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1 //===-- AVRRelaxMemOperations.cpp - Relax out of range loads/stores -------===//
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2 //
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3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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4 // See https://llvm.org/LICENSE.txt for license information.
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5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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6 //
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7 //===----------------------------------------------------------------------===//
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8 //
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9 // This file contains a pass which relaxes out of range memory operations into
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10 // equivalent operations which handle bigger addresses.
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11 //
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12 //===----------------------------------------------------------------------===//
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13
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14 #include "AVR.h"
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15 #include "AVRInstrInfo.h"
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16 #include "AVRTargetMachine.h"
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17 #include "MCTargetDesc/AVRMCTargetDesc.h"
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18
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19 #include "llvm/CodeGen/MachineFunctionPass.h"
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20 #include "llvm/CodeGen/MachineInstrBuilder.h"
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21 #include "llvm/CodeGen/MachineRegisterInfo.h"
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22 #include "llvm/CodeGen/TargetRegisterInfo.h"
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23
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24 using namespace llvm;
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25
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26 #define AVR_RELAX_MEM_OPS_NAME "AVR memory operation relaxation pass"
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27
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28 namespace {
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29
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30 class AVRRelaxMem : public MachineFunctionPass {
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31 public:
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32 static char ID;
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33
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34 AVRRelaxMem() : MachineFunctionPass(ID) {
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35 initializeAVRRelaxMemPass(*PassRegistry::getPassRegistry());
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36 }
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37
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38 bool runOnMachineFunction(MachineFunction &MF) override;
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39
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40 StringRef getPassName() const override { return AVR_RELAX_MEM_OPS_NAME; }
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41
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42 private:
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43 typedef MachineBasicBlock Block;
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44 typedef Block::iterator BlockIt;
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45
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46 const TargetInstrInfo *TII;
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47
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48 template <unsigned OP> bool relax(Block &MBB, BlockIt MBBI);
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49
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50 bool runOnBasicBlock(Block &MBB);
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51 bool runOnInstruction(Block &MBB, BlockIt MBBI);
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52
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53 MachineInstrBuilder buildMI(Block &MBB, BlockIt MBBI, unsigned Opcode) {
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54 return BuildMI(MBB, MBBI, MBBI->getDebugLoc(), TII->get(Opcode));
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55 }
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56 };
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57
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58 char AVRRelaxMem::ID = 0;
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59
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60 bool AVRRelaxMem::runOnMachineFunction(MachineFunction &MF) {
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61 bool Modified = false;
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62
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63 const AVRSubtarget &STI = MF.getSubtarget<AVRSubtarget>();
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64 TII = STI.getInstrInfo();
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65
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66 for (Block &MBB : MF) {
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67 bool BlockModified = runOnBasicBlock(MBB);
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68 Modified |= BlockModified;
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69 }
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70
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71 return Modified;
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72 }
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73
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74 bool AVRRelaxMem::runOnBasicBlock(Block &MBB) {
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75 bool Modified = false;
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76
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77 BlockIt MBBI = MBB.begin(), E = MBB.end();
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78 while (MBBI != E) {
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79 BlockIt NMBBI = std::next(MBBI);
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80 Modified |= runOnInstruction(MBB, MBBI);
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81 MBBI = NMBBI;
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82 }
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83
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84 return Modified;
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85 }
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86
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87 template <>
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88 bool AVRRelaxMem::relax<AVR::STDWPtrQRr>(Block &MBB, BlockIt MBBI) {
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89 MachineInstr &MI = *MBBI;
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90
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91 MachineOperand &Ptr = MI.getOperand(0);
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92 MachineOperand &Src = MI.getOperand(2);
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93 int64_t Imm = MI.getOperand(1).getImm();
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94
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95 // We can definitely optimise this better.
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96 if (Imm > 63) {
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97 // Push the previous state of the pointer register.
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98 // This instruction must preserve the value.
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99 buildMI(MBB, MBBI, AVR::PUSHWRr)
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100 .addReg(Ptr.getReg());
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101
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102 // Add the immediate to the pointer register.
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103 buildMI(MBB, MBBI, AVR::SBCIWRdK)
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104 .addReg(Ptr.getReg(), RegState::Define)
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105 .addReg(Ptr.getReg())
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106 .addImm(-Imm);
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107
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108 // Store the value in the source register to the address
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109 // pointed to by the pointer register.
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110 buildMI(MBB, MBBI, AVR::STWPtrRr)
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111 .addReg(Ptr.getReg())
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112 .addReg(Src.getReg(), getKillRegState(Src.isKill()));
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113
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114 // Pop the original state of the pointer register.
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115 buildMI(MBB, MBBI, AVR::POPWRd)
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116 .addReg(Ptr.getReg(), getKillRegState(Ptr.isKill()));
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117
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118 MI.removeFromParent();
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119 }
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120
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121 return false;
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122 }
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123
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124 bool AVRRelaxMem::runOnInstruction(Block &MBB, BlockIt MBBI) {
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125 MachineInstr &MI = *MBBI;
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126 int Opcode = MBBI->getOpcode();
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127
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128 #define RELAX(Op) \
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129 case Op: \
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130 return relax<Op>(MBB, MI)
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131
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132 switch (Opcode) {
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133 RELAX(AVR::STDWPtrQRr);
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134 }
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135 #undef RELAX
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136 return false;
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137 }
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138
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139 } // end of anonymous namespace
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140
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141 INITIALIZE_PASS(AVRRelaxMem, "avr-relax-mem",
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142 AVR_RELAX_MEM_OPS_NAME, false, false)
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143
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144 namespace llvm {
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145
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146 FunctionPass *createAVRRelaxMemPass() { return new AVRRelaxMem(); }
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147
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148 } // end of namespace llvm
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