SubStmt)){
+ // Recursively walk the AST for the @autoreleasepool part, protected by a new
+ // scope.
+ Scopes.push_back(GotoScope(ParentScope,
+ diag::note_protected_by_objc_autoreleasepool,
+ diag::note_exits_objc_autoreleasepool,
+ AS->getAtLoc()));
+ BuildScopeInformation(AS->getSubStmt(), (newParentScope = Scopes.size()-1));
+ continue;
+ }
+
+ if (const BlockExpr *BE = dyn_cast<BlockExpr>(SubStmt)) {
+ const BlockDecl *BDecl = BE->getBlockDecl();
+ for (BlockDecl::capture_const_iterator ci = BDecl->capture_begin(),
+ ce = BDecl->capture_end(); ci != ce; ++ci) {
+ VarDecl *variable = ci->getVariable();
+ BuildScopeInformation(variable, BDecl, ParentScope);
+ }
+ }
+
+ // 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)) {
+ CheckJump(GS, GS->getLabel()->getStmt(), GS->getGotoLoc(),
+ diag::err_goto_into_protected_scope,
+ diag::warn_goto_into_protected_scope,
+ diag::warn_cxx98_compat_goto_into_protected_scope);
+ 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::warn_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()) {
+ assert(LabelAndGotoScopes.count(SC) && "Case not visited?");
+ CheckJump(SS, SC, SC->getLocStart(),
+ 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;
+ assert(LabelAndGotoScopes.count(IG) &&
+ "indirect jump didn't get added to scopes?");
+ 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;
+ assert(LabelAndGotoScopes.count(TheLabel->getStmt()) &&
+ "Referenced label didn't get added to scopes?");
+ 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().CPlusPlus0x &&
+ 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) {
+ assert(!ToScopes.empty());
+ 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) {
+ assert(JumpScope != TargetScope);
+
+ 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) {
+ assert(LabelAndGotoScopes.count(From) && "Jump didn't get added to scopes?");
+ unsigned FromScope = LabelAndGotoScopes[From];
+
+ assert(LabelAndGotoScopes.count(To) && "Jump didn't get added to scopes?");
+ unsigned ToScope = LabelAndGotoScopes[To];
+
+ // Common case: exactly the same scope, which is fine.
+ if (FromScope == ToScope) return;
+
+ 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().MicrosoftMode && 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 Sema::DiagnoseInvalidJumps(Stmt *Body) {
+ (void)JumpScopeChecker(Body, *this);
+}