https://github.com/boomanaiden154 created
https://github.com/llvm/llvm-project/pull/152556
The landing of #126324 made it so that __has_builtin returns false for aux
triple builtins. CUDA offloading can sometimes compile where the host is in the
aux triple (ie x86_64). This patch explicitly carves out NVPTX so that we do
not run into redefinition errors.
>From f239993ff07a5b146a620a89bc7755afad7cd1c7 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <aidengross...@google.com>
Date: Thu, 7 Aug 2025 17:27:49 +0000
Subject: [PATCH] [Clang] Fix __cpuidex conflict with CUDA
The landing of #126324 made it so that __has_builtin returns false for
aux triple builtins. CUDA offloading can sometimes compile where the
host is in the aux triple (ie x86_64). This patch explicitly carves out
NVPTX so that we do not run into redefinition errors.
---
clang/lib/Headers/cpuid.h | 5 +++++
clang/test/Headers/__cpuidex_conflict.c | 1 +
2 files changed, 6 insertions(+)
diff --git a/clang/lib/Headers/cpuid.h b/clang/lib/Headers/cpuid.h
index 52addb7bfa856..ce8c79e77dc18 100644
--- a/clang/lib/Headers/cpuid.h
+++ b/clang/lib/Headers/cpuid.h
@@ -345,10 +345,15 @@ static __inline int __get_cpuid_count (unsigned int
__leaf,
// In some configurations, __cpuidex is defined as a builtin (primarily
// -fms-extensions) which will conflict with the __cpuidex definition below.
#if !(__has_builtin(__cpuidex))
+// In some cases, offloading will set the host as the aux triple and define the
+// builtin. Given __has_builtin does not detect builtins on aux triples, we
need
+// to explicitly check for some offloading cases.
+#ifndef __NVPTX__
static __inline void __cpuidex(int __cpu_info[4], int __leaf, int __subleaf) {
__cpuid_count(__leaf, __subleaf, __cpu_info[0], __cpu_info[1], __cpu_info[2],
__cpu_info[3]);
}
#endif
+#endif
#endif /* __CPUID_H */
diff --git a/clang/test/Headers/__cpuidex_conflict.c
b/clang/test/Headers/__cpuidex_conflict.c
index 74f45327de2bb..d14ef293e586d 100644
--- a/clang/test/Headers/__cpuidex_conflict.c
+++ b/clang/test/Headers/__cpuidex_conflict.c
@@ -5,6 +5,7 @@
// Ensure that we do not run into conflicts when offloading.
// RUN: %clang_cc1 %s -DIS_STATIC=static -ffreestanding -fopenmp
-fopenmp-is-target-device -aux-triple x86_64-unknown-linux-gnu
+// RUN: %clang_cc1 -DIS_STATIC="" -triple nvptx64-nvidia-cuda -aux-triple
x86_64-unknown-linux-gnu -aux-target-cpu x86-64 -fcuda-is-device
-internal-isystem /home/gha/llvm-project/build/lib/clang/22/include -x cuda %s
-o -
typedef __SIZE_TYPE__ size_t;
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