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List:       llvm-commits
Subject:    [PATCH] D139790: [VPlan] Consider all recipes in replicate blocks as sink candidates.
From:       Ayal Zaks via Phabricator via llvm-commits <llvm-commits () lists ! llvm ! org>
Date:       2022-12-31 23:12:02
Message-ID: iUdZORnLRpCAPX81jZWCyg () geopod-ismtpd-3-0
[Download RAW message or body]

Ayal added inline comments.


================
Comment at: llvm/test/Transforms/LoopVectorize/vplan-sink-scalars-and-merge.ll:38
+; CHECK-NEXT:     vp<[[STEPS:%.+]]> = SCALAR-STEPS vp<[[CAN_IV]]>, ir<1>
 ; CHECK-NEXT:     REPLICATE ir<%gep.b> = getelementptr ir<@b>, ir<0>, vp<[[STEPS]]>
 ; CHECK-NEXT:     REPLICATE ir<%lv.b> = load ir<%gep.b>
----------------
fhahn wrote:
> Ayal wrote:
> > fhahn wrote:
> > > Ayal wrote:
> > > > The iterative scan up use-def chains stops at GEPs?
> > > At the moment only replicate & scalar-steps recipe can be sunk.
> > Right, but curious why the use-def scan failed to sink vp<[[STEPS]]> used by sunk \
> > REPLICATEs of GEPS while scanning all recipes in replicate block succeeded. Is \
> > this due to the now iterative nature of applying sinkScalarOperands()?
> Ah right! I had another look and the issue was that operands of instructions that \
> do not need sinking aren't added to the worklist. Should be fixed by aa2414729ebb
Hmm, that may have been intentional - to prevent revisiting same candidates multiple \
times during a scan up use-def chains. But that assumed operands that do not need \
sinking were sunk in the "current" scan - when activated only once, starting with a \
single seed per replicate region. Whereas now the first scan starts with a single \
seed but repeated iterative scans should indeed consider all / more-than-one?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D139790/new/

https://reviews.llvm.org/D139790

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