[PATCH] D117926: [SLP] Optionally preserve MemorySSA

Philip Reames via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Fri Jan 21 13:29:59 PST 2022


reames created this revision.
reames added reviewers: ABataev, fhahn, nikic, asbirlea, aeubanks.
Herald added subscribers: george.burgess.iv, bollu, hiraditya, mcrosier.
reames requested review of this revision.
Herald added a project: LLVM.

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.  I want to land this so that the slightly more delicate compile time optimization patches are individually reviewable.

Note that I'm intentionally not preserving MemorySSA even if available.  The current update code is *so slow* that it's faster to simply rebuild after SLP is done.

Suggestions on how to make this reasonable fast are welcomed, but I'd strongly prefer to work incrementally and address compile time concerns in following patches.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D117926

Files:
  llvm/include/llvm/Transforms/Vectorize/SLPVectorizer.h
  llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

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