[DAG] visitFREEZE - nodes that allow multiple frozen operands should directly freeze all operands #160914
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RKSimon
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…directly freeze all operands Avoid the ReplaceAllUsesOfValueWith approach that has caused so many problems in previous attempts at this (llvm#145939). Minor step towards llvm#149798 - eventually we're just going to use this path for all node types, but there's a large number of regressions that need addressing first (see llvm#152107). This exposed a couple of things that need to be addressed here: - we need to revisit frozen nodes once we've merged all frozen/unfrozen uses of a node. - RISCVISD::READ_VLENB is never undef/poison Many of the current regressions are due to us not doing more to avoid freeze(load) nodes - if the load is legal, its no longer going to split. I'm not certain exactly when we can split nodes - llvm#160884 tried to catch up to ValueTracking but that might still be wrong.
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Avoid the ReplaceAllUsesOfValueWith approach that has caused so many problems in previous attempts at this (#145939).
Minor step towards #149798 - eventually we're just going to use this path for all node types, but there's a large number of regressions that need addressing first (see #152107).
This exposed a couple of things that need to be addressed here:
Many of the current regressions are due to us not doing more to avoid freeze(load) nodes - if the load is legal, its no longer going to split. I'm not certain exactly when we can split nodes.