[clang] [llvm] [Clang][AMDGPU] Get correct nullptr value for AS3 and AS5 (PR #175610)
Shilei Tian via cfe-commits
cfe-commits at lists.llvm.org
Mon Jan 12 13:08:30 PST 2026
https://github.com/shiltian updated https://github.com/llvm/llvm-project/pull/175610
>From 93cfec6b023050c02e6d332284e9439911d99d83 Mon Sep 17 00:00:00 2001
From: Shilei Tian <i at tianshilei.me>
Date: Mon, 12 Jan 2026 13:56:17 -0500
Subject: [PATCH 1/2] [Clang][AMDGPU] Get correct nullptr value for AS3 and AS5
---
clang/lib/Basic/Targets/AMDGPU.h | 16 ++++--
.../nullptr-in-different-address-spaces.cpp | 57 +++++++++++++++++++
2 files changed, 69 insertions(+), 4 deletions(-)
create mode 100644 clang/test/CodeGen/AMDGPU/nullptr-in-different-address-spaces.cpp
diff --git a/clang/lib/Basic/Targets/AMDGPU.h b/clang/lib/Basic/Targets/AMDGPU.h
index 0076f822c02a1..3cb0d5a63ec81 100644
--- a/clang/lib/Basic/Targets/AMDGPU.h
+++ b/clang/lib/Basic/Targets/AMDGPU.h
@@ -446,10 +446,18 @@ class LLVM_LIBRARY_VISIBILITY AMDGPUTargetInfo final : public TargetInfo {
// value ~0.
uint64_t getNullPointerValue(LangAS AS) const override {
// FIXME: Also should handle region.
- return (AS == LangAS::opencl_local || AS == LangAS::opencl_private ||
- AS == LangAS::sycl_local || AS == LangAS::sycl_private)
- ? ~0
- : 0;
+ // Check language-specific address spaces
+ if (AS == LangAS::opencl_local || AS == LangAS::opencl_private ||
+ AS == LangAS::sycl_local || AS == LangAS::sycl_private)
+ return ~0;
+ // Also check target address spaces that map to local or private
+ if (isTargetAddressSpace(AS)) {
+ unsigned TargetAS = toTargetAddressSpace(AS);
+ if (TargetAS == llvm::AMDGPUAS::LOCAL_ADDRESS ||
+ TargetAS == llvm::AMDGPUAS::PRIVATE_ADDRESS)
+ return ~0;
+ }
+ return 0;
}
void setAuxTarget(const TargetInfo *Aux) override;
diff --git a/clang/test/CodeGen/AMDGPU/nullptr-in-different-address-spaces.cpp b/clang/test/CodeGen/AMDGPU/nullptr-in-different-address-spaces.cpp
new file mode 100644
index 0000000000000..98fa4b51e3131
--- /dev/null
+++ b/clang/test/CodeGen/AMDGPU/nullptr-in-different-address-spaces.cpp
@@ -0,0 +1,57 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 6
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -target-cpu gfx900 -emit-llvm -o - %s | FileCheck %s
+
+extern __attribute__((address_space(3))) unsigned char * ptr_as3;
+extern __attribute__((address_space(5))) unsigned char * ptr_as5;
+
+// CHECK-LABEL: define dso_local noundef ptr @_Z11get_ptr_as3b(
+// CHECK-SAME: i1 noundef zeroext [[V:%.*]]) #[[ATTR0:[0-9]+]] {
+// CHECK-NEXT: [[ENTRY:.*:]]
+// CHECK-NEXT: [[RETVAL:%.*]] = alloca ptr, align 8, addrspace(5)
+// CHECK-NEXT: [[V_ADDR:%.*]] = alloca i8, align 1, addrspace(5)
+// CHECK-NEXT: [[RETVAL_ASCAST:%.*]] = addrspacecast ptr addrspace(5) [[RETVAL]] to ptr
+// CHECK-NEXT: [[V_ADDR_ASCAST:%.*]] = addrspacecast ptr addrspace(5) [[V_ADDR]] to ptr
+// CHECK-NEXT: [[STOREDV:%.*]] = zext i1 [[V]] to i8
+// CHECK-NEXT: store i8 [[STOREDV]], ptr [[V_ADDR_ASCAST]], align 1
