Do not hoist constants if they will not be CSEed #64039
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Tagging subscribers to this area: @JulieLeeMSFT Issue DetailsWe can sometimes see cases where hoisting decides to hoist a constant on platforms where CSEing for them is disabled, leading to wasted work. Fix this by folding the relevant checks into Diffs are RA noise (the pre-header blocks are no longer being created) plus unblocked new hoists of actually profitable trees.
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We can sometimes see cases where hoisting decides to hoist a constant on platforms where CSEing for them is disabled, leading to wasted work. Fix this by folding the relevant checks into "optIsCSEcandidate" that the hoisting code uses. Diffs are RA noise (the pre-header blocks are no longer being created) plus unblocked new hoists of actually profitable trees.
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Due to the regressions, I do not plan to pursue this further. |
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We can sometimes see cases where hoisting decides to hoist a constant on platforms where CSEing for them is disabled, leading to wasted work.
Fix this by folding the relevant checks into
optIsCSEcandidatethat the hoisting code uses.Diffs are mixed... it seems we sometimes get better allocation and better flow with the pre-header, even if we don't get anything out of the hoist itself.