1 //===-- AVRAsmPrinter.cpp - AVR LLVM assembly writer ----------------------===//
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 printer that converts from our internal representation
11 // of machine-dependent LLVM code to GAS-format AVR assembly language.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "AVR.h"
16 #include "AVRMCInstLower.h"
17 #include "AVRSubtarget.h"
18 #include "InstPrinter/AVRInstPrinter.h"
19 
20 #include "llvm/CodeGen/AsmPrinter.h"
21 #include "llvm/CodeGen/MachineInstr.h"
22 #include "llvm/CodeGen/MachineFunction.h"
23 #include "llvm/IR/Mangler.h"
24 #include "llvm/MC/MCInst.h"
25 #include "llvm/MC/MCStreamer.h"
26 #include "llvm/MC/MCSymbol.h"
27 #include "llvm/Support/ErrorHandling.h"
28 #include "llvm/Support/TargetRegistry.h"
29 #include "llvm/Support/raw_ostream.h"
30 #include "llvm/Target/TargetRegisterInfo.h"
31 #include "llvm/Target/TargetSubtargetInfo.h"
32 
33 #define DEBUG_TYPE "avr-asm-printer"
34 
35 namespace llvm {
36 
37 /// An AVR assembly code printer.
38 class AVRAsmPrinter : public AsmPrinter {
39 public:
40   AVRAsmPrinter(TargetMachine &TM,
41                 std::unique_ptr<MCStreamer> Streamer)
42       : AsmPrinter(TM, std::move(Streamer)), MRI(*TM.getMCRegisterInfo()) { }
43 
44   StringRef getPassName() const override { return "AVR Assembly Printer"; }
45 
46   void printOperand(const MachineInstr *MI, unsigned OpNo, raw_ostream &O,
47                     const char *Modifier = 0);
48 
49   bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
50                        unsigned AsmVariant, const char *ExtraCode,
51                        raw_ostream &O) override;
52 
53   bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNum,
54                              unsigned AsmVariant, const char *ExtraCode,
55                              raw_ostream &O) override;
56 
57   void EmitInstruction(const MachineInstr *MI) override;
58 
59 private:
60   const MCRegisterInfo &MRI;
61 };
62 
63 void AVRAsmPrinter::printOperand(const MachineInstr *MI, unsigned OpNo,
64                                  raw_ostream &O, const char *Modifier) {
65   const MachineOperand &MO = MI->getOperand(OpNo);
66 
67   switch (MO.getType()) {
68   case MachineOperand::MO_Register:
69     O << AVRInstPrinter::getPrettyRegisterName(MO.getReg(), MRI);
70     break;
71   case MachineOperand::MO_Immediate:
72     O << MO.getImm();
73     break;
74   case MachineOperand::MO_GlobalAddress:
75     O << getSymbol(MO.getGlobal());
76     break;
77   case MachineOperand::MO_ExternalSymbol:
78     O << *GetExternalSymbolSymbol(MO.getSymbolName());
79     break;
80   case MachineOperand::MO_MachineBasicBlock:
81     O << *MO.getMBB()->getSymbol();
82     break;
83   default:
84     llvm_unreachable("Not implemented yet!");
85   }
86 }
87 
88 bool AVRAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
89                                     unsigned AsmVariant, const char *ExtraCode,
90                                     raw_ostream &O) {
91   // Default asm printer can only deal with some extra codes,
92   // so try it first.
93   bool Error = AsmPrinter::PrintAsmOperand(MI, OpNum, AsmVariant, ExtraCode, O);
94 
95   if (Error && ExtraCode && ExtraCode[0]) {
96     if (ExtraCode[1] != 0)
97       return true; // Unknown modifier.
98 
99     if (ExtraCode[0] >= 'A' && ExtraCode[0] <= 'Z') {
100       const MachineOperand &RegOp = MI->getOperand(OpNum);
101 
102       assert(RegOp.isReg() && "Operand must be a register when you're"
103                               "using 'A'..'Z' operand extracodes.");
104       unsigned Reg = RegOp.getReg();
105 
106       unsigned ByteNumber = ExtraCode[0] - 'A';
107 
108       unsigned OpFlags = MI->getOperand(OpNum - 1).getImm();
109       unsigned NumOpRegs = InlineAsm::getNumOperandRegisters(OpFlags);
110 
111       const AVRSubtarget &STI = MF->getSubtarget<AVRSubtarget>();
112       const TargetRegisterInfo &TRI = *STI.getRegisterInfo();
113 
114       unsigned BytesPerReg = TRI.getMinimalPhysRegClass(Reg)->getSize();
115       assert(BytesPerReg <= 2 && "Only 8 and 16 bit regs are supported.");
116 
117       unsigned RegIdx = ByteNumber / BytesPerReg;
118       assert(RegIdx < NumOpRegs && "Multibyte index out of range.");
119 
120       Reg = MI->getOperand(OpNum + RegIdx).getReg();
121 
122       if (BytesPerReg == 2) {
123         Reg = TRI.getSubReg(Reg, ByteNumber % BytesPerReg ? AVR::sub_hi
124                                                           : AVR::sub_lo);
125       }
126 
127       O << AVRInstPrinter::getPrettyRegisterName(Reg, MRI);
128       return false;
129     }
130   }
131 
132   printOperand(MI, OpNum, O);
133 
134   return false;
135 }
136 
137 bool AVRAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
138                                           unsigned OpNum, unsigned AsmVariant,
139                                           const char *ExtraCode,
140                                           raw_ostream &O) {
141   if (ExtraCode && ExtraCode[0]) {
142     llvm_unreachable("This branch is not implemented yet");
143   }
144 
145   const MachineOperand &MO = MI->getOperand(OpNum);
146   assert(MO.isReg() && "Unexpected inline asm memory operand");
147 
148   // TODO: We can look up the alternative name for the register if it's given.
149   if (MI->getOperand(OpNum).getReg() == AVR::R31R30) {
150     O << "Z";
151   } else {
152     assert(MI->getOperand(OpNum).getReg() == AVR::R29R28 &&
153            "Wrong register class for memory operand.");
154     O << "Y";
155   }
156 
157   // If NumOpRegs == 2, then we assume it is product of a FrameIndex expansion
158   // and the second operand is an Imm.
159   unsigned OpFlags = MI->getOperand(OpNum - 1).getImm();
160   unsigned NumOpRegs = InlineAsm::getNumOperandRegisters(OpFlags);
161 
162   if (NumOpRegs == 2) {
163     O << '+' << MI->getOperand(OpNum + 1).getImm();
164   }
165 
166   return false;
167 }
168 
169 void AVRAsmPrinter::EmitInstruction(const MachineInstr *MI) {
170   AVRMCInstLower MCInstLowering(OutContext, *this);
171 
172   MCInst I;
173   MCInstLowering.lowerInstruction(*MI, I);
174   EmitToStreamer(*OutStreamer, I);
175 }
176 
177 } // end of namespace llvm
178 
179 extern "C" void LLVMInitializeAVRAsmPrinter() {
180   llvm::RegisterAsmPrinter<llvm::AVRAsmPrinter> X(llvm::getTheAVRTarget());
181 }
182 
183