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

[Alex Converse]

On Sun, Jan 30, 2011 at 8:07 PM, Alex Converse <alex.converse at gmail.com> wrote:
> 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
>

Corrected patch attached
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