[PATCH] D82660: [RISCV] Optimize multiplication by specific immediates

Sat Jun 27 01:53:10 PDT 2020

benshi001 added a comment.

Thanks. I have uploaded a new version according to your suggestion!

In D82660#2117161 <https://reviews.llvm.org/D82660#2117161>, @lenary wrote:

> Thanks for the patch!
>
> This optimisation is done by DAGCombine if you instead implement `decomposeMulByConstant` in `RISCVTargetLowering`. Read the comment on the `TargetLoweringBase` class to understand how to use it. This is preferrable, because we don't want to maintain a target-specific copy of this optimisation if we can avoid it.
>
> It would be sensible to base your implementation on the one in the x86 backend: `X86TargetLowering::decomposeMulByConstant`, which deals with some phase ordering issues around legalisation.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D82660/new/

https://reviews.llvm.org/D82660