+// CHECK-NEXT: [[TMP0:%.*]] = load i8, ptr [[V_ADDR_ASCAST]], align 1
+// CHECK-NEXT: [[LOADEDV:%.*]] = trunc i8 [[TMP0]] to i1
+// CHECK-NEXT: br i1 [[LOADEDV]], label %[[COND_TRUE:.*]], label %[[COND_FALSE:.*]]
+// CHECK: [[COND_TRUE]]:
+// CHECK-NEXT: [[TMP1:%.*]] = load ptr addrspace(3), ptr addrspacecast (ptr addrspace(1) @ptr_as3 to ptr), align 4
+// CHECK-NEXT: br label %[[COND_END:.*]]
+// CHECK: [[COND_FALSE]]:
+// CHECK-NEXT: br label %[[COND_END]]
+// CHECK: [[COND_END]]:
+// CHECK-NEXT: [[COND:%.*]] = phi ptr addrspace(3) [ [[TMP1]], %[[COND_TRUE]] ], [ addrspacecast (ptr null to ptr addrspace(3)), %[[COND_FALSE]] ]
+// CHECK-NEXT: [[COND_ASCAST:%.*]] = addrspacecast ptr addrspace(3) [[COND]] to ptr
+// CHECK-NEXT: ret ptr [[COND_ASCAST]]
+//
+unsigned char *get_ptr_as3(bool v) {
+ return v ? ptr_as3 : nullptr;
+}
+
+// CHECK-LABEL: define dso_local noundef ptr @_Z11get_ptr_as5b(
+// CHECK-SAME: i1 noundef zeroext [[V:%.*]]) #[[ATTR0]] {
+// CHECK-NEXT: [[ENTRY:.*:]]
+// CHECK-NEXT: [[RETVAL:%.*]] = alloca ptr, align 8, addrspace(5)
+// CHECK-NEXT: [[V_ADDR:%.*]] = alloca i8, align 1, addrspace(5)
+// CHECK-NEXT: [[RETVAL_ASCAST:%.*]] = addrspacecast ptr addrspace(5) [[RETVAL]] to ptr
+// CHECK-NEXT: [[V_ADDR_ASCAST:%.*]] = addrspacecast ptr addrspace(5) [[V_ADDR]] to ptr
+// CHECK-NEXT: [[STOREDV:%.*]] = zext i1 [[V]] to i8
+// CHECK-NEXT: store i8 [[STOREDV]], ptr [[V_ADDR_ASCAST]], align 1
+// CHECK-NEXT: [[TMP0:%.*]] = load i8, ptr [[V_ADDR_ASCAST]], align 1
+// CHECK-NEXT: [[LOADEDV:%.*]] = trunc i8 [[TMP0]] to i1
+// CHECK-NEXT: br i1 [[LOADEDV]], label %[[COND_TRUE:.*]], label %[[COND_FALSE:.*]]
+// CHECK: [[COND_TRUE]]:
+// CHECK-NEXT: [[TMP1:%.*]] = load ptr addrspace(5), ptr addrspacecast (ptr addrspace(1) @ptr_as5 to ptr), align 4
+// CHECK-NEXT: br label %[[COND_END:.*]]
+// CHECK: [[COND_FALSE]]:
+// CHECK-NEXT: br label %[[COND_END]]
+// CHECK: [[COND_END]]:
+// CHECK-NEXT: [[COND:%.*]] = phi ptr addrspace(5) [ [[TMP1]], %[[COND_TRUE]] ], [ addrspacecast (ptr null to ptr addrspace(5)), %[[COND_FALSE]] ]
+// CHECK-NEXT: [[COND_ASCAST:%.*]] = addrspacecast ptr addrspace(5) [[COND]] to ptr
+// CHECK-NEXT: ret ptr [[COND_ASCAST]]
+//
+unsigned char *get_ptr_as5(bool v) {
+ return v ? ptr_as5 : nullptr;
+}
>From 5c9ab8ede9236cdfcb0a602bed617793da881ded Mon Sep 17 00:00:00 2001
From: Shilei Tian <i at tianshilei.me>
Date: Mon, 12 Jan 2026 16:08:01 -0500
Subject: [PATCH 2/2] resolve comments
---
clang/lib/Basic/Targets/AMDGPU.h | 10 ++--------
.../nullptr-in-different-address-spaces.cpp | 4 ++--
llvm/include/llvm/Support/AMDGPUAddrSpace.h | 15 +++++++++++++++
3 files changed, 19 insertions(+), 10 deletions(-)
diff --git a/clang/lib/Basic/Targets/AMDGPU.h b/clang/lib/Basic/Targets/AMDGPU.h
index 3cb0d5a63ec81..35bca74505b37 100644
--- a/clang/lib/Basic/Targets/AMDGPU.h
+++ b/clang/lib/Basic/Targets/AMDGPU.h
@@ -445,18 +445,12 @@ class LLVM_LIBRARY_VISIBILITY AMDGPUTargetInfo final : public TargetInfo {
// address space has value 0 but in private and local address space has
// value ~0.
