[PATCH] D60522: [KnownBits] Add computeForAddCarry()

[Nikita Popov via Phabricator via llvm-commits]

nikic created this revision.
nikic added reviewers: lebedev.ri, spatel, RKSimon, bjope.
Herald added subscribers: llvm-commits, kristina, hiraditya, mgorny.
Herald added a project: LLVM.

This is for D60460 <https://reviews.llvm.org/D60460>. computeForAddSub() essentially already supports carries because it has to deal with subtractions. This revision extracts a lower-level computeForAddCarry() function, which allows computing the known bits for add (carry known zero), sub (carry known one) and addcarry (carry unknown).

As we don't seem to have any yet, I've added a unit test file for KnownBits and an exhaustive test for the computeForAddCarry functionality.


Repository:
  rL LLVM

https://reviews.llvm.org/D60522

Files:
  llvm/include/llvm/Support/KnownBits.h
  llvm/lib/Support/KnownBits.cpp
  llvm/unittests/Support/CMakeLists.txt
  llvm/unittests/Support/KnownBitsTest.cpp

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