First step of huge frame-related refactoring: move emit{Prologue,Epilogue} out of TargetRegisterInfo to TargetFrameInfo, which is definitely much better suitable place

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119097 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCFrameInfo.cpp b/lib/Target/PowerPC/PPCFrameInfo.cpp
new file mode 100644
index 0000000..3823e3f
--- /dev/null
+++ b/lib/Target/PowerPC/PPCFrameInfo.cpp
@@ -0,0 +1,680 @@
+//=======- PPCFrameInfo.cpp - PPC Frame Information ------------*- C++ -*-====//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the PPC implementation of TargetFrameInfo class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "PPCFrameInfo.h"
+#include "PPCInstrInfo.h"
+#include "PPCMachineFunctionInfo.h"
+#include "llvm/Function.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Target/TargetOptions.h"
+
+using namespace llvm;
+
+// FIXME This disables some code that aligns the stack to a boundary bigger than
+// the default (16 bytes on Darwin) when there is a stack local of greater
+// alignment.  This does not currently work, because the delta between old and
+// new stack pointers is added to offsets that reference incoming parameters
+// after the prolog is generated, and the code that does that doesn't handle a
+// variable delta.  You don't want to do that anyway; a better approach is to
+// reserve another register that retains to the incoming stack pointer, and
+// reference parameters relative to that.
+#define ALIGN_STACK 0
+
+
+/// VRRegNo - Map from a numbered VR register to its enum value.
+///
+static const unsigned short VRRegNo[] = {
+ PPC::V0 , PPC::V1 , PPC::V2 , PPC::V3 , PPC::V4 , PPC::V5 , PPC::V6 , PPC::V7 ,
+ PPC::V8 , PPC::V9 , PPC::V10, PPC::V11, PPC::V12, PPC::V13, PPC::V14, PPC::V15,
+ PPC::V16, PPC::V17, PPC::V18, PPC::V19, PPC::V20, PPC::V21, PPC::V22, PPC::V23,
+ PPC::V24, PPC::V25, PPC::V26, PPC::V27, PPC::V28, PPC::V29, PPC::V30, PPC::V31
+};
+
+/// RemoveVRSaveCode - We have found that this function does not need any code
+/// to manipulate the VRSAVE register, even though it uses vector registers.
+/// This can happen when the only registers used are known to be live in or out
+/// of the function.  Remove all of the VRSAVE related code from the function.
+static void RemoveVRSaveCode(MachineInstr *MI) {
+  MachineBasicBlock *Entry = MI->getParent();
+  MachineFunction *MF = Entry->getParent();
+
+  // We know that the MTVRSAVE instruction immediately follows MI.  Remove it.
+  MachineBasicBlock::iterator MBBI = MI;
+  ++MBBI;
+  assert(MBBI != Entry->end() && MBBI->getOpcode() == PPC::MTVRSAVE);
+  MBBI->eraseFromParent();
+
+  bool RemovedAllMTVRSAVEs = true;
+  // See if we can find and remove the MTVRSAVE instruction from all of the
+  // epilog blocks.
+  for (MachineFunction::iterator I = MF->begin(), E = MF->end(); I != E; ++I) {
+    // If last instruction is a return instruction, add an epilogue
+    if (!I->empty() && I->back().getDesc().isReturn()) {
+      bool FoundIt = false;
+      for (MBBI = I->end(); MBBI != I->begin(); ) {
+        --MBBI;
+        if (MBBI->getOpcode() == PPC::MTVRSAVE) {
+          MBBI->eraseFromParent();  // remove it.
+          FoundIt = true;
+          break;
+        }
+      }
+      RemovedAllMTVRSAVEs &= FoundIt;
+    }
+  }
+
+  // If we found and removed all MTVRSAVE instructions, remove the read of
+  // VRSAVE as well.
