[C11] Correct global atomic pointer initialization from an integer constant

This is a follow-up to 2e275e24355cb224981f9beb2b026a3169fc7232 and
1395cde24b3641e284bb1daae7d56c189a2635e3 which corrects a missed case:
initializing an _Atomic(T *) from a null pointer constant in the form
of the integer literal 0.

Fixes https://github.com/llvm/llvm-project/issues/63550
Differential Revision: https://reviews.llvm.org/D154284

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 777245f..0946625 100644 (file)
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -14896,6 +14896,8 @@ public:
     default:
       return ExprEvaluatorBaseTy::VisitCastExpr(E);
     case CK_NullToPointer:
+      VisitIgnoredValue(E->getSubExpr());
+      return ZeroInitialization(E);
     case CK_NonAtomicToAtomic:
       return This ? EvaluateInPlace(Result, Info, *This, E->getSubExpr())
                   : Evaluate(Result, Info, E->getSubExpr());

diff --git a/clang/test/CodeGen/atomic.c b/clang/test/CodeGen/atomic.c
index 69f06ee..242ec41 100644 (file)
--- a/clang/test/CodeGen/atomic.c
+++ b/clang/test/CodeGen/atomic.c
@@ -1,6 +1,8 @@
 // RUN: %clang_cc1 %s -emit-llvm -o - -triple=i686-apple-darwin9 | FileCheck %s
 
+// CHECK: @[[NONSTATIC_GLOB_POINTER_FROM_INT:.+]] = global ptr null
 // CHECK: @[[GLOB_POINTER:.+]] = internal global ptr null
+// CHECK: @[[GLOB_POINTER_FROM_INT:.+]] = internal global ptr null
 // CHECK: @[[GLOB_INT:.+]] = internal global i32 0
 // CHECK: @[[GLOB_FLT:.+]] = internal global float {{[0e\+-\.]+}}, align
 
@@ -125,6 +127,8 @@ void addrspace(int  __attribute__((address_space(256))) * P) {
 
 // Ensure that global initialization of atomics is correct.
 static _Atomic(int *) glob_pointer = (void *)0;
+static _Atomic(int *) glob_pointer_from_int = 0;
+_Atomic(int *) nonstatic_glob_pointer_from_int = 0LL;
 static _Atomic int glob_int = 0;
 static _Atomic float glob_flt = 0.0f;
 
@@ -132,6 +136,12 @@ void force_global_uses(void) {
   (void)glob_pointer;
   // CHECK: %[[LOCAL_INT:.+]] = load atomic i32, ptr @[[GLOB_POINTER]] seq_cst
   // CHECK-NEXT: inttoptr i32 %[[LOCAL_INT]] to ptr
+  (void)glob_pointer_from_int;
+  // CHECK: %[[LOCAL_INT_2:.+]] = load atomic i32, ptr @[[GLOB_POINTER_FROM_INT]] seq_cst
+  // CHECK-NEXT: inttoptr i32 %[[LOCAL_INT_2]] to ptr
+  (void)nonstatic_glob_pointer_from_int;
+  // CHECK: %[[LOCAL_INT_3:.+]] = load atomic i32, ptr @[[NONSTATIC_GLOB_POINTER_FROM_INT]] seq_cst
+  // CHECK-NEXT: inttoptr i32 %[[LOCAL_INT_3]] to ptr
   (void)glob_int;
   // CHECK: load atomic i32, ptr @[[GLOB_INT]] seq_cst
   (void)glob_flt;