[llvm] r231186 - RegisterCoalescer: Gracefully continue if subrange merging fails.

Chandler Carruth chandlerc at google.com
Tue Mar 3 17:21:05 PST 2015


On Tue, Mar 3, 2015 at 4:43 PM, Matthias Braun <matze at braunis.de> wrote:

> Author: matze
> Date: Tue Mar  3 18:43:50 2015
> New Revision: 231186
>
> URL: http://llvm.org/viewvc/llvm-project?rev=231186&view=rev
> Log:
> RegisterCoalescer: Gracefully continue if subrange merging fails.
>
> There is a known bug where the register coalescer fails to merge
> subranges when multiple ranges end up in the "overflow" bit 32 of the
> lanemasks. A proper fix for this is complicated so for now this is a
> workaround which lets the register coalescer drop the subregister
> liveness information (we just loose some precision by that) and
> continue.
>
> Modified:
>     llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
>

No test case? This seems like something really important to cover...
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