-//=======- MipsFrameLowering.cpp - Mips Frame Information ------*- C++ -*-====//
+//===-- MipsFrameLowering.cpp - Mips Frame Information --------------------===//
//
// The LLVM Compiler Infrastructure
//
//
//===----------------------------------------------------------------------===//
+#include "MipsAnalyzeImmediate.h"
#include "MipsFrameLowering.h"
#include "MipsInstrInfo.h"
#include "MipsMachineFunction.h"
+#include "MCTargetDesc/MipsBaseInfo.h"
#include "llvm/Function.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
// if frame pointer elimination is disabled.
bool MipsFrameLowering::hasFP(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
- return DisableFramePointerElim(MF) || MFI->hasVarSizedObjects();
+ return MF.getTarget().Options.DisableFramePointerElim(MF) ||
+ MFI->hasVarSizedObjects() || MFI->isFrameAddressTaken();
}
-void MipsFrameLowering::adjustMipsStackFrame(MachineFunction &MF) const {
- MachineFrameInfo *MFI = MF.getFrameInfo();
- MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
- const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
- unsigned StackAlign = 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);
+bool MipsFrameLowering::targetHandlesStackFrameRounding() const {
+ return true;
}
-
-// expand pair of register and immediate if the immediate doesn't fit in the 16-bit
-// offset field.
-// e.g.
-// if OrigImm = 0x10000, OrigReg = $sp:
-// generate the following sequence of instrs:
-// lui $at, hi(0x10000)
-// addu $at, $sp, $at
-//
-// (NewReg, NewImm) = ($at, lo(Ox10000))
-// return true
-static bool expandRegLargeImmPair(unsigned OrigReg, int OrigImm,
- unsigned& NewReg, int& NewImm,
- MachineBasicBlock& MBB, MachineBasicBlock::iterator I) {
- // OrigImm fits in the 16-bit field
- if (OrigImm < 0x8000 && OrigImm >= -0x8000) {
- NewReg = OrigReg;
- NewImm = OrigImm;
- return false;
- }
-
- MachineFunction* MF = MBB.getParent();
- const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
- DebugLoc DL = I->getDebugLoc();
- int ImmLo = OrigImm & 0xffff;
- int ImmHi = (((unsigned)OrigImm & 0xffff0000) >> 16) + ((OrigImm & 0x8000) != 0);
+// Build an instruction sequence to load an immediate that is too large to fit
+// in 16-bit and add the result to Reg.
+static void expandLargeImm(unsigned Reg, int64_t Imm, bool IsN64,
+ const MipsInstrInfo &TII, MachineBasicBlock& MBB,
+ MachineBasicBlock::iterator II, DebugLoc DL) {
+ unsigned LUi = IsN64 ? Mips::LUi64 : Mips::LUi;
+ unsigned ADDu = IsN64 ? Mips::DADDu : Mips::ADDu;
+ unsigned ZEROReg = IsN64 ? Mips::ZERO_64 : Mips::ZERO;
+ unsigned ATReg = IsN64 ? Mips::AT_64 : Mips::AT;
+ MipsAnalyzeImmediate AnalyzeImm;
+ const MipsAnalyzeImmediate::InstSeq &Seq =
+ AnalyzeImm.Analyze(Imm, IsN64 ? 64 : 32, false /* LastInstrIsADDiu */);
+ MipsAnalyzeImmediate::InstSeq::const_iterator Inst = Seq.begin();
// FIXME: change this when mips goes MC".
- BuildMI(MBB, I, DL, TII->get(Mips::NOAT));
- BuildMI(MBB, I, DL, TII->get(Mips::LUi), Mips::AT).addImm(ImmHi);
- BuildMI(MBB, I, DL, TII->get(Mips::ADDu), Mips::AT).addReg(OrigReg).addReg(Mips::AT);
- NewReg = Mips::AT;
- NewImm = ImmLo;
-
- return true;
+ BuildMI(MBB, II, DL, TII.get(Mips::NOAT));
+
+ // The first instruction can be a LUi, which is different from other
+ // instructions (ADDiu, ORI and SLL) in that it does not have a register
+ // operand.
