[PATCH] D42402: [GISel]: Eliminate redundant copies b/w VRegs of same regclass at the end of InstructionSelection

[Aditya Nandakumar via Phabricator via llvm-commits]

aditya_nandakumar added a comment.

In https://reviews.llvm.org/D42402#985864, @qcolombet wrote:

> LGTM too. The code is probably simpler to understand like this and if compile-time turns out to be a problem we can revisit.
>  I wonder though if removing this copies upfront wouldn't have helped tablegen current matching table (because it does not look through COPYs right now).


I certainly suspect somehow eliminating these copies upfront will result in tablegen matching patterns more deeply. I wonder if adding another step inside GIM_Try to also walk through copies is too much of a compile time increase as compared to a quick run before ISel removing redundant copies.


https://reviews.llvm.org/D42402