Skip to content

[WinEH] Fix try scopes leaking to caller on inline #167176

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
MuellerMP wants to merge 1 commit into
base: main
Choose a base branch
from
Open

[WinEH] Fix try scopes leaking to caller on inline #167176

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
11 changes: 7 additions & 4 deletions clang/lib/CodeGen/CGCleanup.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1329,8 +1329,11 @@ void CodeGenFunction::EmitCXXTemporary(const CXXTemporary *Temporary,
// Need to set "funclet" in OperandBundle properly for noThrow
// intrinsic (see CGCall.cpp)
static void EmitSehScope(CodeGenFunction &CGF,
llvm::FunctionCallee &SehCppScope) {
llvm::BasicBlock *InvokeDest = CGF.getInvokeDest();
llvm::FunctionCallee &SehCppScope,
llvm::BasicBlock *InvokeDest = nullptr) {
if (!InvokeDest)
InvokeDest = CGF.getInvokeDest();

assert(CGF.Builder.GetInsertBlock() && InvokeDest);
llvm::BasicBlock *Cont = CGF.createBasicBlock("invoke.cont");
SmallVector<llvm::OperandBundleDef, 1> BundleList =
Expand Down Expand Up @@ -1373,11 +1376,11 @@ void CodeGenFunction::EmitSehTryScopeBegin() {
}

// Invoke a llvm.seh.try.end at the end of a SEH scope for -EHa
void CodeGenFunction::EmitSehTryScopeEnd() {
void CodeGenFunction::EmitSehTryScopeEnd(llvm::BasicBlock *InvokeDest) {
assert(getLangOpts().EHAsynch);
llvm::FunctionType *FTy =
llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
llvm::FunctionCallee SehCppScope =
CGM.CreateRuntimeFunction(FTy, "llvm.seh.try.end");
EmitSehScope(*this, SehCppScope);
EmitSehScope(*this, SehCppScope, InvokeDest);
}
57 changes: 50 additions & 7 deletions clang/lib/CodeGen/CGException.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -635,14 +635,30 @@ void CodeGenFunction::EmitCXXTryStmt(const CXXTryStmt &S) {
ExitCXXTryStmt(S);
}

struct TerminateTryScope final : EHScopeStack::Cleanup {
llvm::BasicBlock *InvokeDest;

TerminateTryScope(llvm::BasicBlock *BB) : InvokeDest(BB) {}

void Emit(CodeGenFunction &CGF, Flags flags) override {
CGF.EmitSehTryScopeEnd(InvokeDest);
}
};

struct HandlerInfo {
CatchTypeInfo TypeInfo;
bool RequiresSehScope;
};

void CodeGenFunction::EnterCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
unsigned NumHandlers = S.getNumHandlers();
EHCatchScope *CatchScope = EHStack.pushCatch(NumHandlers);
unsigned NumHandlerInfos = NumHandlers > 0 ? NumHandlers - 1 : 0;
llvm::BasicBlock *DispatchBlock = nullptr;
llvm::SmallVector<HandlerInfo> HandlerInfos;
HandlerInfos.reserve(NumHandlerInfos);
Copy link
Collaborator

@efriedma-quic efriedma-quic Dec 10, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

It's not worth the extra code here to try to reserve the exact amount in the array.


for (unsigned I = 0; I != NumHandlers; ++I) {
const CXXCatchStmt *C = S.getHandler(I);

llvm::BasicBlock *Handler = createBasicBlock("catch");
if (C->getExceptionDecl()) {
// FIXME: Dropping the reference type on the type into makes it
// impossible to correctly implement catch-by-reference
Expand All @@ -660,14 +676,32 @@ void CodeGenFunction::EnterCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
else
TypeInfo = CGM.getCXXABI().getAddrOfCXXCatchHandlerType(
CaughtType, C->getCaughtType());
CatchScope->setHandler(I, TypeInfo, Handler);
HandlerInfos.push_back({TypeInfo, false});
} else {
bool HasEHa = getLangOpts().EHAsynch;
// No exception decl indicates '...', a catch-all.
CatchScope->setHandler(I, CGM.getCXXABI().getCatchAllTypeInfo(), Handler);
HandlerInfos.push_back({CGM.getCXXABI().getCatchAllTypeInfo(), HasEHa});
if (HasEHa) {
DispatchBlock = createBasicBlock("catch.dispatch");
// Push a terminator for the created SEH __try scope
EHStack.pushCleanup<TerminateTryScope>(NormalCleanup, DispatchBlock);
}
}
}

