[PATCH] D134360: [ARM] Enable and/cmp0 folding

[Momchil Velikov via Phabricator via llvm-commits]

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The `CodeGenPrepare` pass can sink bitwise `and` used by compare to
zero into the basic blocks where the users are. This operation is
guarded by lowering hook, which is disabled for ARM.  In the ARM
architecture versions from v7-M up these two operations can be folded
into `tst rN, #imm` instruction. Sinking of `and` can also enable
the cmov-to-bfi DAG combiner.

This patch fixes some benchmark regressions caused
by https://reviews.llvm.org/D129370 as well scoring slightly better overall.


https://reviews.llvm.org/D134360

Files:
  llvm/lib/Target/ARM/ARMISelLowering.cpp
  llvm/lib/Target/ARM/ARMISelLowering.h
  llvm/test/CodeGen/ARM/and-cmp0-sink.ll
  llvm/test/CodeGen/Thumb2/mve-float16regloops.ll
  llvm/test/CodeGen/Thumb2/mve-float32regloops.ll

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