+  if (RemovedAllMTVRSAVEs) {
+    MBBI = MI;
+    assert(MBBI != Entry->begin() && "UPDATE_VRSAVE is first instr in block?");
+    --MBBI;
+    assert(MBBI->getOpcode() == PPC::MFVRSAVE && "VRSAVE instrs wandered?");
+    MBBI->eraseFromParent();
+  }
+
+  // Finally, nuke the UPDATE_VRSAVE.
+  MI->eraseFromParent();
+}
+
+// HandleVRSaveUpdate - MI is the UPDATE_VRSAVE instruction introduced by the
+// instruction selector.  Based on the vector registers that have been used,
+// transform this into the appropriate ORI instruction.
+static void HandleVRSaveUpdate(MachineInstr *MI, const TargetInstrInfo &TII) {
+  MachineFunction *MF = MI->getParent()->getParent();
+  DebugLoc dl = MI->getDebugLoc();
+
+  unsigned UsedRegMask = 0;
+  for (unsigned i = 0; i != 32; ++i)
+    if (MF->getRegInfo().isPhysRegUsed(VRRegNo[i]))
+      UsedRegMask |= 1 << (31-i);
+
+  // Live in and live out values already must be in the mask, so don't bother
+  // marking them.
+  for (MachineRegisterInfo::livein_iterator
+       I = MF->getRegInfo().livein_begin(),
+       E = MF->getRegInfo().livein_end(); I != E; ++I) {
+    unsigned RegNo = PPCRegisterInfo::getRegisterNumbering(I->first);
+    if (VRRegNo[RegNo] == I->first)        // If this really is a vector reg.
+      UsedRegMask &= ~(1 << (31-RegNo));   // Doesn't need to be marked.
+  }
+  for (MachineRegisterInfo::liveout_iterator
+       I = MF->getRegInfo().liveout_begin(),
+       E = MF->getRegInfo().liveout_end(); I != E; ++I) {
+    unsigned RegNo = PPCRegisterInfo::getRegisterNumbering(*I);
+    if (VRRegNo[RegNo] == *I)              // If this really is a vector reg.
+      UsedRegMask &= ~(1 << (31-RegNo));   // Doesn't need to be marked.
+  }
+
+  // If no registers are used, turn this into a copy.
+  if (UsedRegMask == 0) {
+    // Remove all VRSAVE code.
+    RemoveVRSaveCode(MI);
+    return;
+  }
+
+  unsigned SrcReg = MI->getOperand(1).getReg();
+  unsigned DstReg = MI->getOperand(0).getReg();
+
+  if ((UsedRegMask & 0xFFFF) == UsedRegMask) {
+    if (DstReg != SrcReg)
+      BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORI), DstReg)
+        .addReg(SrcReg)
+        .addImm(UsedRegMask);
+    else
+      BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORI), DstReg)
+        .addReg(SrcReg, RegState::Kill)
+        .addImm(UsedRegMask);
+  } else if ((UsedRegMask & 0xFFFF0000) == UsedRegMask) {
+    if (DstReg != SrcReg)
+      BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORIS), DstReg)
+        .addReg(SrcReg)
+        .addImm(UsedRegMask >> 16);
+    else
+      BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORIS), DstReg)
+        .addReg(SrcReg, RegState::Kill)
+        .addImm(UsedRegMask >> 16);
+  } else {
+    if (DstReg != SrcReg)
+      BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORIS), DstReg)
+        .addReg(SrcReg)
+        .addImm(UsedRegMask >> 16);
+    else
+      BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORIS), DstReg)
+        .addReg(SrcReg, RegState::Kill)
+        .addImm(UsedRegMask >> 16);
+
+    BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORI), DstReg)
+      .addReg(DstReg, RegState::Kill)
+      .addImm(UsedRegMask & 0xFFFF);
+  }
+
+  // Remove the old UPDATE_VRSAVE instruction.
+  MI->eraseFromParent();
+}
+
+/// determineFrameLayout - Determine the size of the frame and maximum call
+/// frame size.
