[PATCH] D105207: [debuginfo][lsr] SCEV-based salvaging for LoopStrengthReduction

[Chris Jackson via Phabricator via llvm-commits]

chrisjackson updated this revision to Diff 360392.
chrisjackson added a comment.

This change improves the selection of the IV, by using the PHi node inserted by ScalarEvolutionExpander, which is typically called "%lsr.iv" or similar. The decision to do this resulted from analysis of a build of clang3.4. While the previous method of using Loop->getInductionVariable()/getCanonicalInductionVariable() provided correct IVs, these tended to be relatively short lived and were often optimised away by subsequent passes. Some care is needed in using this PHi as ScalarEvolutionExpander holds Maps of handles to the new PHi node.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D105207/new/

https://reviews.llvm.org/D105207

Files:
  llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
  llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
  llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
  llvm/test/Transforms/LoopStrengthReduce/dbg-preserve-0.ll
  llvm/test/Transforms/LoopStrengthReduce/dbg-preserve-2.ll
  llvm/test/Transforms/LoopStrengthReduce/debuginfo-scev-variadic-value-0.ll
  llvm/test/Transforms/LoopStrengthReduce/debuginfo-scev-variadic-value-2.ll
  llvm/test/Transforms/LoopStrengthReduce/debuginfo-scev-variadic-value-3.ll
  llvm/test/Transforms/LoopStrengthReduce/debuginfo-scev-variadic-value-4.ll

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