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 "Mips16InstrInfo.h"
16 #include "MCTargetDesc/MipsBaseInfo.h"
17 #include "MipsInstrInfo.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/Function.h"
25 #include "llvm/Support/CommandLine.h"
26 #include "llvm/Target/TargetOptions.h"
30 void Mips16FrameLowering::emitPrologue(MachineFunction &MF) const {
31 MachineBasicBlock &MBB = MF.front();
32 MachineFrameInfo *MFI = MF.getFrameInfo();
33 const Mips16InstrInfo &TII =
34 *static_cast<const Mips16InstrInfo*>(MF.getTarget().getInstrInfo());
35 MachineBasicBlock::iterator MBBI = MBB.begin();
36 DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
37 uint64_t StackSize = MFI->getStackSize();
39 // No need to allocate space on the stack.
40 if (StackSize == 0 && !MFI->adjustsStack()) return;
42 MachineModuleInfo &MMI = MF.getMMI();
43 std::vector<MachineMove> &Moves = MMI.getFrameMoves();
44 MachineLocation DstML, SrcML;
47 TII.makeFrame(Mips::SP, StackSize, MBB, MBBI);
49 // emit ".cfi_def_cfa_offset StackSize"
50 MCSymbol *AdjustSPLabel = MMI.getContext().CreateTempSymbol();
51 BuildMI(MBB, MBBI, dl,
52 TII.get(TargetOpcode::PROLOG_LABEL)).addSym(AdjustSPLabel);
53 DstML = MachineLocation(MachineLocation::VirtualFP);
54 SrcML = MachineLocation(MachineLocation::VirtualFP, -StackSize);
55 Moves.push_back(MachineMove(AdjustSPLabel, DstML, SrcML));
57 MCSymbol *CSLabel = MMI.getContext().CreateTempSymbol();
58 BuildMI(MBB, MBBI, dl,
59 TII.get(TargetOpcode::PROLOG_LABEL)).addSym(CSLabel);
60 DstML = MachineLocation(MachineLocation::VirtualFP, -8);
61 SrcML = MachineLocation(Mips::S1);
62 Moves.push_back(MachineMove(CSLabel, DstML, SrcML));
64 DstML = MachineLocation(MachineLocation::VirtualFP, -12);
65 SrcML = MachineLocation(Mips::S0);
66 Moves.push_back(MachineMove(CSLabel, DstML, SrcML));
68 DstML = MachineLocation(MachineLocation::VirtualFP, -4);
69 SrcML = MachineLocation(Mips::RA);
70 Moves.push_back(MachineMove(CSLabel, DstML, SrcML));
73 BuildMI(MBB, MBBI, dl, TII.get(Mips::MoveR3216), Mips::S0)
78 void Mips16FrameLowering::emitEpilogue(MachineFunction &MF,
79 MachineBasicBlock &MBB) const {
80 MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
81 MachineFrameInfo *MFI = MF.getFrameInfo();
82 const Mips16InstrInfo &TII =
83 *static_cast<const Mips16InstrInfo*>(MF.getTarget().getInstrInfo());
84 DebugLoc dl = MBBI->getDebugLoc();
85 uint64_t StackSize = MFI->getStackSize();
91 BuildMI(MBB, MBBI, dl, TII.get(Mips::Move32R16), Mips::SP)
95 // assumes stacksize multiple of 8
96 TII.restoreFrame(Mips::SP, StackSize, MBB, MBBI);
99 bool Mips16FrameLowering::
100 spillCalleeSavedRegisters(MachineBasicBlock &MBB,
101 MachineBasicBlock::iterator MI,
102 const std::vector<CalleeSavedInfo> &CSI,
103 const TargetRegisterInfo *TRI) const {
104 MachineFunction *MF = MBB.getParent();
105 MachineBasicBlock *EntryBlock = MF->begin();
108 // Registers RA, S0,S1 are the callee saved registers and they
109 // will be saved with the "save" instruction
110 // during emitPrologue
112 for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
113 // Add the callee-saved register as live-in. Do not add if the register is
114 // RA and return address is taken, because it has already been added in
115 // method MipsTargetLowering::LowerRETURNADDR.
116 // It's killed at the spill, unless the register is RA and return address
118 unsigned Reg = CSI[i].getReg();
119 bool IsRAAndRetAddrIsTaken = (Reg == Mips::RA)
120 && MF->getFrameInfo()->isReturnAddressTaken();
121 if (!IsRAAndRetAddrIsTaken)
122 EntryBlock->addLiveIn(Reg);
128 bool Mips16FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
129 MachineBasicBlock::iterator MI,
130 const std::vector<CalleeSavedInfo> &CSI,
131 const TargetRegisterInfo *TRI) const {
133 // Registers RA,S0,S1 are the callee saved registers and they will be restored
134 // with the restore instruction during emitEpilogue.
135 // We need to override this virtual function, otherwise llvm will try and
136 // restore the registers on it's on from the stack.
143 Mips16FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
144 const MachineFrameInfo *MFI = MF.getFrameInfo();
145 // Reserve call frame if the size of the maximum call frame fits into 15-bit
146 // immediate field and there are no variable sized objects on the stack.
147 return isInt<15>(MFI->getMaxCallFrameSize()) && !MFI->hasVarSizedObjects();
150 void Mips16FrameLowering::
151 processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
152 RegScavenger *RS) const {
153 MF.getRegInfo().setPhysRegUsed(Mips::RA);
154 MF.getRegInfo().setPhysRegUsed(Mips::S0);
155 MF.getRegInfo().setPhysRegUsed(Mips::S1);
158 const MipsFrameLowering *
159 llvm::createMips16FrameLowering(const MipsSubtarget &ST) {
160 return new Mips16FrameLowering(ST);