[FFmpeg-devel] [PATCH] Fix ff_imdct_calc_sse() on gcc-4.6.

[Alex Converse]

2011/1/30 M?ns Rullg?rd <mans at mansr.com>:
> Alex Converse <alex.converse at gmail.com> writes:
>
>> On Sun, Jan 30, 2011 at 2:13 AM, Reimar D?ffinger
>> <Reimar.Doeffinger at gmx.de> wrote:
>>> On Sun, Jan 30, 2011 at 01:22:05AM -0800, Alex Converse wrote:
>>>> On Sun, Jan 30, 2011 at 1:08 AM, Alex Converse <alex.converse at gmail.com> wrote:
>>>> >
>>>> > Gcc 4.6 only preserves the first value when using a vector with an "m"
>>>> > constraint.
>>>> > ---
>>>> > ?libavcodec/x86/fft_sse.c | ? ?4 ++--
>>>> > ?1 files changed, 2 insertions(+), 2 deletions(-)
>>>> >
>>>> >
>>>>
>>>> oops this generates an extra indirection. Those of you who like to
>>>> defend inline asm, please step up and make some suggestions.
>>>
>>> Use what would be your _only_ option (conceptually, not in implementation
>>> of course) if you didn't use inline asm:
>>> MANGLE and change DECLARE_ALIGNED to DECLARE_ASM_CONST
>>> There's also the option of a gcc bug report, I have some doubts that is
>>> a valid optimization (though there are constraints to make gcc load
>>> directly into a xmm register, but both that and the current code have
>>> needlessly unpredictable performance).
>>
>> With MANGLE this time.
>>
>> From 51a872ff818bbb0071ab1649d104afcea48546c9 Mon Sep 17 00:00:00 2001
>> From: Alex Converse <alex.converse at gmail.com>
>> Date: Sun, 30 Jan 2011 01:04:41 -0800
>> Subject: [PATCH 1/2] Fix ff_imdct_calc_sse() on gcc-4.6.
>> MIME-Version: 1.0
>> Content-Type: multipart/mixed; boundary="------------1"
>>
>> This is a multi-part message in MIME format.
>> --------------1
>> Content-Type: text/plain; charset=UTF-8; format=fixed
>> Content-Transfer-Encoding: 8bit
>>
>>
>> Gcc 4.6 only preserves the first value when using a vector with an "m"
>> constraint.
>> ---
>> ?libavcodec/x86/fft_sse.c | ? ?7 +++----
>> ?1 files changed, 3 insertions(+), 4 deletions(-)
>>
>>
>> --------------1
>> Content-Type: text/x-patch; name="0001-Fix-ff_imdct_calc_sse-on-gcc-4.6.patch"
>> Content-Transfer-Encoding: 8bit
>> Content-Disposition: attachment; filename="0001-Fix-ff_imdct_calc_sse-on-gcc-4.6.patch"
>>
>> diff --git a/libavcodec/x86/fft_sse.c b/libavcodec/x86/fft_sse.c
>> index 9f02816..db591d4 100644
>> --- a/libavcodec/x86/fft_sse.c
>> +++ b/libavcodec/x86/fft_sse.c
>> @@ -23,7 +23,7 @@
>> ?#include "libavcodec/dsputil.h"
>> ?#include "fft.h"
>>
>> -DECLARE_ALIGNED(16, static const int, m1m1m1m1)[4] =
>> +DECLARE_ASM_CONST(16, int, ff_m1m1m1m1)[4] =
>> ? ? ?{ 1 << 31, 1 << 31, 1 << 31, 1 << 31 };
>>
>> ?void ff_fft_dispatch_sse(FFTComplex *z, int nbits);
>> @@ -82,7 +82,7 @@ void ff_imdct_calc_sse(FFTContext *s, FFTSample *output, const FFTSample *input)
>> ? ? ?j = -n;
>> ? ? ?k = n-16;
>> ? ? ?__asm__ volatile(
>> - ? ? ? ?"movaps %4, %%xmm7 \n"
>> + ? ? ? ?"movaps "LOCAL_MANGLE(ff_m1m1m1m1)", %%xmm7 \n"
>
> On second thoughts, wasn't that supposed to be MANGLE (not LOCAL_)?
>

Yes I sent the wrong one, sorry