void MipsFrameInfo::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front();
MachineFrameInfo *MFI = MF.getFrameInfo();
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
const MipsRegisterInfo *RegInfo =
static_cast<const MipsRegisterInfo*>(MF.getTarget().getRegisterInfo());
const MipsInstrInfo &TII =
*static_cast<const MipsInstrInfo*>(MF.getTarget().getInstrInfo());
MachineBasicBlock::iterator MBBI = MBB.begin();
DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
bool isPIC = (MF.getTarget().getRelocationModel() == Reloc::PIC_);
// Get the right frame order for Mips.
adjustMipsStackFrame(MF);
// Get the number of bytes to allocate from the FrameInfo.
unsigned StackSize = MFI->getStackSize();
// No need to allocate space on the stack.
if (StackSize == 0 && !MFI->adjustsStack()) return;
int FPOffset = MipsFI->getFPStackOffset();
int RAOffset = MipsFI->getRAStackOffset();
BuildMI(MBB, MBBI, dl, TII.get(Mips::NOREORDER));
// TODO: check need from GP here.
if (isPIC && STI.isABI_O32())
BuildMI(MBB, MBBI, dl, TII.get(Mips::CPLOAD))
.addReg(RegInfo->getPICCallReg());
BuildMI(MBB, MBBI, dl, TII.get(Mips::NOMACRO));
// Adjust stack : addi sp, sp, (-imm)
BuildMI(MBB, MBBI, dl, TII.get(Mips::ADDiu), Mips::SP)
.addReg(Mips::SP).addImm(-StackSize);
// Save the return address only if the function isnt a leaf one.
// sw $ra, stack_loc($sp)
if (MFI->adjustsStack()) {
BuildMI(MBB, MBBI, dl, TII.get(Mips::SW))
.addReg(Mips::RA).addImm(RAOffset).addReg(Mips::SP);
}
// if framepointer enabled, save it and set it
// to point to the stack pointer
if (hasFP(MF)) {
// sw $fp,stack_loc($sp)
BuildMI(MBB, MBBI, dl, TII.get(Mips::SW))
.addReg(Mips::FP).addImm(FPOffset).addReg(Mips::SP);
// move $fp, $sp
BuildMI(MBB, MBBI, dl, TII.get(Mips::ADDu), Mips::FP)
.addReg(Mips::SP).addReg(Mips::ZERO);
}
// Restore GP from the saved stack location
if (MipsFI->needGPSaveRestore())
BuildMI(MBB, MBBI, dl, TII.get(Mips::CPRESTORE))
.addImm(MipsFI->getGPStackOffset());
}
void MipsRegisterInfo::
processFunctionBeforeFrameFinalized(MachineFunction &MF) const {
// Set the stack offset where GP must be saved/loaded from.
MachineFrameInfo *MFI = MF.getFrameInfo();
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
if (MipsFI->needGPSaveRestore())
MFI->setObjectOffset(MipsFI->getGPFI(), MipsFI->getGPStackOffset());
}
void MipsFrameInfo::adjustMipsStackFrame(MachineFunction &MF) const {
MachineFrameInfo *MFI = MF.getFrameInfo();
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
unsigned StackAlign = MF.getTarget().getFrameInfo()->getStackAlignment();
unsigned RegSize = STI.isGP32bit() ? 4 : 8;
bool HasGP = MipsFI->needGPSaveRestore();
// Min and Max CSI FrameIndex.
int MinCSFI = -1, MaxCSFI = -1;
// See the description at MipsMachineFunction.h
int TopCPUSavedRegOff = -1, TopFPUSavedRegOff = -1;
// Replace the dummy '0' SPOffset by the negative offsets, as explained on
// LowerFormalArguments. Leaving '0' for while is necessary to avoid the
// approach done by calculateFrameObjectOffsets to the stack frame.
