Adding check for OS support to AVX

base/cpu.cc

Index: base/cpu.cc
diff --git a/base/cpu.cc b/base/cpu.cc
index 1761529e046edf2531d2d4612ca6d78c9b96289a..7ea212ef64b205d6025bc8855f784f0ba2ea4f7f 100644
--- a/base/cpu.cc
+++ b/base/cpu.cc
@@ -33,6 +33,7 @@ CPU::CPU()
     has_ssse3_(false),
     has_sse41_(false),
     has_sse42_(false),
+    has_avx_(false),
     has_non_stop_time_stamp_counter_(false),
     cpu_vendor_("unknown") {
   Initialize();
@@ -82,6 +83,17 @@ void __cpuidex(int cpu_info[4], int info_type, int info_index) {
 }
 
 #endif
+
+unsigned long long _xgetbv(unsigned int xcr) {
+  unsigned int eax, edx;
+  __asm__ volatile (
+    ".byte 0x0f, 0x01, 0xd0"
+    : "=a"(eax), "=d"(edx)
+    : "c" (xcr)
+  );
+  return static_cast<unsigned long long>(eax) ^
+         static_cast<unsigned long long>(edx) << 32;
+}
 #endif  // _MSC_VER
 #endif  // ARCH_CPU_X86_FAMILY
 
@@ -120,7 +132,7 @@ void CPU::Initialize() {
     has_ssse3_ = (cpu_info[2] & 0x00000200) != 0;
     has_sse41_ = (cpu_info[2] & 0x00080000) != 0;
     has_sse42_ = (cpu_info[2] & 0x00100000) != 0;
-    has_avx_ = (cpu_info[2] & 0x10000000) != 0;
+    has_avx_ = (cpu_info[2] & 0x10000000) != 0 && (_xgetbv(0) & 6) == 6;
   }
 
   // Get the brand string of the cpu.