Added CPUID change to detect AVX2.

BUG=98
TEST=none
Review URL: https://webrtc-codereview.appspot.com/839004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@373 16f28f9a-4ce2-e073-06de-1de4eb20be90

README.chromium

 Name: libyuv
 URL: http://code.google.com/p/libyuv/
-Version: 372
+Version: 373
 License: BSD
 License File: LICENSE
 

include/libyuv/cpu_id.h

@@ -31,7 +31,7 @@ static const int kCpuHasSSSE3 = 0x40;
 static const int kCpuHasSSE41 = 0x80;
 static const int kCpuHasSSE42 = 0x100;
 static const int kCpuHasAVX = 0x200;
-// 0x400 reserved for AVX2.
+static const int kCpuHasAVX2 = 0x400;
 
 // Detect CPU has SSE2 etc.
 // Test_flag parameter should be one of kCpuHas constants above.

include/libyuv/version.h

@@ -11,6 +11,6 @@
 #ifndef INCLUDE_LIBYUV_VERSION_H_  // NOLINT
 #define INCLUDE_LIBYUV_VERSION_H_
 
-#define LIBYUV_VERSION 372
+#define LIBYUV_VERSION 373
 
 #endif  // INCLUDE_LIBYUV_VERSION_H_  NOLINT

source/cpu_id.cc

@@ -58,6 +58,20 @@ void CpuId(int cpu_info[4], int) {
 }
 #endif
 
+// Low level cpuid for X86.  Returns zeros on other CPUs.
+#if !defined(__CLR_VER) && defined(_M_IX86)
+// TODO(fbarchard): Port to GCC and 64 bit Visual C.
+#define HAS_XGETBV
+// Return low 32 bits of BV - OS support for register saving.
+__declspec(naked)
+static uint32 XGetBV32(void) {
+  _asm _emit 0x0f
+  _asm _emit 0x01
+  _asm _emit 0xd0  // xgetbv
+  _asm ret
+}
+#endif
+
 // based on libvpx arm_cpudetect.c
 // For Arm, but public to allow testing on any CPU
 int ArmCpuCaps(const char* cpuinfo_name) {
@@ -91,8 +105,17 @@ int InitCpuFlags() {
               ((cpu_info[2] & 0x00000200) ? kCpuHasSSSE3 : 0) |
               ((cpu_info[2] & 0x00080000) ? kCpuHasSSE41 : 0) |
               ((cpu_info[2] & 0x00100000) ? kCpuHasSSE42 : 0) |
+              // TODO(fbarchard): AVX test BV same as AVX2.
               (((cpu_info[2] & 0x18000000) == 0x18000000) ? kCpuHasAVX : 0) |
               kCpuInitialized | kCpuHasX86;
+#ifdef HAS_XGETBV
+  if (cpu_info_ & kCpuHasAVX) {
+    __cpuid(cpu_info, 7);
+    if ((cpu_info[1] & 0x00000020) && ((XGetBV32() & 0x06) == 0x06)) {
+      cpu_info_ |= kCpuHasAVX2;
+    }
+  }
+#endif
 
   // environment variable overrides for testing.
   if (getenv("LIBYUV_DISABLE_X86")) {
@@ -113,6 +136,9 @@ int InitCpuFlags() {
   if (getenv("LIBYUV_DISABLE_AVX")) {
     cpu_info_ &= ~kCpuHasAVX;
   }
+  if (getenv("LIBYUV_DISABLE_AVX2")) {
+    cpu_info_ &= ~kCpuHasAVX2;
+  }
   if (getenv("LIBYUV_DISABLE_ASM")) {
     cpu_info_ = kCpuInitialized;
   }

unit_test/cpu_test.cc

@@ -37,6 +37,8 @@ TEST_F(libyuvTest, TestCpuHas) {
   printf("Has SSE4.2 %x\n", has_sse42);
   int has_avx = TestCpuFlag(kCpuHasAVX);
   printf("Has AVX %x\n", has_avx);
+  int has_avx2 = TestCpuFlag(kCpuHasAVX2);
+  printf("Has AVX2 %x\n", has_avx2);
 }
 
 #if defined(__i386__) || defined(__x86_64__) || \