+void PPCFrameInfo::determineFrameLayout(MachineFunction &MF) const {
+  MachineFrameInfo *MFI = MF.getFrameInfo();
+
+  // Get the number of bytes to allocate from the FrameInfo
+  unsigned FrameSize = MFI->getStackSize();
+
+  // Get the alignments provided by the target, and the maximum alignment
+  // (if any) of the fixed frame objects.
+  unsigned MaxAlign = MFI->getMaxAlignment();
+  unsigned TargetAlign = MF.getTarget().getFrameInfo()->getStackAlignment();
+  unsigned AlignMask = TargetAlign - 1;  //
+
+  // If we are a leaf function, and use up to 224 bytes of stack space,
+  // don't have a frame pointer, calls, or dynamic alloca then we do not need
+  // to adjust the stack pointer (we fit in the Red Zone).
+  bool DisableRedZone = MF.getFunction()->hasFnAttr(Attribute::NoRedZone);
+  // FIXME SVR4 The 32-bit SVR4 ABI has no red zone.
+  if (!DisableRedZone &&
+      FrameSize <= 224 &&                          // Fits in red zone.
+      !MFI->hasVarSizedObjects() &&                // No dynamic alloca.
+      !MFI->adjustsStack() &&                      // No calls.
+      (!ALIGN_STACK || MaxAlign <= TargetAlign)) { // No special alignment.
+    // No need for frame
+    MFI->setStackSize(0);
+    return;
+  }
+
+  // Get the maximum call frame size of all the calls.
+  unsigned maxCallFrameSize = MFI->getMaxCallFrameSize();
+
+  // Maximum call frame needs to be at least big enough for linkage and 8 args.
+  unsigned minCallFrameSize = getMinCallFrameSize(Subtarget.isPPC64(),
+                                                  Subtarget.isDarwinABI());
+  maxCallFrameSize = std::max(maxCallFrameSize, minCallFrameSize);
+
+  // If we have dynamic alloca then maxCallFrameSize needs to be aligned so
+  // that allocations will be aligned.
+  if (MFI->hasVarSizedObjects())
+    maxCallFrameSize = (maxCallFrameSize + AlignMask) & ~AlignMask;
+
+  // Update maximum call frame size.
+  MFI->setMaxCallFrameSize(maxCallFrameSize);
+
+  // Include call frame size in total.
+  FrameSize += maxCallFrameSize;
+
+  // Make sure the frame is aligned.
+  FrameSize = (FrameSize + AlignMask) & ~AlignMask;
+
+  // Update frame info.
+  MFI->setStackSize(FrameSize);
+}
+
+void PPCFrameInfo::emitPrologue(MachineFunction &MF) const {
+  MachineBasicBlock &MBB = MF.front();   // Prolog goes in entry BB
+  MachineBasicBlock::iterator MBBI = MBB.begin();
+  MachineFrameInfo *MFI = MF.getFrameInfo();
+  const PPCRegisterInfo *RegInfo =
+    static_cast<const PPCRegisterInfo*>(MF.getTarget().getRegisterInfo());
+  const PPCInstrInfo &TII =
+    *static_cast<const PPCInstrInfo*>(MF.getTarget().getInstrInfo());
+
+  MachineModuleInfo &MMI = MF.getMMI();
+  DebugLoc dl;
+  bool needsFrameMoves = MMI.hasDebugInfo() ||
+       !MF.getFunction()->doesNotThrow() ||
+       UnwindTablesMandatory;
+
+  // Prepare for frame info.
+  MCSymbol *FrameLabel = 0;
+
+  // Scan the prolog, looking for an UPDATE_VRSAVE instruction.  If we find it,
+  // process it.
+  for (unsigned i = 0; MBBI != MBB.end(); ++i, ++MBBI) {
+    if (MBBI->getOpcode() == PPC::UPDATE_VRSAVE) {
+      HandleVRSaveUpdate(MBBI, TII);
+      break;
+    }
+  }
+
+  // Move MBBI back to the beginning of the function.
+  MBBI = MBB.begin();
+
+  // Work out frame sizes.
+  determineFrameLayout(MF);
+  unsigned FrameSize = MFI->getStackSize();
+
+  int NegFrameSize = -FrameSize;
+
+  // Get processor type.
