Commit Graph

5 Commits

Author SHA1 Message Date
Lasse Collin 689e0228ba Change most public domain parts to 0BSD.
Translations and doc/xz-file-format.txt and doc/lzma-file-format.txt
were not touched.

COPYING.0BSD was added.
2024-02-14 18:31:12 +02:00
Lasse Collin fbb3ce541e liblzma: CRC: Add a comment to crc_x86_clmul.h about BUILDING_ macros. 2024-01-11 15:25:00 +02:00
Lasse Collin 4f518c1b6b liblzma: CRC: Remove crc_always_inline, use lzma_always_inline instead.
Now crc_simd_body() in crc_x86_clmul.h is only called once
in a translation unit, we no longer need to be so cautious
about ensuring the always-inline behavior.
2024-01-11 15:24:35 +02:00
Lasse Collin 66f080e801 liblzma: Rename arch-specific CRC functions and macros.
CRC_CLMUL was split to CRC_ARCH_OPTIMIZED and CRC_X86_CLMUL.
CRC_ARCH_OPTIMIZED is defined when an arch-optimized version is used.
Currently the x86 CLMUL implementations are the only arch-optimized
versions, and these also use the CRC_x86_CLMUL macro to tell when
crc_x86_clmul.h needs to be included.

is_clmul_supported() was renamed to is_arch_extension_supported().
crc32_clmul() and crc64_clmul() were renamed to
crc32_arch_optimized() and crc64_arch_optimized().
This way the names make sense with arch-specific non-CLMUL
implementations as well.
2024-01-11 14:29:42 +02:00
Lasse Collin 419f55f9df liblzma: Avoid extern lzma_crc32_clmul() and lzma_crc64_clmul().
A CLMUL-only build will have the crcxx_clmul() inlined into
lzma_crcxx(). Previously a jump to the extern lzma_crcxx_clmul()
was needed. Notes about shared liblzma on ELF platforms:

  - On platforms that support ifunc and -fvisibility=hidden, this
    was silly because CLMUL-only build would have that single extra
    jump instruction of extra overhead.

  - On platforms that support neither -fvisibility=hidden nor linker
    version script (liblzma*.map), jumping to lzma_crcxx_clmul()
    would go via PLT so a few more instructions of overhead (still
    not a big issue but silly nevertheless).

There was a downside with static liblzma too: if an application only
needs lzma_crc64(), static linking would make the linker include the
CLMUL code for both CRC32 and CRC64 from crc_x86_clmul.o even though
the CRC32 code wouldn't be needed, thus increasing code size of the
executable (assuming that -ffunction-sections isn't used).

Also, now compilers are likely to inline crc_simd_body()
even if they don't support the always_inline attribute
(or MSVC's __forceinline). Quite possibly all compilers
that build the code do support such an attribute. But now
it likely isn't a problem even if the attribute wasn't supported.

Now all x86-specific stuff is in crc_x86_clmul.h. If other archs
The other archs can then have their own headers with their own
is_clmul_supported() and crcxx_clmul().

Another bonus is that the build system doesn't need to care if
crc_clmul.c is needed.

is_clmul_supported() stays as inline function as it's not needed
when doing a CLMUL-only build (avoids a warning about unused function).
2024-01-11 14:29:42 +02:00