[PATCH] D15412: [SCEV][LAA] Add no overflow SCEV predicates and use use them to improve strided pointer detection

[silviu.baranga@arm.com via llvm-commits]

sbaranga updated this revision to Diff 42730.
sbaranga added a comment.

Renamed SCEVAddRecOverflowPredicate to SCEVWrapPredicate.

SCEVWrapPredicate now has its own flags for NUW/NSW, with
a slightly different meaning of the NUW flag from SCEV.
These flags allow us to do the transformation:

zext({a,+,b}) -> {zext(a),+,sext(b)}
sext({a,+,b}) -> {sext(a),+,sext(b)}

Updated the predicate checking code to use the Sanjoy's
method of checking:

- we extend to a large enough type to remove all possible overflows
- we check that the the final value (without any overflow) is what we would get if we would compute the expression and then do the extend.

This should also address the remaining review comments.


http://reviews.llvm.org/D15412

Files:
  include/llvm/Analysis/LoopAccessAnalysis.h
  include/llvm/Analysis/ScalarEvolution.h
  include/llvm/Analysis/ScalarEvolutionExpander.h
  lib/Analysis/LoopAccessAnalysis.cpp
  lib/Analysis/ScalarEvolution.cpp
  lib/Analysis/ScalarEvolutionExpander.cpp
  lib/Transforms/Vectorize/LoopVectorize.cpp
  test/Transforms/LoopVectorize/same-base-access.ll

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