1 //===-- AVRRelaxMemOperations.cpp - Relax out of range loads/stores -------===//
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 a pass which relaxes out of range memory operations into
11 // equivalent operations which handle bigger addresses.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "AVR.h"
16 #include "AVRInstrInfo.h"
17 #include "AVRTargetMachine.h"
18 #include "MCTargetDesc/AVRMCTargetDesc.h"
19
20 #include "llvm/CodeGen/MachineFunctionPass.h"
21 #include "llvm/CodeGen/MachineInstrBuilder.h"
22 #include "llvm/CodeGen/MachineRegisterInfo.h"
23 #include "llvm/CodeGen/TargetRegisterInfo.h"
24
25 using namespace llvm;
26
27 #define AVR_RELAX_MEM_OPS_NAME "AVR memory operation relaxation pass"
28
29 namespace {
30
31 class AVRRelaxMem : public MachineFunctionPass {
32 public:
33 static char ID;
34
AVRRelaxMem()35 AVRRelaxMem() : MachineFunctionPass(ID) {
36 initializeAVRRelaxMemPass(*PassRegistry::getPassRegistry());
37 }
38
39 bool runOnMachineFunction(MachineFunction &MF) override;
40
getPassName() const41 StringRef getPassName() const override { return AVR_RELAX_MEM_OPS_NAME; }
42
43 private:
44 typedef MachineBasicBlock Block;
45 typedef Block::iterator BlockIt;
46
47 const TargetInstrInfo *TII;
48
49 template <unsigned OP> bool relax(Block &MBB, BlockIt MBBI);
50
51 bool runOnBasicBlock(Block &MBB);
52 bool runOnInstruction(Block &MBB, BlockIt MBBI);
53
buildMI(Block & MBB,BlockIt MBBI,unsigned Opcode)54 MachineInstrBuilder buildMI(Block &MBB, BlockIt MBBI, unsigned Opcode) {
55 return BuildMI(MBB, MBBI, MBBI->getDebugLoc(), TII->get(Opcode));
56 }
57 };
58
59 char AVRRelaxMem::ID = 0;
60
runOnMachineFunction(MachineFunction & MF)61 bool AVRRelaxMem::runOnMachineFunction(MachineFunction &MF) {
62 bool Modified = false;
63
64 const AVRSubtarget &STI = MF.getSubtarget<AVRSubtarget>();
65 TII = STI.getInstrInfo();
66
67 for (Block &MBB : MF) {
68 bool BlockModified = runOnBasicBlock(MBB);
69 Modified |= BlockModified;
70 }
71
72 return Modified;
73 }
74
runOnBasicBlock(Block & MBB)75 bool AVRRelaxMem::runOnBasicBlock(Block &MBB) {
76 bool Modified = false;
77
78 BlockIt MBBI = MBB.begin(), E = MBB.end();
79 while (MBBI != E) {
80 BlockIt NMBBI = std::next(MBBI);
81 Modified |= runOnInstruction(MBB, MBBI);
82 MBBI = NMBBI;
83 }
84
85 return Modified;
86 }
87
88 template <>
relax(Block & MBB,BlockIt MBBI)89 bool AVRRelaxMem::relax<AVR::STDWPtrQRr>(Block &MBB, BlockIt MBBI) {
90 MachineInstr &MI = *MBBI;
91
92 MachineOperand &Ptr = MI.getOperand(0);
93 MachineOperand &Src = MI.getOperand(2);
94 int64_t Imm = MI.getOperand(1).getImm();
95
96 // We can definitely optimise this better.
97 if (Imm > 63) {
98 // Push the previous state of the pointer register.
99 // This instruction must preserve the value.
100 buildMI(MBB, MBBI, AVR::PUSHWRr)
101 .addReg(Ptr.getReg());
102
103 // Add the immediate to the pointer register.
104 buildMI(MBB, MBBI, AVR::SBCIWRdK)
105 .addReg(Ptr.getReg(), RegState::Define)
106 .addReg(Ptr.getReg())
107 .addImm(-Imm);
108
109 // Store the value in the source register to the address
110 // pointed to by the pointer register.
111 buildMI(MBB, MBBI, AVR::STWPtrRr)
112 .addReg(Ptr.getReg())
113 .addReg(Src.getReg(), getKillRegState(Src.isKill()));
114
115 // Pop the original state of the pointer register.
116 buildMI(MBB, MBBI, AVR::POPWRd)
117 .addReg(Ptr.getReg(), getKillRegState(Ptr.isKill()));
118
119 MI.removeFromParent();
120 }
121
122 return false;
123 }
124
runOnInstruction(Block & MBB,BlockIt MBBI)125 bool AVRRelaxMem::runOnInstruction(Block &MBB, BlockIt MBBI) {
126 MachineInstr &MI = *MBBI;
127 int Opcode = MBBI->getOpcode();
128
129 #define RELAX(Op) \
130 case Op: \
131 return relax<Op>(MBB, MI)
132
133 switch (Opcode) {
134 RELAX(AVR::STDWPtrQRr);
135 }
136 #undef RELAX
137 return false;
138 }
139
140 } // end of anonymous namespace
141
142 INITIALIZE_PASS(AVRRelaxMem, "avr-relax-mem",
143 AVR_RELAX_MEM_OPS_NAME, false, false)
144
145 namespace llvm {
146
createAVRRelaxMemPass()147 FunctionPass *createAVRRelaxMemPass() { return new AVRRelaxMem(); }
148
149 } // end of namespace llvm
150