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diff --git a/llvm/lib/Target/PowerPC/PPCMacroFusion.cpp b/llvm/lib/Target/PowerPC/PPCMacroFusion.cpp
new file mode 100644
index 0000000000000..815dfd1402f47
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+++ b/llvm/lib/Target/PowerPC/PPCMacroFusion.cpp
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+//===- PPCMacroFusion.cpp - PowerPC Macro Fusion --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file This file contains the PowerPC implementation of the DAG scheduling
+///  mutation to pair instructions back to back.
+//
+//===----------------------------------------------------------------------===//
+
+#include "PPC.h"
+#include "PPCSubtarget.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/CodeGen/MacroFusion.h"
+
+using namespace llvm;
+namespace {
+
+class FusionFeature {
+public:
+  typedef SmallDenseSet<unsigned> FusionOpSet;
+
+  enum FusionKind {
+  #define FUSION_KIND(KIND) FK_##KIND
+  #define FUSION_FEATURE(KIND, HAS_FEATURE, DEP_OP_IDX, OPSET1, OPSET2) \
+    FUSION_KIND(KIND),
+  #include "PPCMacroFusion.def"
+  FUSION_KIND(END)
+  };
+private:
+  // Each fusion feature is assigned with one fusion kind. All the
+  // instructions with the same fusion kind have the same fusion characteristic.
+  FusionKind Kd;
+  // True if this feature is enabled.
+  bool Supported;
+  // li rx, si
+  // load rt, ra, rx
+  // The dependent operand index in the second op(load). And the negative means
+  // it could be any one. 
+  int DepOpIdx;
+  // The first fusion op set.
+  FusionOpSet OpSet1;
+  // The second fusion op set.
+  FusionOpSet OpSet2;
+public:
+  FusionFeature(FusionKind Kind, bool HasFeature, int Index,
+                const FusionOpSet &First, const FusionOpSet &Second) :
+    Kd(Kind), Supported(HasFeature), DepOpIdx(Index), OpSet1(First), 
+    OpSet2(Second) {}
+
+  bool hasOp1(unsigned Opc) const { return OpSet1.count(Opc) != 0; }
+  bool hasOp2(unsigned Opc) const { return OpSet2.count(Opc) != 0; }
+  bool isSupported() const { return Supported; }
+  Optional<unsigned> depOpIdx() const {
+    if (DepOpIdx < 0)
+      return None;
+    return DepOpIdx;
+  }
+
+  FusionKind getKind() const { return Kd; }
+};
+
+static bool matchingRegOps(const MachineInstr &FirstMI,
+                           int FirstMIOpIndex,
+                           const MachineInstr &SecondMI,
+                           int SecondMIOpIndex) {
+  const MachineOperand &Op1 = FirstMI.getOperand(FirstMIOpIndex);
+  const MachineOperand &Op2 = SecondMI.getOperand(SecondMIOpIndex);
+  if (!Op1.isReg() || !Op2.isReg())
+    return false;
+
+  return Op1.getReg() == Op2.getReg();
+}
+
+// Return true if the FirstMI meets the constraints of SecondMI according to
+// fusion specification.
+static bool checkOpConstraints(FusionFeature::FusionKind Kd,
+                               const MachineInstr &FirstMI,
+                               const MachineInstr &SecondMI) {
+  switch (Kd) {
+  // The hardware didn't require any specific check for the fused instructions'
+  // operands. Therefore, return true to indicate that, it is fusable.
+  default: return true;
+  // [addi rt,ra,si - lxvd2x xt,ra,rb] etc.
+  case FusionFeature::FK_AddiLoad: {
+    // lxvd2x(ra) cannot be zero
+    const MachineOperand &RA = SecondMI.getOperand(1);
+    if (!RA.isReg())
+      return true;
+
+    return Register::isVirtualRegister(RA.getReg()) ||
+      (RA.getReg() != PPC::ZERO && RA.getReg() != PPC::ZERO8);
+  }
+  // [addis rt,ra,si - ld rt,ds(ra)] etc.
+  case FusionFeature::FK_AddisLoad: {
+    const MachineOperand &RT = SecondMI.getOperand(0);
+    if (!RT.isReg())
+      return true;
+
+    // Only check it for non-virtual register.
