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cpu_id cleanup. no functional change.

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remove old comment about initialize to zero.
remove ifdef and replace with macro defined to zero.

BUG=None
TEST=try bots
R=kjellander@chromium.org

Review URL: https://codereview.chromium.org/2425623004 .
This commit is contained in:
Frank Barchard 2016-10-18 12:26:02 -07:00
parent 93f47948b1
commit e16e3a629f
1 changed files with 5 additions and 6 deletions
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11
source/cpu_id.cc
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@ -68,7 +68,7 @@ void CpuId(uint32 info_eax, uint32 info_ecx, uint32* cpu_info) {
if (info_ecx == 0) {
__cpuid((int*)(cpu_info), info_eax);
} else {
cpu_info[3] = cpu_info[2] = cpu_info[1] = cpu_info[0] = 0;
cpu_info[3] = cpu_info[2] = cpu_info[1] = cpu_info[0] = 0u;
}
#endif
// GCC version uses inline x86 assembly.
@ -114,7 +114,6 @@ void CpuId(uint32 eax, uint32 ecx, uint32* cpu_info) {
#if (defined(_M_IX86) || defined(_M_X64) || \
defined(__i386__) || defined(__x86_64__)) && \
!defined(__pnacl__) && !defined(__CLR_VER) && !defined(__native_client__)
#define HAS_XGETBV
// X86 CPUs have xgetbv to detect OS saves high parts of ymm registers.
int GetXCR0() {
uint32 xcr0 = 0u;
@ -125,6 +124,9 @@ int GetXCR0() {
#endif // defined(__i386__) || defined(__x86_64__)
return xcr0;
}
#else
// xgetbv unavailable to query for OSSave support. Return 0.
#define GetXCR0() 0
#endif // defined(_M_IX86) || defined(_M_X64) ..
// Return optimization to previous setting.
#if defined(_M_IX86) && (_MSC_VER < 1900)
@ -218,7 +220,6 @@ static LIBYUV_BOOL TestEnv(const char*) {
LIBYUV_API SAFEBUFFERS
int InitCpuFlags(void) {
// TODO(fbarchard): swap kCpuInit logic so 0 means uninitialized.
int cpu_info = 0;
#if !defined(__pnacl__) && !defined(__CLR_VER) && defined(CPU_X86)
uint32 cpu_info0[4] = { 0, 0, 0, 0 };
@ -236,8 +237,7 @@ int InitCpuFlags(void) {
((cpu_info1[2] & 0x00100000) ? kCpuHasSSE42 : 0) |
((cpu_info7[1] & 0x00000200) ? kCpuHasERMS : 0);
#ifdef HAS_XGETBV
// AVX requires CPU has AVX, XSAVE and OSXSave for xgetbv
// AVX requires OS saves YMM registers.
if (((cpu_info1[2] & 0x1c000000) == 0x1c000000) && // AVX and OSXSave
((GetXCR0() & 6) == 6)) { // Test OS saves YMM registers
cpu_info |= kCpuHasAVX |
@ -250,7 +250,6 @@ int InitCpuFlags(void) {
cpu_info |= (cpu_info7[1] & 0x40000000) ? kCpuHasAVX3 : 0;
}
}
#endif
// Environment variable overrides for testing.
if (TestEnv("LIBYUV_DISABLE_X86")) {