Add f16c (halffloat) cpuid

R=wangcheng@google.com, hubbe@chromium.org
BUG=libyuv:560

Review URL: https://codereview.chromium.org/2418763006 .

README.chromium

 Name: libyuv
 URL: http://code.google.com/p/libyuv/
-Version: 1626
+Version: 1627
 License: BSD
 License File: LICENSE
 

include/libyuv/cpu_id.h

@@ -31,13 +31,15 @@ static const int kCpuHasX86 = 0x10;
 static const int kCpuHasSSE2 = 0x20;
 static const int kCpuHasSSSE3 = 0x40;
 static const int kCpuHasSSE41 = 0x80;
-static const int kCpuHasSSE42 = 0x100;
+static const int kCpuHasSSE42 = 0x100;  // unused at this time.
 static const int kCpuHasAVX = 0x200;
 static const int kCpuHasAVX2 = 0x400;
 static const int kCpuHasERMS = 0x800;
 static const int kCpuHasFMA3 = 0x1000;
 static const int kCpuHasAVX3 = 0x2000;
-// 0x2000, 0x4000, 0x8000 reserved for future X86 flags.
+static const int kCpuHasF16C = 0x4000;
+
+// 0x8000 reserved for future X86 flags.
 
 // These flags are only valid on MIPS processors.
 static const int kCpuHasMIPS = 0x10000;

include/libyuv/version.h

@@ -11,6 +11,6 @@
 #ifndef INCLUDE_LIBYUV_VERSION_H_
 #define INCLUDE_LIBYUV_VERSION_H_
 
-#define LIBYUV_VERSION 1626
+#define LIBYUV_VERSION 1627
 
 #endif  // INCLUDE_LIBYUV_VERSION_H_

source/cpu_id.cc

@@ -229,19 +229,21 @@ int InitCpuFlags(void) {
   if (cpu_info0[0] >= 7) {
     CpuId(7, 0, cpu_info7);
   }
-  cpu_info = ((cpu_info1[3] & 0x04000000) ? kCpuHasSSE2 : 0) |
+  cpu_info = kCpuHasX86 |
+             ((cpu_info1[3] & 0x04000000) ? kCpuHasSSE2 : 0) |
              ((cpu_info1[2] & 0x00000200) ? kCpuHasSSSE3 : 0) |
              ((cpu_info1[2] & 0x00080000) ? kCpuHasSSE41 : 0) |
              ((cpu_info1[2] & 0x00100000) ? kCpuHasSSE42 : 0) |
-             ((cpu_info7[1] & 0x00000200) ? kCpuHasERMS : 0) |
-             ((cpu_info1[2] & 0x00001000) ? kCpuHasFMA3 : 0) |
-             kCpuHasX86;
+             ((cpu_info7[1] & 0x00000200) ? kCpuHasERMS : 0);
 
 #ifdef HAS_XGETBV
   // AVX requires CPU has AVX, XSAVE and OSXSave for xgetbv
   if (((cpu_info1[2] & 0x1c000000) == 0x1c000000) &&  // AVX and OSXSave
       ((GetXCR0() & 6) == 6)) {  // Test OS saves YMM registers
-    cpu_info |= ((cpu_info7[1] & 0x00000020) ? kCpuHasAVX2 : 0) | kCpuHasAVX;
+    cpu_info |= kCpuHasAVX |
+                ((cpu_info7[1] & 0x00000020) ? kCpuHasAVX2 : 0) |
+                ((cpu_info1[2] & 0x00001000) ? kCpuHasFMA3 : 0) |
+                ((cpu_info1[2] & 0x20000000) ? kCpuHasF16C : 0);
 
     // Detect AVX512bw
     if ((GetXCR0() & 0xe0) == 0xe0) {
@@ -281,6 +283,10 @@ int InitCpuFlags(void) {
   if (TestEnv("LIBYUV_DISABLE_AVX3")) {
     cpu_info &= ~kCpuHasAVX3;
   }
+  if (TestEnv("LIBYUV_DISABLE_F16C")) {
+    cpu_info &= ~kCpuHasF16C;
+  }
+
 #endif
 #if defined(__mips__) && defined(__linux__)
 #if defined(__mips_dspr2)

source/planar_functions.cc

@@ -2570,7 +2570,7 @@ int HalfFloatPlane(const uint16* src_y, int src_stride_y,
   }
 #endif
 #if defined(HAS_HALFFLOATROW_AVX2)
-  if (TestCpuFlag(kCpuHasAVX2)) {
+  if (TestCpuFlag(kCpuHasAVX2) && TestCpuFlag(kCpuHasF16C)) {
     HalfFloatRow = HalfFloatRow_Any_AVX2;
     if (IS_ALIGNED(width, 16)) {
       HalfFloatRow = HalfFloatRow_AVX2;

unit_test/cpu_test.cc

@@ -45,6 +45,8 @@ TEST_F(LibYUVBaseTest, TestCpuHas) {
   printf("Has FMA3 %x\n", has_fma3);
   int has_avx3 = TestCpuFlag(kCpuHasAVX3);
   printf("Has AVX3 %x\n", has_avx3);
+  int has_f16c = TestCpuFlag(kCpuHasF16C);
+  printf("Has F16C %x\n", has_f16c);
   int has_mips = TestCpuFlag(kCpuHasMIPS);
   printf("Has MIPS %x\n", has_mips);
   int has_dspr2 = TestCpuFlag(kCpuHasDSPR2);

util/cpuid.c

@@ -79,6 +79,7 @@ int main(int argc, const char* argv[]) {
     int has_avx3 = TestCpuFlag(kCpuHasAVX3);
     int has_erms = TestCpuFlag(kCpuHasERMS);
     int has_fma3 = TestCpuFlag(kCpuHasFMA3);
+    int has_f16c = TestCpuFlag(kCpuHasF16C);
     printf("Has SSE2 %x\n", has_sse2);
     printf("Has SSSE3 %x\n", has_ssse3);
     printf("Has SSE4.1 %x\n", has_sse41);
@@ -88,6 +89,7 @@ int main(int argc, const char* argv[]) {
     printf("Has AVX3 %x\n", has_avx3);
     printf("Has ERMS %x\n", has_erms);
     printf("Has FMA3 %x\n", has_fma3);
+    printf("Has F16C %x\n", has_f16c);
   }
   return 0;
 }