lib/Target/IA64/IA64RegisterInfo.cpp

//===- IA64RegisterInfo.cpp - IA64 Register Information ---------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by Duraid Madina and is distributed under the
// University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the IA64 implementation of the MRegisterInfo class.  This
// file is responsible for the frame pointer elimination optimization on IA64.
//
//===----------------------------------------------------------------------===//

#include "IA64.h"
#include "IA64RegisterInfo.h"
#include "IA64InstrBuilder.h"
#include "IA64MachineFunctionInfo.h"
#include "llvm/Constants.h"
#include "llvm/Type.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineLocation.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/ADT/STLExtras.h"
#include <iostream>
using namespace llvm;


IA64RegisterInfo::IA64RegisterInfo()
  : IA64GenRegisterInfo(IA64::ADJUSTCALLSTACKDOWN, IA64::ADJUSTCALLSTACKUP) {}

void IA64RegisterInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
                                           MachineBasicBlock::iterator MI,
                                           unsigned SrcReg, int FrameIdx,
                                           const TargetRegisterClass *RC) const{

  if (RC == IA64::FPRegisterClass) {
    BuildMI(MBB, MI, IA64::STF_SPILL, 2).addFrameIndex(FrameIdx).addReg(SrcReg);
  } else if (RC == IA64::GRRegisterClass) {
    BuildMI(MBB, MI, IA64::ST8, 2).addFrameIndex(FrameIdx).addReg(SrcReg);
 }
  else if (RC == IA64::PRRegisterClass) {
    /* we use IA64::r2 as a temporary register for doing this hackery. */
    // first we load 0:
    BuildMI(MBB, MI, IA64::MOV, 1, IA64::r2).addReg(IA64::r0);
    // then conditionally add 1:
    BuildMI(MBB, MI, IA64::CADDIMM22, 3, IA64::r2).addReg(IA64::r2)
      .addImm(1).addReg(SrcReg);
    // and then store it to the stack
    BuildMI(MBB, MI, IA64::ST8, 2).addFrameIndex(FrameIdx).addReg(IA64::r2);
  } else assert(0 &&
      "sorry, I don't know how to store this sort of reg in the stack\n");
}

void IA64RegisterInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
                                            MachineBasicBlock::iterator MI,
                                            unsigned DestReg, int FrameIdx,
                                            const TargetRegisterClass *RC)const{

  if (RC == IA64::FPRegisterClass) {
    BuildMI(MBB, MI, IA64::LDF_FILL, 1, DestReg).addFrameIndex(FrameIdx);
  } else if (RC == IA64::GRRegisterClass) {
    BuildMI(MBB, MI, IA64::LD8, 1, DestReg).addFrameIndex(FrameIdx);
 } else if (RC == IA64::PRRegisterClass) {
   // first we load a byte from the stack into r2, our 'predicate hackery'
   // scratch reg
   BuildMI(MBB, MI, IA64::LD8, 1, IA64::r2).addFrameIndex(FrameIdx);
   // then we compare it to zero. If it _is_ zero, compare-not-equal to
   // r0 gives us 0, which is what we want, so that's nice.
   BuildMI(MBB, MI, IA64::CMPNE, 2, DestReg).addReg(IA64::r2).addReg(IA64::r0);
 } else assert(0 &&
     "sorry, I don't know how to load this sort of reg from the stack\n");
}

void IA64RegisterInfo::copyRegToReg(MachineBasicBlock &MBB,
                                   MachineBasicBlock::iterator MI,
                                   unsigned DestReg, unsigned SrcReg,
                                   const TargetRegisterClass *RC) const {

  if(RC == IA64::PRRegisterClass ) // if a bool, we use pseudocode
    // (SrcReg) DestReg = cmp.eq.unc(r0, r0)
    BuildMI(MBB, MI, IA64::PCMPEQUNC, 3, DestReg).addReg(IA64::r0).addReg(IA64::r0).addReg(SrcReg);
  else // otherwise, MOV works (for both gen. regs and FP regs)
    BuildMI(MBB, MI, IA64::MOV, 1, DestReg).addReg(SrcReg);
}