MipsFI->adjustLoadArgsFI(MFI);
MipsFI->adjustStoreVarArgsFI(MFI);
// It happens that the default stack frame allocation order does not directly
// map to the convention used for mips. So we must fix it. We move the callee
// save register slots after the local variables area, as described in the
// stack frame above.
unsigned CalleeSavedAreaSize = 0;
if (!CSI.empty()) {
MinCSFI = CSI[0].getFrameIdx();
MaxCSFI = CSI[CSI.size()-1].getFrameIdx();
}
for (unsigned i = 0, e = CSI.size(); i != e; ++i)
CalleeSavedAreaSize += MFI->getObjectAlignment(CSI[i].getFrameIdx());
unsigned StackOffset = HasGP ? (MipsFI->getGPStackOffset()+RegSize)
: (STI.isABI_O32() ? 16 : 0);
// Adjust local variables. They should come on the stack right
// after the arguments.
int LastOffsetFI = -1;
for (int i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
if (i >= MinCSFI && i <= MaxCSFI)
continue;
if (MFI->isDeadObjectIndex(i))
continue;
unsigned Offset =
StackOffset + MFI->getObjectOffset(i) - CalleeSavedAreaSize;
if (LastOffsetFI == -1)
LastOffsetFI = i;
if (Offset > MFI->getObjectOffset(LastOffsetFI))
LastOffsetFI = i;
MFI->setObjectOffset(i, Offset);
}
// Adjust CPU Callee Saved Registers Area. Registers RA and FP must
// be saved in this CPU Area. This whole area must be aligned to the
// default Stack Alignment requirements.
if (LastOffsetFI >= 0)
StackOffset = MFI->getObjectOffset(LastOffsetFI)+
MFI->getObjectSize(LastOffsetFI);
StackOffset = ((StackOffset+StackAlign-1)/StackAlign*StackAlign);
for (unsigned i = 0, e = CSI.size(); i != e ; ++i) {
unsigned Reg = CSI[i].getReg();
if (!Mips::CPURegsRegisterClass->contains(Reg))
break;
MFI->setObjectOffset(CSI[i].getFrameIdx(), StackOffset);
TopCPUSavedRegOff = StackOffset;
StackOffset += MFI->getObjectAlignment(CSI[i].getFrameIdx());
}
// Stack locations for FP and RA. If only one of them is used,
// the space must be allocated for both, otherwise no space at all.
if (hasFP(MF) || MFI->adjustsStack()) {
// FP stack location
MFI->setObjectOffset(MFI->CreateStackObject(RegSize, RegSize, true),
StackOffset);
MipsFI->setFPStackOffset(StackOffset);
TopCPUSavedRegOff = StackOffset;
StackOffset += RegSize;
// SP stack location
MFI->setObjectOffset(MFI->CreateStackObject(RegSize, RegSize, true),
StackOffset);
MipsFI->setRAStackOffset(StackOffset);
StackOffset += RegSize;
if (MFI->adjustsStack())
TopCPUSavedRegOff += RegSize;
}
StackOffset = ((StackOffset+StackAlign-1)/StackAlign*StackAlign);
// Adjust FPU Callee Saved Registers Area. This Area must be
// aligned to the default Stack Alignment requirements.
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
unsigned Reg = CSI[i].getReg();
if (Mips::CPURegsRegisterClass->contains(Reg))
continue;
MFI->setObjectOffset(CSI[i].getFrameIdx(), StackOffset);
TopFPUSavedRegOff = StackOffset;
StackOffset += MFI->getObjectAlignment(CSI[i].getFrameIdx());
}
StackOffset = ((StackOffset+StackAlign-1)/StackAlign*StackAlign);
// Update frame info
MFI->setStackSize(StackOffset);
// Recalculate the final tops offset. The final values must be '0'
// if there isn't a callee saved register for CPU or FPU, otherwise
// a negative offset is needed.
if (TopCPUSavedRegOff >= 0)
MipsFI->setCPUTopSavedRegOff(TopCPUSavedRegOff-StackOffset);
if (TopFPUSavedRegOff >= 0)
MipsFI->setFPUTopSavedRegOff(TopFPUSavedRegOff-StackOffset);
}
