[PATCH] D55373: [LSR] Generate formulae to enable more post-incs

[Sam Parker via Phabricator via llvm-commits]

samparker updated this revision to Diff 181251.
samparker added a comment.

- Added a command line option to 'EnableBackedgePostIncs'.
- Added a command line option to enable narrowing the search space by collapsing unrolled code.
- The TTI hook now accepts the loop so that the target can make a more informed decision on when it 'shouldFavorBackedgePostIncs'.
- LSRInstance contains a boolean 'FavorBackedgePostInc' which is equal to EnableBackedgePostIncs && shouldFavorBackedgePostIncs.
- When FavorBackedgePostIncs: > Generate the new constant offsets. > In RateRegister, the LoopCost is now set to 0 if the step recurrence is equal to the base offset of the parent formula. > IsProfitableChain has a higher limit > The last expression in the IVChain is not added to IVIncSet so it's a target for optimising.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D55373/new/

https://reviews.llvm.org/D55373

Files:
  include/llvm/Analysis/TargetTransformInfo.h
  include/llvm/Analysis/TargetTransformInfoImpl.h
  lib/Analysis/TargetTransformInfo.cpp
  lib/Target/ARM/ARMTargetTransformInfo.h
  lib/Transforms/Scalar/LoopStrengthReduce.cpp
  test/CodeGen/ARM/dsp-post-incs.ll
  test/CodeGen/ARM/loop-align-cortex-m.ll
  test/CodeGen/ARM/loop-post-incs.ll
  test/Transforms/LoopStrengthReduce/ARM/complexity.ll

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