[PATCH] D132828: Add new optimization pass of Tree Height Reduction

Tue Aug 30 04:38:15 PDT 2022

kawashima-fj added a comment.

In D132828#3757715 <https://reviews.llvm.org/D132828#3757715>, @fhahn wrote:

> Have you considered implementing this as MachineFunctionPass instead of an LLVM IR pass?

No. Just because the original patch D67383 <https://reviews.llvm.org/D67383> was implemented as an LLVM IR pass and I'm not familier with MachineFunctionPass.

> Doing the transformation on MachineIR would allow for more precise cost estimates, including more accurate information about register usage, selected instructions and processor resource usage. `MachineCombiner.cpp` might be interesting example to look at for similar (although simpler) transformations with relatively accurate uarch-driven cost-modeling.

Thanks for your advice. It seems to have an advantage but porting to MachineFunctionPass may take time for me. I'll see about it.

> It might be interesting to also run SPECrate instead of just running speed with one thread?

OK. I'll do.

Repository:
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https://reviews.llvm.org/D132828