[PATCH] D82258: [RegisterCoalescer] Fix IMPLICIT_DEF init removal for a register on joining

[Quentin Colombet via Phabricator via llvm-commits]

qcolombet added a comment.

Hi,

I had a (slightly) closer look and I have a question:

> I think its sufficient to erase IMPLICIT_DEF on any other incoming other value - in any case the reg would be initialized, no matter of subregs involved.

If we were to remove the implicit_def, wouldn't we get another verifier error of the sort "definition doesn't dominate all of its uses" because of the lack of any (implicit) definition on the 0 -> 2 -> 3 path for %0?

Basically, I am wondering if we set `ErasableImplicitDef` correctly for subranges.

Cheers,
-Quentin


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