[PATCH] D61754: [PowerPC] Custom lower known CR bit spills

[Lei Huang via Phabricator via llvm-commits]

lei created this revision.
lei added reviewers: power-llvm-team, hfinkel, echristo, nemanjai, stefanp.
Herald added subscribers: jsji, kbarton, hiraditya, qcolombet.
Herald added a project: LLVM.

For known CRBit spills, CRSET/CRUNSET, it is more efficient to just load and spill the known value instead of extracting the bit.

eg. This sequence is currently used to spill a CRUNSET:

  crclr   4*cr5+lt
  mfocrf  r3,4
  rlwinm  r3,r3,20,0,0
  stw     r3,132(r1)

This patch custom lower it to:

  li  r3,0
  stw r3,132(r1)


Repository:
  rL LLVM

https://reviews.llvm.org/D61754

Files:
  llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp
  llvm/test/CodeGen/PowerPC/knowCRBitSpill.ll

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