+    if (!Register::isVirtualRegister(RT.getReg()))
+      // addis(rt) = ld(ra) = ld(rt)
+      // ld(rt) cannot be zero
+      if (!matchingRegOps(SecondMI, 0, SecondMI, 2) ||
+          (RT.getReg() == PPC::ZERO || RT.getReg() == PPC::ZERO8))
+          return false;
+
+    // addis(si) first 12 bits must be all 1s or all 0s
+    const MachineOperand &SI = FirstMI.getOperand(2);
+    if (!SI.isImm())
+      return true;
+    int64_t Imm = SI.getImm();
+    if (((Imm & 0xFFF0) != 0) && ((Imm & 0xFFF0) != 0xFFF0))
+      return false;
+
+    // If si = 1111111111110000 and the msb of the d/ds field of the load equals 
+    // 1, then fusion does not occur.
+    if ((Imm & 0xFFF0) == 0xFFF0) {
+      const MachineOperand &D = SecondMI.getOperand(1);
+      if (!D.isImm())
+        return true;
+
+      // 14 bit for DS field, while 16 bit for D field.
+      int MSB = 15;
+      if (SecondMI.getOpcode() == PPC::LD)
+        MSB = 13;
+
+      return (D.getImm() & (1ULL << MSB)) == 0;
+    }
+    return true;
+  }
+  }
+
+  llvm_unreachable("All the cases should have been handled");
+  return true;
+}
+
+/// Check if the instr pair, FirstMI and SecondMI, should be fused together.
+/// Given SecondMI, when FirstMI is unspecified, then check if SecondMI may be
+/// part of a fused pair at all.
+static bool shouldScheduleAdjacent(const TargetInstrInfo &TII,
+                                   const TargetSubtargetInfo &TSI,
+                                   const MachineInstr *FirstMI,
+                                   const MachineInstr &SecondMI) {
+  // We use the PPC namespace to avoid the need to prefix opcodes with PPC:: in
+  // the def file.
+  using namespace PPC;
+
+  const PPCSubtarget &ST = static_cast<const PPCSubtarget&>(TSI);
+  static const FusionFeature FusionFeatures[] = {
+  #define FUSION_FEATURE(KIND, HAS_FEATURE, DEP_OP_IDX, OPSET1, OPSET2) { \
+    FusionFeature::FUSION_KIND(KIND), ST.HAS_FEATURE(), DEP_OP_IDX, { OPSET1 },\
+    { OPSET2 } },
+   #include "PPCMacroFusion.def"
+  };
+  #undef FUSION_KIND
+
+  for (auto &Feature : FusionFeatures) {
+    // Skip if the feature is not supported.
+    if (!Feature.isSupported())
+      continue;
+
+    // Only when the SecondMI is fusable, we are starting to look for the
+    // fusable FirstMI.
+    if (Feature.hasOp2(SecondMI.getOpcode())) {
+      // If FirstMI == nullptr, that means, we're only checking whether SecondMI
+      // can be fused at all.
+      if (!FirstMI)
+        return true;
+
+      // Checking if the FirstMI is fusable with the SecondMI.
+      if (!Feature.hasOp1(FirstMI->getOpcode()))
+        continue;
+
+      auto DepOpIdx = Feature.depOpIdx();
+      if (DepOpIdx.hasValue()) {
+        // Checking if the result of the FirstMI is the desired operand of the
+        // SecondMI if the DepOpIdx is set. Otherwise, ignore it.
+        if (!matchingRegOps(*FirstMI, 0, SecondMI, *DepOpIdx))
+          return false;
+      }
+  
+      // Checking more on the instruction operands.
+      if (checkOpConstraints(Feature.getKind(), *FirstMI, SecondMI))
+        return true;
+    }
+  }
+
+  return false;
+}
+
+} // end anonymous namespace
+
+namespace llvm {
+
+std::unique_ptr<ScheduleDAGMutation> createPowerPCMacroFusionDAGMutation () {
+  return createMacroFusionDAGMutation(shouldScheduleAdjacent);
+}
+
+} // end namespace llvm