//===----------------------------------------------------------------------===//
// Stack Frame Processing methods
//===----------------------------------------------------------------------===//

// hasFP - Return true if the specified function should have a dedicated frame
// pointer register.  This is true if the function has variable sized allocas or
// if frame pointer elimination is disabled.
//
static bool hasFP(MachineFunction &MF) {
  return NoFramePointerElim || MF.getFrameInfo()->hasVarSizedObjects();
}

void IA64RegisterInfo::
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
                              MachineBasicBlock::iterator I) const {

  if (hasFP(MF)) {
    // If we have a frame pointer, turn the adjcallstackup instruction into a
    // 'sub SP, <amt>' and the adjcallstackdown instruction into 'add SP,
    // <amt>'
    MachineInstr *Old = I;
    unsigned Amount = Old->getOperand(0).getImmedValue();
    if (Amount != 0) {
      // We need to keep the stack aligned properly.  To do this, we round the
      // amount of space needed for the outgoing arguments up to the next
      // alignment boundary.
      unsigned Align = MF.getTarget().getFrameInfo()->getStackAlignment();
      Amount = (Amount+Align-1)/Align*Align;

      MachineInstr *New;
      if (Old->getOpcode() == IA64::ADJUSTCALLSTACKDOWN) {
        New=BuildMI(IA64::ADDIMM22, 2, IA64::r12).addReg(IA64::r12)
          .addSImm(-Amount);
      } else {
        assert(Old->getOpcode() == IA64::ADJUSTCALLSTACKUP);
        New=BuildMI(IA64::ADDIMM22, 2, IA64::r12).addReg(IA64::r12)
          .addSImm(Amount);
      }

      // Replace the pseudo instruction with a new instruction...
      MBB.insert(I, New);
    }
  }

  MBB.erase(I);
}

void IA64RegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II) const{
  unsigned i = 0;
  MachineInstr &MI = *II;
  MachineBasicBlock &MBB = *MI.getParent();
  MachineFunction &MF = *MBB.getParent();

  bool FP = hasFP(MF);

  while (!MI.getOperand(i).isFrameIndex()) {
    ++i;
    assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
  }

  int FrameIndex = MI.getOperand(i).getFrameIndex();

  // choose a base register: ( hasFP? framepointer : stack pointer )
  unsigned BaseRegister = FP ? IA64::r5 : IA64::r12;
  // Add the base register
  MI.SetMachineOperandReg(i, BaseRegister);

  // Now add the frame object offset to the offset from r1.
  int Offset = MF.getFrameInfo()->getObjectOffset(FrameIndex);

  // If we're not using a Frame Pointer that has been set to the value of the
  // SP before having the stack size subtracted from it, then add the stack size
  // to Offset to get the correct offset.
  Offset += MF.getFrameInfo()->getStackSize();

  // XXX: we use 'r22' as another hack+slash temporary register here :(
  if ( Offset <= 8191 && Offset >= -8192) { // smallish offset
    //fix up the old:
    MI.SetMachineOperandReg(i, IA64::r22);
    MI.getOperand(i).setUse(); // mark r22 as being used
                               // (the bundler wants to know this)
    //insert the new
    MachineInstr* nMI=BuildMI(IA64::ADDIMM22, 2, IA64::r22)
      .addReg(BaseRegister).addSImm(Offset);
    MBB.insert(II, nMI);
  } else { // it's big
    //fix up the old:
    MI.SetMachineOperandReg(i, IA64::r22);
    MI.getOperand(i).setUse(); // mark r22 as being used
                               // (the bundler wants to know this)
    MachineInstr* nMI;
    nMI=BuildMI(IA64::MOVLIMM64, 1, IA64::r22).addSImm(Offset);
    MBB.insert(II, nMI);
    nMI=BuildMI(IA64::ADD, 2, IA64::r22).addReg(BaseRegister)
      .addReg(IA64::r22);
    MBB.insert(II, nMI);
  }

