1 //===-- AVRAsmPrinter.cpp - AVR LLVM assembly writer ----------------------===//
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 a printer that converts from our internal representation
10 // of machine-dependent LLVM code to GAS-format AVR assembly language.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "AVR.h"
15 #include "AVRMCInstLower.h"
16 #include "AVRSubtarget.h"
17 #include "MCTargetDesc/AVRInstPrinter.h"
18 #include "MCTargetDesc/AVRMCExpr.h"
19 #include "TargetInfo/AVRTargetInfo.h"
20 
21 #include "llvm/CodeGen/AsmPrinter.h"
22 #include "llvm/CodeGen/MachineFunction.h"
23 #include "llvm/CodeGen/MachineInstr.h"
24 #include "llvm/CodeGen/TargetRegisterInfo.h"
25 #include "llvm/CodeGen/TargetSubtargetInfo.h"
26 #include "llvm/IR/Mangler.h"
27 #include "llvm/MC/MCInst.h"
28 #include "llvm/MC/MCStreamer.h"
29 #include "llvm/MC/MCSymbol.h"
30 #include "llvm/Support/ErrorHandling.h"
31 #include "llvm/Support/TargetRegistry.h"
32 #include "llvm/Support/raw_ostream.h"
33 
34 #define DEBUG_TYPE "avr-asm-printer"
35 
36 namespace llvm {
37 
38 /// An AVR assembly code printer.
39 class AVRAsmPrinter : public AsmPrinter {
40 public:
AVRAsmPrinter(TargetMachine & TM,std::unique_ptr<MCStreamer> Streamer)41   AVRAsmPrinter(TargetMachine &TM,
42                 std::unique_ptr<MCStreamer> Streamer)
43       : AsmPrinter(TM, std::move(Streamer)), MRI(*TM.getMCRegisterInfo()) { }
44 
getPassName() const45   StringRef getPassName() const override { return "AVR Assembly Printer"; }
46 
47   void printOperand(const MachineInstr *MI, unsigned OpNo, raw_ostream &O);
48 
49   bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
50                        const char *ExtraCode, raw_ostream &O) override;
51 
52   bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNum,
53                              const char *ExtraCode, raw_ostream &O) override;
54 
55   void emitInstruction(const MachineInstr *MI) override;
56 
57   const MCExpr *lowerConstant(const Constant *CV) override;
58 
59 private:
60   const MCRegisterInfo &MRI;
61 };
62 
printOperand(const MachineInstr * MI,unsigned OpNo,raw_ostream & O)63 void AVRAsmPrinter::printOperand(const MachineInstr *MI, unsigned OpNo,
64                                  raw_ostream &O) {
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 
PrintAsmOperand(const MachineInstr * MI,unsigned OpNum,const char * ExtraCode,raw_ostream & O)88 bool AVRAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
89                                     const char *ExtraCode, raw_ostream &O) {
90   // Default asm printer can only deal with some extra codes,
91   // so try it first.
92   bool Error = AsmPrinter::PrintAsmOperand(MI, OpNum, ExtraCode, O);
93 
94   if (Error && ExtraCode && ExtraCode[0]) {
95     if (ExtraCode[1] != 0)
96       return true; // Unknown modifier.
