(no title)
asb
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1 year ago
I think they should probably set LoopMicroOpBufferSize to a non-zero value even if its not microarchitecturally accurate. This value is used in LLVM to control whether partial and runtime loop unrolling are enabled (actually only for that). Although some targets override this default behaviour, AArch64 only overrides it to enable partial and runtime unrolling for in-order models. I've left a review comment https://github.com/llvm/llvm-project/pull/91022/files#r16026... and as I note there, the setting seems to have become very divorced from microarchitectural reality if you look at how and why different scheduling models set it in-tree (e.g. all the Neoverse cores, set it to 16 with a comment they just copied it from the A57).
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