[PATCH] D68954: [IndVars] Convert (fcmp (sitofp x), sitofp(int-con)) to equivelent icmp where possible

[Philip Reames via Phabricator via llvm-commits]

reames created this revision.
reames added reviewers: nikic, ebrevnov, scanon.
Herald added subscribers: bollu, mcrosier.
Herald added a project: LLVM.

If we have a known trip count for a loop - either because of an existing integer exit which gives us a useful max or say, https://reviews.llvm.org/D68844 - then we can eliminate fcmps of integer IVs.

The eventual goal of this is to combine w/the patch mentioned to let us generalize handleFloatingPointIV for multi-exit loops, but it's also a useful standalone transform of it's own right.  The concept of a precise integer sub-range of floating point types doesn't appear to be cleanly expressed in LLVM, so introducing the concept, and then factoring it into a common place is a nice side benefit.


Repository:
  rL LLVM

https://reviews.llvm.org/D68954

Files:
  lib/Transforms/Scalar/IndVarSimplify.cpp
  test/Transforms/IndVarSimplify/floating-point-iv.ll

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