https://bugs.freedesktop.org/show_bug.cgi?id=90523

acab@digitalfuture.it changed:

What |Removed |Added ---------------------------------------------------------------------------- Hardware|Other |x86-64 (AMD64) OS|All |Linux (All)

https://bugs.freedesktop.org/show_bug.cgi?id=90523

--- Comment #2 from acab@digitalfuture.it --- I am sorry, but while trying to get a crash I've realized it's not mesa. The culprit appears to be llvm.

In short: llvm 3.5.2 + mesa 10.5.5 -> ok llvm 3.6.0 + mesa 10.5.5 -> lockup

I'm going to attach the logs anyway. Feel free to close this bug if it doesn't belong in here.

https://bugs.freedesktop.org/show_bug.cgi?id=90523

--- Comment #4 from acab@digitalfuture.it --- Created attachment 115901 --> https://bugs.freedesktop.org/attachment.cgi?id=115901&action=edit xorg.log

https://bugs.freedesktop.org/show_bug.cgi?id=90523

Michel Dänzer michel@daenzer.net changed:

What |Removed |Added ---------------------------------------------------------------------------- Attachment #115901|text/plain |application/gzip mime type| |

https://bugs.freedesktop.org/show_bug.cgi?id=90523

--- Comment #6 from acab@digitalfuture.it --- (In reply to Michel Dänzer from comment #5)

Can you try isolating the LLVM change introducing it with git bisect? Note that this might require some tweaking because current Mesa might fail to build against some development snapshots of LLVM.

Yes I could, however upsteam appears to maintain llvm in svn. There is a git repository as well but it lacks branches and tags.

Additionally the branch history doesn't look very linear and so far i've failed to match the proper commit from the branch in master. For example the top commit in http://llvm.org/svn/llvm-project/llvm/tags/RELEASE_352/final is: ------------------------------------------------------------------------ r214336 | rafael.espindola | 2014-07-30 17:04:00 -0400 (Wed, 30 Jul 2014) | 9 lines

SimplifyCFG: Avoid miscompilations due to removed lifetime intrinsics.

Which appears to match commit 7fef5a3d1907c813712fcb2a44d8187a65ba08cd: Author: Rafael Espindola rafael.espindola@gmail.com Date: Wed Jul 30 21:04:00 2014 +0000

SimplifyCFG: Avoid miscompilations due to removed lifetime intrinsics.

However mesa 10.5.5 doesn't build against that llvm (doesn't like TM->getSubtargetImpl()->getInstrInfo() in lp_bld_debug.cpp), but it does build against 3.5.2.

Can you suggest some commit ids i could use as good and bad markers?

https://bugs.freedesktop.org/show_bug.cgi?id=90523

--- Comment #8 from acab@digitalfuture.it --- Bisecting across llvm major releases was a total pain in the arse, but then I've realized that the bug was fixed recently in the 3.6 branch so I've given up.

If it helps, i can tell you that the bug was fixed here (mind you good and bad are reversed): $ git bisect good b5344bfff41583c00026e321d6831d4e8790b309 is the first bad commit commit b5344bfff41583c00026e321d6831d4e8790b309 Author: Tom Stellard thomas.stellard@amd.com Date: Mon May 4 19:50:17 2015 +0000

Merging r236307:

------------------------------------------------------------------------ r236307 | thomas.stellard | 2015-04-30 23:44:09 -0400 (Thu, 30 Apr 2015) | 4 lines

R600/SI: Add VCC as an implict def of SI_KILL

When SI_KILL has a register operand, its lowered form writes to vcc.

------------------------------------------------------------------------

Feel free to close the bug. Thanks.