[RISCV][RFC/WIP] Enable load clustering in SelectionDAG scheduler #74600
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asb
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…ustering Reordering based on the sort order of the MemOpInfo array was disabled in <https://reviews.llvm.org/D72706>. However, it's not clear this is desirable for al targets. It also makes it more difficult to compare the incremental benefit of enabling load clustering in the selectiondag scheduler as well was the machinescheduler, as the sdag scheduler does seem to allow this reordering. This patch adds a parameter that can control the behaviour on a per-target basis.
Split out from llvm#73789. Clusters if the operations are within a cache line of each other (as AMDGPU does in shouldScheduleLoadsNear). X86 does something similar, but does `((Offset2 - Offset1) / 8 > 64)`. I'm not sure if that's intentionally set to 512 bytes or if the division is in error. Adopts the suggestion from @wangpc-pp to query the cache line size and use it if available.
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Rebased on top of #73789 to make this easier to analyse. |
wangpc-pp
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dtcxzyw,
kito-cheng,
lukel97,
michaelmaitland,
preames,
topperc and
wangpc-pp
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Reverse ping! |
Sorry I commented the wrong PR. |
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Builds on top of #73789.
Many changes are just noise (slightly different register choice), but there do seem to be some cases where additional clustering is taking place that I want to investigate further.
If we can get by with clustering in just the MachineScheduler, that would be preferable.
Posting at this point primarily for others to reference, not ready for direct review.