EHCatchScope *CatchScope = EHStack.pushCatch(NumHandlers);

for (unsigned I = 0; I < HandlerInfos.size(); ++I) {
llvm::BasicBlock *Handler = createBasicBlock("catch");
auto HandlerInfo = HandlerInfos[I];
CatchScope->setHandler(I, HandlerInfo.TypeInfo, Handler);

if (HandlerInfo.RequiresSehScope) {
// Under async exceptions, catch(...) need to catch HW exception too
// Mark scope with SehTryBegin as a SEH __try scope
if (getLangOpts().EHAsynch)
EmitSehTryScopeBegin();
auto &Scope = *EHStack.find(EHStack.getInnermostEHScope());
Scope.setCachedEHDispatchBlock(DispatchBlock);
EmitSehTryScopeBegin();
}
}
}
Expand Down Expand Up @@ -2186,7 +2220,16 @@ void CodeGenFunction::EnterSEHTryStmt(const SEHTryStmt &S) {
// Otherwise, we must have an __except block.
const SEHExceptStmt *Except = S.getExceptHandler();
assert(Except);

auto *DispatchBlock = createBasicBlock("catch.dispatch");
if (getLangOpts().EHAsynch) {
EHStack.pushCleanup<TerminateTryScope>(NormalCleanup, DispatchBlock);
}

EHCatchScope *CatchScope = EHStack.pushCatch(1);
auto &Scope = *EHStack.find(EHStack.getInnermostEHScope());
Scope.setCachedEHDispatchBlock(DispatchBlock);

SEHCodeSlotStack.push_back(
CreateMemTemp(getContext().IntTy, "__exception_code"));

Expand Down
2 changes: 1 addition & 1 deletion clang/lib/CodeGen/CodeGenFunction.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3241,7 +3241,7 @@ class CodeGenFunction : public CodeGenTypeCache {
void EmitSehCppScopeBegin();
void EmitSehCppScopeEnd();
void EmitSehTryScopeBegin();
void EmitSehTryScopeEnd();
void EmitSehTryScopeEnd(llvm::BasicBlock *InvokeDest = nullptr);

bool EmitLifetimeStart(llvm::Value *Addr);
void EmitLifetimeEnd(llvm::Value *Addr);
Expand Down
62 changes: 62 additions & 0 deletions clang/test/CodeGen/windows-seh-EHa-Inline1.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,62 @@
// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 6
// RUN: %clang_cc1 -O3 -triple x86_64-windows -fasync-exceptions -fcxx-exceptions -fexceptions -fms-extensions -x c++ -Wno-implicit-function-declaration -emit-llvm %s -o - | FileCheck %s
Copy link
Collaborator

@efriedma-quic efriedma-quic Dec 10, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

We generally prefer clang tests to run with optimizations disabled: it makes it easier to see the correspondence between what we're testing and what's actually getting generated, and it makes the tests less sensitive to optimizer changes. (There's a minor downside that it doesn't always capture the end-to-end result, but usually a set of clang tests plus a set of LLVM optimizer tests is sufficient.)

// Check that the try scope of ExitOnThrow is terminated upon inlining into main.
int AlwaysThrows(int);
[[noreturn]] void Exit();

int ExitOnThrow(int argc) noexcept
{
try {
if (!argc) { throw -1; }
return argc;
} catch (...) {
}

