[clang][X86] Fix -Wundef warning in cpuid.h

[DanShaders]

Caught by compiling a project (SerenityOS) that uses compiler-rt and not silencing warnings from system headers.

[llvmbot]

@llvm/pr-subscribers-backend-x86

@llvm/pr-subscribers-clang

Author: Dan Klishch (DanShaders)

Changes

Caught by compiling a project (SerenityOS) that uses compiler-rt and not silencing warnings from system headers.

---

Full diff: https://github.com/llvm/llvm-project/pull/89842.diff

1 Files Affected:

• (modified) clang/lib/Headers/cpuid.h (+3-3)

diff --git a/clang/lib/Headers/cpuid.h b/clang/lib/Headers/cpuid.h
index 0bb9912b465ffe..bb7692efb78ffe 100644
--- a/clang/lib/Headers/cpuid.h
+++ b/clang/lib/Headers/cpuid.h
@@ -10,7 +10,7 @@
 #ifndef __CPUID_H
 #define __CPUID_H
 
-#if !(__x86_64__ || __i386__)
+#if !defined(__x86_64__) && !defined(__i386__)
 #error this header is for x86 only
 #endif
 
@@ -256,7 +256,7 @@
 #define bit_AVX10_256   0x00020000
 #define bit_AVX10_512   0x00040000
 
-#if __i386__
+#ifdef __i386__
 #define __cpuid(__leaf, __eax, __ebx, __ecx, __edx) \
     __asm("cpuid" : "=a"(__eax), "=b" (__ebx), "=c"(__ecx), "=d"(__edx) \
                   : "0"(__leaf))
@@ -285,7 +285,7 @@ static __inline unsigned int __get_cpuid_max (unsigned int __leaf,
                                               unsigned int *__sig)
 {
     unsigned int __eax, __ebx, __ecx, __edx;
-#if __i386__
+#ifdef __i386__
     int __cpuid_supported;
 
     __asm("  pushfl\n"

[nico]

If your project disables warning for system headers (why even do that?), I'm guessing there's going to be a bunch of other issues you'll run into. But this change here is fine, it makes cpuid.h consisten with all the other headers in clang/lib/Headers :)