1 //===-- Mips16FrameLowering.cpp - Mips16 Frame Information ----------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file contains the Mips16 implementation of TargetFrameLowering class. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "Mips16FrameLowering.h" 15 #include "MCTargetDesc/MipsBaseInfo.h" 16 #include "Mips16InstrInfo.h" 17 #include "MipsInstrInfo.h" 18 #include "MipsRegisterInfo.h" 19 #include "MipsSubtarget.h" 20 #include "llvm/CodeGen/MachineFrameInfo.h" 21 #include "llvm/CodeGen/MachineFunction.h" 22 #include "llvm/CodeGen/MachineInstrBuilder.h" 23 #include "llvm/CodeGen/MachineModuleInfo.h" 24 #include "llvm/CodeGen/MachineRegisterInfo.h" 25 #include "llvm/IR/DataLayout.h" 26 #include "llvm/IR/Function.h" 27 #include "llvm/Target/TargetOptions.h" 28 29 using namespace llvm; 30 31 Mips16FrameLowering::Mips16FrameLowering(const MipsSubtarget &STI) 32 : MipsFrameLowering(STI, STI.stackAlignment()) {} 33 34 void Mips16FrameLowering::emitPrologue(MachineFunction &MF, 35 MachineBasicBlock &MBB) const { 36 assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported"); 37 MachineFrameInfo *MFI = MF.getFrameInfo(); 38 const Mips16InstrInfo &TII = 39 *static_cast<const Mips16InstrInfo *>(STI.getInstrInfo()); 40 MachineBasicBlock::iterator MBBI = MBB.begin(); 41 42 // Debug location must be unknown since the first debug location is used 43 // to determine the end of the prologue. 44 DebugLoc dl; 45 46 uint64_t StackSize = MFI->getStackSize(); 47 48 // No need to allocate space on the stack. 49 if (StackSize == 0 && !MFI->adjustsStack()) return; 50 51 MachineModuleInfo &MMI = MF.getMMI(); 52 const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo(); 53 MachineLocation DstML, SrcML; 54 55 // Adjust stack. 56 TII.makeFrame(Mips::SP, StackSize, MBB, MBBI); 57 58 // emit ".cfi_def_cfa_offset StackSize" 59 unsigned CFIIndex = MMI.addFrameInst( 60 MCCFIInstruction::createDefCfaOffset(nullptr, -StackSize)); 61 BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION)) 62 .addCFIIndex(CFIIndex); 63 64 const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo(); 65 66 if (CSI.size()) { 67 const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo(); 68 69 for (std::vector<CalleeSavedInfo>::const_iterator I = CSI.begin(), 70 E = CSI.end(); I != E; ++I) { 71 int64_t Offset = MFI->getObjectOffset(I->getFrameIdx()); 72 unsigned Reg = I->getReg(); 73 unsigned DReg = MRI->getDwarfRegNum(Reg, true); 74 unsigned CFIIndex = MMI.addFrameInst( 75 MCCFIInstruction::createOffset(nullptr, DReg, Offset)); 76 BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION)) 77 .addCFIIndex(CFIIndex); 78 } 79 } 80 if (hasFP(MF)) 81 BuildMI(MBB, MBBI, dl, TII.get(Mips::MoveR3216), Mips::S0) 82 .addReg(Mips::SP).setMIFlag(MachineInstr::FrameSetup); 83 84 } 85 86 void Mips16FrameLowering::emitEpilogue(MachineFunction &MF, 87 MachineBasicBlock &MBB) const { 88 MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr(); 89 MachineFrameInfo *MFI = MF.getFrameInfo(); 90 const Mips16InstrInfo &TII = 91 *static_cast<const Mips16InstrInfo *>(STI.getInstrInfo()); 92 DebugLoc dl = MBBI->getDebugLoc(); 93 uint64_t StackSize = MFI->getStackSize(); 94 95 if (!StackSize) 96 return; 97 98 if (hasFP(MF)) 99 BuildMI(MBB, MBBI, dl, TII.get(Mips::Move32R16), Mips::SP) 100 .addReg(Mips::S0); 101 102 // Adjust stack. 103 // assumes stacksize multiple of 8 104 TII.restoreFrame(Mips::SP, StackSize, MBB, MBBI); 105 } 106 107 bool Mips16FrameLowering:: 108 spillCalleeSavedRegisters(MachineBasicBlock &MBB, 109 MachineBasicBlock::iterator MI, 110 const std::vector<CalleeSavedInfo> &CSI, 111 const TargetRegisterInfo *TRI) const { 112 MachineFunction *MF = MBB.getParent(); 113 MachineBasicBlock *EntryBlock = &MF->front(); 114 115 // 116 // Registers RA, S0,S1 are the callee saved registers and they 117 // will be saved with the "save" instruction 118 // during emitPrologue 119 // 120 for (unsigned i = 0, e = CSI.size(); i != e; ++i) { 121 // Add the callee-saved register as live-in. Do not add if the register is 122 // RA and return address is taken, because it has already been added in 123 // method MipsTargetLowering::LowerRETURNADDR. 124 // It's killed at the spill, unless the register is RA and return address 125 // is taken. 126 unsigned Reg = CSI[i].getReg(); 127 bool IsRAAndRetAddrIsTaken = (Reg == Mips::RA) 128 && MF->getFrameInfo()->isReturnAddressTaken(); 129 if (!IsRAAndRetAddrIsTaken) 130 EntryBlock->addLiveIn(Reg); 131 } 132 133 return true; 134 } 135 136 bool Mips16FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB, 137 MachineBasicBlock::iterator MI, 138 const std::vector<CalleeSavedInfo> &CSI, 139 const TargetRegisterInfo *TRI) const { 140 // 141 // Registers RA,S0,S1 are the callee saved registers and they will be restored 142 // with the restore instruction during emitEpilogue. 143 // We need to override this virtual function, otherwise llvm will try and 144 // restore the registers on it's on from the stack. 145 // 146 147 return true; 148 } 149 150 bool 151 Mips16FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const { 152 const MachineFrameInfo *MFI = MF.getFrameInfo(); 153 // Reserve call frame if the size of the maximum call frame fits into 15-bit 154 // immediate field and there are no variable sized objects on the stack. 155 return isInt<15>(MFI->getMaxCallFrameSize()) && !MFI->hasVarSizedObjects(); 156 } 157 158 void Mips16FrameLowering::determineCalleeSaves(MachineFunction &MF, 159 BitVector &SavedRegs, 160 RegScavenger *RS) const { 161 TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS); 162 const Mips16InstrInfo &TII = 163 *static_cast<const Mips16InstrInfo *>(STI.getInstrInfo()); 164 const MipsRegisterInfo &RI = TII.getRegisterInfo(); 165 const BitVector Reserved = RI.getReservedRegs(MF); 166 bool SaveS2 = Reserved[Mips::S2]; 167 if (SaveS2) 168 SavedRegs.set(Mips::S2); 169 if (hasFP(MF)) 170 SavedRegs.set(Mips::S0); 171 } 172 173 const MipsFrameLowering * 174 llvm::createMips16FrameLowering(const MipsSubtarget &ST) { 175 return new Mips16FrameLowering(ST); 176 } 177
