diff options
author | H.J. Lu <hjl.tools@gmail.com> | 2020-06-29 18:30:54 -0700 |
---|---|---|
committer | H.J. Lu <hjl.tools@gmail.com> | 2020-09-11 17:20:52 -0700 |
commit | 9620398097de3981c1adf5233e2b3478d36bc1b3 (patch) | |
tree | 20e492ba12ab22a57ed91df3698fdf57eba54810 /gnulib | |
parent | a92f4e6299fe0e3cb6f77e79de00817aece501ce (diff) | |
download | glibc-9620398097de3981c1adf5233e2b3478d36bc1b3.tar.gz glibc-9620398097de3981c1adf5233e2b3478d36bc1b3.tar.xz glibc-9620398097de3981c1adf5233e2b3478d36bc1b3.zip |
x86: Install <sys/platform/x86.h> [BZ #26124]
Install <sys/platform/x86.h> so that programmers can do #if __has_include(<sys/platform/x86.h>) #include <sys/platform/x86.h> #endif ... if (CPU_FEATURE_USABLE (SSE2)) ... if (CPU_FEATURE_USABLE (AVX2)) ... <sys/platform/x86.h> exports only: enum { COMMON_CPUID_INDEX_1 = 0, COMMON_CPUID_INDEX_7, COMMON_CPUID_INDEX_80000001, COMMON_CPUID_INDEX_D_ECX_1, COMMON_CPUID_INDEX_80000007, COMMON_CPUID_INDEX_80000008, COMMON_CPUID_INDEX_7_ECX_1, /* Keep the following line at the end. */ COMMON_CPUID_INDEX_MAX }; struct cpuid_features { struct cpuid_registers cpuid; struct cpuid_registers usable; }; struct cpu_features { struct cpu_features_basic basic; struct cpuid_features features[COMMON_CPUID_INDEX_MAX]; }; /* Get a pointer to the CPU features structure. */ extern const struct cpu_features *__x86_get_cpu_features (unsigned int max) __attribute__ ((const)); Since all feature checks are done through macros, programs compiled with a newer <sys/platform/x86.h> are compatible with the older glibc binaries as long as the layout of struct cpu_features is identical. The features array can be expanded with backward binary compatibility for both .o and .so files. When COMMON_CPUID_INDEX_MAX is increased to support new processor features, __x86_get_cpu_features in the older glibc binaries returns NULL and HAS_CPU_FEATURE/CPU_FEATURE_USABLE return false on the new processor feature. No new symbol version is neeeded. Both CPU_FEATURE_USABLE and HAS_CPU_FEATURE are provided. HAS_CPU_FEATURE can be used to identify processor features. Note: Although GCC has __builtin_cpu_supports, it only supports a subset of <sys/platform/x86.h> and it is equivalent to CPU_FEATURE_USABLE. It doesn't support HAS_CPU_FEATURE.
Diffstat (limited to 'gnulib')
0 files changed, 0 insertions, 0 deletions