inline cpuid for better branch prediction

BUG=none
TEST=disassembly shows 6 instructions (due to auto init)
Review URL: http://webrtc-codereview.appspot.com/285001

git-svn-id: http://libyuv.googlecode.com/svn/trunk@90 16f28f9a-4ce2-e073-06de-1de4eb20be90

README.chromium

 Name: libyuv
 URL: http://code.google.com/p/libyuv/
-Version: 89
+Version: 90
 License: BSD
 License File: LICENSE
 

include/libyuv/cpu_id.h

@@ -24,7 +24,13 @@ static const int kCpuHasNEON = 4;
 static const int kCpuInitialized = 8;
 
 // Detect CPU has SSE2 etc.
-bool TestCpuFlag(int flag);
+// test_flag parameter should be one of kCpuHas constants above
+// returns non-zero if instruction set is detected
+static inline int TestCpuFlag(int test_flag) {
+  extern int cpu_info_;
+  extern int InitCpuFlags();
+  return (cpu_info_ ? cpu_info_ : InitCpuFlags()) & test_flag;
+}
 
 // For testing, allow CPU flags to be disabled.
 // ie MaskCpuFlags(~kCpuHasSSSE3) to disable SSSE3.

source/cpu_id.cc

@@ -43,10 +43,9 @@ static inline void __cpuid(int cpu_info[4], int info_type) {
 namespace libyuv {
 
 // CPU detect function for SIMD instruction sets.
-static int cpu_info_ = 0;
+int cpu_info_ = 0;
 
-// TODO(fbarchard): (cpu_info[2] & 0x10000000 ? kCpuHasAVX : 0)
-static void InitCpuFlags() {
+int InitCpuFlags() {
 #ifdef CPU_X86
   int cpu_info[4];
   __cpuid(cpu_info, 1);
@@ -65,6 +64,7 @@ static void InitCpuFlags() {
 #else
   cpu_info_ = kCpuInitialized;
 #endif
+  return cpu_info_;
 }
 
 void MaskCpuFlags(int enable_flags) {
@@ -72,11 +72,4 @@ void MaskCpuFlags(int enable_flags) {
   cpu_info_ = (cpu_info_ & enable_flags) | kCpuInitialized;
 }
 
-bool TestCpuFlag(int flag) {
-  if (0 == cpu_info_) {
-    InitCpuFlags();
-  }
-  return (cpu_info_ & flag) ? true : false;
-}
-
 }  // namespace libyuv