+  bool isPPC64 = Subtarget.isPPC64();
+  // Get operating system
+  bool isDarwinABI = Subtarget.isDarwinABI();
+  // Check if the link register (LR) must be saved.
+  PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
+  bool MustSaveLR = FI->mustSaveLR();
+  // Do we have a frame pointer for this function?
+  bool HasFP = RegInfo->hasFP(MF) && FrameSize;
+
+  int LROffset = PPCFrameInfo::getReturnSaveOffset(isPPC64, isDarwinABI);
+
+  int FPOffset = 0;
+  if (HasFP) {
+    if (Subtarget.isSVR4ABI()) {
+      MachineFrameInfo *FFI = MF.getFrameInfo();
+      int FPIndex = FI->getFramePointerSaveIndex();
+      assert(FPIndex && "No Frame Pointer Save Slot!");
+      FPOffset = FFI->getObjectOffset(FPIndex);
+    } else {
+      FPOffset = PPCFrameInfo::getFramePointerSaveOffset(isPPC64, isDarwinABI);
+    }
+  }
+
+  if (isPPC64) {
+    if (MustSaveLR)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::MFLR8), PPC::X0);
+
+    if (HasFP)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::STD))
+        .addReg(PPC::X31)
+        .addImm(FPOffset/4)
+        .addReg(PPC::X1);
+
+    if (MustSaveLR)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::STD))
+        .addReg(PPC::X0)
+        .addImm(LROffset / 4)
+        .addReg(PPC::X1);
+  } else {
+    if (MustSaveLR)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::MFLR), PPC::R0);
+
+    if (HasFP)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::STW))
+        .addReg(PPC::R31)
+        .addImm(FPOffset)
+        .addReg(PPC::R1);
+
+    if (MustSaveLR)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::STW))
+        .addReg(PPC::R0)
+        .addImm(LROffset)
+        .addReg(PPC::R1);
+  }
+
+  // Skip if a leaf routine.
+  if (!FrameSize) return;
+
+  // Get stack alignments.
+  unsigned TargetAlign = MF.getTarget().getFrameInfo()->getStackAlignment();
+  unsigned MaxAlign = MFI->getMaxAlignment();
+
+  // Adjust stack pointer: r1 += NegFrameSize.
+  // If there is a preferred stack alignment, align R1 now
+  if (!isPPC64) {
+    // PPC32.
+    if (ALIGN_STACK && MaxAlign > TargetAlign) {
+      assert(isPowerOf2_32(MaxAlign) && isInt<16>(MaxAlign) &&
+             "Invalid alignment!");
+      assert(isInt<16>(NegFrameSize) && "Unhandled stack size and alignment!");
+
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::RLWINM), PPC::R0)
+        .addReg(PPC::R1)
+        .addImm(0)
+        .addImm(32 - Log2_32(MaxAlign))
+        .addImm(31);
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::SUBFIC) ,PPC::R0)
+        .addReg(PPC::R0, RegState::Kill)
+        .addImm(NegFrameSize);
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::STWUX))
+        .addReg(PPC::R1)
+        .addReg(PPC::R1)
+        .addReg(PPC::R0);
+    } else if (isInt<16>(NegFrameSize)) {
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::STWU), PPC::R1)
+        .addReg(PPC::R1)
+        .addImm(NegFrameSize)
+        .addReg(PPC::R1);
+    } else {
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::LIS), PPC::R0)
+        .addImm(NegFrameSize >> 16);
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::ORI), PPC::R0)
+        .addReg(PPC::R0, RegState::Kill)
+        .addImm(NegFrameSize & 0xFFFF);
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::STWUX))
+        .addReg(PPC::R1)
+        .addReg(PPC::R1)
+        .addReg(PPC::R0);
+    }
+  } else {    // PPC64.
