[PATCH] D43451: [ARM] Mark -1 as cheap in xor's for thumb1

[Dave Green via Phabricator via llvm-commits]

dmgreen created this revision.
dmgreen added reviewers: eli.friedman, spatel, samparker, john.brawn.
Herald added subscribers: kristof.beyls, javed.absar.

We can always convert xor %a, -1 into MVN, even in thumb 1 where the -1
would not otherwise be considered a cheap constant. This prevents the
-1's from being pulled out into constants and potentially hoisted.

The loop_2 tests are the only ones that change here.


https://reviews.llvm.org/D43451

Files:
  lib/Target/ARM/ARMTargetTransformInfo.cpp
  test/CodeGen/Thumb/mvn.ll

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