[FFmpeg-devel] ICC version checks

[Alexander Strange]

On Mar 10, 2010, at 9:01 PM, Carl Eugen Hoyos wrote:

> Frank Barchard <fbarchard <at> google.com> writes:
> 
>>>> __attribute__((cold))
>>> 
>>> This is (together with alloc_size) Intel issue 540761.
>>> 
>>>> __attribute__((flatten))
>>> 
>>> Intel issue 554092.
> 
> [...]
> 
>> Intel say the first 2 are 'mostly complete' but not released.
> 
> Good news, thank you for asking!
> Allow me to repeat (I wrote the same in a private mail) that I believe the
> vc1_mc_4mv_chroma() bug is significantly more important;-)
> 
> [edited]
> 
>> Thilo thinks its O3 related.
> 
> It is (It disappears for -O2 and -O3 -parallel).
> 
>> As a work around, I'd suggest an ifdef and
>> #*pragma optimize* ( "", off )
>> around the code you suspect.  That would also help Intel track down the bug.
> 
> It would not help significantly, I already posted that the problem is
> decode_var_block_data(). Nobody wanted to look into the assembly of
> vc1_mc_4mv_chroma(), so I will not post asm files if not explicitly asked to.

I'll look but I don't promise anything. It looks fairly long.
Can I reproduce it by building with the available icc for Linux?

In case anyone's curious about other compilers, llvm miscompiles cabac on x86-32:
http://llvm.org/bugs/show_bug.cgi?id=6539
and fails to assemble dsputil_mmx on x86-32+pic:
http://llvm.org/bugs/show_bug.cgi?id=5991

I have a bunch of gcc bugs but they're all requests to backport stuff like NEG_SSR32 into C. gcc-svn -flto and -fwhopr both fail to build ffmpeg with everything enabled, but I have yet to figure out how to minimize bugs like that.

>> They ask if you could file a bug for the ALS bug.
> 
> The reason I wanted to wait for our 0.6 release is that it was extraordinarily
> difficult to report the vc1 bug, and it will be even more difficult if svn is
> involved. I will try to put a alsdec-only version of FFmpeg together this
> weekend.
> 
> Carl Eugen
> 
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