[all-commits] [llvm/llvm-project] 650f36: [ValueLattice] Add singlecrfromundef lattice value.

[Florian Hahn via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 650f363bd75a2c112e58a9c9efbe8ad52ba943c0
      https://github.com/llvm/llvm-project/commit/650f363bd75a2c112e58a9c9efbe8ad52ba943c0
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2020-03-15 (Sun, 15 Mar 2020)

  Changed paths:
    M llvm/include/llvm/Analysis/ValueLattice.h
    M llvm/lib/Analysis/ValueLattice.cpp
    M llvm/test/Transforms/CorrelatedValuePropagation/merge-range-and-undef.ll

  Log Message:
  -----------
  [ValueLattice] Add singlecrfromundef lattice value.

This patch adds a new singlecrfromundef lattice value, indicating a
single element constant range which was merge with undef at some point.
Merging it with another constant range results in overdefined, as we
won't be able to replace all users with a single value.

This patch uses a ConstantRange instead of a Constant*, because regular
integer constants are represented as single element constant ranges as
well and this allows the existing code working without additional
changes.

Reviewers: efriedma, nikic, reames, davide

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D75845