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 03fd6fc9478e8ef87d0f7191b9f80539e9c3e939..73c15480350adfe86a055ecaa2f8c581623e9a78 100644 (file)
--- 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);