+ if (Inst->Opc == LUi)
+ BuildMI(MBB, II, DL, TII.get(LUi), ATReg)
+ .addImm(SignExtend64<16>(Inst->ImmOpnd));
+ else
+ BuildMI(MBB, II, DL, TII.get(Inst->Opc), ATReg).addReg(ZEROReg)
+ .addImm(SignExtend64<16>(Inst->ImmOpnd));
+
+ // Build the remaining instructions in Seq.
+ for (++Inst; Inst != Seq.end(); ++Inst)
+ BuildMI(MBB, II, DL, TII.get(Inst->Opc), ATReg).addReg(ATReg)
+ .addImm(SignExtend64<16>(Inst->ImmOpnd));
+
+ BuildMI(MBB, II, DL, TII.get(ADDu), Reg).addReg(Reg).addReg(ATReg);
+ BuildMI(MBB, II, DL, TII.get(Mips::ATMACRO));
}
void MipsFrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock::iterator MBBI = MBB.begin();
DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
bool isPIC = (MF.getTarget().getRelocationModel() == Reloc::PIC_);
- unsigned NewReg = 0;
- int NewImm = 0;
- bool ATUsed;
+ unsigned SP = STI.isABI_N64() ? Mips::SP_64 : Mips::SP;
+ unsigned FP = STI.isABI_N64() ? Mips::FP_64 : Mips::FP;
+ unsigned ZERO = STI.isABI_N64() ? Mips::ZERO_64 : Mips::ZERO;
+ unsigned ADDu = STI.isABI_N64() ? Mips::DADDu : Mips::ADDu;
+ unsigned ADDiu = STI.isABI_N64() ? Mips::DADDiu : Mips::ADDiu;
- // Get the right frame order for Mips.
- adjustMipsStackFrame(MF);
+ // First, compute final stack size.
+ unsigned RegSize = STI.isGP32bit() ? 4 : 8;
+ unsigned StackAlign = getStackAlignment();
+ unsigned LocalVarAreaOffset = MipsFI->needGPSaveRestore() ?
+ (MFI->getObjectOffset(MipsFI->getGPFI()) + RegSize) :
+ MipsFI->getMaxCallFrameSize();
+ uint64_t StackSize = RoundUpToAlignment(LocalVarAreaOffset, StackAlign) +
+ RoundUpToAlignment(MFI->getStackSize(), StackAlign);
+
+ // Update stack size
+ MFI->setStackSize(StackSize);
- // Get the number of bytes to allocate from the FrameInfo.
- unsigned StackSize = MFI->getStackSize();
+ BuildMI(MBB, MBBI, dl, TII.get(Mips::NOREORDER));
+ BuildMI(MBB, MBBI, dl, TII.get(Mips::NOMACRO));
+
+ // Emit instructions that set the global base register if the target ABI is
+ // O32.
+ if (isPIC && MipsFI->globalBaseRegSet() && STI.isABI_O32()) {
+ if (MipsFI->globalBaseRegFixed())
+ BuildMI(MBB, llvm::prior(MBBI), dl, TII.get(Mips::CPLOAD))
+ .addReg(RegInfo->getPICCallReg());
+ else
+ // See MipsInstrInfo.td for explanation.
+ BuildMI(MBB, MBBI, dl, TII.get(Mips:: SETGP01), Mips::V0);
+ }
// No need to allocate space on the stack.
if (StackSize == 0 && !MFI->adjustsStack()) return;
- int FPOffset = MipsFI->getFPStackOffset();
- int RAOffset = MipsFI->getRAStackOffset();
+ MachineModuleInfo &MMI = MF.getMMI();
+ std::vector<MachineMove> &Moves = MMI.getFrameMoves();
+ MachineLocation DstML, SrcML;
- BuildMI(MBB, MBBI, dl, TII.get(Mips::NOREORDER));
+ // Adjust stack.
