[PATCH] D70651: [Power8] Add the MacroFusion support for Power8

[qshanz via Phabricator via llvm-commits]

steven.zhang created this revision.
steven.zhang added reviewers: nemanjai, jsji, hfinkel, kbarton, PowerPC.
Herald added subscribers: wuzish, hiraditya, mgorny.
Herald added a project: LLVM.

Power8 User's Manual Section 10.1.12 Instruction Fusion

  There are two fuse types:
    {addi} followed by one of these {lxvd2x, lxvw4x, lxvdsx, lvebx, lvehx, lvewx, lvx, lxsdx}
    Requirements:
      addi(rt) = lxvd2x(rb)
      lxvd2x(ra) cannot be ‘0’
    Result:
      addi - no changelxvd2x gets the immed field from addi., rb is not used.This effectively provides a d-form version for the vector loads.The dependency between the two operations is removed.
    {addis) followed by one of these {ld, lbz, lhz, lwz}
    Requirements:
      addis(rt) = ld(ra) = ld(rt) - (cannot be ‘0’)
      addis(SI) first 12 bits must be all 0’s or all 1’sTA = 0 for this fusion to occur and if SI = 111111111110000 and the msb of the d/ds field of the load equals ‘1’, then fusion does not occur.
    Result:addis gets changed to a NOP. (It still takes up a dispatch slot, but is sent directly to completion.)The last 5 bits of addis(SI) are sent with the ld (information from the addis is passed to the ld).The addis is removed from execution.

This patch is intend to implement the missing P8 <https://reviews.llvm.org/P8> MacroFusion for LLVM.


https://reviews.llvm.org/D70651

Files:
  llvm/lib/Target/PowerPC/CMakeLists.txt
  llvm/lib/Target/PowerPC/PPC.td
  llvm/lib/Target/PowerPC/PPCMacroFusion.cpp
  llvm/lib/Target/PowerPC/PPCMacroFusion.def
  llvm/lib/Target/PowerPC/PPCMacroFusion.h
  llvm/lib/Target/PowerPC/PPCSubtarget.cpp
  llvm/lib/Target/PowerPC/PPCSubtarget.h
  llvm/lib/Target/PowerPC/PPCTargetMachine.cpp

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