[x86] Disable AVX unless the operating system explicitly claims to support it.

src/base/cpu.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/base/cpu.h"
 
 #if V8_LIBC_MSVCRT
 #include <intrin.h>  // __cpuid()
 #endif
 #if V8_OS_LINUX
@@ skipping 298 matching lines @@
       has_cmov_(false),
       has_sahf_(false),
       has_mmx_(false),
       has_sse_(false),
       has_sse2_(false),
       has_sse3_(false),
       has_ssse3_(false),
       has_sse41_(false),
       has_sse42_(false),
       is_atom_(false),
+      has_osxsave_(false),
       has_avx_(false),
       has_fma3_(false),
       has_idiva_(false),
       has_neon_(false),
       has_thumb2_(false),
       has_vfp_(false),
       has_vfp3_(false),
       has_vfp3_d32_(false),
       is_fp64_mode_(false) {
   memcpy(vendor_, "Unknown", 8);
@@ skipping 28 matching lines @@
     ext_family_ = (cpu_info[0] >> 20) & 0xff;
     has_fpu_ = (cpu_info[3] & 0x00000001) != 0;
     has_cmov_ = (cpu_info[3] & 0x00008000) != 0;
     has_mmx_ = (cpu_info[3] & 0x00800000) != 0;
     has_sse_ = (cpu_info[3] & 0x02000000) != 0;
     has_sse2_ = (cpu_info[3] & 0x04000000) != 0;
     has_sse3_ = (cpu_info[2] & 0x00000001) != 0;
     has_ssse3_ = (cpu_info[2] & 0x00000200) != 0;
     has_sse41_ = (cpu_info[2] & 0x00080000) != 0;
     has_sse42_ = (cpu_info[2] & 0x00100000) != 0;
+    has_osxsave_ = (cpu_info[2] & 0x08000000) != 0;
     has_avx_ = (cpu_info[2] & 0x10000000) != 0;
-    if (has_avx_) has_fma3_ = (cpu_info[2] & 0x00001000) != 0;
+    has_fma3_ = (cpu_info[2] & 0x00001000) != 0;
 
     if (family_ == 0x6) {
       switch (model_) {
         case 0x1c:  // SLT
         case 0x26:
         case 0x36:
         case 0x27:
         case 0x35:
         case 0x37:  // SLM
         case 0x4a:
@@ skipping 272 matching lines @@
       part_ = PPC_PA6T;
     }
   }
 
 #endif  // V8_OS_LINUX
 #endif  // !USE_SIMULATOR
 #endif  // V8_HOST_ARCH_PPC
 }
 
 } }  // namespace v8::base