On Mon, 25 May 2020, Martin Storsjö wrote:
On Sun, 24 May 2020, Carl Eugen Hoyos wrote:
Am So., 24. Mai 2020 um 21:53 Uhr schrieb Martin Storsjö
<mar...@martin.st>:
configure --enable-gpl --arch=i686 --cc=clang-cl --ld=lld-link
--target-os=win32 --toolchain=msvc --enable-cross-compile --ar=llvm-ar
--nm=llvm-nm --disable-stripping --extra-cflags=-m32
Why are you cross-compiling?
On which system are you testing this?
Because I normally only ever cross compile for windows.
There seems to be a subtle difference in this case, between using clang-cl
and "clang -target i686-win32-msvc"; clang-cl passes "-mdisable-fp-elim"
to the compiler internals, while "clang -target i686-win32-msvc" doesn't.
And cross compiling does seem to affect this particular case; there's a
check for whether ebp is available, which requires running the built
executable. When cross compiling, it's assumed the built executable is ok
and it isn't test run.
So with clang-cl running on windows, you'll end up with "#define
HAVE_EBP_AVAILABLE 0" in config.h, and the x86 cabac code won't end up
used at all - i.e. this patch wouldn't make any difference.
With clang-cl in cross compilation, and other invocations of "clang"
instead of "clang-cl", targeting i686 windows, you'll end up with
ebp_available enabled.
For a case where it does make a difference, in the same setup, try
configuring this way instead:
--cc='clang -target i686-win32-msvc' --ld=lld-link
--extra-ldflags='msvcrt.lib oldnames.lib' --toolchain=msvc
In this case, the ebp_available test will succeed, it will proceed to
trying to build the x86 inline cabac code, which fails.
Any further comments on this patch?
// Martin
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