On 5/6/2016 9:56 PM, Hendrik Leppkes wrote: > On Sat, May 7, 2016 at 2:02 AM, James Almer <jamr...@gmail.com> wrote: >> On 5/6/2016 8:48 PM, Timothy Gu wrote: >>> On Fri, May 06, 2016 at 12:08:14PM +0200, Hendrik Leppkes wrote: >>>> >>>> Just to document it, this has caused build breakage in various >>>> scenarios, even in GCC 5.3 (6.1 not tested). >>>> >>>> The latest reported on IRC just today here: >>>> libavcodec/sbrdsp.c: In function 'sbr_neg_odd_64_c': >>>> libavcodec/sbrdsp.c:47:13: internal compiler error: in >>>> vect_analyze_data_ref_accesses, at tree-vect-data-refs.c:2596 >>>> static void sbr_neg_odd_64_c(float *x) >>>> >>>> There are various other cases which usually involve inline asm when >>>> building with SIMD (ie. --cpu=host) and the optimizer running out of >>>> registers, for example: >>>> libavcodec/x86/cabac.h:192:5: error: 'asm' operand has impossible >>>> constraints >>>> >>>> IMHO this feature is not quite ready to be enabled unconditionally in >>>> our code base, and we should re-evaluate this change. >>> >>> I don't have a problem with reverting this commit, but as James mentioned I >>> do >>> prefer the bug to be reported to GCC if possible. >>> >>> Have you also considered the possibility to enable this feature only if >>> inline >>> assembly is not enabled? >> >> Nobody disables inline asm when using GCC, so it'd be the same as removing >> tree >> vectorization altogether to begin with. >> >> This feature gives some nice speed boost on parts of the code that don't have >> hand written asm, so I'd very much rather keep it and try to get GCC to fix >> bugs >> on their compilers. > > Fixing would be nice of course, but it should then only be enabled in > versions we know do not have problems, which is none right now. > > - Hendrik
Again, do you know the configure options or compile flags that triggered these compiler errors? None of the many GCC 5.3 FATE clients reproduce them, so it must be a specific combination of compile flags. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
