This commit alone doesn't change anything in the real-world:
- configure.ac currently checks for clock_gettime() only
when using pthreads.
- CMakeLists.txt doesn't check for clock_gettime() on Windows.
So clock_gettime() wasn't used with MinGW-w64 before either.
clock_gettime() provides monotonic time and it's better than
gettimeofday() in this sense. But clock_gettime() is defined
in winpthreads, and liblzma or xz needs nothing else from
winpthreads. By avoiding clock_gettime(), we avoid the dependency on
libwinpthread-1.dll or the need to link against the static version.
As a bonus, GetTickCount64() and MinGW-w64's gettimeofday() can be
faster than clock_gettime(CLOCK_MONOTONIC, &tv). The resolution
is more than good enough for the progress indicator in xz.
This partially reverts creating crc_clmul.c
(8c0f9376f5) where is_clmul_supported()
was moved, extern'ed, and renamed to lzma_is_clmul_supported(). This
caused a problem when the function call to lzma_is_clmul_supported()
results in a call through the PLT. ifunc resolvers run very early in
the dynamic loading sequence, so the PLT may not be setup properly at
this point. Whether the PLT is used or not for
lzma_is_clmul_supported() depened upon the compiler-toolchain used and
flags.
In liblzma compiled with GCC, for instance, GCC will go through the PLT
for function calls internal to liblzma if the version scripts and
symbol visibility hiding are not used. If lazy-binding is disabled,
then it would have made any program linked with liblzma fail during
dynamic loading in the ifunc resolver.
Currently crc32 is always enabled, so COND_CHECK_CRC32 must always be
set. Because of this, it makes the recent change to conditionally
compile check/crc_clmul.c appear wrong since that file has CLMUL
implementations for both CRC32 and CRC64.
The option is enabled by default, but will only be visible to a user
listing cache variables or using a CMake GUI application if the
immintrin.h header file is found.
This mirrors our Autotools build --disable-clmul-crc functionality.
After forcing crc_simd_body() to always be inlined it caused
-fsanitize=address to fail for lzma_crc32_clmul() and
lzma_crc64_clmul(). The __no_sanitize_address__ attribute was added
to lzma_crc32_clmul() and lzma_crc64_clmul(), but not removed from
crc_simd_body(). ASAN and inline functions behavior has changed over
the years for GCC specifically, so while strictly required we will
keep __attribute__((__no_sanitize_address__)) on crc_simd_body() in
case this becomes a requirement in the future.
Older GCC versions refuse to inline a function with ASAN if the
caller and callee do not agree on sanitization flags
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89124#c3). If the
function was forced to be inlined, it will not compile if the callee
function has __no_sanitize_address__ but the caller doesn't.
PowerPC64LE wasn't tested but it seems like a safe change.
POWER8 supports unaligned access in little endian mode. Testing
on godbolt.org shows that GCC uses unaligned access by default.
The RISC-V macro __riscv_misaligned_fast is very new and not
in any stable compiler release yet.
Documentation in INSTALL was updated to match.
Documentation about an autodetection bug when using ARM64 GCC
with -mstrict-align was added to INSTALL.
CMake files weren't updated yet.
In XZ Utils context this doesn't matter much because
unaligned reads and writes aren't used in hot code
when TUKLIB_FAST_UNALIGNED_ACCESS isn't #defined.
After testing a 32-bit Release build on MSVC, only lzma_crc64_clmul()
has the bug. crc_simd_body() and lzma_crc32_clmul() do not need the
optimizations disabled.
Forcing this to be inline has a significant speed improvement at the
cost of a few repeated instructions. The compilers tested on did not
inline this function since it is large and is used twice in the same
translation unit.
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.
A detailed description of the three dispatch methods was added. Also,
duplicated comments now only appear in crc32_fast.c or were removed from
both crc32_fast.c and crc64_fast.c if they appeared in crc_clmul.c.
Both crc32_clmul() and crc64_clmul() are now exported from
crc32_clmul.c as lzma_crc32_clmul() and lzma_crc64_clmul(). This
ensures that is_clmul_supported() (now lzma_is_clmul_supported()) is
not duplicated between crc32_fast.c and crc64_fast.c.
Also, it encapsulates the complexity of the CLMUL implementations into a
single file and reduces the complexity of crc32_fast.c and crc64_fast.c.
Before, CLMUL code was present in crc32_fast.c, crc64_fast.c, and
crc_common.h.
