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.
This commit is contained in:
Jia Tan 2023-10-18 22:48:19 +08:00
parent 96b663f67c
commit a5966c276b
1 changed files with 15 additions and 0 deletions

View File

@ -33,6 +33,21 @@
#endif #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_GENERIC
#undef CRC_CLMUL #undef CRC_CLMUL
#undef CRC_USE_IFUNC #undef CRC_USE_IFUNC