+ if (isInt<16>(-StackSize)) // addi sp, sp, (-stacksize)
+ BuildMI(MBB, MBBI, dl, TII.get(ADDiu), SP).addReg(SP).addImm(-StackSize);
+ else // Expand immediate that doesn't fit in 16-bit.
+ expandLargeImm(SP, -StackSize, STI.isABI_N64(), TII, MBB, MBBI, dl);
- // 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));
+ // emit ".cfi_def_cfa_offset StackSize"
+ MCSymbol *AdjustSPLabel = MMI.getContext().CreateTempSymbol();
+ BuildMI(MBB, MBBI, dl,
+ TII.get(TargetOpcode::PROLOG_LABEL)).addSym(AdjustSPLabel);
+ DstML = MachineLocation(MachineLocation::VirtualFP);
+ SrcML = MachineLocation(MachineLocation::VirtualFP, -StackSize);
+ Moves.push_back(MachineMove(AdjustSPLabel, DstML, SrcML));
- // Adjust stack : addi sp, sp, (-imm)
- ATUsed = expandRegLargeImmPair(Mips::SP, -StackSize, NewReg, NewImm, MBB,
- MBBI);
- BuildMI(MBB, MBBI, dl, TII.get(Mips::ADDiu), Mips::SP)
- .addReg(NewReg).addImm(NewImm);
+ const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
- // FIXME: change this when mips goes MC".
- if (ATUsed)
- BuildMI(MBB, MBBI, dl, TII.get(Mips::ATMACRO));
-
- // Save the return address only if the function isnt a leaf one.
- // sw $ra, stack_loc($sp)
- if (MFI->adjustsStack()) {
- ATUsed = expandRegLargeImmPair(Mips::SP, RAOffset, NewReg, NewImm, MBB,
- MBBI);
- BuildMI(MBB, MBBI, dl, TII.get(Mips::SW))
- .addReg(Mips::RA).addImm(NewImm).addReg(NewReg);
-
- // FIXME: change this when mips goes MC".
- if (ATUsed)
- BuildMI(MBB, MBBI, dl, TII.get(Mips::ATMACRO));
+ if (CSI.size()) {
+ // Find the instruction past the last instruction that saves a callee-saved
+ // register to the stack.
+ for (unsigned i = 0; i < CSI.size(); ++i)
+ ++MBBI;
+
+ // Iterate over list of callee-saved registers and emit .cfi_offset
+ // directives.
+ MCSymbol *CSLabel = MMI.getContext().CreateTempSymbol();
+ BuildMI(MBB, MBBI, dl,
+ TII.get(TargetOpcode::PROLOG_LABEL)).addSym(CSLabel);
+
+ for (std::vector<CalleeSavedInfo>::const_iterator I = CSI.begin(),
+ E = CSI.end(); I != E; ++I) {
+ int64_t Offset = MFI->getObjectOffset(I->getFrameIdx());
+ unsigned Reg = I->getReg();
+
+ // If Reg is a double precision register, emit two cfa_offsets,
+ // one for each of the paired single precision registers.
+ if (Mips::AFGR64RegisterClass->contains(Reg)) {
+ const uint16_t *SubRegs = RegInfo->getSubRegisters(Reg);
+ MachineLocation DstML0(MachineLocation::VirtualFP, Offset);
+ MachineLocation DstML1(MachineLocation::VirtualFP, Offset + 4);
+ MachineLocation SrcML0(*SubRegs);
+ MachineLocation SrcML1(*(SubRegs + 1));
+
+ if (!STI.isLittle())
+ std::swap(SrcML0, SrcML1);
+
+ Moves.push_back(MachineMove(CSLabel, DstML0, SrcML0));
+ Moves.push_back(MachineMove(CSLabel, DstML1, SrcML1));
+ }
+ else {
+ // Reg is either in CPURegs or FGR32.
