diff options
| author | Frank Barchard <fbarchard@google.com> | 2017-05-23 18:43:40 -0700 |
|---|---|---|
| committer | Commit Bot <commit-bot@chromium.org> | 2017-05-24 02:09:03 +0000 |
| commit | 651ccc0c3a3f507b8ab0895e4ba018b9a6dedbfa (patch) | |
| tree | d304ddd0ad8bb368beb5fb7be9a418e5c351eaa3 /source/cpu_id.cc | |
| parent | 77f6916da2ebc16ad441c8dbeb8a73b0d3a150df (diff) | |
| download | libyuv-651ccc0c3a3f507b8ab0895e4ba018b9a6dedbfa.tar.gz | |
Fix data races in libyuv::TestCpuFlag().
Detect the compiler's support of C11 atomics, and use C11 atomics when
available.
Note that libyuv::MaskCpuFlags() is still not thread-safe.
BUG=libyuv:641
TEST= cpu_thread_test.cc adds a pthread based test
R=wangcheng@google.com
Change-Id: If05b1e16da833105a0159ed67ef20f4e61bc7abd
Reviewed-on: https://chromium-review.googlesource.com/510079
Commit-Queue: Frank Barchard <fbarchard@google.com>
Reviewed-by: Cheng Wang <wangcheng@google.com>
Diffstat (limited to 'source/cpu_id.cc')
| -rw-r--r-- | source/cpu_id.cc | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/source/cpu_id.cc b/source/cpu_id.cc index afb5d282..04403967 100644 --- a/source/cpu_id.cc +++ b/source/cpu_id.cc @@ -43,6 +43,9 @@ extern "C" { #define SAFEBUFFERS #endif +// cpu_info_ variable for SIMD instruction sets detected. +LIBYUV_API int cpu_info_ = 0; + // Low level cpuid for X86. #if (defined(_M_IX86) || defined(_M_X64) || defined(__i386__) || \ defined(__x86_64__)) && \ @@ -192,10 +195,6 @@ LIBYUV_API SAFEBUFFERS int MipsCpuCaps(const char* cpuinfo_name, return 0; } -// CPU detect function for SIMD instruction sets. -LIBYUV_API -int cpu_info_ = 0; // cpu_info is not initialized yet. - // Test environment variable for disabling CPU features. Any non-zero value // to disable. Zero ignored to make it easy to set the variable on/off. #if !defined(__native_client__) && !defined(_M_ARM) @@ -215,7 +214,7 @@ static LIBYUV_BOOL TestEnv(const char*) { } #endif -LIBYUV_API SAFEBUFFERS int InitCpuFlags(void) { +static SAFEBUFFERS int GetCpuFlags(void) { int cpu_info = 0; #if !defined(__pnacl__) && !defined(__CLR_VER) && defined(CPU_X86) uint32 cpu_info0[4] = {0, 0, 0, 0}; @@ -321,14 +320,27 @@ LIBYUV_API SAFEBUFFERS int InitCpuFlags(void) { cpu_info = 0; } cpu_info |= kCpuInitialized; - 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; +#ifdef __ATOMIC_RELAXED + __atomic_store_n(&cpu_info_, GetCpuFlags() & enable_flags, __ATOMIC_RELAXED); +#else + cpu_info_ = GetCpuFlags() & enable_flags; +#endif +} + +LIBYUV_API +int InitCpuFlags(void) { + MaskCpuFlags(-1); +#ifdef __ATOMIC_RELAXED + return __atomic_load_n(&cpu_info_, __ATOMIC_RELAXED); +#else + return cpu_info_; +#endif } #ifdef __cplusplus |