During the conversion, various cleanups were applied to code (thanks to
Lasse Collin) including:
- Require using semicolons with MASK_/L/H/LH macros.
- Variable typing and const handling improvements.
- Improvements to comments.
- Fixes to the pragmas used.
- Removed unneeded variables.
- Whitespace improvements.
- Fixed CRC_USE_GENERIC_FOR_SMALL_INPUTS handling.
- Silenced warnings and removed the need for some #pragmas
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CMake doesn't set WIN32 on CYGWIN but the workaround is
probably needed on Cygwin too. Same for MSYS and MSYS2.
The workaround must not be used with Clang that is acting in
MSVC mode. This fixes it by checking for the known environments
that need the workaround instead of using "NOT MSVC".
Thanks to Martin Storsjö.
0570308ddd (commitcomment-129098431)
lld 17.0.1 searches for libraries to link first in the toolchain
directories before the local directory when building. The is a problem
for us because liblzma.a is installed in MSYS2 CLANG64 by default and
xz.exe will thus use the installed library instead of the one being
built.
This causes tests to fail when they are expecting features to be
disabled. More importantly, it will compile xz.exe with an incorrect
liblzma and could cause unexpected behavior by being unable to update
liblzma code in static builds. The CLANG64 environment can be tested
again once this is fixed.
Link to bug: https://github.com/llvm/llvm-project/issues/67779.
The Ninja Generator for CMake cannot have a custom target and its
BYPRODUCTS have the same name. This has prevented Ninja builds on
Unix-like systems since the xz symlinks were introduced in
80a1a8bb83.
llvm-windres 17.0.0 has more accurate emulation of GNU windres, so
the hack for GNU windres must now be used with llvm-windres too.
LLVM 16.0.6 has the old behavior and there likely won't be more
16.x releases. So we can simply check for >= 17.0.0.
See also:
2bcc0fdc58
The C standards don't allow an empty translation unit which can be
avoided by declaring something, without exporting any symbols.
When I committed f644473a21 I had
a feeling that some specific toolchain somewhere didn't like
empty object files (assembler or maybe "ar" complained) but
I cannot find anything to confirm this now. Quite likely I
remembered nonsense. I leave this here as a note to my future self. :-)
When the generic fast crc64 method is used, then we omit
lzma_crc64_table[][]. Similar to
d9166b52cf, we can avoid compiler warnings
with -Wempty-translation-unit (Clang) or -pedantic (GCC) by creating a
never used typedef instead of an extra symbol.
Now if user-supplied CFLAGS contains -Wall -Wextra -Wpedantic
the two checks that need -Werror will still work.
At CMake side there is add_compile_options(-Wall -Wextra)
but it didn't affect the -Werror tests. So with both Autotools
and CMake only user-supplied CFLAGS could make the checks fail
when they shouldn't.
This is not a full fix as things like -Wunused-macros in
user-supplied CFLAGS will still cause problems with both
GCC and Clang.
There were two uses of AC_COMPILE_IFELSE that didn't use
AC_LANG_SOURCE and Autoconf warned about these. The omission
had been intentional but it turned out that this didn't do
what I thought it would.
Autoconf 2.71 manual gives an impression that AC_LANG_SOURCE
inserts all #defines that have been made with AC_DEFINE so
far (confdefs.h). The idea was that omitting AC_LANG_SOURCE
would mean that only the exact code included in the
AC_COMPILE_IFELSE call would be compiled.
With C programs this is not true: the #defines get added without
AC_LANG_SOURCE too. There seems to be no neat way to avoid this.
Thus, with the C language at least, adding AC_LANG_SOURCE makes
no other difference than silencing a warning from Autoconf. The
generated "configure" remains identical. (Docs of AC_LANG_CONFTEST
say that the #defines have been inserted since Autoconf 2.63b and
that AC_COMPILE_IFELSE uses AC_LANG_CONFTEST. So the behavior is
documented if one also reads the docs of macros that one isn't
calling directly.)
Any extra code, including #defines, can cause problems for
these two tests because these tests must use -Werror.
CC=clang CFLAGS=-Weverything is the most extreme example.
It enables -Wreserved-macro-identifier which warns about
#define __EXTENSIONS__ 1 because it begins with two underscores.
It's possible to write a test file that passes -Weverything but
it becomes impossible when Autoconf inserts confdefs.h.
So this commit adds AC_LANG_SOURCE to silence Autoconf warnings.
A different solution is needed for -Werror tests.
