/// calculateCalleeSavedRegisters - Scan the function for modified callee saved
/// registers.
void PEI::calculateCalleeSavedRegisters(MachineFunction &Fn) {
const TargetRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
const TargetFrameLowering *TFI = Fn.getTarget().getFrameLowering();
MachineFrameInfo *MFI = Fn.getFrameInfo();
// Get the callee saved register list...
const unsigned *CSRegs = RegInfo->getCalleeSavedRegs(&Fn);
// These are used to keep track the callee-save area. Initialize them.
MinCSFrameIndex = INT_MAX;
MaxCSFrameIndex = 0;
// Early exit for targets which have no callee saved registers.
if (CSRegs == 0 || CSRegs[0] == 0)
return;
// In Naked functions we aren't going to save any registers.
if (Fn.getFunction()->hasFnAttr(Attribute::Naked))
return;
std::vector<CalleeSavedInfo> CSI;
for (unsigned i = 0; CSRegs[i]; ++i) {
unsigned Reg = CSRegs[i];
if (Fn.getRegInfo().isPhysRegUsed(Reg)) {
// If the reg is modified, save it!
CSI.push_back(CalleeSavedInfo(Reg));
} else {
for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
*AliasSet; ++AliasSet) { // Check alias registers too.
if (Fn.getRegInfo().isPhysRegUsed(*AliasSet)) {
CSI.push_back(CalleeSavedInfo(Reg));
break;
}
}
}
}
if (CSI.empty())
return; // Early exit if no callee saved registers are modified!
unsigned NumFixedSpillSlots;
const TargetFrameLowering::SpillSlot *FixedSpillSlots =
TFI->getCalleeSavedSpillSlots(NumFixedSpillSlots);
// Now that we know which registers need to be saved and restored, allocate
// stack slots for them.
for (std::vector<CalleeSavedInfo>::iterator
I = CSI.begin(), E = CSI.end(); I != E; ++I) {
unsigned Reg = I->getReg();
const TargetRegisterClass *RC = RegInfo->getMinimalPhysRegClass(Reg);
int FrameIdx;
if (RegInfo->hasReservedSpillSlot(Fn, Reg, FrameIdx)) {
I->setFrameIdx(FrameIdx);
continue;
}
// Check to see if this physreg must be spilled to a particular stack slot
// on this target.
const TargetFrameLowering::SpillSlot *FixedSlot = FixedSpillSlots;
while (FixedSlot != FixedSpillSlots+NumFixedSpillSlots &&
FixedSlot->Reg != Reg)
++FixedSlot;
if (FixedSlot == FixedSpillSlots + NumFixedSpillSlots) {
// Nope, just spill it anywhere convenient.
unsigned Align = RC->getAlignment();
unsigned StackAlign = TFI->getStackAlignment();
// We may not be able to satisfy the desired alignment specification of
// the TargetRegisterClass if the stack alignment is smaller. Use the
// min.
Align = std::min(Align, StackAlign);
FrameIdx = MFI->CreateStackObject(RC->getSize(), Align, true);
if ((unsigned)FrameIdx < MinCSFrameIndex) MinCSFrameIndex = FrameIdx;
if ((unsigned)FrameIdx > MaxCSFrameIndex) MaxCSFrameIndex = FrameIdx;
} else {
// Spill it to the stack where we must.
FrameIdx = MFI->CreateFixedObject(RC->getSize(), FixedSlot->Offset, true);
}
I->setFrameIdx(FrameIdx);
}
MFI->setCalleeSavedInfo(CSI);
}
void PEI::assignCalleeSavedSpillSlots(MachineFunction &F,
const BitVector &SavedRegs) {
// These are used to keep track the callee-save area. Initialize them.
MinCSFrameIndex = INT_MAX;
MaxCSFrameIndex = 0;
if (SavedRegs.empty())
return;
const TargetRegisterInfo *RegInfo = F.getSubtarget().getRegisterInfo();
const MCPhysReg *CSRegs = RegInfo->getCalleeSavedRegs(&F);
std::vector<CalleeSavedInfo> CSI;
for (unsigned i = 0; CSRegs[i]; ++i) {
unsigned Reg = CSRegs[i];
if (SavedRegs.test(Reg))
CSI.push_back(CalleeSavedInfo(Reg));
}
const TargetFrameLowering *TFI = F.getSubtarget().getFrameLowering();
MachineFrameInfo *MFI = F.getFrameInfo();
if (!TFI->assignCalleeSavedSpillSlots(F, RegInfo, CSI)) {
// If target doesn't implement this, use generic code.
if (CSI.empty())
return; // Early exit if no callee saved registers are modified!
unsigned NumFixedSpillSlots;
const TargetFrameLowering::SpillSlot *FixedSpillSlots =
TFI->getCalleeSavedSpillSlots(NumFixedSpillSlots);
// Now that we know which registers need to be saved and restored, allocate
// stack slots for them.
for (std::vector<CalleeSavedInfo>::iterator I = CSI.begin(), E = CSI.end();
I != E; ++I) {
unsigned Reg = I->getReg();
const TargetRegisterClass *RC = RegInfo->getMinimalPhysRegClass(Reg);
int FrameIdx;
if (RegInfo->hasReservedSpillSlot(F, Reg, FrameIdx)) {
I->setFrameIdx(FrameIdx);
continue;
}
// Check to see if this physreg must be spilled to a particular stack slot
// on this target.
const TargetFrameLowering::SpillSlot *FixedSlot = FixedSpillSlots;
while (FixedSlot != FixedSpillSlots + NumFixedSpillSlots &&
FixedSlot->Reg != Reg)
++FixedSlot;
if (FixedSlot == FixedSpillSlots + NumFixedSpillSlots) {
// Nope, just spill it anywhere convenient.
unsigned Align = RC->getAlignment();
unsigned StackAlign = TFI->getStackAlignment();
// We may not be able to satisfy the desired alignment specification of
// the TargetRegisterClass if the stack alignment is smaller. Use the
// min.
Align = std::min(Align, StackAlign);
FrameIdx = MFI->CreateStackObject(RC->getSize(), Align, true);
if ((unsigned)FrameIdx < MinCSFrameIndex) MinCSFrameIndex = FrameIdx;
if ((unsigned)FrameIdx > MaxCSFrameIndex) MaxCSFrameIndex = FrameIdx;
} else {
// Spill it to the stack where we must.
FrameIdx =
MFI->CreateFixedSpillStackObject(RC->getSize(), FixedSlot->Offset);
}
I->setFrameIdx(FrameIdx);
}
}
MFI->setCalleeSavedInfo(CSI);
}
