[all-commits] [llvm/llvm-project] bb024c: [DSE, MemorySSA] Remove short-cut to check if all p...

[Florian Hahn via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: bb024c3c4e03458ae30721cb5e9cf9832dba56d7
      https://github.com/llvm/llvm-project/commit/bb024c3c4e03458ae30721cb5e9cf9832dba56d7
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2020-08-27 (Thu, 27 Aug 2020)

  Changed paths:
    M llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
    M llvm/test/Transforms/DeadStoreElimination/MSSA/pr47285-not-overwritten-on-all-exit-paths.ll

  Log Message:
  -----------
  [DSE,MemorySSA] Remove short-cut to check if all paths are covered.

The post-order number early continue does not work in some cases, e.g.
if a path from EarlierAccess to an exit includes a node that dominates
EarlierAccess in a cycle.

The short-cut only has very minor impact on compile-time, so it seems
straight-forward to remove it for now:

http://llvm-compile-time-tracker.com/compare.php?from=062412e79fcfedf2cf004433e42036b0333e3f83&to=d7386016a77ce1387bdbbf360f1de157faea9d31&stat=instructions

Fixes PR47285.