LLVM Bugzilla is read-only and represents the historical archive of all LLVM issues filled before November 26, 2021. Use github to submit LLVM bugs

Bug 33524 - Couldn't join subrange unreachable for RegisterCoalescer remat
Summary: Couldn't join subrange unreachable for RegisterCoalescer remat
Status: RESOLVED FIXED
Alias: None
Product: libraries
Classification: Unclassified
Component: Register Allocator (show other bugs)
Version: trunk
Hardware: PC All
: P enhancement
Assignee: Unassigned LLVM Bugs
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2017-06-20 02:20 PDT by David Stuttard
Modified: 2017-07-06 10:10 PDT (History)
2 users (show)

See Also:
Fixed By Commit(s):

Attachments
Test case (3.61 KB, text/plain)
2017-06-20 02:20 PDT, David Stuttard 		Details
Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description David Stuttard 2017-06-20 02:20:12 PDT 
Created attachment 18668 [details]
Test case

I'm seeing an issue for the AMDGCN backend (llc -march=amdgcn <testcase>.ll) where the RegisterCoalescer hits unreachable for a SubRange join

I think I've narrowed this down to an issue in a remat (hence the name)

I've got a potential fix for this that I'll post to reviews.llvm.org (and link from here)

I've already verified that the fix doesn't make any difference to bug 33152 which superficially seems similar.
bug 32773 may also be related
Comment 1 David Stuttard 2017-06-20 02:23:16 PDT 
See https://reviews.llvm.org/D34391 for a potential fix
Comment 2 Matt Arsenault 2017-06-20 10:28:26 PDT 
Possibly the same as bug 33152
Comment 3 David Stuttard 2017-07-06 10:10:58 PDT 
https://reviews.llvm.org/D34391 now submitted