97 
98     if (ExtraCode[0] >= 'A' && ExtraCode[0] <= 'Z') {
99       const MachineOperand &RegOp = MI->getOperand(OpNum);
100 
101       assert(RegOp.isReg() && "Operand must be a register when you're"
102                               "using 'A'..'Z' operand extracodes.");
103       Register Reg = RegOp.getReg();
104 
105       unsigned ByteNumber = ExtraCode[0] - 'A';
106 
107       unsigned OpFlags = MI->getOperand(OpNum - 1).getImm();
108       unsigned NumOpRegs = InlineAsm::getNumOperandRegisters(OpFlags);
109       (void)NumOpRegs;
110 
111       const AVRSubtarget &STI = MF->getSubtarget<AVRSubtarget>();
112       const TargetRegisterInfo &TRI = *STI.getRegisterInfo();
113 
114       const TargetRegisterClass *RC = TRI.getMinimalPhysRegClass(Reg);
115       unsigned BytesPerReg = TRI.getRegSizeInBits(*RC) / 8;
116       assert(BytesPerReg <= 2 && "Only 8 and 16 bit regs are supported.");
117 
118       unsigned RegIdx = ByteNumber / BytesPerReg;
119       assert(RegIdx < NumOpRegs && "Multibyte index out of range.");
120 
121       Reg = MI->getOperand(OpNum + RegIdx).getReg();
122 
123       if (BytesPerReg == 2) {
124         Reg = TRI.getSubReg(Reg, ByteNumber % BytesPerReg ? AVR::sub_hi
125                                                           : AVR::sub_lo);
126       }
127 
128       O << AVRInstPrinter::getPrettyRegisterName(Reg, MRI);
129       return false;
130     }
131   }
132 
133   if (Error)
134     printOperand(MI, OpNum, O);
135 
136   return false;
137 }
138 
PrintAsmMemoryOperand(const MachineInstr * MI,unsigned OpNum,const char * ExtraCode,raw_ostream & O)139 bool AVRAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
140                                           unsigned OpNum, const char *ExtraCode,
141                                           raw_ostream &O) {
142   if (ExtraCode && ExtraCode[0]) {
143     llvm_unreachable("This branch is not implemented yet");
144   }
145 
146   const MachineOperand &MO = MI->getOperand(OpNum);
147   (void)MO;
148   assert(MO.isReg() && "Unexpected inline asm memory operand");
149 
150   // TODO: We should be able to look up the alternative name for
151   // the register if it's given.
152   // TableGen doesn't expose a way of getting retrieving names
153   // for registers.
154   if (MI->getOperand(OpNum).getReg() == AVR::R31R30) {
155     O << "Z";
156   } else {
157     assert(MI->getOperand(OpNum).getReg() == AVR::R29R28 &&
158            "Wrong register class for memory operand.");
159     O << "Y";
160   }
161 
162   // If NumOpRegs == 2, then we assume it is product of a FrameIndex expansion
163   // and the second operand is an Imm.
164   unsigned OpFlags = MI->getOperand(OpNum - 1).getImm();
165   unsigned NumOpRegs = InlineAsm::getNumOperandRegisters(OpFlags);
166 
167   if (NumOpRegs == 2) {
168     O << '+' << MI->getOperand(OpNum + 1).getImm();
169   }
170 
171   return false;
172 }
173 
emitInstruction(const MachineInstr * MI)174 void AVRAsmPrinter::emitInstruction(const MachineInstr *MI) {
175   AVRMCInstLower MCInstLowering(OutContext, *this);
176 
177   MCInst I;
178   MCInstLowering.lowerInstruction(*MI, I);
179   EmitToStreamer(*OutStreamer, I);
180 }
181 
lowerConstant(const Constant * CV)182 const MCExpr *AVRAsmPrinter::lowerConstant(const Constant *CV) {
183   MCContext &Ctx = OutContext;
184 
185   if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV)) {
186     bool IsProgMem = GV->getAddressSpace() == AVR::ProgramMemory;
187     if (IsProgMem) {
188       const MCExpr *Expr = MCSymbolRefExpr::create(getSymbol(GV), Ctx);
189       return AVRMCExpr::create(AVRMCExpr::VK_AVR_PM, Expr, false, Ctx);
190     }
191   }
192 
193   return AsmPrinter::lowerConstant(CV);
194 }
195 
196 } // end of namespace llvm
197 
LLVMInitializeAVRAsmPrinter()198 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeAVRAsmPrinter() {
199   llvm::RegisterAsmPrinter<llvm::AVRAsmPrinter> X(llvm::getTheAVRTarget());
200 }
201 
202