}

void IA64RegisterInfo::emitPrologue(MachineFunction &MF) const {
  MachineBasicBlock &MBB = MF.front();   // Prolog goes in entry BB
  MachineBasicBlock::iterator MBBI = MBB.begin();
  MachineFrameInfo *MFI = MF.getFrameInfo();
  MachineInstr *MI;
  bool FP = hasFP(MF);

  // first, we handle the 'alloc' instruction, that should be right up the
  // top of any function
  static const unsigned RegsInOrder[96] = { // there are 96 GPRs the
                                            // RSE worries about
        IA64::r32, IA64::r33, IA64::r34, IA64::r35,
        IA64::r36, IA64::r37, IA64::r38, IA64::r39, IA64::r40, IA64::r41,
        IA64::r42, IA64::r43, IA64::r44, IA64::r45, IA64::r46, IA64::r47,
        IA64::r48, IA64::r49, IA64::r50, IA64::r51, IA64::r52, IA64::r53,
        IA64::r54, IA64::r55, IA64::r56, IA64::r57, IA64::r58, IA64::r59,
        IA64::r60, IA64::r61, IA64::r62, IA64::r63, IA64::r64, IA64::r65,
        IA64::r66, IA64::r67, IA64::r68, IA64::r69, IA64::r70, IA64::r71,
        IA64::r72, IA64::r73, IA64::r74, IA64::r75, IA64::r76, IA64::r77,
        IA64::r78, IA64::r79, IA64::r80, IA64::r81, IA64::r82, IA64::r83,
        IA64::r84, IA64::r85, IA64::r86, IA64::r87, IA64::r88, IA64::r89,
        IA64::r90, IA64::r91, IA64::r92, IA64::r93, IA64::r94, IA64::r95,
        IA64::r96, IA64::r97, IA64::r98, IA64::r99, IA64::r100, IA64::r101,
        IA64::r102, IA64::r103, IA64::r104, IA64::r105, IA64::r106, IA64::r107,
        IA64::r108, IA64::r109, IA64::r110, IA64::r111, IA64::r112, IA64::r113,
        IA64::r114, IA64::r115, IA64::r116, IA64::r117, IA64::r118, IA64::r119,
        IA64::r120, IA64::r121, IA64::r122, IA64::r123, IA64::r124, IA64::r125,
        IA64::r126, IA64::r127 };

  unsigned numStackedGPRsUsed=0;
  for(int i=0; i<96; i++) {
    if(MF.isPhysRegUsed(RegsInOrder[i]))
      numStackedGPRsUsed=i+1; // (i+1 and not ++ - consider fn(fp, fp, int)
  }

  unsigned numOutRegsUsed=MF.getInfo<IA64FunctionInfo>()->outRegsUsed;

  // XXX FIXME : this code should be a bit more reliable (in case there _isn't_ a pseudo_alloc in the MBB)
  unsigned dstRegOfPseudoAlloc;
  for(MBBI = MBB.begin(); /*MBBI->getOpcode() != IA64::PSEUDO_ALLOC*/; ++MBBI) {
    assert(MBBI != MBB.end());
    if(MBBI->getOpcode() == IA64::PSEUDO_ALLOC) {
      dstRegOfPseudoAlloc=MBBI->getOperand(0).getReg();
      break;
    }
  }

  MI=BuildMI(IA64::ALLOC,5).addReg(dstRegOfPseudoAlloc).addImm(0).\
     addImm(numStackedGPRsUsed).addImm(numOutRegsUsed).addImm(0);
  MBB.insert(MBBI, MI);

