[PATCH] D75845: [ValueLattice] Add singlecrfromundef lattice value.

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
fhahn added reviewers: efriedma, nikic, reames, davide.
Herald added a subscriber: hiraditya.
Herald added a project: LLVM.

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.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D75845

Files:
  llvm/include/llvm/Analysis/ValueLattice.h
  llvm/lib/Analysis/ValueLattice.cpp
  llvm/test/Transforms/CorrelatedValuePropagation/merge-range-and-undef.ll
  llvm/test/Transforms/SCCP/range-and-ip.ll

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