compiler: Restore lifting cache in SROA perform_lifting!#61020
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compiler: Restore lifting cache in SROA perform_lifting!#61020
perform_lifting!#61020Conversation
When multiple `getfield` calls access the same field of the same phi node, the SROA pass creates duplicate lifted phi nodes. A lifting cache was originally intended to prevent this (#43927), but had been broken and later removed in PR #51014. This restores a working lifting cache. The cache key includes both the field index and `stmt_val` (the original `getfield` argument) to distinguish liftings through the same phi node with different type constraints (e.g. direct access vs access through a PiNode that narrows the type). Without `stmt_val` in the key, a narrower type-constrained lifting could be incorrectly reused for a wider constraint, producing phi nodes with missing edges. Separate caches are used for `getfield` and `isdefined` liftings since they produce phi nodes with different value types. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Does this have any performance improvements? |
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Since the number of generated |
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Would be nice to see some benchmarks to ensure this is positive/neutral. |
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@nanosoldier |
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When multiple
getfieldcalls access the same field of the same phi node, the SROA pass creates duplicate lifted phi nodes. A lifting cache was originally intended to prevent this (#43927), but had been broken and later removed in PR #51014.This restores a working lifting cache. The cache key includes both the field index and
stmt_val(the originalgetfieldargument) to distinguish liftings through the same phi node with different type constraints (e.g. direct access vs access through a PiNode that narrows the type). Withoutstmt_valin the key, a narrower type-constrained lifting could be incorrectly reused for a wider constraint, producing phi nodes with missing edges. Separate caches are used forgetfieldandisdefinedliftings since they produce phi nodes with different value types.