/// 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);
}
}
}
StringRef ClangAsmParserCallback::LookupInlineAsmLabel(StringRef Identifier,
llvm::SourceMgr &LSM,
llvm::SMLoc Location,
bool Create) {
SourceLocation Loc = translateLocation(LSM, Location);
LabelDecl *Label =
TheParser.getActions().GetOrCreateMSAsmLabel(Identifier, Loc, Create);
return Label->getMSAsmLabel();
}
/// 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);
}
}
}
LabelDecl *Sema::GetOrCreateMSAsmLabel(StringRef ExternalLabelName,
SourceLocation Location,
bool AlwaysCreate) {
LabelDecl* Label = LookupOrCreateLabel(PP.getIdentifierInfo(ExternalLabelName),
Location);
if (Label->isMSAsmLabel()) {
// If we have previously created this label implicitly, mark it as used.
Label->markUsed(Context);
} else {
// Otherwise, insert it, but only resolve it if we have seen the label itself.
std::string InternalName;
llvm::raw_string_ostream OS(InternalName);
// Create an internal name for the label. The name should not be a valid mangled
// name, and should be unique. We use a dot to make the name an invalid mangled
// name.
OS << "__MSASMLABEL_." << MSAsmLabelNameCounter++ << "__" << ExternalLabelName;
Label->setMSAsmLabel(OS.str());
}
if (AlwaysCreate) {
// The label might have been created implicitly from a previously encountered
// goto statement. So, for both newly created and looked up labels, we mark
// them as resolved.
Label->setMSAsmLabelResolved();
}
// Adjust their location for being able to generate accurate diagnostics.
Label->setLocation(Location);
return Label;
}
LabelDecl *Sema::GetOrCreateMSAsmLabel(StringRef ExternalLabelName,
SourceLocation Location,
bool AlwaysCreate) {
LabelDecl* Label = LookupOrCreateLabel(PP.getIdentifierInfo(ExternalLabelName),
Location);
if (Label->isMSAsmLabel()) {
// If we have previously created this label implicitly, mark it as used.
Label->markUsed(Context);
} else {
// Otherwise, insert it, but only resolve it if we have seen the label itself.
std::string InternalName;
llvm::raw_string_ostream OS(InternalName);
// Create an internal name for the label. The name should not be a valid
// mangled name, and should be unique. We use a dot to make the name an
// invalid mangled name. We use LLVM's inline asm ${:uid} escape so that a
// unique label is generated each time this blob is emitted, even after
// inlining or LTO.
OS << "__MSASMLABEL_.${:uid}__";
for (char C : ExternalLabelName) {
OS << C;
// We escape '$' in asm strings by replacing it with "$$"
if (C == '$')
OS << '$';
}
Label->setMSAsmLabel(OS.str());
}
if (AlwaysCreate) {
// The label might have been created implicitly from a previously encountered
// goto statement. So, for both newly created and looked up labels, we mark
// them as resolved.
Label->setMSAsmLabelResolved();
}
// Adjust their location for being able to generate accurate diagnostics.
Label->setLocation(Location);
return Label;
}
/// 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);
}
}
}
