Checks if the host cpu supports X86-INSTRUCTION-SET. The instruction set that can be tested are "mmx, popcnt, sse, sse2, sse3, sse4.1, sse4.2, sse4a, avx, avx2, avx512f, fma, fma4, bmi, bmi2". If the instruction set is supported by the host cpu, the C preprocessor macro HAVE_XXX_INSTRUCTIONS is set to 1. The XXX is up-cased instruction case with dot replaced by underscore. For example, the test for "sse4.2" would export HAVE_SSE4_2_INSTRUCTIONS=1. This macro requires gcc extended builtin function "__builtin_cpu_init" and "__builtin_cpu_supports" to detect the cpu features. It will error out if the compiler doesn’t has these builtins.
If the test for the instruction set succeeded, the hook ACTION-IF-FOUND would run. Otherwise the hook ACTION-IF-NOT-FOUND would run if specified.
See also AX_CHECK_X86_FEATURES, which checks all the possible instruction set and export the corresponding CFLAGS.
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Copyright © 2016 Felix Chern firstname.lastname@example.org
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