Exit();
return 0;
}

// CHECK-LABEL: define dso_local noundef i32 @main(
// CHECK-SAME: i32 noundef [[ARGC:%.*]], ptr noundef readnone captures(none) [[TMP0:%.*]]) local_unnamed_addr #[[ATTR3:[0-9]+]] personality ptr @__CxxFrameHandler3 {
// CHECK-NEXT: [[ENTRY:.*:]]
// CHECK-NEXT: [[TMP_I:%.*]] = alloca i32, align 4
// CHECK-NEXT: call void @llvm.lifetime.start.p0(ptr nonnull [[TMP_I]])
// CHECK-NEXT: invoke void @llvm.seh.try.begin()
// CHECK-NEXT: to label %[[INVOKE_CONT_I:.*]] unwind label %[[CATCH_DISPATCH_I:.*]]
// CHECK: [[INVOKE_CONT_I]]:
// CHECK-NEXT: [[TOBOOL_NOT_I:%.*]] = icmp eq i32 [[ARGC]], 0
// CHECK-NEXT: br i1 [[TOBOOL_NOT_I]], label %[[IF_THEN_I:.*]], label %[[IF_END_I:.*]]
// CHECK: [[IF_THEN_I]]:
// CHECK-NEXT: store i32 -1, ptr [[TMP_I]], align 4, !tbaa [[INT_TBAA7:![0-9]+]]
// CHECK-NEXT: invoke void @_CxxThrowException(ptr nonnull [[TMP_I]], ptr nonnull @_TI1H) #[[ATTR6:[0-9]+]]
// CHECK-NEXT: to label %[[UNREACHABLE_I:.*]] unwind label %[[CATCH_DISPATCH_I]]
// CHECK: [[CATCH_DISPATCH_I]]:
// CHECK-NEXT: [[TMP1:%.*]] = catchswitch within none [label %[[CATCH_I:.*]]] unwind to caller
// CHECK: [[CATCH_I]]:
// CHECK-NEXT: [[TMP2:%.*]] = catchpad within [[TMP1]] [ptr null, i32 0, ptr null]
// CHECK-NEXT: catchret from [[TMP2]] to label %[[TRY_CONT_I:.*]]
// CHECK: [[TRY_CONT_I]]:
// CHECK-NEXT: call void @"?Exit@@YAXXZ"() #[[ATTR7:[0-9]+]]
// CHECK-NEXT: unreachable
// CHECK: [[IF_END_I]]:
// CHECK-NEXT: invoke void @llvm.seh.try.end()
// CHECK-NEXT: to label %"?ExitOnThrow@@[email protected]" unwind label %[[CATCH_DISPATCH_I]]
// CHECK: [[UNREACHABLE_I]]:
// CHECK-NEXT: unreachable
// CHECK: "?ExitOnThrow@@[email protected]":
// CHECK-NEXT: call void @llvm.lifetime.end.p0(ptr nonnull [[TMP_I]])
// CHECK-NEXT: [[CALL1:%.*]] = tail call noundef i32 @"?AlwaysThrows@@YAHH@Z"(i32 noundef [[ARGC]])
// CHECK-NEXT: [[ADD:%.*]] = add nsw i32 [[CALL1]], [[ARGC]]
// CHECK-NEXT: ret i32 [[ADD]]
//
int main(int argc, char**)
{
auto data = ExitOnThrow(argc);
return data + AlwaysThrows(data);
}
//.
// CHECK: [[INT_TBAA7]] = !{[[META8:![0-9]+]], [[META8]], i64 0}
// CHECK: [[META8]] = !{!"int", [[META9:![0-9]+]], i64 0}
// CHECK: [[META9]] = !{!"omnipotent char", [[META10:![0-9]+]], i64 0}
// CHECK: [[META10]] = !{!"Simple C++ TBAA"}
//.
121 changes: 121 additions & 0 deletions clang/test/CodeGen/windows-seh-EHa-Inline2.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,121 @@
// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 6
// RUN: %clang_cc1 -O3 -triple x86_64-windows -fasync-exceptions -fcxx-exceptions -fexceptions -fms-extensions -x c++ -Wno-implicit-function-declaration -emit-llvm %s -o - | FileCheck %s
// Check that only the outermost try scope containing a return statement is terminated upon inlining into main.
void DoSth();
int AlwaysThrows(int);
[[noreturn]] void Exit();

int ExitOnThrow(int argc) noexcept
{
try {
try {
DoSth();
} catch(...) {}
} catch(...) {}

try {
try {
if (!argc) { throw -1; }
return argc;
} catch (...) {}
} catch (...) {}