  // Get the number of bytes to allocate from the FrameInfo
  unsigned NumBytes = MFI->getStackSize();

  if (MFI->hasCalls() && !FP) {
    // We reserve argument space for call sites in the function immediately on
    // entry to the current function.  This eliminates the need for add/sub
    // brackets around call sites.
    NumBytes += MFI->getMaxCallFrameSize();
  }

  if(FP)
    NumBytes += 8; // reserve space for the old FP

  // Do we need to allocate space on the stack?
  if (NumBytes == 0)
    return;

  // Add 16 bytes at the bottom of the stack (scratch area)
  // and round the size to a multiple of the alignment.
  unsigned Align = MF.getTarget().getFrameInfo()->getStackAlignment();
  unsigned Size = 16 + (FP ? 8 : 0);
  NumBytes = (NumBytes+Size+Align-1)/Align*Align;

  // Update frame info to pretend that this is part of the stack...
  MFI->setStackSize(NumBytes);

  // adjust stack pointer: r12 -= numbytes
  if (NumBytes <= 8191) {
    MI=BuildMI(IA64::ADDIMM22, 2, IA64::r12).addReg(IA64::r12).addImm(-NumBytes);
    MBB.insert(MBBI, MI);
  } else { // we use r22 as a scratch register here
    MI=BuildMI(IA64::MOVLIMM64, 1, IA64::r22).addSImm(-NumBytes);
    // FIXME: MOVLSI32 expects a _u_32imm
    MBB.insert(MBBI, MI);  // first load the decrement into r22
    MI=BuildMI(IA64::ADD, 2, IA64::r12).addReg(IA64::r12).addReg(IA64::r22);
    MBB.insert(MBBI, MI);  // then add (subtract) it to r12 (stack ptr)
  }

  // now if we need to, save the old FP and set the new
  if (FP) {
    MI = BuildMI(IA64::ST8, 2).addReg(IA64::r12).addReg(IA64::r5);
    MBB.insert(MBBI, MI);
    // this must be the last instr in the prolog ?  (XXX: why??)
    MI = BuildMI(IA64::MOV, 1, IA64::r5).addReg(IA64::r12);
    MBB.insert(MBBI, MI);
  }

}

void IA64RegisterInfo::emitEpilogue(MachineFunction &MF,
                                   MachineBasicBlock &MBB) const {
  const MachineFrameInfo *MFI = MF.getFrameInfo();
  MachineBasicBlock::iterator MBBI = prior(MBB.end());
  MachineInstr *MI;
  assert(MBBI->getOpcode() == IA64::RET &&
         "Can only insert epilog into returning blocks");

  bool FP = hasFP(MF);

  // Get the number of bytes allocated from the FrameInfo...
  unsigned NumBytes = MFI->getStackSize();

  //now if we need to, restore the old FP
  if (FP)
  {
    //copy the FP into the SP (discards allocas)
    MI=BuildMI(IA64::MOV, 1, IA64::r12).addReg(IA64::r5);
    MBB.insert(MBBI, MI);
    //restore the FP
    MI=BuildMI(IA64::LD8, 1, IA64::r5).addReg(IA64::r5);
    MBB.insert(MBBI, MI);
  }

  if (NumBytes != 0)
  {
    if (NumBytes <= 8191) {
      MI=BuildMI(IA64::ADDIMM22, 2, IA64::r12).addReg(IA64::r12).addImm(NumBytes);
      MBB.insert(MBBI, MI);
    } else {
      MI=BuildMI(IA64::MOVLIMM64, 1, IA64::r22).addImm(NumBytes);
      MBB.insert(MBBI, MI);
      MI=BuildMI(IA64::ADD, 2, IA64::r12).addReg(IA64::r12).addReg(IA64::r22);
      MBB.insert(MBBI, MI);
    }
  }

}

unsigned IA64RegisterInfo::getFrameRegister(MachineFunction &MF) const {
  return getDwarfRegNum(hasFP(MF) ? IA64::r5 : IA64::r12);
}

#include "IA64GenRegisterInfo.inc"