libatomic: Improve cpuid usage in __libat_feat1_init

Check the result of __get_cpuid and process FEAT1_REGISTER only when
__get_cpuid returns success.  Use __cpuid instead of nested __get_cpuid.

libatomic/ChangeLog:

	* config/x86/init.c (__libat_feat1_init): Check the result of
	__get_cpuid and process FEAT1_REGISTER only when __get_cpuid
	returns success.  Use __cpuid instead of nested __get_cpuid.

diff --git a/libatomic/config/x86/init.c b/libatomic/config/x86/init.c
index a75be3f175c3f847a816c294fc3157354e5c28f8..26168d468324fa0e4e571fa06f082fc51fb03aed 100644 (file)
--- a/libatomic/config/x86/init.c
+++ b/libatomic/config/x86/init.c
@@ -33,21 +33,23 @@ __libat_feat1_init (void)
 {
   unsigned int eax, ebx, ecx, edx;
   FEAT1_REGISTER = 0;
-  __get_cpuid (1, &eax, &ebx, &ecx, &edx);
-#ifdef __x86_64__
-  if ((FEAT1_REGISTER & (bit_AVX | bit_CMPXCHG16B))
-      == (bit_AVX | bit_CMPXCHG16B))
+  if (__get_cpuid (1, &eax, &ebx, &ecx, &edx))
     {
-      /* Intel SDM guarantees that 16-byte VMOVDQA on 16-byte aligned address
-        is atomic, and AMD is going to do something similar soon.
-        We don't have a guarantee from vendors of other CPUs with AVX,
-        like Zhaoxin and VIA.  */
-      unsigned int ecx2 = 0;
-      __get_cpuid (0, &eax, &ebx, &ecx2, &edx);
-      if (ecx2 != signature_INTEL_ecx && ecx2 != signature_AMD_ecx)
-       FEAT1_REGISTER &= ~bit_AVX;
-    }
+#ifdef __x86_64__
+      if ((FEAT1_REGISTER & (bit_AVX | bit_CMPXCHG16B))
+         == (bit_AVX | bit_CMPXCHG16B))
+       {
+         /* Intel SDM guarantees that 16-byte VMOVDQA on 16-byte aligned
+            address is atomic, and AMD is going to do something similar soon.
+            We don't have a guarantee from vendors of other CPUs with AVX,
+            like Zhaoxin and VIA.  */
+         unsigned int ecx2;
+         __cpuid (0, eax, ebx, ecx2, edx);
+         if (ecx2 != signature_INTEL_ecx && ecx2 != signature_AMD_ecx)
+           FEAT1_REGISTER &= ~bit_AVX;
+       }
 #endif
+    }
   /* See the load in load_feat1.  */
   __atomic_store_n (&__libat_feat1, FEAT1_REGISTER, __ATOMIC_RELAXED);
   return FEAT1_REGISTER;