[PATCH] D93617: [DemandedBits] Add a whitelist when computing demanded bits of Trunc Instruction

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When computing demanded bits for Instruction::Trunc's operands, for
some cases, such as shift, remainder and selection, we cannot blindly
say these operands have the same live bits as the trunc instruction itself.
To be conservative, we can add a whitelist of instructions that are
always truncation friendly.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D93617

Files:
  llvm/lib/Analysis/DemandedBits.cpp
  llvm/test/Transforms/LoopVectorize/avoid-truncate-icmp-operands.ll
  llvm/test/Transforms/LoopVectorize/avoid-truncate-remainder-operands.ll
  llvm/test/Transforms/LoopVectorize/avoid-truncate-shift-operands.ll

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