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Gate ARM64-accelerated impl on hwcap() having the HWCAP_PMULL flag. #6

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Merged
cmumford merged 1 commit into from
Sep 12, 2017
Merged

Gate ARM64-accelerated impl on hwcap() having the HWCAP_PMULL flag. #6

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6 changes: 4 additions & 2 deletions src/crc32c_arm64_linux_check.h
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Original file line number Diff line number Diff line change
Expand Up @@ -31,9 +31,11 @@ namespace crc32c {
inline bool CanUseArm64Linux() {
#if defined(HAVE_STRONG_GETAUXVAL) || defined(HAVE_WEAK_GETAUXVAL)
// From 'arch/arm64/include/uapi/asm/hwcap.h' in Linux kernel source code.
constexpr unsigned long kHwCapCrc32 = 1 << 7;
constexpr unsigned long kHWCAP_PMULL = 1 << 4;
constexpr unsigned long kHWCAP_CRC32 = 1 << 7;
unsigned long hwcap = (&getauxval != nullptr) ? getauxval(AT_HWCAP) : 0;
return (hwcap & kHwCapCrc32) != 0;
return (hwcap & (kHWCAP_PMULL | kHWCAP_CRC32)) ==
(kHWCAP_PMULL | kHWCAP_CRC32);
#else
return false;
#endif // defined(HAVE_STRONG_GETAUXVAL) || defined(HAVE_WEAK_GETAUXVAL)
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