From c2d00cb97b68cdaf3cc52dc910eecbeb4bee5015 Mon Sep 17 00:00:00 2001 From: Ben Niu Date: Thu, 27 Jan 2022 11:04:06 -0800 Subject: Add comments --- lib/lz4.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/lib/lz4.c b/lib/lz4.c index fb91047..6a02ef5 100644 --- a/lib/lz4.c +++ b/lib/lz4.c @@ -518,6 +518,11 @@ static unsigned LZ4_NbCommonBytes (reg_t val) if (LZ4_isLittleEndian()) { if (sizeof(val) == 8) { # if defined(_MSC_VER) && (_MSC_VER >= 1800) && (defined(_M_AMD64) && !defined(_M_ARM64EC)) && !defined(LZ4_FORCE_SW_BITCOUNT) +/*-************************************************************************************************* +* ARM64EC is a Microsoft-designed ARM64 ABI compatible with AMD64 applications on ARM64 Windows 11. +* The ARM64EC ABI does not support AVX/AVX2/AVX512 instructions, nor their relevant intrinsics +* including _tzcnt_u64. Therefore, we need to neuter the _tzcnt_u64 code path for ARM64EC. +****************************************************************************************************/ # if defined(__clang__) && (__clang_major__ < 10) /* Avoid undefined clang-cl intrinics issue. * See https://github.com/lz4/lz4/pull/1017 for details. */ -- cgit v0.12