+    if (ALIGN_STACK && MaxAlign > TargetAlign) {
+      assert(isPowerOf2_32(MaxAlign) && isInt<16>(MaxAlign) &&
+             "Invalid alignment!");
+      assert(isInt<16>(NegFrameSize) && "Unhandled stack size and alignment!");
+
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::RLDICL), PPC::X0)
+        .addReg(PPC::X1)
+        .addImm(0)
+        .addImm(64 - Log2_32(MaxAlign));
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::SUBFIC8), PPC::X0)
+        .addReg(PPC::X0)
+        .addImm(NegFrameSize);
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::STDUX))
+        .addReg(PPC::X1)
+        .addReg(PPC::X1)
+        .addReg(PPC::X0);
+    } else if (isInt<16>(NegFrameSize)) {
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::STDU), PPC::X1)
+        .addReg(PPC::X1)
+        .addImm(NegFrameSize / 4)
+        .addReg(PPC::X1);
+    } else {
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::LIS8), PPC::X0)
+        .addImm(NegFrameSize >> 16);
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::ORI8), PPC::X0)
+        .addReg(PPC::X0, RegState::Kill)
+        .addImm(NegFrameSize & 0xFFFF);
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::STDUX))
+        .addReg(PPC::X1)
+        .addReg(PPC::X1)
+        .addReg(PPC::X0);
+    }
+  }
+
+  std::vector<MachineMove> &Moves = MMI.getFrameMoves();
+
+  // Add the "machine moves" for the instructions we generated above, but in
+  // reverse order.
+  if (needsFrameMoves) {
+    // Mark effective beginning of when frame pointer becomes valid.
+    FrameLabel = MMI.getContext().CreateTempSymbol();
+    BuildMI(MBB, MBBI, dl, TII.get(PPC::PROLOG_LABEL)).addSym(FrameLabel);
+
+    // Show update of SP.
+    if (NegFrameSize) {
+      MachineLocation SPDst(MachineLocation::VirtualFP);
+      MachineLocation SPSrc(MachineLocation::VirtualFP, NegFrameSize);
+      Moves.push_back(MachineMove(FrameLabel, SPDst, SPSrc));
+    } else {
+      MachineLocation SP(isPPC64 ? PPC::X31 : PPC::R31);
+      Moves.push_back(MachineMove(FrameLabel, SP, SP));
+    }
+
+    if (HasFP) {
+      MachineLocation FPDst(MachineLocation::VirtualFP, FPOffset);
+      MachineLocation FPSrc(isPPC64 ? PPC::X31 : PPC::R31);
+      Moves.push_back(MachineMove(FrameLabel, FPDst, FPSrc));
+    }
+
+    if (MustSaveLR) {
+      MachineLocation LRDst(MachineLocation::VirtualFP, LROffset);
+      MachineLocation LRSrc(isPPC64 ? PPC::LR8 : PPC::LR);
+      Moves.push_back(MachineMove(FrameLabel, LRDst, LRSrc));
+    }
+  }
+
+  MCSymbol *ReadyLabel = 0;
+
+  // If there is a frame pointer, copy R1 into R31
+  if (HasFP) {
+    if (!isPPC64) {
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::OR), PPC::R31)
+        .addReg(PPC::R1)
+        .addReg(PPC::R1);
+    } else {
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::OR8), PPC::X31)
+        .addReg(PPC::X1)
+        .addReg(PPC::X1);
+    }
+
+    if (needsFrameMoves) {
+      ReadyLabel = MMI.getContext().CreateTempSymbol();
+
+      // Mark effective beginning of when frame pointer is ready.
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::PROLOG_LABEL)).addSym(ReadyLabel);
+
+      MachineLocation FPDst(HasFP ? (isPPC64 ? PPC::X31 : PPC::R31) :
+                                    (isPPC64 ? PPC::X1 : PPC::R1));
+      MachineLocation FPSrc(MachineLocation::VirtualFP);
+      Moves.push_back(MachineMove(ReadyLabel, FPDst, FPSrc));
+    }
+  }
+
+  if (needsFrameMoves) {
+    MCSymbol *Label = HasFP ? ReadyLabel : FrameLabel;
+
+    // Add callee saved registers to move list.
