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Bug 649450

Summary: sys-devel/gcc-7 - Issues with BMI on 32bit x86 apps
Product: Gentoo Linux Reporter: sigurse
Component: Current packagesAssignee: Gentoo Toolchain Maintainers <toolchain>
Status: RESOLVED DUPLICATE    
Severity: normal Keywords: PATCH
Priority: Normal    
Version: unspecified   
Hardware: x86   
OS: Linux   
See Also: https://bugs.freedesktop.org/show_bug.cgi?id=101881
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81763
https://bugs.gentoo.org/show_bug.cgi?id=645776
Whiteboard:
Package list:
Runtime testing required: ---
Bug Depends on:    
Bug Blocks: 617524    

Description sigurse 2018-03-03 12:52:36 UTC
I recently rebuilt my entire system using gcc 7.3, and from that moment on several Steam games crashed with a segmentation fault related to graphics/AMDGPU/LLVM (e.g. Black Mesa, Stellaris) while other games worked flawlessly (e.g. Civilization VI).

After searching around I found the following bug report in mesa
https://bugs.freedesktop.org/show_bug.cgi?id=101881
which lead to the following bug report in gcc
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81763.

By creating my own gcc-7.3.0-r1 whose only difference from gcc-7.3.0 was the addition of the patch in https://gcc.gnu.org/viewcvs/gcc/branches/gcc-7-branch/gcc/config/i386/i386.md?view=patch&r1=257154&r2=257153&pathrev=257154
and rebuilding everything, the segmentation faults are gone. I would guess this could be of use for the wider Gentoo community while we wait for gcc 7.4 which will include the aforementioned patch.
Comment 1 sigurse 2018-03-13 06:31:37 UTC
The suggested patch seems identical to the patch from Mike Lothian to https://bugs.gentoo.org/show_bug.cgi?id=645776 (https://645776.bugs.gentoo.org/attachment.cgi?id=516792), so this is probably a duplicate bug.
Comment 2 sigurse 2018-03-13 06:35:29 UTC

*** This bug has been marked as a duplicate of bug 645776 ***