[PATCH] D90371: [DSE] Improve partial overlap detection

[Evgeniy via Phabricator via llvm-commits]

ebrevnov created this revision.
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Currently isOverwrite returns OW_MaybePartial even for accesss known not to overlap. This is not a big problem for legacy implementation (since isPartialOverwrite follows isOverwrite and clarifies the result). Contrary SSA based version does a lot of work to later find out that accesses doesn't overlap. Besides negative impact on compile time we quickly reach MemorySSAPartialStoreLimit and miss optimization opportunities.

Note: In fact, I think it would be cleaner implementation if isOverwrite returned fully clarified result in the first place whithout need to call isPartialOverwrite. This can be done as a follow up. What do you think?


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D90371

Files:
  llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
  llvm/test/Transforms/DeadStoreElimination/MSSA/combined-partial-overwrites.ll
  llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-overlap.ll

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