//
//===----------------------------------------------------------------------===//
+#include "llvm/ADT/BitVector.h"
#include "Sema.h"
#include "clang/AST/Expr.h"
#include "clang/AST/StmtObjC.h"
/// the parent scope is the function body.
unsigned ParentScope;
- /// Diag - The diagnostic to emit if there is a jump into this scope.
- unsigned Diag;
+ /// InDiag - The diagnostic to emit if there is a jump into this scope.
+ unsigned InDiag;
+
+ /// OutDiag - The diagnostic 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 diag, SourceLocation L)
- : ParentScope(parentScope), Diag(diag), Loc(L) {}
+ GotoScope(unsigned parentScope, unsigned InDiag, unsigned OutDiag,
+ SourceLocation L)
+ : ParentScope(parentScope), InDiag(InDiag), OutDiag(OutDiag), Loc(L) {}
};
llvm::SmallVector<GotoScope, 48> Scopes;
llvm::DenseMap<Stmt*, unsigned> LabelAndGotoScopes;
llvm::SmallVector<Stmt*, 16> Jumps;
+
+ llvm::SmallVector<IndirectGotoStmt*, 4> IndirectJumps;
+ llvm::SmallVector<LabelStmt*, 4> IndirectJumpTargets;
public:
JumpScopeChecker(Stmt *Body, Sema &S);
private:
void BuildScopeInformation(Stmt *S, unsigned ParentScope);
void VerifyJumps();
+ void VerifyIndirectJumps();
+ void DiagnoseIndirectJump(IndirectGotoStmt *IG, unsigned IGScope,
+ LabelStmt *Target, unsigned TargetScope);
void CheckJump(Stmt *From, Stmt *To,
SourceLocation DiagLoc, unsigned JumpDiag);
};
JumpScopeChecker::JumpScopeChecker(Stmt *Body, Sema &s) : S(s) {
// Add a scope entry for function scope.
- Scopes.push_back(GotoScope(~0U, ~0U, SourceLocation()));
+ 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.
// Check that all jumps we saw are kosher.
VerifyJumps();
+ VerifyIndirectJumps();
}
/// 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 unsigned GetDiagForGotoScopeDecl(const Decl *D, bool isCPlusPlus) {
+static std::pair<unsigned,unsigned>
+ GetDiagForGotoScopeDecl(const Decl *D, bool isCPlusPlus) {
if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
+ unsigned InDiag = 0, OutDiag = 0;
if (VD->getType()->isVariablyModifiedType())
- return diag::note_protected_by_vla;
- if (VD->hasAttr<CleanupAttr>())
- return diag::note_protected_by_cleanup;
- if (VD->hasAttr<BlocksAttr>())
- return diag::note_protected_by___block;
- // FIXME: In C++0x, we have to check more conditions than "did we
- // just give it an initializer?". See 6.7p3.
- if (isCPlusPlus && VD->hasLocalStorage() && VD->hasInit())
- return diag::note_protected_by_variable_init;
+ InDiag = diag::note_protected_by_vla;
+
+ if (VD->hasAttr<BlocksAttr>()) {
+ InDiag = diag::note_protected_by___block;
+ OutDiag = diag::note_exits___block;
+ } else if (VD->hasAttr<CleanupAttr>()) {
+ InDiag = diag::note_protected_by_cleanup;
+ OutDiag = diag::note_exits_cleanup;
+ } else if (isCPlusPlus) {
+ // FIXME: In C++0x, we have to check more conditions than "did we
+ // just give it an initializer?". See 6.7p3.
+ if (VD->hasLocalStorage() && VD->hasInit())
+ InDiag = diag::note_protected_by_variable_init;
+
+ CanQualType T = VD->getType()->getCanonicalTypeUnqualified();
+ while (CanQual<ArrayType> AT = T->getAs<ArrayType>())
+ T = AT->getElementType();
+ if (CanQual<RecordType> RT = T->getAs<RecordType>())
+ if (!cast<CXXRecordDecl>(RT->getDecl())->hasTrivialDestructor())
+ OutDiag = diag::note_exits_dtor;
+ }
- } else if (const TypedefDecl *TD = dyn_cast<TypedefDecl>(D)) {
+ return std::make_pair(InDiag, OutDiag);
+ }
+
+ if (const TypedefDecl *TD = dyn_cast<TypedefDecl>(D)) {
if (TD->getUnderlyingType()->isVariablyModifiedType())
- return diag::note_protected_by_vla_typedef;
+ return std::make_pair((unsigned) diag::note_protected_by_vla_typedef, 0);
}
- return 0;
+ return std::make_pair(0U, 0U);
}
void JumpScopeChecker::BuildScopeInformation(Stmt *S, unsigned ParentScope) {
// If we found a label, remember that it is in ParentScope scope.
