[FFmpeg-devel] [PATCH] compilation error in libavcodec/x86/mpegaudiodsp.c

[Michael Niedermayer]

On Tue, May 06, 2014 at 02:53:04PM +1000, Matt Oliver wrote:
> On 6 May 2014 04:31, Derek Buitenhuis <derek.buitenhuis at gmail.com> wrote:
> 
> > On 5/5/2014 12:42 PM, Paweł Witas wrote:
> > > +#if HAVE_AVX_EXTERNAL
> > >       if (EXTERNAL_AVX(cpu_flags)) {
> > >           s->imdct36_blocks_float = imdct36_blocks_avx;
> > >       }
> > > +#endif
> >
> > I am incline not to accept this. This is a hack to fix improper DCE.
> >
> > > I use MinGW/MSys tools.
> > > My ffmpeg compilation configuration for Pentium III and above, that
> > causes this error:
> > >
> > > ./configure --toolchain=msvc --prefix=/usr/local \
> > >   --extra-cflags="-arch:SSE -O2 -MT -LD -I/usr/local/include
> > -D_BIND_TO_CURRENT_CRT_VERSION=1 -D_BIND_TO_CURRENT_MFC_VERSION=1" \
> > >   --arch=x86 --cpu=c3-2 --disable-runtime-cpudetect --disable-sse2
> > --disable-sse3 --disable-ssse3 --disable-sse4 --disable-sse42 \
> > >   --disable-amd3dnow --disable-amd3dnowext --disable-avx --disable-avx2
> > --disable-xop --disable-fma3 --disable-fma4 \
> > >   --disable-gpl --disable-debug --enable-shared --enable-swscale \
> > >   --disable-decoder=aac --disable-encoder=aac --enable-decoder=aac_latm \
> > >   --enable-libfdk-aac --disable-libaacplus --enable-nonfree
> >
> > Let's break this down, as it seems you do not know what you are doing.
> >
> > > --extra-cflags="-arch:SSE -O2 -MT -LD -I/usr/local/include
> > -D_BIND_TO_CURRENT_CRT_VERSION=1 -D_BIND_TO_CURRENT_MFC_VERSION=1"
> >
> > This makes no sense. Also, please try a build without all the custom flags.
> >
> > In order:
> >
> > > -arch:SSE
> >
> > All recent MSVC compiles default to SSE (SSE2 even I think). This is
> > superfluous.
> >
> > > -O2 -MT
> >
> > All of these are default for FFmpeg. Why are you specifying them twice?
> >
> > > -LD
> >
> > Incorrect. If you want DLLs, use --enable-shared alone.
> >
> > > -I/usr/local/include
> >
> > Very wrong. Do NOT pass MSVC your *MinGW* includes folder.
> >
> > >  -D_BIND_TO_CURRENT_CRT_VERSION=1 -D_BIND_TO_CURRENT_MFC_VERSION=1
> >
> > Why?
> >
> > > --cpu=c3-2
> >
> > Welcome to 15 years ago I guess.
> >
> > > --disable-runtime-cpudetect
> >
> > This is the exact opposite of what you want. You *want* it to see what the
> > CPU
> > can do at runtime, and in fact this is pretty much the only way we support
> > nowadays.
> >
> > > --disable-sse2 --disable-sse3 --disable-ssse3 --disable-sse4
> > --disable-sse42 \
> > >   --disable-amd3dnow --disable-amd3dnowext --disable-avx --disable-avx2
> > --disable-xop --disable-fma3 --disable-fma4
> >
> > Do not do this. You are crippling the build. The binary will run perfectly
> > fine on a P3,
> > since we detect the CPU capabilities at runtime.
> >
> > > --disable-gpl
> >
> > Pointless. LGPL is default.
> >
> > > --enable-swscale
> >
> > Pointless. It is enabled by default.
> >
> > > --enable-decoder=aac_latm
> >
> > Ditto.
> >
> > > --disable-libaacplus
> >
> > Pointless, as you have to explicitly enable this.
> >
> > After trying a build with default settings, please tell us your compiler
> > version.
> >
> > - Derek
> >
> 
> I agree with Derek that your configure options could do with some serious
> cleanups. That said however based on the error given I was able to
> reproduce the problem using nothing more than "--disable-avx" which causes
> compilation errors for msvc and icl. It appears msvc will generate the
> error before the dead code elimination stage (gcc is smart enough to just
> give a warning).
> The same issue will arise if compiling with --disable-sse as well. So i
> added to the patch to handle this possible situation as well. I wouldnt
> recommend anyone compile without sse but then I wouldnt compile without avx
> either and this patch report is evidence that some people do. So ive made
> an updated patch that fixes both situations just in case.

>  mpegaudiodsp.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 15629371dda0579bdbaffc9d4dbafaa557554127  x86-mpegaudiodsp.c-msvc-compilation-error-without-ss.patch
> From 26021955254d1bc6118eda84ba8d225a9a8bd4aa Mon Sep 17 00:00:00 2001
> From: Matt Oliver <protogonoi at gmail.com>
> Date: Tue, 6 May 2014 14:42:38 +1000
> Subject: [PATCH] x86/mpegaudiodsp.c: msvc compilation error without
>  sse/avx_external

patch applied

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If you think the mosad wants you dead since a long time then you are either
wrong or dead since a long time.
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