[Ffmpeg-devel] Re: [PATCH] fix build for --cpu=i686

[Ramiro Ribeiro Polla]

Michael Niedermayer wrote:

>Hi
>
>On Tue, Mar 27, 2007 at 06:21:15PM -0300, Ramiro Ribeiro Polla wrote:
>  
>
>>Hello,
>>
>>Attached patch makes regression tests succeed with gcc 4.x when 
>>--cpu=i686 is passed to configure. gcc svn didn't work either.
>>
>>I don't know why exactly it does work. Maybe it works around a bug in 
>>gcc 4.x. I still didn't understand what an "earlyclobber" operand means.
>>
>>Ramiro Polla
>>    
>>
>
>  
>
>>Index: libavutil/internal.h
>>===================================================================
>>--- libavutil/internal.h	(revision 8535)
>>+++ libavutil/internal.h	(working copy)
>>@@ -230,7 +230,7 @@
>>     "cmovl %3, %0       \n\t"\
>>     "cmovl %4, %1       \n\t"\
>>     "cmovl %5, %2       \n\t"\
>>-    : "+r" (x), "+r" (a), "+r" (c)\
>>+    : "+r" (x), "+&r" (a), "+&r" (c)\
>>     : "r" (y), "r" (b), "r" (d)\
>>    
>>
>
>hmm, could someone ask the gcc devels if "+r" are supposed to be able
>to overlap "r" ?
>
>though either way the change is wrong, the early clobbers would have to
>be on the first and second not second and third
>  
>
Patch attached with earlyclobbers for all 3 outputs, as suggested by a 
gcc dev on http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31386

Ramiro Polla
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