uint64_t getNullPointerValue(LangAS AS) const override {
- // FIXME: Also should handle region.
// Check language-specific address spaces
if (AS == LangAS::opencl_local || AS == LangAS::opencl_private ||
AS == LangAS::sycl_local || AS == LangAS::sycl_private)
return ~0;
- // Also check target address spaces that map to local or private
- if (isTargetAddressSpace(AS)) {
- unsigned TargetAS = toTargetAddressSpace(AS);
- if (TargetAS == llvm::AMDGPUAS::LOCAL_ADDRESS ||
- TargetAS == llvm::AMDGPUAS::PRIVATE_ADDRESS)
- return ~0;
- }
+ if (isTargetAddressSpace(AS))
+ return llvm::AMDGPU::getNullPointerValue(toTargetAddressSpace(AS));
return 0;
}
diff --git a/clang/test/CodeGen/AMDGPU/nullptr-in-different-address-spaces.cpp b/clang/test/CodeGen/AMDGPU/nullptr-in-different-address-spaces.cpp
index 98fa4b51e3131..6f00e5e2bfed1 100644
--- a/clang/test/CodeGen/AMDGPU/nullptr-in-different-address-spaces.cpp
+++ b/clang/test/CodeGen/AMDGPU/nullptr-in-different-address-spaces.cpp
@@ -1,8 +1,8 @@
// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 6
// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -target-cpu gfx900 -emit-llvm -o - %s | FileCheck %s
-extern __attribute__((address_space(3))) unsigned char * ptr_as3;
-extern __attribute__((address_space(5))) unsigned char * ptr_as5;
+extern __attribute__((address_space(3))) unsigned char * ptr_as3; // local address space
+extern __attribute__((address_space(5))) unsigned char * ptr_as5; // private address space
// CHECK-LABEL: define dso_local noundef ptr @_Z11get_ptr_as3b(
// CHECK-SAME: i1 noundef zeroext [[V:%.*]]) #[[ATTR0:[0-9]+]] {
diff --git a/llvm/include/llvm/Support/AMDGPUAddrSpace.h b/llvm/include/llvm/Support/AMDGPUAddrSpace.h
index 0c89512310289..3fe6492584d84 100644
--- a/llvm/include/llvm/Support/AMDGPUAddrSpace.h
+++ b/llvm/include/llvm/Support/AMDGPUAddrSpace.h
@@ -15,6 +15,8 @@
#ifndef LLVM_SUPPORT_AMDGPUADDRSPACE_H
#define LLVM_SUPPORT_AMDGPUADDRSPACE_H
+#include <cstdint>
+
namespace llvm {
/// OpenCL uses address spaces to differentiate between
/// various memory regions on the hardware. On the CPU
@@ -165,6 +167,19 @@ constexpr int mapToDWARFAddrSpace(unsigned LLVMAddrSpace) {
return impl::LLVMToDWARFAddrSpaceMapping[LLVMAddrSpace];
return -1;
}
+
+/// Get the null pointer value for the given address space.
+constexpr int64_t getNullPointerValue(unsigned AS) {
+ switch (AS) {
+ using namespace AMDGPUAS;
+ case PRIVATE_ADDRESS:
+ case LOCAL_ADDRESS:
+ case REGION_ADDRESS:
+ return -1;
+ default:
+ return 0;
+ }
+}
} // end namespace AMDGPU
} // end namespace llvm
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