Mips16FrameLowering.cpp revision 243830
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 "MipsInstrInfo.h" 16#include "MCTargetDesc/MipsBaseInfo.h" 17#include "llvm/Function.h" 18#include "llvm/CodeGen/MachineFrameInfo.h" 19#include "llvm/CodeGen/MachineFunction.h" 20#include "llvm/CodeGen/MachineInstrBuilder.h" 21#include "llvm/CodeGen/MachineModuleInfo.h" 22#include "llvm/CodeGen/MachineRegisterInfo.h" 23#include "llvm/DataLayout.h" 24#include "llvm/Target/TargetOptions.h" 25#include "llvm/Support/CommandLine.h" 26 27using namespace llvm; 28 29void Mips16FrameLowering::emitPrologue(MachineFunction &MF) const { 30 MachineBasicBlock &MBB = MF.front(); 31 MachineFrameInfo *MFI = MF.getFrameInfo(); 32 const MipsInstrInfo &TII = 33 *static_cast<const MipsInstrInfo*>(MF.getTarget().getInstrInfo()); 34 MachineBasicBlock::iterator MBBI = MBB.begin(); 35 DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc(); 36 uint64_t StackSize = MFI->getStackSize(); 37 38 // No need to allocate space on the stack. 39 if (StackSize == 0 && !MFI->adjustsStack()) return; 40 41 // Adjust stack. 42 if (isInt<16>(-StackSize)) 43 BuildMI(MBB, MBBI, dl, TII.get(Mips::SaveRaF16)).addImm(StackSize); 44 45 if (hasFP(MF)) 46 BuildMI(MBB, MBBI, dl, TII.get(Mips::MoveR3216), Mips::S0) 47 .addReg(Mips::SP); 48 49} 50 51void Mips16FrameLowering::emitEpilogue(MachineFunction &MF, 52 MachineBasicBlock &MBB) const { 53 MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr(); 54 MachineFrameInfo *MFI = MF.getFrameInfo(); 55 const MipsInstrInfo &TII = 56 *static_cast<const MipsInstrInfo*>(MF.getTarget().getInstrInfo()); 57 DebugLoc dl = MBBI->getDebugLoc(); 58 uint64_t StackSize = MFI->getStackSize(); 59 60 if (!StackSize) 61 return; 62 63 if (hasFP(MF)) 64 BuildMI(MBB, MBBI, dl, TII.get(Mips::Move32R16), Mips::SP) 65 .addReg(Mips::S0); 66 67 // Adjust stack. 68 if (isInt<16>(StackSize)) 69 // assumes stacksize multiple of 8 70 BuildMI(MBB, MBBI, dl, TII.get(Mips::RestoreRaF16)).addImm(StackSize); 71} 72 73bool Mips16FrameLowering:: 74spillCalleeSavedRegisters(MachineBasicBlock &MBB, 75 MachineBasicBlock::iterator MI, 76 const std::vector<CalleeSavedInfo> &CSI, 77 const TargetRegisterInfo *TRI) const { 78 MachineFunction *MF = MBB.getParent(); 79 MachineBasicBlock *EntryBlock = MF->begin(); 80 81 // 82 // Registers RA, S0,S1 are the callee saved registers and they 83 // will be saved with the "save" instruction 84 // during emitPrologue 85 // 86 for (unsigned i = 0, e = CSI.size(); i != e; ++i) { 87 // Add the callee-saved register as live-in. Do not add if the register is 88 // RA and return address is taken, because it has already been added in 89 // method MipsTargetLowering::LowerRETURNADDR. 90 // It's killed at the spill, unless the register is RA and return address 91 // is taken. 92 unsigned Reg = CSI[i].getReg(); 93 bool IsRAAndRetAddrIsTaken = (Reg == Mips::RA) 94 && MF->getFrameInfo()->isReturnAddressTaken(); 95 if (!IsRAAndRetAddrIsTaken) 96 EntryBlock->addLiveIn(Reg); 97 } 98 99 return true; 100} 101 102bool Mips16FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB, 103 MachineBasicBlock::iterator MI, 104 const std::vector<CalleeSavedInfo> &CSI, 105 const TargetRegisterInfo *TRI) const { 106 // 107 // Registers RA,S0,S1 are the callee saved registers and they will be restored 108 // with the restore instruction during emitEpilogue. 109 // We need to override this virtual function, otherwise llvm will try and 110 // restore the registers on it's on from the stack. 111 // 112 113 return true; 114} 115 116bool 117Mips16FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const { 118 const MachineFrameInfo *MFI = MF.getFrameInfo(); 119 // Reserve call frame if the size of the maximum call frame fits into 15-bit 120 // immediate field and there are no variable sized objects on the stack. 121 return isInt<15>(MFI->getMaxCallFrameSize()) && !MFI->hasVarSizedObjects(); 122} 123 124void Mips16FrameLowering:: 125processFunctionBeforeCalleeSavedScan(MachineFunction &MF, 126 RegScavenger *RS) const { 127 MF.getRegInfo().setPhysRegUsed(Mips::RA); 128 MF.getRegInfo().setPhysRegUsed(Mips::S0); 129 MF.getRegInfo().setPhysRegUsed(Mips::S1); 130} 131 132const MipsFrameLowering * 133llvm::createMips16FrameLowering(const MipsSubtarget &ST) { 134 return new Mips16FrameLowering(ST); 135} 136