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Diffstat (limited to '')
| -rw-r--r-- | src/liblzma/check/crc_clmul.c | 45 |
1 files changed, 0 insertions, 45 deletions
diff --git a/src/liblzma/check/crc_clmul.c b/src/liblzma/check/crc_clmul.c index 7110fd7e..640415e7 100644 --- a/src/liblzma/check/crc_clmul.c +++ b/src/liblzma/check/crc_clmul.c @@ -372,48 +372,3 @@ lzma_crc64_clmul(const uint8_t *buf, size_t size, uint64_t crc) && defined(_M_IX86) # pragma optimize("", on) #endif - - -//////////////////////// -// Detect CPU support // -//////////////////////// - -extern bool -lzma_is_clmul_supported(void) -{ - int success = 1; - uint32_t r[4]; // eax, ebx, ecx, edx - -#if defined(_MSC_VER) - // This needs <intrin.h> with MSVC. ICC has it as a built-in - // on all platforms. - __cpuid(r, 1); -#elif defined(HAVE_CPUID_H) - // Compared to just using __asm__ to run CPUID, this also checks - // that CPUID is supported and saves and restores ebx as that is - // needed with GCC < 5 with position-independent code (PIC). - success = __get_cpuid(1, &r[0], &r[1], &r[2], &r[3]); -#else - // Just a fallback that shouldn't be needed. - __asm__("cpuid\n\t" - : "=a"(r[0]), "=b"(r[1]), "=c"(r[2]), "=d"(r[3]) - : "a"(1), "c"(0)); -#endif - - // Returns true if these are supported: - // CLMUL (bit 1 in ecx) - // SSSE3 (bit 9 in ecx) - // SSE4.1 (bit 19 in ecx) - const uint32_t ecx_mask = (1 << 1) | (1 << 9) | (1 << 19); - return success && (r[2] & ecx_mask) == ecx_mask; - - // Alternative methods that weren't used: - // - ICC's _may_i_use_cpu_feature: the other methods should work too. - // - GCC >= 6 / Clang / ICX __builtin_cpu_supports("pclmul") - // - // CPUID decding is needed with MSVC anyway and older GCC. This keeps - // the feature checks in the build system simpler too. The nice thing - // about __builtin_cpu_supports would be that it generates very short - // code as is it only reads a variable set at startup but a few bytes - // doesn't matter here. -} |