[PATCH] D109077: Do not attempt rematerialization with a killed register use

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec added a comment.

I.e. rationale: when we do remat original instruction is still in place and one of its operands is killed. It is certainly either dead or VNI is different at the point of rematerialization, so it will not pass a check for "all uses are available". There is no even a point to report it can be rematerialized when an extensive check will say it is not. For the very same reason I was unable to create a test for it, it never happens.

@arsenm We may want to add this check for VOP, just to speedup RA a bit. This will be an extra work, however. Generic implementation scans operands anyway, so it is cheap, but we don't.


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  https://reviews.llvm.org/D109077/new/

https://reviews.llvm.org/D109077