[clang] [CIR] Fix codegen for MemberPoint with nullptr value (PR #185309)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Amr Hesham (AmrDeveloper)

<details>
<summary>Changes</summary>

Fix codegen for the MemberPoint with a nullptr value

---
Full diff: https://github.com/llvm/llvm-project/pull/185309.diff


2 Files Affected:

- (modified) clang/lib/CIR/CodeGen/CIRGenExprConstant.cpp (+3) 
- (modified) clang/test/CIR/CodeGen/pointer-to-data-member.cpp (+6) 


``````````diff
diff --git a/clang/lib/CIR/CodeGen/CIRGenExprConstant.cpp b/clang/lib/CIR/CodeGen/CIRGenExprConstant.cpp
index b697ca5cd3f6d..338d64e323391 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprConstant.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprConstant.cpp
@@ -1897,6 +1897,9 @@ mlir::Attribute ConstantEmitter::tryEmitPrivate(const APValue &value,
     assert(!cir::MissingFeatures::cxxABI());
 
     const ValueDecl *memberDecl = value.getMemberPointerDecl();
+    if (!memberDecl)
+      return builder.getZeroInitAttr(cgm.convertType(destType));
+
     if (value.isMemberPointerToDerivedMember()) {
       cgm.errorNYI(
           "ConstExprEmitter::tryEmitPrivate member pointer to derived member");
diff --git a/clang/test/CIR/CodeGen/pointer-to-data-member.cpp b/clang/test/CIR/CodeGen/pointer-to-data-member.cpp
index acb413a95ba8f..78af6cf5bb8e6 100644
--- a/clang/test/CIR/CodeGen/pointer-to-data-member.cpp
+++ b/clang/test/CIR/CodeGen/pointer-to-data-member.cpp
@@ -12,6 +12,12 @@ struct Point {
   int z;
 };
 
+int Point::*ptr_none = nullptr;
+// CIR-BEFORE: cir.global external @ptr_none = #cir.data_member<null> : !cir.data_member<!s32i in !rec_Point>
+// CIR-AFTER: cir.global external @ptr_none = #cir.int<-1> : !s64i
+// LLVM: @ptr_none = global i64 -1
+// OGCG: @ptr_none = global i64 -1
+
 int Point::*pt_member = &Point::z;
 // CIR-BEFORE: cir.global external @pt_member = #cir.data_member<2> : !cir.data_member<!s32i in !rec_Point>
 // CIR-AFTER: cir.global external @pt_member = #cir.int<8> : !s64i

``````````

</details>


https://github.com/llvm/llvm-project/pull/185309