Exit();
return 0;
}

// CHECK-LABEL: define dso_local noundef i32 @main(
// CHECK-SAME: i32 noundef [[ARGC:%.*]], ptr noundef readnone captures(none) [[TMP0:%.*]]) local_unnamed_addr #[[ATTR5:[0-9]+]] personality ptr @__CxxFrameHandler3 {
// CHECK-NEXT: [[ENTRY:.*:]]
// CHECK-NEXT: [[TMP_I:%.*]] = alloca i32, align 4
// CHECK-NEXT: call void @llvm.lifetime.start.p0(ptr nonnull [[TMP_I]])
// CHECK-NEXT: invoke void @llvm.seh.try.begin()
// CHECK-NEXT: to label %[[INVOKE_CONT_I:.*]] unwind label %[[CATCH_DISPATCH6_I:.*]]
// CHECK: [[INVOKE_CONT_I]]:
// CHECK-NEXT: invoke void @llvm.seh.try.begin()
// CHECK-NEXT: to label %[[INVOKE_CONT1_I:.*]] unwind label %[[CATCH_DISPATCH_I:.*]]
// CHECK: [[INVOKE_CONT1_I]]:
// CHECK-NEXT: invoke void @"?DoSth@@YAXXZ"()
// CHECK-NEXT: to label %[[TRY_CONT_I:.*]] unwind label %[[CATCH_DISPATCH_I]]
// CHECK: [[CATCH_DISPATCH_I]]:
// CHECK-NEXT: [[TMP1:%.*]] = catchswitch within none [label %[[CATCH_I:.*]]] unwind label %[[CATCH_DISPATCH6_I]]
// CHECK: [[CATCH_I]]:
// CHECK-NEXT: [[TMP2:%.*]] = catchpad within [[TMP1]] [ptr null, i32 0, ptr null]
// CHECK-NEXT: invoke void @llvm.seh.scope.end() [ "funclet"(token [[TMP2]]) ]
// CHECK-NEXT: to label %[[INVOKE_CONT3_I:.*]] unwind label %[[CATCH_DISPATCH6_I]]
// CHECK: [[INVOKE_CONT3_I]]:
// CHECK-NEXT: catchret from [[TMP2]] to label %[[TRY_CONT_I]]
// CHECK: [[TRY_CONT_I]]:
// CHECK-NEXT: invoke void @llvm.seh.scope.end()
// CHECK-NEXT: to label %[[INVOKE_CONT4_I:.*]] unwind label %[[CATCH_DISPATCH6_I]]
// CHECK: [[CATCH_DISPATCH6_I]]:
// CHECK-NEXT: [[TMP3:%.*]] = catchswitch within none [label %[[CATCH7_I:.*]]] unwind to caller
// CHECK: [[CATCH7_I]]:
// CHECK-NEXT: [[TMP4:%.*]] = catchpad within [[TMP3]] [ptr null, i32 0, ptr null]
// CHECK-NEXT: catchret from [[TMP4]] to label %[[TRY_CONT9_I:.*]]
// CHECK: [[TRY_CONT9_I]]:
// CHECK-NEXT: invoke void @llvm.seh.try.begin()
// CHECK-NEXT: to label %[[INVOKE_CONT10_I:.*]] unwind label %[[CATCH_DISPATCH19_I:.*]]
// CHECK: [[INVOKE_CONT10_I]]:
// CHECK-NEXT: invoke void @llvm.seh.try.begin()
// CHECK-NEXT: to label %[[INVOKE_CONT11_I:.*]] unwind label %[[CATCH_DISPATCH12_I:.*]]
// CHECK: [[INVOKE_CONT11_I]]:
// CHECK-NEXT: [[TOBOOL_NOT_I:%.*]] = icmp eq i32 [[ARGC]], 0
// CHECK-NEXT: br i1 [[TOBOOL_NOT_I]], label %[[IF_THEN_I:.*]], label %[[CLEANUP_I:.*]]
// CHECK: [[IF_THEN_I]]:
// CHECK-NEXT: store i32 -1, ptr [[TMP_I]], align 4, !tbaa [[INT_TBAA7:![0-9]+]]
// CHECK-NEXT: invoke void @_CxxThrowException(ptr nonnull [[TMP_I]], ptr nonnull @_TI1H) #[[ATTR7:[0-9]+]]
// CHECK-NEXT: to label %[[UNREACHABLE_I:.*]] unwind label %[[CATCH_DISPATCH12_I]]
// CHECK: [[CATCH_DISPATCH12_I]]:
