[PATCH] D144535: [RISCV] Enable machine copy propagation for copy-like instructions

[Wang Pengcheng via Phabricator via llvm-commits]

pcwang-thead added a comment.

In D144535#4166316 <https://reviews.llvm.org/D144535#4166316>, @craig.topper wrote:

> Is this expensive compile time wise? Why did AArch64 make it -O3 only?

I haven't evaluated the impact on compile time, there is about 0.16% increase from AArch64's result. And I think it won't be too expensive since there are already two runs of `Machine Copy Propagation Pass` in the pipeline.
The reason why AArch64 made it -O3 only is because the gains is not very large compared with the increase of compile time, may we be more aggressive since the gains seem to be larger for RISCV?


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