[PATCH] D58650: Add support for computing "zext of value" in KnownBits. NFCI

[Bjorn Pettersson via Phabricator via llvm-commits]

bjope created this revision.
bjope added a reviewer: craig.topper.
Herald added subscribers: jdoerfert, hiraditya, javed.absar.
Herald added a project: LLVM.

The description of KnownBits::zext() and
KnownBits::zextOrTrunc() has confusingly been telling
that the operation is equivalent to zero extending the
value we're tracking. That has not been true, instead
the user has been forced to explicitly set the extended
bits as known zero afterwards.

This patch adds a second argument to KnownBits::zext()
and KnownBits::zextOrTrunc() to control if the extended
bits should be considered as known zero or as unknown.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D58650

Files:
  llvm/include/llvm/Support/KnownBits.h
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
  llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
  llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
  llvm/lib/Target/ARM/ARMISelLowering.cpp
  llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp

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