- if (isa<LabelStmt>(S) || isa<DefaultStmt>(S) || isa<CaseStmt>(S)) {
+ switch (S->getStmtClass()) {
+ case Stmt::LabelStmtClass:
+ case Stmt::DefaultStmtClass:
+ case Stmt::CaseStmtClass:
+ LabelAndGotoScopes[S] = ParentScope;
+ break;
+
+ case Stmt::AddrLabelExprClass:
+ IndirectJumpTargets.push_back(cast<AddrLabelExpr>(S)->getLabel());
+ break;
+
+ case Stmt::IndirectGotoStmtClass:
LabelAndGotoScopes[S] = ParentScope;
- } else if (isa<GotoStmt>(S) || isa<SwitchStmt>(S) ||
- isa<IndirectGotoStmt>(S) || isa<AddrLabelExpr>(S)) {
+ IndirectJumps.push_back(cast<IndirectGotoStmt>(S));
+ break;
+
+ case Stmt::GotoStmtClass:
+ case Stmt::SwitchStmtClass:
// 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_iterator CI = S->child_begin(), E = S->child_end(); CI != E;
for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end();
I != E; ++I) {
// If this decl causes a new scope, push and switch to it.
- if (unsigned Diag = GetDiagForGotoScopeDecl(*I, isCPlusPlus)) {
- Scopes.push_back(GotoScope(ParentScope, Diag, (*I)->getLocation()));
+ std::pair<unsigned,unsigned> Diags
+ = GetDiagForGotoScopeDecl(*I, isCPlusPlus);
+ if (Diags.first || Diags.second) {
+ Scopes.push_back(GotoScope(ParentScope, Diags.first, Diags.second,
+ (*I)->getLocation()));
ParentScope = Scopes.size()-1;
}
// walking all sub-stmts in that scope.
if (ObjCAtTryStmt *AT = dyn_cast<ObjCAtTryStmt>(SubStmt)) {
// Recursively walk the AST for the @try part.
- Scopes.push_back(GotoScope(ParentScope,diag::note_protected_by_objc_try,
+ 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, Scopes.size()-1);
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(), Scopes.size()-1);
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, Scopes.size()-1);
}
// scope.
Scopes.push_back(GotoScope(ParentScope,
diag::note_protected_by_objc_synchronized,
+ diag::note_exits_objc_synchronized,
AS->getAtSynchronizedLoc()));
BuildScopeInformation(AS->getSynchBody(), 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,
+ 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, Scopes.size()-1);
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(), Scopes.size()-1);
}
continue;
}
- if (SwitchStmt *SS = dyn_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);
- }
- 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);
}
+ }
+}
+
+/// VerifyIndirectJumps - Verify whether any possible indirect jump might
+/// cross a protection boundary.
+///
+/// An indirect jump is "trivial" if it bypasses no initializations
+/// and no teardowns. More formally, the 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.
+/// 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.
+/// Jump-triviality is transitive but asymmetric.
+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;
+ }
+
+ // Build a vector of source scopes. This serves to unique source
+ // scopes as well as to eliminate redundant lookups into
+ // LabelAndGotoScopes.
+ typedef std::pair<unsigned, IndirectGotoStmt*> JumpScope;
+ llvm::SmallVector<JumpScope, 32> JumpScopes;
+ {
+ llvm::DenseMap<unsigned, IndirectGotoStmt*> JumpScopesMap;
+ for (llvm::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);
+ }
+
+ // Find a representative label from each protection scope.
+ llvm::DenseMap<unsigned, LabelStmt*> TargetScopes;
+ for (llvm::SmallVectorImpl<LabelStmt*>::iterator
+ I = IndirectJumpTargets.begin(), E = IndirectJumpTargets.end();
+ I != E; ++I) {
+ LabelStmt *TheLabel = *I;
+ assert(LabelAndGotoScopes.count(TheLabel) &&
+ "Referenced label didn't get added to scopes?");
+ unsigned LabelScope = LabelAndGotoScopes[TheLabel];
+ LabelStmt *&Target = TargetScopes[LabelScope];
+ if (!Target) Target = TheLabel;
+ }
+
+ llvm::BitVector Reachable(Scopes.size(), false);
+ for (llvm::DenseMap<unsigned,LabelStmt*>::iterator
+ TI = TargetScopes.begin(), TE = TargetScopes.end(); TI != TE; ++TI) {
+ unsigned TargetScope = TI->first;
+ LabelStmt *TargetLabel = TI->second;
+
+ Reachable.reset();
+
+ // Mark all the enclosing scopes from which you can safely jump
+ // into the target scope.
+ unsigned Min = TargetScope;
+ while (true) {
+ Reachable.set(Min);
+
+ // Don't go beyond the outermost scope.
+ if (Min == 0) break;
+
+ // Don't go further if we couldn't trivially enter this scope.
+ if (Scopes[Min].InDiag) break;
- unsigned DiagnosticScope;
-
- // We don't know where an indirect goto goes, require that it be at the
- // top level of scoping.
