On 2015-09-27 23:43, Andreas Cadhalpun wrote: > Hi Aurelien, > > On 27.09.2015 23:10, Aurelien Jarno wrote: > > On 2015-09-27 20:37, Andreas Cadhalpun wrote: > > Thanks for the detailed testcase. I have been able to reproduce the > > issue on mipsel, but not on mips. > > Indeed, this test case only works on mipsel. > However, the same tests of ffmpeg's testsuite fail on mips, just with > different > checksums. So it likely has the same cause. > > >> This works correctly with gcc-5 5.2.1-16, so it is a regression in > >> 5.2.1-17. > >> The changelog reveals: > >> [ Aurelien Jarno ] > >> * Use --with-mips-plt on mips*. > >> * Build for R2 ISA on mips, mips64 and mips64el. > >> * Optimize for R2 ISA on mipsel. > >> * Only apply mips-fix-loongson2f-nop on mipsel. > >> > >> I assume one of these changes is responsible for this regression. > > > > Indeed. At least on mipsel the issue is due to the use of > > -mtune=mips32r2 by default. I guess the best is to change it back to > > -mtune=mips32 until we better understand the issue. > > OK. > > > Does someone have time to look at the issue more in details? The > > generated code is quite different between -mtune=mips32 and > > -mtune=mips32r2 (not in terms of instructions, but in terms of > > sequencing). > > > > As for mips, given I am not able to reproduce the issue, my guess is > > that it's due to the switch to -march=mips32r2, but I currently have > > no way to make sure. > > A slightly larger test case for mips is compiling ffmpeg...
It what I did to test if the failure is due to the above changes. ffmpeg builds fine with gcc version 5.2.1-17 and -march=mips2 -mtune=mips32 (instead of the new default -march=mips32r2), and passes the testsuite. I'll see if I can isolate a smaller testcase so that we can understand the problem. Aurelien -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurel...@aurel32.net http://www.aurel32.net