[all-commits] [llvm/llvm-project] 139810: [DSE, MemorySSA] Account for ScanLimit == 0 on entry.

[Florian Hahn via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 139810449ba4c2203dbd9021b7ec4153bbfab269
      https://github.com/llvm/llvm-project/commit/139810449ba4c2203dbd9021b7ec4153bbfab269
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2020-08-17 (Mon, 17 Aug 2020)

  Changed paths:
    M llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
    M llvm/test/Transforms/DeadStoreElimination/MSSA/memoryssa-scan-limit.ll

  Log Message:
  -----------
  [DSE,MemorySSA] Account for ScanLimit == 0 on entry.

Currently the code does not account for the fact that getDomMemoryDef
can be called with ScanLimit == 0, if we reached the limit while
processing an earlier access. Also tighten the check a bit more and bump
the scan limit now that it is handled properly.

In some cases, this brings a 2x speedup in terms of compile-time.