[clang] [TBAA] Only emit pointer tbaa metedata for record types. (PR #116991)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-codegen

Author: Florian Hahn (fhahn)

<details>
<summary>Changes</summary>

Be conservative if the type isn't a record type. Handling other types may
require stripping const-qualifiers inside the type, e.g. MemberPointerType.

Without this, we assign different tags to the accesses for p an q in the
second test in cwg158.

---
Full diff: https://github.com/llvm/llvm-project/pull/116991.diff


2 Files Affected:

- (modified) clang/lib/CodeGen/CodeGenTBAA.cpp (+6) 
- (modified) clang/test/CXX/drs/cwg158.cpp (+7-5) 


``````````diff
diff --git a/clang/lib/CodeGen/CodeGenTBAA.cpp b/clang/lib/CodeGen/CodeGenTBAA.cpp
index c31579e8323174..73aae6b0db8d90 100644
--- a/clang/lib/CodeGen/CodeGenTBAA.cpp
+++ b/clang/lib/CodeGen/CodeGenTBAA.cpp
@@ -230,6 +230,12 @@ llvm::MDNode *CodeGenTBAA::getTypeInfoHelper(const Type *Ty) {
               ->getString();
       TyName = Name;
     } else {
+      // Be conservative if the type isn't a record type. Handling other types
+      // may require stripping const-qualifiers inside the type, e.g.
+      // MemberPointerType.
+      if (!Ty->isRecordType())
+        return AnyPtr;
+
       // For non-builtin types use the mangled name of the canonical type.
       llvm::raw_svector_ostream TyOut(TyName);
       MangleCtx->mangleCanonicalTypeName(QualType(Ty, 0), TyOut);
diff --git a/clang/test/CXX/drs/cwg158.cpp b/clang/test/CXX/drs/cwg158.cpp
index 9301c790297e9d..d20f715d637917 100644
--- a/clang/test/CXX/drs/cwg158.cpp
+++ b/clang/test/CXX/drs/cwg158.cpp
@@ -1,12 +1,14 @@
-// RUN: %clang_cc1 -triple x86_64-linux -std=c++98 %s -O3 -disable-llvm-passes -pedantic-errors -emit-llvm -o - | FileCheck %s
-// RUN: %clang_cc1 -triple x86_64-linux -std=c++11 %s -O3 -disable-llvm-passes -pedantic-errors -emit-llvm -o - | FileCheck %s
-// RUN: %clang_cc1 -triple x86_64-linux -std=c++14 %s -O3 -disable-llvm-passes -pedantic-errors -emit-llvm -o - | FileCheck %s
-// RUN: %clang_cc1 -triple x86_64-linux -std=c++1z %s -O3 -disable-llvm-passes -pedantic-errors -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-linux -std=c++98 %s -O3 -disable-llvm-passes -pedantic-errors -emit-llvm -o - | FileCheck --check-prefixes=CHECK %s
+// RUN: %clang_cc1 -triple x86_64-linux -std=c++11 %s -O3 -disable-llvm-passes -pedantic-errors -emit-llvm -o - | FileCheck --check-prefixes=CHECK %s
+// RUN: %clang_cc1 -triple x86_64-linux -std=c++14 %s -O3 -disable-llvm-passes -pedantic-errors -emit-llvm -o - | FileCheck --check-prefixes=CHECK %s
+// RUN: %clang_cc1 -triple x86_64-linux -std=c++1z %s -O3 -disable-llvm-passes -pedantic-errors -emit-llvm -o - | FileCheck --check-prefixes=CHECK %s
+// RUN: %clang_cc1 -triple x86_64-linux -std=c++1z %s -O3 -pointer-tbaa -disable-llvm-passes -pedantic-errors -emit-llvm -o - | FileCheck --check-prefixes=CHECK %s
 
 // cwg158: yes
 
 // CHECK-LABEL: define {{.*}} @_Z1f
 const int *f(const int * const *p, int **q) {
+  // CHECK: load ptr, ptr %p.addr
   // CHECK: load ptr, {{.*}}, !tbaa ![[INTPTR_TBAA:[^,]*]]
   const int *x = *p;
   // CHECK: store ptr null, {{.*}}, !tbaa ![[INTPTR_TBAA]]
@@ -18,10 +20,10 @@ struct A {};
 
 // CHECK-LABEL: define {{.*}} @_Z1g
 const int *(A::*const *g(const int *(A::* const **p)[3], int *(A::***q)[3]))[3] {
+  // CHECK: load ptr, ptr %p.addr
   // CHECK: load ptr, {{.*}}, !tbaa ![[MEMPTR_TBAA:[^,]*]]
   const int *(A::*const *x)[3] = *p;
   // CHECK: store ptr null, {{.*}}, !tbaa ![[MEMPTR_TBAA]]
   *q = 0;
   return x;
 }
-

``````````

</details>


https://github.com/llvm/llvm-project/pull/116991