+ DstML = MachineLocation(MachineLocation::VirtualFP, Offset);
+ SrcML = MachineLocation(Reg);
+ Moves.push_back(MachineMove(CSLabel, DstML, SrcML));
+ }
+ }
}
- // if framepointer enabled, save it and set it
- // to point to the stack pointer
+ // if framepointer enabled, set it to point to the stack pointer.
if (hasFP(MF)) {
- // sw $fp,stack_loc($sp)
- ATUsed = expandRegLargeImmPair(Mips::SP, FPOffset, NewReg, NewImm, MBB,
- MBBI);
- BuildMI(MBB, MBBI, dl, TII.get(Mips::SW))
- .addReg(Mips::FP).addImm(NewImm).addReg(NewReg);
-
- // FIXME: change this when mips goes MC".
- if (ATUsed)
- BuildMI(MBB, MBBI, dl, TII.get(Mips::ATMACRO));
-
- // move $fp, $sp
- BuildMI(MBB, MBBI, dl, TII.get(Mips::ADDu), Mips::FP)
- .addReg(Mips::SP).addReg(Mips::ZERO);
+ // Insert instruction "move $fp, $sp" at this location.
+ BuildMI(MBB, MBBI, dl, TII.get(ADDu), FP).addReg(SP).addReg(ZERO);
+
+ // emit ".cfi_def_cfa_register $fp"
+ MCSymbol *SetFPLabel = MMI.getContext().CreateTempSymbol();
+ BuildMI(MBB, MBBI, dl,
+ TII.get(TargetOpcode::PROLOG_LABEL)).addSym(SetFPLabel);
+ DstML = MachineLocation(FP);
+ SrcML = MachineLocation(MachineLocation::VirtualFP);
+ Moves.push_back(MachineMove(SetFPLabel, DstML, SrcML));
}
// Restore GP from the saved stack location
- if (MipsFI->needGPSaveRestore())
- BuildMI(MBB, MBBI, dl, TII.get(Mips::CPRESTORE))
- .addImm(MipsFI->getGPStackOffset());
+ if (MipsFI->needGPSaveRestore()) {
+ unsigned Offset = MFI->getObjectOffset(MipsFI->getGPFI());
+ BuildMI(MBB, MBBI, dl, TII.get(Mips::CPRESTORE)).addImm(Offset);
+
+ if (Offset >= 0x8000) {
+ BuildMI(MBB, llvm::prior(MBBI), dl, TII.get(Mips::MACRO));
+ BuildMI(MBB, MBBI, dl, TII.get(Mips::NOMACRO));
+ }
+ }
}
void MipsFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
MachineFrameInfo *MFI = MF.getFrameInfo();
- MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
const MipsInstrInfo &TII =
*static_cast<const MipsInstrInfo*>(MF.getTarget().getInstrInfo());
DebugLoc dl = MBBI->getDebugLoc();
+ unsigned SP = STI.isABI_N64() ? Mips::SP_64 : Mips::SP;
+ unsigned FP = STI.isABI_N64() ? Mips::FP_64 : Mips::FP;
+ unsigned ZERO = STI.isABI_N64() ? Mips::ZERO_64 : Mips::ZERO;
+ unsigned ADDu = STI.isABI_N64() ? Mips::DADDu : Mips::ADDu;
+ unsigned ADDiu = STI.isABI_N64() ? Mips::DADDiu : Mips::ADDiu;
- // Get the number of bytes from FrameInfo
- int NumBytes = (int) MFI->getStackSize();
-
- // Get the FI's where RA and FP are saved.
- int FPOffset = MipsFI->getFPStackOffset();
- int RAOffset = MipsFI->getRAStackOffset();
+ // if framepointer enabled, restore the stack pointer.
+ if (hasFP(MF)) {
+ // Find the first instruction that restores a callee-saved register.
