[PATCH] D142424: DAG: Relax foldBitcastedFPLogic conditions

[Matt Arsenault via Phabricator via llvm-commits]

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Requiring a bitcast to exist was unhelpful. The most basic cases
are always going to be a CopyFromReg or load, so they would need
a new cast inserted.

We should also get rid of this hasBitPreservingFPLogic hook. fabs/fneg
are bitpreserving or incorrectly implemented, so this should just be a
regular legality check.


https://reviews.llvm.org/D142424

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  llvm/test/CodeGen/AMDGPU/fneg-modifier-casting.ll
  llvm/test/CodeGen/AMDGPU/fneg.ll

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