Re: [FFmpeg-devel] [PATCH] configure: autodetect libglslang ldflags

[Lynne <dev@lynne.ee>]

Jan 22, 2024, 22:19 by martin@martin.st:

> On Mon, 22 Jan 2024, Lynne wrote:
>
>> Jan 22, 2024, 07:52 by ffmpeg-devel@ffmpeg.org:
>>
>>> Since glslang 14.0.0, OGLCompiler and HLSL stub libraries have been
>>> fully removed from the build.
>>>
>>> This fixes the configuration by detecting if the stub libraries are
>>> still present (glslang releases before version 14.0.0).
>>>
>>> ffbuild/config.log:
>>> /usr/lib/gcc/x86_64-pc-linux-gnu/13/../../../../x86_64-pc-linux-gnu/bin/ld: cannot find -lOSDependent: No such file or directory
>>> /usr/lib/gcc/x86_64-pc-linux-gnu/13/../../../../x86_64-pc-linux-gnu/bin/ld: cannot find -lHLSL: No such file or directory
>>> /usr/lib/gcc/x86_64-pc-linux-gnu/13/../../../../x86_64-pc-linux-gnu/bin/ld: cannot find -lOGLCompiler: No such file or directory
>>>
>>> Addresses https://trac.ffmpeg.org/ticket/10713
>>> See https://bugs.gentoo.org/show_bug.cgi?id=918989
>>> Should fix https://ffmpeg.org/pipermail/ffmpeg-devel/2023-August/313666.html
>>>
>>> Signed-off-by: Matthew White <mehw.is.me@inventati.org>
>>> ---
>>> configure | 23 +++++++++++++++++++++--
>>> 1 file changed, 21 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/configure b/configure
>>> index c8ae0a061d..abff488dc0 100755
>>> --- a/configure
>>> +++ b/configure
>>> @@ -2626,6 +2626,7 @@ CMDLINE_SET="
>>> ignore_tests
>>> install
>>> ld
>>> +    libglslang_ldflags
>>> ln_s
>>> logfile
>>> malloc_prefix
>>> @@ -6652,6 +6653,24 @@ if enabled_all libglslang libshaderc; then
>>> die "ERROR: libshaderc and libglslang are mutually exclusive, if in doubt, disable libglslang"
>>> fi
>>>
>>> +if enabled libglslang; then
>>> +    if [ -x "$(command -v glslang)" ]; then
>>> +        # https://github.com/KhronosGroup/glslang
>>> +        # commit 6be56e45e574b375d759b89dad35f780bbd4792f: Remove `OGLCompiler` and `HLSL` stub libraries from build
>>> +        # StandAlone/StandAlone.cpp: "SpirvGeneratorVersion:GLSLANG_VERSION_MAJOR.GLSLANG_VERSION_MINOR.GLSLANG_VERSION_PATCH GLSLANG_VERSION_FLAVOR"
>>> +        glslang_version="$(glslang -dumpversion)"
>>> +        glslang_major="${glslang_version%%.*}"
>>> +        glslang_major="${glslang_major#*:}"
>>> +        if test ${glslang_major} -le 13; then
>>> +            libglslang_ldflags=" -lOSDependent -lHLSL -lOGLCompiler"
>>> +        elif ! [[ ${glslang_major} =~ ^[0-9]+$ ]]; then
>>> +            die "ERROR: glslang's computed major version isn't a number: '${glslang_major}'"
>>> +        fi
>>> +    else
>>> +        die "ERROR: glslang binary not found, impossible to determine installed glslang's version"
>>> +    fi
>>> +fi
>>> +
>>> check_cpp_condition winrt windows.h "!WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP)"
>>>
>>> if ! disabled w32threads && ! enabled pthreads; then
>>> @@ -6771,10 +6790,10 @@ enabled libfreetype       && require_pkg_config libfreetype freetype2 "ft2build.
>>> enabled libfribidi        && require_pkg_config libfribidi fribidi fribidi.h fribidi_version_info
>>> enabled libharfbuzz       && require_pkg_config libharfbuzz harfbuzz hb.h hb_buffer_create
>>> enabled libglslang && { check_lib spirv_compiler glslang/Include/glslang_c_interface.h glslang_initialize_process \
>>> -                            -lglslang -lMachineIndependent -lOSDependent -lHLSL -lOGLCompiler -lGenericCodeGen \
>>> +                            -lglslang -lMachineIndependent "${libglslang_ldflags}" -lGenericCodeGen \
>>> -lSPVRemapper -lSPIRV -lSPIRV-Tools-opt -lSPIRV-Tools -lpthread -lstdc++ -lm ||
>>> require spirv_compiler glslang/Include/glslang_c_interface.h glslang_initialize_process \
>>> -                            -lglslang -lOSDependent -lHLSL -lOGLCompiler \
>>> +                            -lglslang "${libglslang_ldflags}" \
>>> -lSPVRemapper -lSPIRV -lSPIRV-Tools-opt -lSPIRV-Tools -lpthread -lstdc++ -lm; }
>>> enabled libgme            && { check_pkg_config libgme libgme gme/gme.h gme_new_emu ||
>>> require libgme gme/gme.h gme_new_emu -lgme -lstdc++; }
>>> --
>>> 2.43.0
>>>
>>
>> This is very very cursed. Fitting for the public API of the world's fifth worst library. Debian is stuck on version 13, so the majority of users are still stuck on version 13. Debian ships a pkg-config file, but of course it's incorrect, if you try to compile against it. Oh, and libshaderc in Debian ships with a bug such that it segfaults on init, so it's not like you can avoid that. And that package's pkg-config file got broken in the past.
>>
>> I think this is fine for now. I'll let it be discussed for a few more days before merging it.
>>
>
> I think breaking cross compilation with glslang is pretty bad. Apparently VLC doesn't enable glslang in their ffmpeg builds though, but I would expect that some does.
>
> Wouldn't it just be possible to test whether linkins succeeds with one set of libraries, and if not, try with the other set, and pick whichever set works with the library at hand? That would be way much simpler than this patch, and also work for cross compilation.
>

Debian has updated its version of glslang, so I'm more inclined
to just depend on version 14 and hope the next time they break the
API happens in less than a year, or however much that is in hours for them.
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