[PATCH] D129293: [IndVars] Simplify instructions after replacing header phi with preheader value

[Nikita Popov via Phabricator via llvm-commits]

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After replacing a loop phi with the preheader value, it's usually possible to simplify some of the using instructions, so do that as part of replaceLoopPHINodesWithPreheaderValues().

Doing this as part of IndVars is valuable, because it may make GEPs in the loop have constant offsets and allow the following SROA run to succeed. (I can add a phase ordering test for this if desired.)

Depends on D129214 <https://reviews.llvm.org/D129214>.


https://reviews.llvm.org/D129293

Files:
  llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
  llvm/test/Transforms/IndVarSimplify/X86/pr35406.ll
  llvm/test/Transforms/IndVarSimplify/eliminate-backedge.ll
  llvm/test/Transforms/IndVarSimplify/eliminate-exit-no-dl.ll
  llvm/test/Transforms/IndVarSimplify/floating-point-iv.ll
  llvm/test/Transforms/IndVarSimplify/lcssa-preservation.ll
  llvm/test/Transforms/IndVarSimplify/no-iv-rewrite.ll
  llvm/test/Transforms/IndVarSimplify/pr22222.ll
  llvm/test/Transforms/IndVarSimplify/pr40454.ll
  llvm/test/Transforms/IndVarSimplify/scev-expander-preserve-lcssa.ll
  llvm/test/Transforms/IndVarSimplify/sentinel.ll
  llvm/test/Transforms/LoopDeletion/pr53969.ll

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