From a5966c276bd6fa975f0389f8a8dc61393de750b0 Mon Sep 17 00:00:00 2001 From: Jia Tan Date: Wed, 18 Oct 2023 22:48:19 +0800 Subject: liblzma: Create crc_always_inline macro. This macro must be used instead of the inline keyword. On MSVC, it is a replacement for __forceinline which is an MSVC specific keyword that should not be used with inline (it will issue a warning if it is). It does not use a build system check to determine if __attribute__((__always_inline__)) since all compilers that can use CLMUL extensions (except the special case for MSVC) should support this attribute. If this assumption is incorrect then it will result in a bug report instead of silently producing slow code. --- src/liblzma/check/crc_common.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'src') diff --git a/src/liblzma/check/crc_common.h b/src/liblzma/check/crc_common.h index b0176adc..7aef383c 100644 --- a/src/liblzma/check/crc_common.h +++ b/src/liblzma/check/crc_common.h @@ -33,6 +33,21 @@ #endif +// The inline keyword is only a suggestion to the compiler to substitute the +// body of the function into the places where it is called. If a function +// is large and called multiple times then compiler may choose to ignore the +// inline suggestion at a sometimes high performance cost. +// +// MSVC's __forceinline is a keyword that should be used in place of inline. +// If both __forceinline and inline are used, MSVC will issue a warning. +// Since MSVC's keyword is a replacement keyword, the lzma_always_inline +// macro must also contain the inline keyword when its not used in MSVC. +#ifdef _MSC_VER +# define crc_always_inline __forceinline +#else +# define crc_always_inline __attribute__((__always_inline__)) inline +#endif + #undef CRC_GENERIC #undef CRC_CLMUL #undef CRC_USE_IFUNC -- cgit v1.2.3