From: Jan Hubicka <jh@suse.cz>
Date: Sun, 6 Aug 2023 20:53:14 +0000 (+0200)
Subject: Add builtin_expect to predict that CPU supports cpuid to cpuid.h
X-Git-Tag: basepoints/gcc-15~7128
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1fc96cdd0a3df2ba90a04dc507a44a02fbebd1f3;p=thirdparty%2Fgcc.git

Add builtin_expect to predict that CPU supports cpuid to cpuid.h

This is needed to avoid impossible threading update in vectorizer testcase,
but should also reflect reality on most CPUs we care about.

gcc/ChangeLog:

	* config/i386/cpuid.h (__get_cpuid_count, __get_cpuid_max): Add
	__builtin_expect that CPU likely supports cpuid.
---

diff --git a/gcc/config/i386/cpuid.h b/gcc/config/i386/cpuid.h
index 03fd6fc9478e..73c15480350a 100644
--- a/gcc/config/i386/cpuid.h
+++ b/gcc/config/i386/cpuid.h
@@ -295,7 +295,7 @@ __get_cpuid_max (unsigned int __ext, unsigned int *__sig)
 	   : "i" (0x00200000));
 #endif
 
-  if (!((__eax ^ __ebx) & 0x00200000))
+  if (__builtin_expect (!((__eax ^ __ebx) & 0x00200000), 0))
     return 0;
 #endif
 
@@ -338,7 +338,7 @@ __get_cpuid_count (unsigned int __leaf, unsigned int __subleaf,
   unsigned int __ext = __leaf & 0x80000000;
   unsigned int __maxlevel = __get_cpuid_max (__ext, 0);
 
-  if (__maxlevel == 0 || __maxlevel < __leaf)
+  if (__builtin_expect (__maxlevel == 0, 0) || __maxlevel < __leaf)
     return 0;
 
   __cpuid_count (__leaf, __subleaf, *__eax, *__ebx, *__ecx, *__edx);