[PATCH] D118642: [IVDescriptor] Find original 'Previous' for first-order recurrences.

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
fhahn added reviewers: Ayal, spatel.
Herald added a subscriber: hiraditya.
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This patch extends first-order recurrence handling to support cases
where we already sunk an instruction for a different recurrence, but
LastPrev comes before Previous.

To handle those cases correctly, we need to find the earliest entry for
the sink-after chain, because this is references the Previous from the
original recurrence. This is needed to ensure we use the correct
instruction as sink point.

Depends on D118558 <https://reviews.llvm.org/D118558>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D118642

Files:
  llvm/lib/Analysis/IVDescriptors.cpp
  llvm/test/Transforms/LoopVectorize/first-order-recurrence-complex.ll

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