[PATCH] D34391: [RegisterCoalescer] Fix for SubRange join unreachable

David Stuttard via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Jun 21 12:09:13 PDT 2017


dstuttard added a comment.

In https://reviews.llvm.org/D34391#786792, @npjdesres wrote:

> FYI I tried this patch in my out-of-tree backend (hoping to resolve http://llvm.org/PR32773).  I observed a segfault SR.removeValNo(RmValNo) because RmValNo may be null.
>
> I don't know yet whether this is specific to my backend, but I thought I'd mention it in case it indicates a more general problem.


Doh = forgot the check for null. I'll upload a change for this.
The fact that you got a segfault here is promising - it could mean it might be a similar problem. Try the new patch.
If it fails then take a look at the SubRanges around the failing SubRange join - it could be a similar problem to the one this fix addresses (but isn't caught by it) - in particular any remats that happen before the failing SubRange join.
There are a couple of failures logged in bugzilla that look similar but aren't fixed by this change, so there are definitely some other issues in this area.


https://reviews.llvm.org/D34391





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