https://github.com/tbaederr updated
https://github.com/llvm/llvm-project/pull/150164
>From b9655ff6d54475b5697a63571734192c92a6af07 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbae...@redhat.com>
Date: Wed, 23 Jul 2025 06:05:21 +0200
Subject: [PATCH] [clang][ExprConst] Consider integer pointers of value 0
nullptr
When casting a 0 to a pointer type, the IsNullPtr flag was always set
to false, leading to weird results like a pointer with value 0 that
isn't a null pointer.
This caused
struct B { const int *p;};
template<B> void f() {}
template void f<B{nullptr}>();
template void f<B{fold(reinterpret_cast<int*>(0))}>();
to be valid code, since nullptr and (int*)0 aren't equal. This seems
weird and GCC doesn't behave like this.
---
clang/lib/AST/ExprConstant.cpp | 14 +++++++++-----
clang/test/AST/ByteCode/functions.cpp | 2 +-
clang/test/CodeGenCXX/mangle-class-nttp.cpp | 6 ------
clang/test/SemaOpenCLCXX/amdgpu-nullptr.clcpp | 9 +++++++++
4 files changed, 19 insertions(+), 12 deletions(-)
create mode 100644 clang/test/SemaOpenCLCXX/amdgpu-nullptr.clcpp
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 0d12161756467..8622162359cb1 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -9830,11 +9830,15 @@ bool PointerExprEvaluator::VisitCastExpr(const CastExpr
*E) {
if (Value.isInt()) {
unsigned Size = Info.Ctx.getTypeSize(E->getType());
uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue();
- Result.Base = (Expr*)nullptr;
- Result.InvalidBase = false;
- Result.Offset = CharUnits::fromQuantity(N);
- Result.Designator.setInvalid();
- Result.IsNullPtr = false;
+ if (N == Info.Ctx.getTargetNullPointerValue(E->getType())) {
+ Result.setNull(Info.Ctx, E->getType());
+ } else {
+ Result.Base = (Expr *)nullptr;
+ Result.InvalidBase = false;
+ Result.Offset = CharUnits::fromQuantity(N);
+ Result.Designator.setInvalid();
+ Result.IsNullPtr = false;
+ }
return true;
} else {
// In rare instances, the value isn't an lvalue.
diff --git a/clang/test/AST/ByteCode/functions.cpp
b/clang/test/AST/ByteCode/functions.cpp
index b5e6f5bd7ece2..9b05d54fa8435 100644
--- a/clang/test/AST/ByteCode/functions.cpp
+++ b/clang/test/AST/ByteCode/functions.cpp
@@ -620,7 +620,7 @@ namespace FromIntegral {
int a[(int)DoubleFn((void*)-1)()]; // both-error {{not allowed at file
scope}} \
// both-warning {{variable length arrays}}
int b[(int)DoubleFn((void*)(-1 + 1))()]; // both-error {{not allowed at file
scope}} \
- // expected-note {{evaluates to a
null function pointer}} \
+ // both-note {{evaluates to a null
function pointer}} \
// both-warning {{variable length
arrays}}
#endif
}
diff --git a/clang/test/CodeGenCXX/mangle-class-nttp.cpp
b/clang/test/CodeGenCXX/mangle-class-nttp.cpp
index 12c81f2ba0514..c250be7c73c72 100644
--- a/clang/test/CodeGenCXX/mangle-class-nttp.cpp
+++ b/clang/test/CodeGenCXX/mangle-class-nttp.cpp
@@ -27,12 +27,6 @@ template void f<B{nullptr}>();
// CHECK: define weak_odr void @_Z1fIXtl1BLPKi32EEEEvv(
// MSABI: define {{.*}} @"??$f@$2UB@@PEBH0CA@H0A@@@@YAXXZ"
template void f<B{fold((int*)32)}>();
-#ifndef _WIN32
-// FIXME: On MS ABI, we mangle this the same as nullptr, despite considering a
-// null pointer and zero bitcast to a pointer to be distinct pointer values.
-// CHECK: define weak_odr void @_Z1fIXtl1BrcPKiLi0EEEEvv(
-template void f<B{fold(reinterpret_cast<int*>(0))}>();
-#endif
// Pointers to subobjects.
struct Nested { union { int k; int arr[2]; }; } nested[2];
diff --git a/clang/test/SemaOpenCLCXX/amdgpu-nullptr.clcpp
b/clang/test/SemaOpenCLCXX/amdgpu-nullptr.clcpp
new file mode 100644
index 0000000000000..5bc147c2deba7
--- /dev/null
+++ b/clang/test/SemaOpenCLCXX/amdgpu-nullptr.clcpp
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -triple amdgcn -cl-std=clc++ -verify %s
+
+// expected-no-diagnostics
+
+#define fold(x) (__builtin_constant_p(x) ? (x) : (x))
+static_assert(nullptr != fold(reinterpret_cast<private int*>(0)));
+
+static_assert(nullptr == (private int *)0);
+
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