[all-commits] [llvm/llvm-project] cf9ee4: [DSE] Lift post-dominance for objs not accessible ...

[Florian Hahn via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: cf9ee49b4d7f2e1341b84f941ad55cce1b16722d
      https://github.com/llvm/llvm-project/commit/cf9ee49b4d7f2e1341b84f941ad55cce1b16722d
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2020-04-15 (Wed, 15 Apr 2020)

  Changed paths:
    M llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
    M llvm/test/Transforms/DeadStoreElimination/MSSA/memset-unknown-sizes.ll
    M llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-malloc-free.ll
    M llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-memintrinsics.ll
    M llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-multipath.ll
    M llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-simple.ll

  Log Message:
  -----------
  [DSE] Lift post-dominance for objs not accessible in caller.

We can eliminate MemoryDefs of objects not accessible after the function
returns (e.g. alloca), if there are no reads between the MemoryDef and
any function exits. We can stop traversing paths that completely
overwrite the memory location of the MemoryDef.

This patch was split off D73763.

Reviewers: dmgreen, bryant, asbirlea, Tyker, efriedma, george.burgess.iv

Reviewed By: asbirlea, george.burgess.iv

Differential Revision: https://reviews.llvm.org/D77736