[PATCH] D86087: [ARM] Use mov operand if the mov cannot be moved while tail predicating

[Sam Tebbs via Phabricator via llvm-commits]

samtebbs created this revision.
samtebbs added reviewers: samparker, SjoerdMeijer, dmgreen, simon_tatham, olista01, t.p.northover.
Herald added subscribers: llvm-commits, danielkiss, hiraditya, kristof.beyls.
Herald added a project: LLVM.
samtebbs requested review of this revision.

There are some cases where the instruction that sets up the iteration
count for a tail predicated loop cannot be moved before the dlstp,
stopping tail predication entirely. This patch checks if the mov operand
can be used and if so, uses that instead.

Not for review: I am not sure if my approach to overriding getCount()
and adding TPNumElements is
the best possible approach, please give feedback if you can think of a
better one.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D86087

Files:
  llvm/lib/Target/ARM/ARMLowOverheadLoops.cpp
  llvm/test/CodeGen/Thumb2/LowOverheadLoops/mov-operand.ll

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