[PATCH] D59193: [ConstantRange] Add overflow check helpers

[Nikita Popov via Phabricator via llvm-commits]

nikic created this revision.
nikic added reviewers: spatel, craig.topper.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.

Add functions to ConstantRange that determine whether the unsigned/signed addition/subtraction of two ConstantRanges may/always/never overflows. This will allow checking overflow conditions based on known constant ranges in addition to known bits (with D59071 <https://reviews.llvm.org/D59071> in mind).

I'm implementing these methods on ConstantRange to allow them to be unit tested independently of any ValueTracking machinery.

The OverflowResult enum is redeclared on ConstantRange, because I wanted to avoid a dependency in either direction between ValueTracking.h and ConstantRange.h.


Repository:
  rL LLVM

https://reviews.llvm.org/D59193

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

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