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write to cpu_flags once

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To make init cpu flags thread safe, there can only be one write to the variable.

R=richard.winterton@intel.com, harryjin@google.com
BUG=libyuv:508

Review URL: https://codereview.chromium.org/1412793006 .
This commit is contained in:
Frank Barchard 2015-10-20 16:24:01 -07:00
parent d99324dd4c
commit 9be6d21ae7
3 changed files with 33 additions and 32 deletions
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2
README.chromium
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@ -1,6 +1,6 @@
Name: libyuv
URL: http://code.google.com/p/libyuv/
Version: 1515
Version: 1516
License: BSD
License File: LICENSE

2
include/libyuv/version.h
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@ -11,6 +11,6 @@
#ifndef INCLUDE_LIBYUV_VERSION_H_ // NOLINT
#define INCLUDE_LIBYUV_VERSION_H_
#define LIBYUV_VERSION 1515
#define LIBYUV_VERSION 1516
#endif // INCLUDE_LIBYUV_VERSION_H_ NOLINT

61
source/cpu_id.cc
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@ -198,7 +198,7 @@ static LIBYUV_BOOL TestEnv(const char*) {
LIBYUV_API SAFEBUFFERS
int InitCpuFlags(void) {
#if !defined(__pnacl__) && !defined(__CLR_VER) && defined(CPU_X86)
int cpu_info;
uint32 cpu_info0[4] = { 0, 0, 0, 0 };
uint32 cpu_info1[4] = { 0, 0, 0, 0 };
uint32 cpu_info7[4] = { 0, 0, 0, 0 };
@ -207,64 +207,63 @@ int InitCpuFlags(void) {
if (cpu_info0[0] >= 7) {
CpuId(7, 0, cpu_info7);
}
cpu_info_ = ((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_info = ((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;
#ifdef HAS_XGETBV
// AVX requires CPU has AVX, XSAVE and OSXSave for xgetbv
if ((cpu_info1[2] & 0x1c000000) == 0x1c000000 && // AVX and OSXSave
!TestEnv("LIBYUV_DISABLE_AVX") && TestOsSaveYmm()) { // Saves YMM.
cpu_info_ |= ((cpu_info7[1] & 0x00000020) ? kCpuHasAVX2 : 0) |
kCpuHasAVX;
cpu_info |= ((cpu_info7[1] & 0x00000020) ? kCpuHasAVX2 : 0) | kCpuHasAVX;
}
#endif
// Environment variable overrides for testing.
if (TestEnv("LIBYUV_DISABLE_X86")) {
cpu_info_ &= ~kCpuHasX86;
cpu_info &= ~kCpuHasX86;
}
if (TestEnv("LIBYUV_DISABLE_SSE2")) {
cpu_info_ &= ~kCpuHasSSE2;
cpu_info &= ~kCpuHasSSE2;
}
if (TestEnv("LIBYUV_DISABLE_SSSE3")) {
cpu_info_ &= ~kCpuHasSSSE3;
cpu_info &= ~kCpuHasSSSE3;
}
if (TestEnv("LIBYUV_DISABLE_SSE41")) {
cpu_info_ &= ~kCpuHasSSE41;
cpu_info &= ~kCpuHasSSE41;
}
if (TestEnv("LIBYUV_DISABLE_SSE42")) {
cpu_info_ &= ~kCpuHasSSE42;
cpu_info &= ~kCpuHasSSE42;
}
if (TestEnv("LIBYUV_DISABLE_AVX2")) {
cpu_info_ &= ~kCpuHasAVX2;
cpu_info &= ~kCpuHasAVX2;
}
if (TestEnv("LIBYUV_DISABLE_ERMS")) {
cpu_info_ &= ~kCpuHasERMS;
cpu_info &= ~kCpuHasERMS;
}
if (TestEnv("LIBYUV_DISABLE_FMA3")) {
cpu_info_ &= ~kCpuHasFMA3;
cpu_info &= ~kCpuHasFMA3;
}
#endif
#if defined(__mips__) && defined(__linux__)
// Linux mips parse text file for dsp detect.
cpu_info_ = MipsCpuCaps("dsp"); // set kCpuHasMIPS_DSP.
cpu_info = MipsCpuCaps("dsp"); // set kCpuHasMIPS_DSP.
#if defined(__mips_dspr2)
cpu_info_ |= kCpuHasMIPS_DSPR2;
cpu_info |= kCpuHasMIPS_DSPR2;
#endif
cpu_info_ |= kCpuHasMIPS;
cpu_info |= kCpuHasMIPS;
if (getenv("LIBYUV_DISABLE_MIPS")) {
cpu_info_ &= ~kCpuHasMIPS;
cpu_info &= ~kCpuHasMIPS;
}
if (getenv("LIBYUV_DISABLE_MIPS_DSP")) {
cpu_info_ &= ~kCpuHasMIPS_DSP;
cpu_info &= ~kCpuHasMIPS_DSP;
}
if (getenv("LIBYUV_DISABLE_MIPS_DSPR2")) {
cpu_info_ &= ~kCpuHasMIPS_DSPR2;
cpu_info &= ~kCpuHasMIPS_DSPR2;
}
#endif
#if defined(__arm__) || defined(__aarch64__)
@ -272,28 +271,30 @@ int InitCpuFlags(void) {
// __ARM_NEON__ generates code that requires Neon. NaCL also requires Neon.
// For Linux, /proc/cpuinfo can be tested but without that assume Neon.
#if defined(__ARM_NEON__) || defined(__native_client__) || !defined(__linux__)
cpu_info_ = kCpuHasNEON;
cpu_info = kCpuHasNEON;
// For aarch64(arm64), /proc/cpuinfo's feature is not complete, e.g. no neon
// flag in it.
// So for aarch64, neon enabling is hard coded here.
#endif
#if defined(__aarch64__)
cpu_info_ = kCpuHasNEON;
cpu_info = kCpuHasNEON;
#else
// Linux arm parse text file for neon detect.
cpu_info_ = ArmCpuCaps("/proc/cpuinfo");
cpu_info = ArmCpuCaps("/proc/cpuinfo");
#endif
cpu_info_ |= kCpuHasARM;
cpu_info |= kCpuHasARM;
if (TestEnv("LIBYUV_DISABLE_NEON")) {
cpu_info_ &= ~kCpuHasNEON;
cpu_info &= ~kCpuHasNEON;
}
#endif // __arm__
if (TestEnv("LIBYUV_DISABLE_ASM")) {
cpu_info_ = 0;
cpu_info = 0;
}
cpu_info_ = cpu_info;
return cpu_info_;
}
// Note that use of this function is not thread safe.
LIBYUV_API
void MaskCpuFlags(int enable_flags) {
cpu_info_ = InitCpuFlags() & enable_flags;