+    const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
+    for (unsigned I = 0, E = CSI.size(); I != E; ++I) {
+      int Offset = MFI->getObjectOffset(CSI[I].getFrameIdx());
+      unsigned Reg = CSI[I].getReg();
+      if (Reg == PPC::LR || Reg == PPC::LR8 || Reg == PPC::RM) continue;
+      MachineLocation CSDst(MachineLocation::VirtualFP, Offset);
+      MachineLocation CSSrc(Reg);
+      Moves.push_back(MachineMove(Label, CSDst, CSSrc));
+    }
+  }
+}
+
+void PPCFrameInfo::emitEpilogue(MachineFunction &MF,
+                                MachineBasicBlock &MBB) const {
+  MachineBasicBlock::iterator MBBI = prior(MBB.end());
+  const PPCRegisterInfo *RegInfo =
+    static_cast<const PPCRegisterInfo*>(MF.getTarget().getRegisterInfo());
+  const PPCInstrInfo &TII =
+    *static_cast<const PPCInstrInfo*>(MF.getTarget().getInstrInfo());
+
+  unsigned RetOpcode = MBBI->getOpcode();
+  DebugLoc dl;
+
+  assert( (RetOpcode == PPC::BLR ||
+           RetOpcode == PPC::TCRETURNri ||
+           RetOpcode == PPC::TCRETURNdi ||
+           RetOpcode == PPC::TCRETURNai ||
+           RetOpcode == PPC::TCRETURNri8 ||
+           RetOpcode == PPC::TCRETURNdi8 ||
+           RetOpcode == PPC::TCRETURNai8) &&
+         "Can only insert epilog into returning blocks");
+
+  // Get alignment info so we know how to restore r1
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
+  unsigned TargetAlign = MF.getTarget().getFrameInfo()->getStackAlignment();
+  unsigned MaxAlign = MFI->getMaxAlignment();
+
+  // Get the number of bytes allocated from the FrameInfo.
+  int FrameSize = MFI->getStackSize();
+
+  // Get processor type.
+  bool isPPC64 = Subtarget.isPPC64();
+  // Get operating system
+  bool isDarwinABI = Subtarget.isDarwinABI();
+  // Check if the link register (LR) has been saved.
+  PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
+  bool MustSaveLR = FI->mustSaveLR();
+  // Do we have a frame pointer for this function?
+  bool HasFP = RegInfo->hasFP(MF) && FrameSize;
+
+  int LROffset = PPCFrameInfo::getReturnSaveOffset(isPPC64, isDarwinABI);
+
+  int FPOffset = 0;
+  if (HasFP) {
+    if (Subtarget.isSVR4ABI()) {
+      MachineFrameInfo *FFI = MF.getFrameInfo();
+      int FPIndex = FI->getFramePointerSaveIndex();
+      assert(FPIndex && "No Frame Pointer Save Slot!");
+      FPOffset = FFI->getObjectOffset(FPIndex);
+    } else {
+      FPOffset = PPCFrameInfo::getFramePointerSaveOffset(isPPC64, isDarwinABI);
+    }
+  }
+
+  bool UsesTCRet =  RetOpcode == PPC::TCRETURNri ||
+    RetOpcode == PPC::TCRETURNdi ||
+    RetOpcode == PPC::TCRETURNai ||
+    RetOpcode == PPC::TCRETURNri8 ||
+    RetOpcode == PPC::TCRETURNdi8 ||
+    RetOpcode == PPC::TCRETURNai8;
+
+  if (UsesTCRet) {
+    int MaxTCRetDelta = FI->getTailCallSPDelta();
+    MachineOperand &StackAdjust = MBBI->getOperand(1);
+    assert(StackAdjust.isImm() && "Expecting immediate value.");
+    // Adjust stack pointer.