+ MachineBasicBlock::iterator I = MBBI;
- unsigned NewReg = 0;
- int NewImm = 0;
- bool ATUsed = false;
+ for (unsigned i = 0; i < MFI->getCalleeSavedInfo().size(); ++i)
+ --I;
- // if framepointer enabled, restore it and restore the
- // stack pointer
- if (hasFP(MF)) {
- // move $sp, $fp
- BuildMI(MBB, MBBI, dl, TII.get(Mips::ADDu), Mips::SP)
- .addReg(Mips::FP).addReg(Mips::ZERO);
-
- // lw $fp,stack_loc($sp)
- ATUsed = expandRegLargeImmPair(Mips::SP, FPOffset, NewReg, NewImm, MBB,
- MBBI);
- BuildMI(MBB, MBBI, dl, TII.get(Mips::LW), Mips::FP)
- .addImm(NewImm).addReg(NewReg);
-
- // FIXME: change this when mips goes MC".
- if (ATUsed)
- BuildMI(MBB, MBBI, dl, TII.get(Mips::ATMACRO));
+ // Insert instruction "move $sp, $fp" at this location.
+ BuildMI(MBB, I, dl, TII.get(ADDu), SP).addReg(FP).addReg(ZERO);
}
- // Restore the return address only if the function isnt a leaf one.
- // lw $ra, stack_loc($sp)
- if (MFI->adjustsStack()) {
- ATUsed = expandRegLargeImmPair(Mips::SP, RAOffset, NewReg, NewImm, MBB,
- MBBI);
- BuildMI(MBB, MBBI, dl, TII.get(Mips::LW), Mips::RA)
- .addImm(NewImm).addReg(NewReg);
-
- // FIXME: change this when mips goes MC".
- if (ATUsed)
- BuildMI(MBB, MBBI, dl, TII.get(Mips::ATMACRO));
- }
+ // Get the number of bytes from FrameInfo
+ uint64_t StackSize = MFI->getStackSize();
- // adjust stack : insert addi sp, sp, (imm)
- if (NumBytes) {
- ATUsed = expandRegLargeImmPair(Mips::SP, NumBytes, NewReg, NewImm, MBB,
- MBBI);
- BuildMI(MBB, MBBI, dl, TII.get(Mips::ADDiu), Mips::SP)
- .addReg(NewReg).addImm(NewImm);
+ if (!StackSize)
+ return;
- // FIXME: change this when mips goes MC".
- if (ATUsed)
- BuildMI(MBB, MBBI, dl, TII.get(Mips::ATMACRO));
- }
+ // Adjust stack.
+ if (isInt<16>(StackSize)) // addi sp, sp, (-stacksize)
+ BuildMI(MBB, MBBI, dl, TII.get(ADDiu), SP).addReg(SP).addImm(StackSize);
+ else // Expand immediate that doesn't fit in 16-bit.
+ expandLargeImm(SP, StackSize, STI.isABI_N64(), TII, MBB, MBBI, dl);
}
void MipsFrameLowering::
-processFunctionBeforeFrameFinalized(MachineFunction &MF) const {
- const MipsRegisterInfo *RegInfo =
- static_cast<const MipsRegisterInfo*>(MF.getTarget().getRegisterInfo());
- RegInfo->processFunctionBeforeFrameFinalized(MF);
+processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
+ RegScavenger *RS) const {
+ MachineRegisterInfo& MRI = MF.getRegInfo();
+ unsigned FP = STI.isABI_N64() ? Mips::FP_64 : Mips::FP;
+
+ // FIXME: remove this code if register allocator can correctly mark
+ // $fp and $ra used or unused.
+
+ // Mark $fp and $ra as used or unused.
+ if (hasFP(MF))
+ MRI.setPhysRegUsed(FP);
+
+ // The register allocator might determine $ra is used after seeing
+ // instruction "jr $ra", but we do not want PrologEpilogInserter to insert
+ // instructions to save/restore $ra unless there is a function call.
+ // To correct this, $ra is explicitly marked unused if there is no
+ // function call.
+ if (MF.getFrameInfo()->hasCalls())
+ MRI.setPhysRegUsed(Mips::RA);
+ else {
+ MRI.setPhysRegUnused(Mips::RA);
+ MRI.setPhysRegUnused(Mips::RA_64);
+ }
}
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