[PATCH] D12345: [Reassociate]: Add intermediate subtract instructions created while negating to be redone later for more reassociate opportunities

[Aditya Nandakumar via llvm-commits]

aditya_nandakumar created this revision.
aditya_nandakumar added reviewers: llvm-commits, majnemer.
aditya_nandakumar set the repository for this revision to rL LLVM.

This is tackling the same issue as in http://reviews.llvm.org/D12096. Reassociate is currently unable to simplify expressions such as (2 * b - (5 * a - 3 * b))
As David Majnemer pointed out, running reassociate twice did simplify the same.
Redoing the intermediate instructions created while breaking up a subtract (Negating) can open up more opportunities for reassociation and in this case simplifies the above expression to 5 * (b - a)


Repository:
  rL LLVM

http://reviews.llvm.org/D12345

Files:
  lib/Transforms/Scalar/Reassociate.cpp
  test/Transforms/Reassociate/fast-ReassociateVector.ll
  test/Transforms/Reassociate/fast-basictest.ll
  test/Transforms/Reassociate/fast-fp-commute.ll
  test/Transforms/Reassociate/fast-multistep.ll
  test/Transforms/Reassociate/multistep.ll
  test/Transforms/Reassociate/reassoc-intermediate-fnegs.ll
  test/Transforms/Reassociate/secondary.ll
  test/Transforms/Reassociate/xor_reassoc.ll

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