[PATCH] D116053: [MachineSink] Allow sinking of constant or ignorable physreg uses

[Vang Thao via Phabricator via llvm-commits]

vangthao added a comment.

In D116053#3203538 <https://reviews.llvm.org/D116053#3203538>, @rampitec wrote:

> I am not sure I can prove to myself this is legal. For example you are sinking a def into a loop with divergent condition and this def is used after the loop. Can this happen? If so a def might be done with an exec smaller than a use which creates an undef. Hoisting was OK because def was moved into a direction where exec is strictly not less than before. Did you run PSDB on it?

I believe the requirement for defs to dominate all uses prevents this from happening but I can add more test cases to check for this. This passed PSDB.


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