34a1888bea
Introduce a lightweight, targeted dead-op eliminator that complements the existing liveness-based runRegionDCE. The algorithm is O(ops): step 1 walks each op in reverse program order, erases it outright if trivially dead, or recurses into nested regions when recursive cleanup is enabled; step 2 drives a per-region worklist that only ever holds ops already verified dead, propagating new deadness by dropping each operand's use before re-checking isOpTriviallyDead on the defining op. Unlike runRegionDCE, this does not touch dead block arguments, dead successor operands, or dead use-def cycles. Use runRegionDCE when those are required. An includeNestedRegions parameter lets callers restrict simplification to the top-level region. Switch transform.apply_dce to use the new helper, dropping a custom worklist that had subtle invariants: SetVector dedup, linear search on every erase, and pre-order walk with skip. In general it is bad practice to implement complex custom logic in Transform ops apply methods: this should be an adaptor exposing MLIR transformations to the transform dialect; non-trivial logic deserves a public API for reusability and proper layering. Introduce a TrivialDeadCodeEliminationPass exposed as -trivial-dce. The pass removes trivially dead operations and, when removeBlocks is enabled, unreachable blocks. It does not run liveness analysis and does not remove dead use-def cycles. Add recursive and removeBlocks options, both defaulting to true, to control whether nested regions are visited and whether unreachable blocks are erased. Assisted-by: Claude Code
1.2 KiB
1.2 KiB