[PATCH] D82709: [MachineLICM] [PowerPC] hoisting rematerializable cheap instructions based on register pressure.

[ChenZheng via Phabricator via llvm-commits]

shchenz added a comment.
Herald added a subscriber: danielkiss.

Hi @qcolombet, for the log in https://reviews.llvm.org/P8231, you can just see the RA result at the end. Ideally, we can remat registers %267 ~ %309(2132B - 2216B) to their use, and then we can free some physical registers and assign the physical registers to %166 ~ %190 to save the spills.

I checked the log, when we do spill for %0, LIS instruction, for example %157, is assigned with physical register, but seems RA will only remat instructions when the remat instructions are going to be spilled?

We should add logic inside `selectOrSplitImpl` like: when we try to spill a non-remat instruction, we should check if there is any remat instruction assigned with a physical register. If there is one, we should first remat the remat instruction and assign the physical register to the spilled one? Is this a reasonable change in RA?

Thanks for your comments in advance.


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https://reviews.llvm.org/D82709