[PATCH] D58364: [PowerPC] exploit P9 new instruction maddld

[ChenZheng via Phabricator via llvm-commits]

shchenz created this revision.
shchenz added reviewers: jsji, steven.zhang, nemanjai, hfinkel, stefanp.
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  typedef long long T;
  T foo(T a, T b)
  {
      return a*b+a;
  }

on Power8 we get:

  0000000000000000 <foo>:
     0:   f0 ff 61 f8     std     r3,-16(r1)
     4:   e8 ff 81 f8     std     r4,-24(r1)
     8:   f0 ff 61 e8     ld      r3,-16(r1)
     c:   e8 ff 81 e8     ld      r4,-24(r1)
    10:   d2 21 63 7c     mulld   r3,r3,r4
    14:   f0 ff 81 e8     ld      r4,-16(r1)
    18:   14 22 63 7c     add     r3,r3,r4
    1c:   20 00 80 4e     blr

On power9 we can fold `add` + `mulld` to `maddld`


https://reviews.llvm.org/D58364

Files:
  llvm/lib/Target/PowerPC/P9InstrResources.td
  llvm/lib/Target/PowerPC/PPCInstr64Bit.td
  llvm/test/CodeGen/PowerPC/maddld.ll

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