-//===----------------------------------------------------------------------===//
-//
-// Stack Frame Processing methods
-// +----------------------------+
-//
-// The stack is allocated decrementing the stack pointer on
-// the first instruction of a function prologue. Once decremented,
-// all stack referencesare are done thought a positive offset
-// from the stack/frame pointer, so the stack is considering
-// to grow up! Otherwise terrible hacks would have to be made
-// to get this stack ABI compliant :)
-//
-// The stack frame required by the ABI (after call):
-// Offset
-//
-// 0 ----------
-// 4 Args to pass
-// . saved $GP (used in PIC)
-// . Alloca allocations
-// . Local Area
-// . CPU "Callee Saved" Registers
-// . saved FP
-// . saved RA
-// . FPU "Callee Saved" Registers
-// StackSize -----------
-//
-// Offset - offset from sp after stack allocation on function prologue
-//
-// The sp is the stack pointer subtracted/added from the stack size
-// at the Prologue/Epilogue
-//
-// References to the previous stack (to obtain arguments) are done
-// with offsets that exceeds the stack size: (stacksize+(4*(num_arg-1))
-//
-// Examples:
-// - reference to the actual stack frame
-// for any local area var there is smt like : FI >= 0, StackOffset: 4
-// sw REGX, 4(SP)
-//
-// - reference to previous stack frame
-// suppose there's a load to the 5th arguments : FI < 0, StackOffset: 16.
-// The emitted instruction will be something like:
-// lw REGX, 16+StackSize(SP)
-//
-// Since the total stack size is unknown on LowerFORMAL_ARGUMENTS, all
-// stack references (ObjectOffset) created to reference the function
-// arguments, are negative numbers. This way, on eliminateFrameIndex it's
-// possible to detect those references and the offsets are adjusted to
-// their real location.
-//
-//===----------------------------------------------------------------------===//
-
-void MipsRegisterInfo::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();
-
- // 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
- // LowerFORMAL_ARGUMENTS. 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());
-
- // 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 = 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 there is the need. This whole Area must
- // be aligned to the default Stack Alignment requirements.
- unsigned StackOffset = 0;
- unsigned RegSize = Subtarget.isGP32bit() ? 4 : 8;
-
- 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) {
- if (CSI[i].getRegClass() != Mips::CPURegsRegisterClass)
- break;
- MFI->setObjectOffset(CSI[i].getFrameIdx(), StackOffset);
- TopCPUSavedRegOff = StackOffset;
- StackOffset += MFI->getObjectAlignment(CSI[i].getFrameIdx());
- }
-
- if (hasFP(MF)) {
- MFI->setObjectOffset(MFI->CreateStackObject(RegSize, RegSize),
- StackOffset);
- MipsFI->setFPStackOffset(StackOffset);
- TopCPUSavedRegOff = StackOffset;
- StackOffset += RegSize;
- }
-
- if (MFI->hasCalls()) {
- MFI->setObjectOffset(MFI->CreateStackObject(RegSize, RegSize),
- StackOffset);
- MipsFI->setRAStackOffset(StackOffset);
- TopCPUSavedRegOff = StackOffset;
- StackOffset += 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) {
- if (CSI[i].getRegClass() == Mips::CPURegsRegisterClass)
- 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);
-}
-
-// 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.
-bool MipsRegisterInfo::
-hasFP(const MachineFunction &MF) const {
- const MachineFrameInfo *MFI = MF.getFrameInfo();
- return NoFramePointerElim || MFI->hasVarSizedObjects();
-}
-
-// This function eliminate ADJCALLSTACKDOWN,