CMake: Add manual support for 32-bit x86 assembly files

One has to pass -DENABLE_X86_ASM=ON to cmake to enable the
CRC assembly code. Autodetection isn't done. Looking at
CMAKE_SYSTEM_PROCESSOR might not work as it comes from uname
unless cross-compilation is done using a CMake toolchain file.

On top of this, if the code is run on modern processors that support
the CLMUL instruction, then the C code should be faster (but then
one should also be using a x86-64 build if possible).

(cherry picked from commit 24387c234b)
This commit is contained in:
Lasse Collin 2024-05-23 15:15:18 +03:00
parent c1b001b09e
commit 3670e0616e
1 changed files with 31 additions and 3 deletions

View File

@ -10,7 +10,17 @@
#
# A few things are still missing compared to the Autotools-based build:
#
# - 32-bit x86 assembly code for CRC32 and CRC64 isn't used.
# - 32-bit x86 assembly code for CRC32 and CRC64 isn't used by default.
# Use the option -DENABLE_X86_ASM=ON on the CMake command line to
# enable the assembly files. They are compatible with Linux, *BSDs,
# Cygwin, MinGW-w64, and Darwin. They are NOT compatible with MSVC.
#
# NOTE: The C code includes a generic version compatible with all
# processors and CLMUL version that requires a new enough processor
# with the PCLMULQDQ instruction. If the 32-bit x86 assembly files
# are used, the CLMUL version in the C code is NOT built. On modern
# processors with CLMUL support, the C code should be faster than
# the assembly code while on old processors the assembly code wins.
#
# - External SHA-256 code isn't supported but it's disabled by
# default in the Autotools build too (--enable-external-sha256).
@ -149,6 +159,14 @@ endif()
set(CMAKE_C_STANDARD 99)
set(CMAKE_C_STANDARD_REQUIRED ON)
# Support 32-bit x86 assembly files.
if(NOT MSVC)
option(ENABLE_X86_ASM "Enable 32-bit x86 assembly code" OFF)
if(ENABLE_X86_ASM)
enable_language(ASM)
endif()
endif()
# On Apple OSes, don't build executables as bundles:
set(CMAKE_MACOSX_BUNDLE OFF)
@ -482,11 +500,16 @@ if(ENABLE_SMALL)
target_sources(liblzma PRIVATE src/liblzma/check/crc32_small.c)
else()
target_sources(liblzma PRIVATE
src/liblzma/check/crc32_fast.c
src/liblzma/check/crc32_table.c
src/liblzma/check/crc32_table_be.h
src/liblzma/check/crc32_table_le.h
)
if(ENABLE_X86_ASM)
target_sources(liblzma PRIVATE src/liblzma/check/crc32_x86.S)
else()
target_sources(liblzma PRIVATE src/liblzma/check/crc32_fast.c)
endif()
endif()
if("crc64" IN_LIST ADDITIONAL_CHECK_TYPES)
@ -496,11 +519,16 @@ if("crc64" IN_LIST ADDITIONAL_CHECK_TYPES)
target_sources(liblzma PRIVATE src/liblzma/check/crc64_small.c)
else()
target_sources(liblzma PRIVATE
src/liblzma/check/crc64_fast.c
src/liblzma/check/crc64_table.c
src/liblzma/check/crc64_table_be.h
src/liblzma/check/crc64_table_le.h
)
if(ENABLE_X86_ASM)
target_sources(liblzma PRIVATE src/liblzma/check/crc64_x86.S)
else()
target_sources(liblzma PRIVATE src/liblzma/check/crc64_fast.c)
endif()
endif()
endif()