Autotools based build uses -pthread and thus adds it to Libs.private
in liblzma.pc. CMake doesn't use -pthread at all if pthread functions
are available in libc so Libs.private doesn't get -pthread either.
Using set(ENABLE_THREADS "posix") is confusing because it sets
a new normal variable and leaves the cache entry with the same
name unchanged. The intent wasn't to change the cache entry so
this switches to a different variable name.
This way typos are caught quickly and compounding error messages
are avoided (a single typo could cause more than one error).
This keeps using SEND_ERROR when the system is lacking a feature
(like threading library or sandboxing method). This way the whole
configuration log will be generated in case someone wishes to
report a problem upstream.
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.
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.
The workaround must not be used with Clang that is acting in
MSVC mode. This checks for the known environments that need
the workaround instead of using "NOT MSVC".
See also:
2bcc0fdc58
There are several new policies. CMP0149 may affect the Windows SDK
version that CMake will choose by default. The new behavior is more
predictable, always choosing the latest SDK version by default.
The other new policies shouldn't affect this package.
If CMake was configured more than once, HAVE_CLOCK_GETTIME and
HAVE_CLOCK_MONOTONIC would not be set as compile definitions. The check
for librt being needed to provide HAVE_CLOCK_GETTIME was also
simplified.
The CMake build will try to create broken symlinks on Unix and Unix-like
platforms. Cygwin and MSYS2 are Unix-like, but may not be able to create
broken symlinks. The value of the CYGWIN or MSYS environment variables
determine if broken symlinks are valid.
The default for MSYS2 does not allow for broken symlinks, so the CMake
build has been broken for MSYS2 since commit
80a1a8bb83.
Boost iostream uses `find_package` in quiet mode and then again uses
`find_package` with required. This second call triggers a
`add_library cannot create imported target "LibLZMA::LibLZMA"
because another target with the same name already exists.`
This can simply be fixed by skipping the alias part on secondary
`find_package` runs.
The thread method is now configurable for the CMake build. It matches
the Autotools build by allowing ON (pick the best threading method),
OFF (no threading), posix, win95, and vista. If both Windows and
posix threading are both available, then ON will choose Windows
threading. Windows threading will also not use:
target_link_libraries(liblzma Threads::Threads)
since on systems like MinGW-w64 it would link the posix threads
without purpose.
This allows users to change the features they build either in
CMakeCache.txt or by using a CMake GUI. The sources built for
liblzma are affected by this too, so only the necessary files
will be compiled.
Now, the LZMA_VERSION_MAJOR, LZMA_VERSION_MINOR, and LZMA_VERSION_PATCH
macros do not need to be on consecutive lines in version.h. They can be
separated by more whitespace, comments, or even other content, as long
as they appear in the proper order (major, minor, patch).
This is combined from the following commits in the master branch:
443dfebced6b117d3b1f5e34774c31
Thanks to Iouri Kharon for the bug report, the original patch,
and testing.
The command line tools cannot be built with MSVC for now but
they can be built with MinGW-w64.
Thanks to Iouri Kharon for the bug report and the original patch.
Previously, if threading was enabled HAVE_DECL_CLOCK_MONOTONIC would always
be set to 0 or 1. However, this macro was needed in xz so if xz was not
built with threading and HAVE_DECL_CLOCK_MONOTONIC was not defined but
HAVE_CLOCK_GETTIME was, it caused a warning during build. Now,
HAVE_DECL_CLOCK_MONOTONIC has been renamed to HAVE_CLOCK_MONOTONIC and
will only be set if it is 1.
It not only makes no sense to put symbol versions into a static library
but it can also cause breakage.
By default Libtool #defines PIC if building a shared library and
doesn't define it for static libraries. This is documented in the
Libtool manual. It can be overriden using --with-pic or --without-pic.
configure.ac detects if --with-pic or --without-pic is used and then
gives an error if neither --disable-shared nor --disable-static was
used at the same time. Thus, in normal situations it works to build
both shared and static library at the same time on GNU/Linux,
only --with-pic or --without-pic requires that only one type of
library is built.
Thanks to John Paul Adrian Glaubitz from Debian for reporting
the problem that occurred on ia64:
https://www.mail-archive.com/xz-devel@tukaani.org/msg00610.html
It also works on E2K as it supports these intrinsics.
On x86-64 runtime detection is used so the code keeps working on
older processors too. A CLMUL-only build can be done by using
-msse4.1 -mpclmul in CFLAGS and this will reduce the library
size since the generic implementation and its 8 KiB lookup table
will be omitted.
On 32-bit x86 this isn't used by default for now because by default
on 32-bit x86 the separate assembly file crc64_x86.S is used.
If --disable-assembler is used then this new CLMUL code is used
the same way as on 64-bit x86. However, a CLMUL-only build
(-msse4.1 -mpclmul) won't omit the 8 KiB lookup table on
32-bit x86 due to a currently-missing check for disabled
assembler usage.
The configure.ac check should be such that the code won't be
built if something in the toolchain doesn't support it but
--disable-clmul-crc option can be used to unconditionally
disable this feature.
CLMUL speeds up decompression of files that have compressed very
well (assuming CRC64 is used as a check type). It is know that
the CLMUL code is significantly slower than the generic code for
tiny inputs (especially 1-8 bytes but up to 16 bytes). If that
is a real-world problem then there is already a commented-out
variant that uses the generic version for small inputs.
Thanks to Ilya Kurdyukov for the original patch which was
derived from a white paper from Intel [1] (published in 2009)
and public domain code from [2] (released in 2016).
[1] https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/fast-crc-computation-generic-polynomials-pclmulqdq-paper.pdf
[2] https://github.com/rawrunprotected/crc
This uses it for CRC table initializations when using --disable-small.
It avoids mythread_once() overhead. It also means that then
--disable-small --disable-threads is thread-safe if this attribute
is supported.
That is, the Filter ID will be changed once the design is final.
The current version will be removed. So files created with the
tempoary Filter ID won't be supported in the future.
Lasse Collin