[PATCH] D45366: Support generic expansion of ordered vector reduction (PR36732)

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon created this revision.
RKSimon added reviewers: aemerson, gnzlbg, chandlerc, hfinkel, rengolin, mkuper, ABataev, spatel.

Without the fast math flags, the llvm.experimental.vector.reduce.fadd/fmul intrinsic expansions must be expanded in order.

This patch scalarizes the reduction, applying the accumulator at the start of the sequence: ((((Acc + Scl[0]) + Scl[1]) + Scl[2]) + ) ... + Scl[NumElts-1]


Repository:
  rL LLVM

https://reviews.llvm.org/D45366

Files:
  include/llvm/Transforms/Utils/LoopUtils.h
  lib/CodeGen/ExpandReductions.cpp
  lib/Transforms/Utils/LoopUtils.cpp
  test/CodeGen/Generic/expand-experimental-reductions.ll

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