[all-commits] [llvm/llvm-project] 1cfa98: [SLP] Optionally preserve MemorySSA

[Philip Reames via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1cfa986d68e2f04854ef30c432b8aa28e13a9706
      https://github.com/llvm/llvm-project/commit/1cfa986d68e2f04854ef30c432b8aa28e13a9706
  Author: Philip Reames <listmail at philipreames.com>
  Date:   2022-03-15 (Tue, 15 Mar 2022)

  Changed paths:
    M llvm/include/llvm/Transforms/Vectorize/SLPVectorizer.h
    M llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

  Log Message:
  -----------
  [SLP] Optionally preserve MemorySSA

This initial patch adds code to preserve MemorySSA through a run of SLP vectorizer. The eventual plan is to use MemorySSA to accelerate SLP's memory dependence checking, but we're a ways from that.  In particular, this patch is correct, but really slow. It's being landed so that we can work incrementally in tree, not because it's expected to be useful to anyone just yet.

The broader effort is being tracked in https://github.com/llvm/llvm-project/issues/54256.  Its worth noting expicitly that this may not work out, and if not, we will be reverting all of the MSSA support in SLP at some point in the next few weeks.

Differential Revision: https://reviews.llvm.org/D117926