[PATCH] D38486: [PPC] Implement the heuristic to choose between a X-Form VSX ld/st vs a X-Form FP ld/st.

[Tony Jiang via Phabricator via llvm-commits]

jtony created this revision.

The VSX versions have the advantage of a full 64-register target whereas the FP ones have the advantage of lower latency and higher throughput. So what we’re after is using the faster instructions in low register pressure situations and using the larger register file in high register pressure situations.

The heuristic chooses between the following 7 pairs of instructions.

PPC::LXSSPX vs PPC::LFSX
PPC::LXSDX vs PPC::LFDX
PPC::STXSSPX vs PPC::STFSX
 PPC::STXSDX vs PPC::STFDX
 PPC::LXSIWAX vs PPC::LFIWAX
PPC::LXSIWZX vs PPC::LFIWZX
PPC::STXSIWX vs  PPC::STFIWX


https://reviews.llvm.org/D38486

Files:
  lib/Target/PowerPC/P9InstrResources.td
  lib/Target/PowerPC/PPCInstrInfo.cpp
  lib/Target/PowerPC/PPCInstrInfo.td
  lib/Target/PowerPC/PPCInstrVSX.td
  test/CodeGen/PowerPC/build-vector-tests.ll
  test/CodeGen/PowerPC/pr25157-peephole.ll
  test/CodeGen/PowerPC/pr25157.ll
  test/CodeGen/PowerPC/select_const.ll
  test/CodeGen/PowerPC/vsx_scalar_ld_st.ll

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