[PATCH] D32663: [SCEV] createAddRecFromPHI: Optimize for the most common case.

[Michael Zolotukhin via Phabricator via llvm-commits]

mzolotukhin created this revision.

The existing implementation creates a symbolic SCEV expression every
time we analyze a phi node and then has to remove it, when the analysis
is finished. This is very expensive, and in most of the cases it's also
unnecessary. According to the data I collected, ~60-70% of analyzed phi
nodes (measured on SPEC) have the following form:

  PN = phi(Start, OP(Self, Constant))

Handling such cases separately significantly speeds this up.


https://reviews.llvm.org/D32663

Files:
  include/llvm/Analysis/ScalarEvolution.h
  lib/Analysis/ScalarEvolution.cpp

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