[PATCH] D55630: [ARM] Complete the Thumb1 shift+and->shift+shift transforms.

[Eli Friedman via Phabricator via llvm-commits]

efriedma created this revision.
efriedma added reviewers: SjoerdMeijer, samparker, spatel.
Herald added subscribers: kristof.beyls, javed.absar.

This saves materializing the immediate.  The additional forms are less common, but they're still relevant in some situations.

I had to add a new target hook to prevent DAGCombine from reversing the transform. That isn't the only possible way to solve the conflict, but it seems straightforward enough.


Repository:
  rL LLVM

https://reviews.llvm.org/D55630

Files:
  include/llvm/CodeGen/TargetLowering.h
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  lib/Target/ARM/ARMISelLowering.cpp
  lib/Target/ARM/ARMISelLowering.h
  test/CodeGen/Thumb/shift-and.ll

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