[PATCH] D72700: [DSE] Add first version of MemorySSA-backed DSE (Bottom up walk).

[Florian Hahn via Phabricator via llvm-commits]

fhahn updated this revision to Diff 241544.
fhahn added a comment.

Address comments, rework to correctly check for reads between Current and DomAccess by visiting all uses (including non-aliasing MemoryDefs) until we reach the original def.

There are some cases where we might visit more uses than necessary (e.g. if Current does not post-dominate DomAccess), but I think it is better to get a correct version and fairly complete version in and then tune for compile-time. I will also post a bunch of follow-up changes that implement various additional cases. I measured compile-time on X86 for the full patch series (covering a lot more cases) and without much tuning the worst compile-time difference is around ~1.5%.

It would be great if you could have another look.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D72700/new/

https://reviews.llvm.org/D72700

Files:
  llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
  llvm/test/Transforms/DeadStoreElimination/MSSA/PartialStore.ll
  llvm/test/Transforms/DeadStoreElimination/MSSA/fence-todo.ll
  llvm/test/Transforms/DeadStoreElimination/MSSA/fence.ll
  llvm/test/Transforms/DeadStoreElimination/MSSA/memoryssa-scan-limit.ll
  llvm/test/Transforms/DeadStoreElimination/MSSA/memset-and-memcpy.ll
  llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-captures.ll
  llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-exceptions.ll
  llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-loops.ll
  llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-partial.ll
  llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-simple.ll
  llvm/test/Transforms/DeadStoreElimination/MSSA/simple.ll

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