+    int StackAdj = StackAdjust.getImm();
+    int Delta = StackAdj - MaxTCRetDelta;
+    assert((Delta >= 0) && "Delta must be positive");
+    if (MaxTCRetDelta>0)
+      FrameSize += (StackAdj +Delta);
+    else
+      FrameSize += StackAdj;
+  }
+
+  if (FrameSize) {
+    // The loaded (or persistent) stack pointer value is offset by the 'stwu'
+    // on entry to the function.  Add this offset back now.
+    if (!isPPC64) {
+      // If this function contained a fastcc call and GuaranteedTailCallOpt is
+      // enabled (=> hasFastCall()==true) the fastcc call might contain a tail
+      // call which invalidates the stack pointer value in SP(0). So we use the
+      // value of R31 in this case.
+      if (FI->hasFastCall() && isInt<16>(FrameSize)) {
+        assert(RegInfo->hasFP(MF) && "Expecting a valid the frame pointer.");
+        BuildMI(MBB, MBBI, dl, TII.get(PPC::ADDI), PPC::R1)
+          .addReg(PPC::R31).addImm(FrameSize);
+      } else if(FI->hasFastCall()) {
+        BuildMI(MBB, MBBI, dl, TII.get(PPC::LIS), PPC::R0)
+          .addImm(FrameSize >> 16);
+        BuildMI(MBB, MBBI, dl, TII.get(PPC::ORI), PPC::R0)
+          .addReg(PPC::R0, RegState::Kill)
+          .addImm(FrameSize & 0xFFFF);
+        BuildMI(MBB, MBBI, dl, TII.get(PPC::ADD4))
+          .addReg(PPC::R1)
+          .addReg(PPC::R31)
+          .addReg(PPC::R0);
+      } else if (isInt<16>(FrameSize) &&
+                 (!ALIGN_STACK || TargetAlign >= MaxAlign) &&
+                 !MFI->hasVarSizedObjects()) {
+        BuildMI(MBB, MBBI, dl, TII.get(PPC::ADDI), PPC::R1)
+          .addReg(PPC::R1).addImm(FrameSize);
+      } else {
+        BuildMI(MBB, MBBI, dl, TII.get(PPC::LWZ),PPC::R1)
+          .addImm(0).addReg(PPC::R1);
+      }
+    } else {
+      if (FI->hasFastCall() && isInt<16>(FrameSize)) {
+        assert(RegInfo->hasFP(MF) && "Expecting a valid the frame pointer.");
+        BuildMI(MBB, MBBI, dl, TII.get(PPC::ADDI8), PPC::X1)
+          .addReg(PPC::X31).addImm(FrameSize);
+      } else if(FI->hasFastCall()) {
+        BuildMI(MBB, MBBI, dl, TII.get(PPC::LIS8), PPC::X0)
+          .addImm(FrameSize >> 16);
+        BuildMI(MBB, MBBI, dl, TII.get(PPC::ORI8), PPC::X0)
+          .addReg(PPC::X0, RegState::Kill)
+          .addImm(FrameSize & 0xFFFF);
+        BuildMI(MBB, MBBI, dl, TII.get(PPC::ADD8))
+          .addReg(PPC::X1)
+          .addReg(PPC::X31)
+          .addReg(PPC::X0);
+      } else if (isInt<16>(FrameSize) && TargetAlign >= MaxAlign &&
+            !MFI->hasVarSizedObjects()) {
+        BuildMI(MBB, MBBI, dl, TII.get(PPC::ADDI8), PPC::X1)
+           .addReg(PPC::X1).addImm(FrameSize);
+      } else {
+        BuildMI(MBB, MBBI, dl, TII.get(PPC::LD), PPC::X1)
+           .addImm(0).addReg(PPC::X1);
+      }
+    }
+  }
+
+  if (isPPC64) {
+    if (MustSaveLR)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::LD), PPC::X0)
+        .addImm(LROffset/4).addReg(PPC::X1);
+
+    if (HasFP)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::LD), PPC::X31)
+        .addImm(FPOffset/4).addReg(PPC::X1);
+
