[PATCH] D86468: [WIP][GlobalISel] CSE copies

[Jay Foad via Phabricator via llvm-commits]

foad added a comment.

> I thought the argument for having a CSEMIRBuilder is as a compile time improvement to avoid creating the instructions in the first place. I do think we are missing optimization combines during legalization though, copy propagation being among them.

I think MIRBuilders in general should be doing way more up-front simplification to avoid generating redundant instructions. ConstantFoldingMIRBuilder doesn't seem to be used at all, and none of the MIRBuilders seem to do other trivial simplifications like x+0 -> x.


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  https://reviews.llvm.org/D86468/new/

https://reviews.llvm.org/D86468