Skip to content
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

[Clang][CodeGen] Fix use of CXXThisValue with StrictVTablePointers #68169

Merged
merged 1 commit into from
Oct 4, 2023
Merged

[Clang][CodeGen] Fix use of CXXThisValue with StrictVTablePointers #68169

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
7 changes: 3 additions & 4 deletions clang/lib/CodeGen/CGClass.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@
#include "clang/CodeGen/CGFunctionInfo.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Metadata.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Transforms/Utils/SanitizerStats.h"
#include <optional>

Expand Down Expand Up @@ -1291,10 +1292,10 @@ void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD,
assert(BaseCtorContinueBB);
}

llvm::Value *const OldThis = CXXThisValue;
for (; B != E && (*B)->isBaseInitializer() && (*B)->isBaseVirtual(); B++) {
if (!ConstructVBases)
continue;
SaveAndRestore ThisRAII(CXXThisValue);
if (CGM.getCodeGenOpts().StrictVTablePointers &&
CGM.getCodeGenOpts().OptimizationLevel > 0 &&
isInitializerOfDynamicClass(*B))
Expand All @@ -1311,16 +1312,14 @@ void CodeGenFunction::EmitCtorPrologue(const CXXConstructorDecl *CD,
// Then, non-virtual base initializers.
for (; B != E && (*B)->isBaseInitializer(); B++) {
assert(!(*B)->isBaseVirtual());

SaveAndRestore ThisRAII(CXXThisValue);
if (CGM.getCodeGenOpts().StrictVTablePointers &&
CGM.getCodeGenOpts().OptimizationLevel > 0 &&
isInitializerOfDynamicClass(*B))
CXXThisValue = Builder.CreateLaunderInvariantGroup(LoadCXXThis());
EmitBaseInitializer(*this, ClassDecl, *B);
}

CXXThisValue = OldThis;

InitializeVTablePointers(ClassDecl);

// And finally, initialize class members.
Expand Down
11 changes: 2 additions & 9 deletions clang/test/CodeGenCXX/strict-vtable-pointers-GH67937.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,6 +1,5 @@
// RUN: %clang_cc1 %s -I%S -triple=x86_64-pc-windows-msvc -fstrict-vtable-pointers -disable-llvm-passes -disable-llvm-verifier -O1 -emit-llvm -o %t.ll
// RUN: %clang_cc1 %s -I%S -triple=x86_64-pc-windows-msvc -fstrict-vtable-pointers -disable-llvm-passes -O1 -emit-llvm -o %t.ll
// RUN: FileCheck %s < %t.ll
// RUN: not llvm-as < %t.ll -o /dev/null 2>&1 | FileCheck %s --check-prefix=CHECK-VERIFIER

struct A {
virtual ~A();
Expand All @@ -9,11 +8,6 @@ struct B : virtual A {};
class C : B {};
C foo;

// FIXME: This is not supposed to generate invalid IR!
// CHECK-VERIFIER: Instruction does not dominate all uses!
// CHECK-VERIFIER-NEXT: %1 = call ptr @llvm.launder.invariant.group.p0(ptr %this1)
// CHECK-VERIFIER-NEXT: %3 = call ptr @llvm.launder.invariant.group.p0(ptr %1)

// CHECK-LABEL: define {{.*}} @"??0C@@QEAA@XZ"(ptr {{.*}} %this, i32 {{.*}} %is_most_derived)
// CHECK: ctor.init_vbases:
// CHECK-NEXT: %0 = getelementptr inbounds i8, ptr %this1, i64 0
Expand All @@ -24,6 +18,5 @@ C foo;
// CHECK-NEXT: br label %ctor.skip_vbases
// CHECK-EMPTY:
// CHECK-NEXT: ctor.skip_vbases:
// FIXME: Should be using '%this1' instead of %1 below.
// CHECK-NEXT: %3 = call ptr @llvm.launder.invariant.group.p0(ptr %1)
// CHECK-NEXT: %3 = call ptr @llvm.launder.invariant.group.p0(ptr %this1)
// CHECK-NEXT: %call3 = call noundef ptr @"??0B@@QEAA@XZ"(ptr {{.*}} %3, i32 noundef 0) #2