[PATCH] D111530: [TargetLowering] Optimize expanded SRL/SHL fed into SETCC ne/eq 0

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


================
Comment at: llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp:4153
       // all bits clear: (X | (Y<<32)) ==  0 --> (X | Y) ==  0
       // all bits set:   (X | (Y<<32)) == -1 --> (X & Y) == -1
       bool CmpZero = N1C->getAPIntValue().isZero();
----------------
This is doing something pretty similar, its more limited to the 'concat' pattern but handles the -1 'allbits' case as well.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D111530/new/

https://reviews.llvm.org/D111530