[PATCH] D25631: [LV] Avoid emitting trivially dead instructions

[Matthew Simpson via llvm-commits]

mssimpso added a comment.

In https://reviews.llvm.org/D25631#570826, @mkuper wrote:

> I assume the motivation is that we don't want to run adce after the vectorizer, and "regular" dce doesn't catch this because of loop-carried dependencies?


No, this is mostly motivated by the sinking patch I submitted. These trivially dead instructions can create uses of scalar instructions that can potentially be sunk into predicated blocks. They prevent sinking because if we were to move the scalars, their definitions would no longer dominate the uses, even though the uses should later be deleted.


https://reviews.llvm.org/D25631