1//===-- Mips16RegisterInfo.cpp - MIPS16 Register Information --------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains the MIPS16 implementation of the TargetRegisterInfo class.
10//
11//===----------------------------------------------------------------------===//
12
13#include "Mips16RegisterInfo.h"
14#include "Mips.h"
15#include "Mips16InstrInfo.h"
16#include "MipsInstrInfo.h"
17#include "MipsMachineFunction.h"
18#include "MipsSubtarget.h"
19#include "llvm/ADT/STLExtras.h"
20#include "llvm/CodeGen/MachineFrameInfo.h"
21#include "llvm/CodeGen/MachineFunction.h"
22#include "llvm/CodeGen/MachineInstrBuilder.h"
23#include "llvm/CodeGen/MachineRegisterInfo.h"
24#include "llvm/CodeGen/TargetFrameLowering.h"
25#include "llvm/CodeGen/TargetInstrInfo.h"
26#include "llvm/IR/Constants.h"
27#include "llvm/IR/DebugInfo.h"
28#include "llvm/IR/Function.h"
29#include "llvm/IR/Type.h"
30#include "llvm/Support/Debug.h"
31#include "llvm/Support/ErrorHandling.h"
32#include "llvm/Support/raw_ostream.h"
33#include "llvm/Target/TargetMachine.h"
34#include "llvm/Target/TargetOptions.h"
35
36using namespace llvm;
37
38#define DEBUG_TYPE "mips16-registerinfo"
39
40Mips16RegisterInfo::Mips16RegisterInfo() = default;
41
42bool Mips16RegisterInfo::requiresRegisterScavenging
43  (const MachineFunction &MF) const {
44  return false;
45}
46bool Mips16RegisterInfo::requiresFrameIndexScavenging
47  (const MachineFunction &MF) const {
48  return false;
49}
50
51bool Mips16RegisterInfo::useFPForScavengingIndex
52  (const MachineFunction &MF) const {
53  return false;
54}
55
56bool Mips16RegisterInfo::saveScavengerRegister(
57    MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
58    MachineBasicBlock::iterator &UseMI, const TargetRegisterClass *RC,
59    Register Reg) const {
60  DebugLoc DL;
61  const TargetInstrInfo &TII = *MBB.getParent()->getSubtarget().getInstrInfo();
62  TII.copyPhysReg(MBB, I, DL, Mips::T0, Reg, true);
63  TII.copyPhysReg(MBB, UseMI, DL, Reg, Mips::T0, true);
64  return true;
65}
66
67const TargetRegisterClass *
68Mips16RegisterInfo::intRegClass(unsigned Size) const {
69  assert(Size == 4);
70  return &Mips::CPU16RegsRegClass;
71}
72
73void Mips16RegisterInfo::eliminateFI(MachineBasicBlock::iterator II,
74                                     unsigned OpNo, int FrameIndex,
75                                     uint64_t StackSize,
76                                     int64_t SPOffset) const {
77  MachineInstr &MI = *II;
78  MachineFunction &MF = *MI.getParent()->getParent();
79  MachineFrameInfo &MFI = MF.getFrameInfo();
80
81  const std::vector<CalleeSavedInfo> &CSI = MFI.getCalleeSavedInfo();
82  int MinCSFI = 0;
83  int MaxCSFI = -1;
84
85  if (CSI.size()) {
86    MinCSFI = CSI[0].getFrameIdx();
87    MaxCSFI = CSI[CSI.size() - 1].getFrameIdx();
88  }
89
90  // The following stack frame objects are always
91  // referenced relative to $sp:
92  //  1. Outgoing arguments.
93  //  2. Pointer to dynamically allocated stack space.
94  //  3. Locations for callee-saved registers.
95  // Everything else is referenced relative to whatever register
96  // getFrameRegister() returns.
97  Register FrameReg;
98
99  if (FrameIndex >= MinCSFI && FrameIndex <= MaxCSFI)
100    FrameReg = Mips::SP;
101  else {
102    const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
103    if (TFI->hasFP(MF)) {
104      FrameReg = Mips::S0;
105    }
106    else {
107      if ((MI.getNumOperands()> OpNo+2) && MI.getOperand(OpNo+2).isReg())
108        FrameReg = MI.getOperand(OpNo+2).getReg();
109      else
110        FrameReg = Mips::SP;
111    }
112  }
113  // Calculate final offset.
114  // - There is no need to change the offset if the frame object
115  //   is one of the
116  //   following: an outgoing argument, pointer to a dynamically allocated
117  //   stack space or a $gp restore location,
118  // - If the frame object is any of the following,
119  //   its offset must be adjusted
120  //   by adding the size of the stack:
121  //   incoming argument, callee-saved register location or local variable.
122  int64_t Offset;
123  bool IsKill = false;
124  Offset = SPOffset + (int64_t)StackSize;
125  Offset += MI.getOperand(OpNo + 1).getImm();
126
127  LLVM_DEBUG(errs() << "Offset     : " << Offset << "\n"
128                    << "<--------->\n");
129
130  if (!MI.isDebugValue() &&
131      !Mips16InstrInfo::validImmediate(MI.getOpcode(), FrameReg, Offset)) {
132    MachineBasicBlock &MBB = *MI.getParent();
133    DebugLoc DL = II->getDebugLoc();
134    unsigned NewImm;
135    const Mips16InstrInfo &TII =
136        *static_cast<const Mips16InstrInfo *>(MF.getSubtarget().getInstrInfo());
137    FrameReg = TII.loadImmediate(FrameReg, Offset, MBB, II, DL, NewImm);
138    Offset = SignExtend64<16>(NewImm);
139    IsKill = true;
140  }
141  MI.getOperand(OpNo).ChangeToRegister(FrameReg, false, false, IsKill);
142  MI.getOperand(OpNo + 1).ChangeToImmediate(Offset);
143
144
145}
146