[clang] [clang] Change placeholder from `undef` to `poison` (PR #120446)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-codegen

Author: Pedro Lobo (pedroclobo)

<details>
<summary>Changes</summary>

Call `insertvalue` with a `poison` operand instead of `undef`.

---
Full diff: https://github.com/llvm/llvm-project/pull/120446.diff


2 Files Affected:

- (modified) clang/lib/CodeGen/MicrosoftCXXABI.cpp (+1-1) 
- (modified) clang/test/CodeGenCXX/microsoft-abi-member-pointers.cpp (+2-2) 


``````````diff
diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
index d587daac5a88a9..90651c3bafe26e 100644
--- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -3454,7 +3454,7 @@ llvm::Value *MicrosoftCXXABI::EmitNonNullMemberPointerConversion(
   if (inheritanceModelHasOnlyOneField(IsFunc, DstInheritance)) {
     Dst = FirstField;
   } else {
-    Dst = llvm::UndefValue::get(ConvertMemberPointerType(DstTy));
+    Dst = llvm::PoisonValue::get(ConvertMemberPointerType(DstTy));
     unsigned Idx = 0;
     Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++);
     if (inheritanceModelHasNVOffsetField(IsFunc, DstInheritance))
diff --git a/clang/test/CodeGenCXX/microsoft-abi-member-pointers.cpp b/clang/test/CodeGenCXX/microsoft-abi-member-pointers.cpp
index 2ac1961465d8a8..fc8a31e0350e5f 100644
--- a/clang/test/CodeGenCXX/microsoft-abi-member-pointers.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-member-pointers.cpp
@@ -647,7 +647,7 @@ void (Multiple::*convertB2FuncToMultiple(void (B2::*mp)()))() {
 // CHECK:   br i1 %{{.*}} label %{{.*}}, label %{{.*}}
 //
 //        memptr.convert:                                   ; preds = %entry
-// CHECK:   insertvalue { ptr, i32 } undef, ptr %[[mp]], 0
+// CHECK:   insertvalue { ptr, i32 } poison, ptr %[[mp]], 0
 // CHECK:   insertvalue { ptr, i32 } %{{.*}}, i32 4, 1
 // CHECK:   br label
 //
@@ -705,7 +705,7 @@ void (D::*convertCToD(void (C::*mp)()))() {
 // CHECK:   %[[nv_adj:.*]] = select i1 %[[is_nvbase]], i32 %[[nv_disp]], i32 0
 // CHECK:   %[[dst_adj:.*]] = select i1 %[[is_nvbase]], i32 4, i32 0
 // CHECK:   %[[adj:.*]] = sub nsw i32 %[[nv_adj]], %[[dst_adj]]
-// CHECK:   insertvalue { ptr, i32, i32 } undef, ptr {{.*}}, 0
+// CHECK:   insertvalue { ptr, i32, i32 } poison, ptr {{.*}}, 0
 // CHECK:   insertvalue { ptr, i32, i32 } {{.*}}, i32 %[[adj]], 1
 // CHECK:   insertvalue { ptr, i32, i32 } {{.*}}, i32 {{.*}}, 2
 // CHECK:   br label

``````````

</details>


https://github.com/llvm/llvm-project/pull/120446