[PATCH] D29777: [Reassociate] Convert shl by constant into multiply during tree linearization.

[Chad Rosier via Phabricator via llvm-commits]

mcrosier created this revision.

If we're linearizing a multiply expression, convert any left shift by a constant into a multiply, so they can be reassociated.  We already do a similar optimization where we convert a negation into a multiply by -1.

See the test case for an example of what this hits.

Also, this addresses PR30256, which is a 4.0 release blocker.

Chad


https://reviews.llvm.org/D29777

Files:
  lib/Transforms/Scalar/Reassociate.cpp
  test/Transforms/Reassociate/basictest.ll

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