[PATCH] D57954: [ARM] LoadStoreOptimizer: reoder limit

Sjoerd Meijer via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Mon Feb 11 01:27:13 PST 2019

SjoerdMeijer added a comment.

Thanks Eli, also for your thoughts on this:

> Ultimately, the whole design here is sort of flaky: the scheduling code here isn't aware of register pressure, and the register allocator isn't aware of the possibility of generating ldm/stm, so the end result is very unreliable.

Unreliable results is exactly what I was seeing, and that's why I started studying first what exactly this loadstoreoptimiser is doing.

> I'm not sure what the right solution is, but tweaking the scheduling heuristics isn't going to help much.

Agreed. Also sounds a little bit like a can of worms. I need to first investigate more where exactly my problems are caused, depending on that I might be looking more into this. Making this rescheduling register pressure aware might be a good step in the right direction? But as you also said, not the complete answer...



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