Mips16FrameLowering.cpp revision 288943
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/Support/CommandLine.h" 28#include "llvm/Target/TargetOptions.h" 29 30using namespace llvm; 31 32Mips16FrameLowering::Mips16FrameLowering(const MipsSubtarget &STI) 33 : MipsFrameLowering(STI, STI.stackAlignment()) {} 34 35void Mips16FrameLowering::emitPrologue(MachineFunction &MF, 36 MachineBasicBlock &MBB) const { 37 assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported"); 38 MachineFrameInfo *MFI = MF.getFrameInfo(); 39 const Mips16InstrInfo &TII = 40 *static_cast<const Mips16InstrInfo *>(STI.getInstrInfo()); 41 MachineBasicBlock::iterator MBBI = MBB.begin(); 42 DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc(); 43 uint64_t StackSize = MFI->getStackSize(); 44 45 // No need to allocate space on the stack. 46 if (StackSize == 0 && !MFI->adjustsStack()) return; 47 48 MachineModuleInfo &MMI = MF.getMMI(); 49 const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo(); 50 MachineLocation DstML, SrcML; 51 52 // Adjust stack. 53 TII.makeFrame(Mips::SP, StackSize, MBB, MBBI); 54 55 // emit ".cfi_def_cfa_offset StackSize" 56 unsigned CFIIndex = MMI.addFrameInst( 57 MCCFIInstruction::createDefCfaOffset(nullptr, -StackSize)); 58 BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION)) 59 .addCFIIndex(CFIIndex); 60 61 const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo(); 62 63 if (CSI.size()) { 64 const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo(); 65 66 for (std::vector<CalleeSavedInfo>::const_iterator I = CSI.begin(), 67 E = CSI.end(); I != E; ++I) { 68 int64_t Offset = MFI->getObjectOffset(I->getFrameIdx()); 69 unsigned Reg = I->getReg(); 70 unsigned DReg = MRI->getDwarfRegNum(Reg, true); 71 unsigned CFIIndex = MMI.addFrameInst( 72 MCCFIInstruction::createOffset(nullptr, DReg, Offset)); 73 BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION)) 74 .addCFIIndex(CFIIndex); 75 } 76 } 77 if (hasFP(MF)) 78 BuildMI(MBB, MBBI, dl, TII.get(Mips::MoveR3216), Mips::S0) 79 .addReg(Mips::SP).setMIFlag(MachineInstr::FrameSetup); 80 81} 82 83void Mips16FrameLowering::emitEpilogue(MachineFunction &MF, 84 MachineBasicBlock &MBB) const { 85 MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr(); 86 MachineFrameInfo *MFI = MF.getFrameInfo(); 87 const Mips16InstrInfo &TII = 88 *static_cast<const Mips16InstrInfo *>(STI.getInstrInfo()); 89 DebugLoc dl = MBBI->getDebugLoc(); 90 uint64_t StackSize = MFI->getStackSize(); 91 92 if (!StackSize) 93 return; 94 95 if (hasFP(MF)) 96 BuildMI(MBB, MBBI, dl, TII.get(Mips::Move32R16), Mips::SP) 97 .addReg(Mips::S0); 98 99 // Adjust stack. 100 // assumes stacksize multiple of 8 101 TII.restoreFrame(Mips::SP, StackSize, MBB, MBBI); 102} 103 104bool Mips16FrameLowering:: 105spillCalleeSavedRegisters(MachineBasicBlock &MBB, 106 MachineBasicBlock::iterator MI, 107 const std::vector<CalleeSavedInfo> &CSI, 108 const TargetRegisterInfo *TRI) const { 109 MachineFunction *MF = MBB.getParent(); 110 MachineBasicBlock *EntryBlock = MF->begin(); 111 112 // 113 // Registers RA, S0,S1 are the callee saved registers and they 114 // will be saved with the "save" instruction 115 // during emitPrologue 116 // 117 for (unsigned i = 0, e = CSI.size(); i != e; ++i) { 118 // Add the callee-saved register as live-in. Do not add if the register is 119 // RA and return address is taken, because it has already been added in 120 // method MipsTargetLowering::LowerRETURNADDR. 121 // It's killed at the spill, unless the register is RA and return address 122 // is taken. 123 unsigned Reg = CSI[i].getReg(); 124 bool IsRAAndRetAddrIsTaken = (Reg == Mips::RA) 125 && MF->getFrameInfo()->isReturnAddressTaken(); 126 if (!IsRAAndRetAddrIsTaken) 127 EntryBlock->addLiveIn(Reg); 128 } 129 130 return true; 131} 132 133bool Mips16FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB, 134 MachineBasicBlock::iterator MI, 135 const std::vector<CalleeSavedInfo> &CSI, 136 const TargetRegisterInfo *TRI) const { 137 // 138 // Registers RA,S0,S1 are the callee saved registers and they will be restored 139 // with the restore instruction during emitEpilogue. 140 // We need to override this virtual function, otherwise llvm will try and 141 // restore the registers on it's on from the stack. 142 // 143 144 return true; 145} 146 147bool 148Mips16FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const { 149 const MachineFrameInfo *MFI = MF.getFrameInfo(); 150 // Reserve call frame if the size of the maximum call frame fits into 15-bit 151 // immediate field and there are no variable sized objects on the stack. 152 return isInt<15>(MFI->getMaxCallFrameSize()) && !MFI->hasVarSizedObjects(); 153} 154 155void Mips16FrameLowering::determineCalleeSaves(MachineFunction &MF, 156 BitVector &SavedRegs, 157 RegScavenger *RS) const { 158 TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS); 159 const Mips16InstrInfo &TII = 160 *static_cast<const Mips16InstrInfo *>(STI.getInstrInfo()); 161 const MipsRegisterInfo &RI = TII.getRegisterInfo(); 162 const BitVector Reserved = RI.getReservedRegs(MF); 163 bool SaveS2 = Reserved[Mips::S2]; 164 if (SaveS2) 165 SavedRegs.set(Mips::S2); 166 if (hasFP(MF)) 167 SavedRegs.set(Mips::S0); 168} 169 170const MipsFrameLowering * 171llvm::createMips16FrameLowering(const MipsSubtarget &ST) { 172 return new Mips16FrameLowering(ST); 173} 174