1 //===-- Mips16FrameLowering.cpp - Mips16 Frame Information ----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the Mips16 implementation of TargetFrameLowering class.
12 //===----------------------------------------------------------------------===//
14 #include "Mips16FrameLowering.h"
15 #include "MCTargetDesc/MipsBaseInfo.h"
16 #include "MipsInstrInfo.h"
17 #include "llvm/CodeGen/MachineFrameInfo.h"
18 #include "llvm/CodeGen/MachineFunction.h"
19 #include "llvm/CodeGen/MachineInstrBuilder.h"
20 #include "llvm/CodeGen/MachineModuleInfo.h"
21 #include "llvm/CodeGen/MachineRegisterInfo.h"
22 #include "llvm/DataLayout.h"
23 #include "llvm/Function.h"
24 #include "llvm/Support/CommandLine.h"
25 #include "llvm/Target/TargetOptions.h"
29 void 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();
38 // No need to allocate space on the stack.
39 if (StackSize == 0 && !MFI->adjustsStack()) return;
42 if (isInt<16>(-StackSize))
43 BuildMI(MBB, MBBI, dl, TII.get(Mips::SaveRaF16)).addImm(StackSize);
46 BuildMI(MBB, MBBI, dl, TII.get(Mips::MoveR3216), Mips::S0)
51 void 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();
64 BuildMI(MBB, MBBI, dl, TII.get(Mips::Move32R16), Mips::SP)
68 if (isInt<16>(StackSize))
69 // assumes stacksize multiple of 8
70 BuildMI(MBB, MBBI, dl, TII.get(Mips::RestoreRaF16)).addImm(StackSize);
73 bool Mips16FrameLowering::
74 spillCalleeSavedRegisters(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();
82 // Registers RA, S0,S1 are the callee saved registers and they
83 // will be saved with the "save" instruction
84 // during emitPrologue
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
92 unsigned Reg = CSI[i].getReg();
93 bool IsRAAndRetAddrIsTaken = (Reg == Mips::RA)
94 && MF->getFrameInfo()->isReturnAddressTaken();
95 if (!IsRAAndRetAddrIsTaken)
96 EntryBlock->addLiveIn(Reg);
102 bool Mips16FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
103 MachineBasicBlock::iterator MI,
104 const std::vector<CalleeSavedInfo> &CSI,
105 const TargetRegisterInfo *TRI) const {
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.
117 Mips16FrameLowering::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();
124 void Mips16FrameLowering::
125 processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
126 RegScavenger *RS) const {
127 MF.getRegInfo().setPhysRegUsed(Mips::RA);
128 MF.getRegInfo().setPhysRegUsed(Mips::S0);
129 MF.getRegInfo().setPhysRegUsed(Mips::S1);
132 const MipsFrameLowering *
133 llvm::createMips16FrameLowering(const MipsSubtarget &ST) {
134 return new Mips16FrameLowering(ST);