[PATCH] D60946: [ConstantRange] Add saturating add/sub methods

[Nikita Popov via Phabricator via llvm-commits]

nikic created this revision.
nikic added a reviewer: lebedev.ri.
Herald added subscribers: llvm-commits, hiraditya.
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Add support for uadd_sat and friends to ConstantRange, so we can handle uadd.sat and friends in LVI. The implementation is forwarding to the corresponding APInt methods with appropriate bounds.

One thing worth pointing out here is that the handling of wrapping ranges is not maximally accurate. A simple example is that adding 0 to a wrapped range will return a full range, rather than the original wrapping range. The tests also only check that the non-wrapping envelope is correct and minimal.


Repository:
  rL LLVM

https://reviews.llvm.org/D60946

Files:
  llvm/include/llvm/IR/ConstantRange.h
  llvm/lib/IR/ConstantRange.cpp
  llvm/unittests/IR/ConstantRangeTest.cpp

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