[PATCH] D140542: [MachineCombiner] Support local strategy for traces

[Gerolf Hoflehner via Phabricator via llvm-commits]

Gerolf added a comment.

Given that this is RISC-V and under a flag, this LGTM. I would like to see stats on the FMA's plus the changes to the cycle counts on the critical path, and see how the data correlate to your measured run-time performance numbers.  And ditto for the current heuristic. This might also help understand the wide variety of results in your SPEC data. Your numbers look all over the place. Also, you can probably push your idea more by allowing a parameterized schedule window (eg 10 or 15 instructions) rather than a basic block. This would allow you to catch cases across blocks and should work better for large blocks. Finally, I would not be surprised - just learning from your insights here and guessing - that various in-order processors  show best performance for different window sizes. All this is just food for thought for additional/future work though. Cheers!


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https://reviews.llvm.org/D140542