[clang][Sema] Propagate qualifiers during derived-to-base conversion by antoniofrighetto · Pull Request #127824 · llvm/llvm-project (original) (raw)

@llvm/pr-subscribers-clang-codegen

@llvm/pr-subscribers-clang

Author: Antonio Frighetto (antoniofrighetto)

Changes

A miscompilation issue has been addressed with improved handling.

Fixes: #127683.

Full diff: https://github.com/llvm/llvm-project/pull/127824.diff

2 Files Affected:

• (modified) clang/lib/CodeGen/CGExpr.cpp (+6-2)
• (modified) clang/test/CodeGenCXX/derived-to-base.cpp (+19)

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp index 191912ca7d800..3bba142f2b96e 100644 --- a/clang/lib/CodeGen/CGExpr.cpp +++ b/clang/lib/CodeGen/CGExpr.cpp @@ -5403,8 +5403,12 @@ LValue CodeGenFunction::EmitCastLValue(const CastExpr *E) { // TODO: Support accesses to members of base classes in TBAA. For now, we // conservatively pretend that the complete object is of the base class // type.

• return MakeAddrLValue(Base, E->getType(), LV.getBaseInfo(),

•                      CGM.getTBAAInfoForSubobject(LV, E->getType()));

• LValue CastedLV =

•    MakeAddrLValue(Base, E->getType(), LV.getBaseInfo(),

•                   CGM.getTBAAInfoForSubobject(LV, E->getType()));

• if (LV.isVolatile())

•  CastedLV.getQuals().addVolatile();

• return CastedLV;

} case CK_ToUnion: return EmitAggExprToLValue(E); diff --git a/clang/test/CodeGenCXX/derived-to-base.cpp b/clang/test/CodeGenCXX/derived-to-base.cpp index c8dbd5bf5cb05..37a8e6f7ea6b6 100644 --- a/clang/test/CodeGenCXX/derived-to-base.cpp +++ b/clang/test/CodeGenCXX/derived-to-base.cpp @@ -46,4 +46,23 @@ namespace test3 { } }

+// Ensure volatile is preserved during derived-to-base conversion. +namespace PR127683 { + +struct Base {

• int Val; +};
• +struct Derived : Base { };
• +volatile Derived Obj;
• +// CHECK-LABEL: define void @_ZN8PR12768319test_volatile_storeEv() #0 +// CHECK: store volatile i32 0, ptr @_ZN8PR1276833ObjE, align 4 +void test_volatile_store() {
• Obj.Val = 0; +}
• +}
• // CHECK: attributes [[NUW]] = { mustprogress noinline nounwind{{.*}} }