// CHECK-NEXT: [[TMP5:%.*]] = catchswitch within none [label %[[CATCH13_I:.*]]] unwind label %[[CATCH_DISPATCH19_I]]
// CHECK: [[CATCH13_I]]:
// CHECK-NEXT: [[TMP6:%.*]] = catchpad within [[TMP5]] [ptr null, i32 0, ptr null]
// CHECK-NEXT: invoke void @llvm.seh.scope.end() [ "funclet"(token [[TMP6]]) ]
// CHECK-NEXT: to label %[[INVOKE_CONT14_I:.*]] unwind label %[[CATCH_DISPATCH19_I]]
// CHECK: [[INVOKE_CONT14_I]]:
// CHECK-NEXT: catchret from [[TMP6]] to label %[[CLEANUP_I]]
// CHECK: [[CLEANUP_I]]:
// CHECK-NEXT: [[COND_I:%.*]] = phi i1 [ true, %[[INVOKE_CONT14_I]] ], [ false, %[[INVOKE_CONT11_I]] ]
// CHECK-NEXT: invoke void @llvm.seh.scope.end()
// CHECK-NEXT: to label %[[INVOKE_CONT17_I:.*]] unwind label %[[CATCH_DISPATCH19_I]]
// CHECK: [[CATCH_DISPATCH19_I]]:
// CHECK-NEXT: [[TMP7:%.*]] = catchswitch within none [label %[[CATCH20_I:.*]]] unwind to caller
// CHECK: [[CATCH20_I]]:
// CHECK-NEXT: [[TMP8:%.*]] = catchpad within [[TMP7]] [ptr null, i32 0, ptr null]
// CHECK-NEXT: catchret from [[TMP8]] to label %[[TRY_CONT22_I:.*]]
// CHECK: [[TRY_CONT22_I]]:
// CHECK-NEXT: call void @"?Exit@@YAXXZ"() #[[ATTR8:[0-9]+]]
// CHECK-NEXT: unreachable
// CHECK: [[INVOKE_CONT17_I]]:
// CHECK-NEXT: invoke void @llvm.seh.try.end()
// CHECK-NEXT: to label %[[INVOKE_CONT18_I:.*]] unwind label %[[CATCH_DISPATCH12_I]]
// CHECK: [[INVOKE_CONT18_I]]:
// CHECK-NEXT: br i1 [[COND_I]], label %[[TRY_CONT22_I]], label %[[CLEANUP23_I:.*]]
// CHECK: [[INVOKE_CONT4_I]]:
// CHECK-NEXT: invoke void @llvm.seh.try.end()
// CHECK-NEXT: to label %[[TRY_CONT9_I]] unwind label %[[CATCH_DISPATCH_I]]
// CHECK: [[CLEANUP23_I]]:
// CHECK-NEXT: invoke void @llvm.seh.try.end()
// CHECK-NEXT: to label %[[INVOKE_CONT24_I:.*]] unwind label %[[CATCH_DISPATCH19_I]]
// CHECK: [[INVOKE_CONT24_I]]:
// CHECK-NEXT: invoke void @llvm.seh.try.end()
// CHECK-NEXT: to label %"?ExitOnThrow@@[email protected]" unwind label %[[CATCH_DISPATCH6_I]]
// CHECK: [[UNREACHABLE_I]]:
// CHECK-NEXT: unreachable
// CHECK: "?ExitOnThrow@@[email protected]":
// CHECK-NEXT: call void @llvm.lifetime.end.p0(ptr nonnull [[TMP_I]])
// CHECK-NEXT: [[CALL1:%.*]] = call noundef i32 @"?AlwaysThrows@@YAHH@Z"(i32 noundef [[ARGC]])
// CHECK-NEXT: [[ADD:%.*]] = add nsw i32 [[CALL1]], [[ARGC]]
// CHECK-NEXT: ret i32 [[ADD]]
//
int main(int argc, char**)
{
auto data = ExitOnThrow(argc);
return data + AlwaysThrows(data);
}
//.
// CHECK: [[INT_TBAA7]] = !{[[META8:![0-9]+]], [[META8]], i64 0}
// CHECK: [[META8]] = !{!"int", [[META9:![0-9]+]], i64 0}
// CHECK: [[META9]] = !{!"omnipotent char", [[META10:![0-9]+]], i64 0}
// CHECK: [[META10]] = !{!"Simple C++ TBAA"}
//.
Loading
Loading