+    if (MustSaveLR)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::MTLR8)).addReg(PPC::X0);
+  } else {
+    if (MustSaveLR)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::LWZ), PPC::R0)
+          .addImm(LROffset).addReg(PPC::R1);
+
+    if (HasFP)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::LWZ), PPC::R31)
+          .addImm(FPOffset).addReg(PPC::R1);
+
+    if (MustSaveLR)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::MTLR)).addReg(PPC::R0);
+  }
+
+  // Callee pop calling convention. Pop parameter/linkage area. Used for tail
+  // call optimization
+  if (GuaranteedTailCallOpt && RetOpcode == PPC::BLR &&
+      MF.getFunction()->getCallingConv() == CallingConv::Fast) {
+     PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
+     unsigned CallerAllocatedAmt = FI->getMinReservedArea();
+     unsigned StackReg = isPPC64 ? PPC::X1 : PPC::R1;
+     unsigned FPReg = isPPC64 ? PPC::X31 : PPC::R31;
+     unsigned TmpReg = isPPC64 ? PPC::X0 : PPC::R0;
+     unsigned ADDIInstr = isPPC64 ? PPC::ADDI8 : PPC::ADDI;
+     unsigned ADDInstr = isPPC64 ? PPC::ADD8 : PPC::ADD4;
+     unsigned LISInstr = isPPC64 ? PPC::LIS8 : PPC::LIS;
+     unsigned ORIInstr = isPPC64 ? PPC::ORI8 : PPC::ORI;
+
+     if (CallerAllocatedAmt && isInt<16>(CallerAllocatedAmt)) {
+       BuildMI(MBB, MBBI, dl, TII.get(ADDIInstr), StackReg)
+         .addReg(StackReg).addImm(CallerAllocatedAmt);
+     } else {
+       BuildMI(MBB, MBBI, dl, TII.get(LISInstr), TmpReg)
+          .addImm(CallerAllocatedAmt >> 16);
+       BuildMI(MBB, MBBI, dl, TII.get(ORIInstr), TmpReg)
+          .addReg(TmpReg, RegState::Kill)
+          .addImm(CallerAllocatedAmt & 0xFFFF);
+       BuildMI(MBB, MBBI, dl, TII.get(ADDInstr))
+          .addReg(StackReg)
+          .addReg(FPReg)
+          .addReg(TmpReg);
+     }
+  } else if (RetOpcode == PPC::TCRETURNdi) {
+    MBBI = prior(MBB.end());
+    MachineOperand &JumpTarget = MBBI->getOperand(0);
+    BuildMI(MBB, MBBI, dl, TII.get(PPC::TAILB)).
+      addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset());
+  } else if (RetOpcode == PPC::TCRETURNri) {
+    MBBI = prior(MBB.end());
+    assert(MBBI->getOperand(0).isReg() && "Expecting register operand.");
+    BuildMI(MBB, MBBI, dl, TII.get(PPC::TAILBCTR));
+  } else if (RetOpcode == PPC::TCRETURNai) {
+    MBBI = prior(MBB.end());
+    MachineOperand &JumpTarget = MBBI->getOperand(0);
+    BuildMI(MBB, MBBI, dl, TII.get(PPC::TAILBA)).addImm(JumpTarget.getImm());
+  } else if (RetOpcode == PPC::TCRETURNdi8) {
+    MBBI = prior(MBB.end());
+    MachineOperand &JumpTarget = MBBI->getOperand(0);
+    BuildMI(MBB, MBBI, dl, TII.get(PPC::TAILB8)).
+      addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset());
+  } else if (RetOpcode == PPC::TCRETURNri8) {
+    MBBI = prior(MBB.end());
+    assert(MBBI->getOperand(0).isReg() && "Expecting register operand.");
+    BuildMI(MBB, MBBI, dl, TII.get(PPC::TAILBCTR8));
+  } else if (RetOpcode == PPC::TCRETURNai8) {
+    MBBI = prior(MBB.end());
+    MachineOperand &JumpTarget = MBBI->getOperand(0);
+    BuildMI(MBB, MBBI, dl, TII.get(PPC::TAILBA8)).addImm(JumpTarget.getImm());
+  }
+}