- if (IndirectGotoStmt *IG = dyn_cast<IndirectGotoStmt>(Jump)) {
- assert(LabelAndGotoScopes.count(Jump) &&
- "Jump didn't get added to scopes?");
- unsigned GotoScope = LabelAndGotoScopes[IG];
- if (GotoScope == 0) continue; // indirect jump is ok.
- S.Diag(IG->getGotoLoc(), diag::err_indirect_goto_in_protected_scope);
- DiagnosticScope = GotoScope;
- } else {
- // We model &&Label as a jump for purposes of scope tracking. We actually
- // don't care *where* the address of label is, but we require the *label
- // itself* to be in scope 0. If it is nested inside of a VLA scope, then
- // it is possible for an indirect goto to illegally enter the VLA scope by
- // indirectly jumping to the label.
- assert(isa<AddrLabelExpr>(Jump) && "Unknown jump type");
- LabelStmt *TheLabel = cast<AddrLabelExpr>(Jump)->getLabel();
-
- assert(LabelAndGotoScopes.count(TheLabel) &&
- "Referenced label didn't get added to scopes?");
- unsigned LabelScope = LabelAndGotoScopes[TheLabel];
- if (LabelScope == 0) continue; // Addr of label is ok.
-
- S.Diag(Jump->getLocStart(), diag::err_addr_of_label_in_protected_scope);
- DiagnosticScope = LabelScope;
+ Min = Scopes[Min].ParentScope;
}
- // Report all the things that would be skipped over by this &&label or
- // indirect goto.
- while (DiagnosticScope != 0) {
- S.Diag(Scopes[DiagnosticScope].Loc, Scopes[DiagnosticScope].Diag);
- DiagnosticScope = Scopes[DiagnosticScope].ParentScope;
+ // Walk through all the jump sites, checking that they can trivially
+ // reach this label scope.
+ for (llvm::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.
+ 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);
}
}
}
+void JumpScopeChecker::DiagnoseIndirectJump(IndirectGotoStmt *Jump,
+ unsigned JumpScope,
+ LabelStmt *Target,
+ unsigned TargetScope) {
+ assert(JumpScope != TargetScope);
+
+ S.Diag(Jump->getGotoLoc(), diag::warn_indirect_goto_in_protected_scope);
+ S.Diag(Target->getIdentLoc(), diag::note_indirect_goto_target);
+
+ // Collect everything in the target scope chain.
+ llvm::DenseSet<unsigned> TargetScopeChain;
+ for (unsigned SI = TargetScope; SI != 0; SI = Scopes[SI].ParentScope)
+ TargetScopeChain.insert(SI);
+ TargetScopeChain.insert(0);
+
+ // Walk out the scopes containing the indirect goto until we find a
+ // common ancestor with the target label.
+ unsigned Common = JumpScope;
+ while (!TargetScopeChain.count(Common)) {
+ // FIXME: this isn't necessarily a problem! Not every protected
+ // scope requires destruction.
+ S.Diag(Scopes[Common].Loc, Scopes[Common].OutDiag);
+ Common = Scopes[Common].ParentScope;
+ }
+
+ // Now walk into the scopes containing the label whose address was taken.
+ for (unsigned SI = TargetScope; SI != Common; SI = Scopes[SI].ParentScope)
+ S.Diag(Scopes[SI].Loc, Scopes[SI].InDiag);
+}
+
/// 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,
TestScope = Scopes[TestScope].ParentScope;
}
- // If we get here, then we know we have invalid code. Diagnose the bad jump,
- // and then emit a note at each VLA being jumped out of.
- S.Diag(DiagLoc, JumpDiag);
+ // If we get here, then either we have invalid code or we're jumping in
+ // past some cleanup blocks. It may seem strange to have a declaration
+ // with a trivial constructor and a non-trivial destructor, but it's
+ // possible.
// Eliminate the common prefix of the jump and the target. Start by
// linearizing both scopes, reversing them as we go.
ToScopes.push_back(TestScope);
// Remove any common entries (such as the top-level function scope).
- while (!FromScopes.empty() && FromScopes.back() == ToScopes.back()) {
+ while (!FromScopes.empty() && (FromScopes.back() == ToScopes.back())) {
FromScopes.pop_back();
ToScopes.pop_back();
}
+ // Ignore any cleanup blocks on the way in.
+ while (!ToScopes.empty()) {
+ if (Scopes[ToScopes.back()].InDiag) break;
+ ToScopes.pop_back();
+ }
+ if (ToScopes.empty()) return;
+
+ S.Diag(DiagLoc, JumpDiag);
+
// Emit diagnostics for whatever is left in ToScopes.
for (unsigned i = 0, e = ToScopes.size(); i != e; ++i)
- S.Diag(Scopes[ToScopes[i]].Loc, Scopes[ToScopes[i]].Diag);
+ S.Diag(Scopes[ToScopes[i]].Loc, Scopes[ToScopes[i]].InDiag);
}
void Sema::DiagnoseInvalidJumps(Stmt *Body) {