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 "AVRTargetMachine.h" 18 #include "MCTargetDesc/AVRInstPrinter.h" 19 #include "MCTargetDesc/AVRMCExpr.h" 20 #include "TargetInfo/AVRTargetInfo.h" 21 22 #include "llvm/BinaryFormat/ELF.h" 23 #include "llvm/CodeGen/AsmPrinter.h" 24 #include "llvm/CodeGen/MachineFunction.h" 25 #include "llvm/CodeGen/MachineInstr.h" 26 #include "llvm/CodeGen/MachineModuleInfo.h" 27 #include "llvm/CodeGen/TargetRegisterInfo.h" 28 #include "llvm/CodeGen/TargetSubtargetInfo.h" 29 #include "llvm/IR/Mangler.h" 30 #include "llvm/IR/Module.h" 31 #include "llvm/MC/MCContext.h" 32 #include "llvm/MC/MCInst.h" 33 #include "llvm/MC/MCSectionELF.h" 34 #include "llvm/MC/MCStreamer.h" 35 #include "llvm/MC/MCSymbol.h" 36 #include "llvm/MC/TargetRegistry.h" 37 #include "llvm/Support/ErrorHandling.h" 38 #include "llvm/Support/raw_ostream.h" 39 #include "llvm/Target/TargetLoweringObjectFile.h" 40 41 #define DEBUG_TYPE "avr-asm-printer" 42 43 namespace llvm { 44 45 /// An AVR assembly code printer. 46 class AVRAsmPrinter : public AsmPrinter { 47 public: 48 AVRAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer) 49 : AsmPrinter(TM, std::move(Streamer)), MRI(*TM.getMCRegisterInfo()) {} 50 51 StringRef getPassName() const override { return "AVR Assembly Printer"; } 52 53 void printOperand(const MachineInstr *MI, unsigned OpNo, raw_ostream &O); 54 55 bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNum, 56 const char *ExtraCode, raw_ostream &O) override; 57 58 bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNum, 59 const char *ExtraCode, raw_ostream &O) override; 60 61 void emitInstruction(const MachineInstr *MI) override; 62 63 const MCExpr *lowerConstant(const Constant *CV) override; 64 65 void emitXXStructor(const DataLayout &DL, const Constant *CV) override; 66 67 bool doFinalization(Module &M) override; 68 69 void emitStartOfAsmFile(Module &M) override; 70 71 private: 72 const MCRegisterInfo &MRI; 73 bool EmittedStructorSymbolAttrs = false; 74 }; 75 76 void AVRAsmPrinter::printOperand(const MachineInstr *MI, unsigned OpNo, 77 raw_ostream &O) { 78 const MachineOperand &MO = MI->getOperand(OpNo); 79 80 switch (MO.getType()) { 81 case MachineOperand::MO_Register: 82 O << AVRInstPrinter::getPrettyRegisterName(MO.getReg(), MRI); 83 break; 84 case MachineOperand::MO_Immediate: 85 O << MO.getImm(); 86 break; 87 case MachineOperand::MO_GlobalAddress: 88 O << getSymbol(MO.getGlobal()); 89 break; 90 case MachineOperand::MO_ExternalSymbol: 91 O << *GetExternalSymbolSymbol(MO.getSymbolName()); 92 break; 93 case MachineOperand::MO_MachineBasicBlock: 94 O << *MO.getMBB()->getSymbol(); 95 break; 96 default: 97 llvm_unreachable("Not implemented yet!"); 98 } 99 } 100 101 bool AVRAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum, 102 const char *ExtraCode, raw_ostream &O) { 103 // Default asm printer can only deal with some extra codes, 104 // so try it first. 105 if (!AsmPrinter::PrintAsmOperand(MI, OpNum, ExtraCode, O)) 106 return false; 107 108 const MachineOperand &MO = MI->getOperand(OpNum); 109 110 if (ExtraCode && ExtraCode[0]) { 111 // Unknown extra code. 112 if (ExtraCode[1] != 0 || ExtraCode[0] < 'A' || ExtraCode[0] > 'Z') 113 return true; 114 115 // Operand must be a register when using 'A' ~ 'Z' extra code. 116 if (!MO.isReg()) 117 return true; 118 119 Register Reg = MO.getReg(); 120 121 unsigned ByteNumber = ExtraCode[0] - 'A'; 122 const InlineAsm::Flag OpFlags(MI->getOperand(OpNum - 1).getImm()); 123 const unsigned NumOpRegs = OpFlags.getNumOperandRegisters(); 124 125 const AVRSubtarget &STI = MF->getSubtarget<AVRSubtarget>(); 126 const TargetRegisterInfo &TRI = *STI.getRegisterInfo(); 127 128 const TargetRegisterClass *RC = TRI.getMinimalPhysRegClass(Reg); 129 unsigned BytesPerReg = TRI.getRegSizeInBits(*RC) / 8; 130 assert(BytesPerReg <= 2 && "Only 8 and 16 bit regs are supported."); 131 132 unsigned RegIdx = ByteNumber / BytesPerReg; 133 if (RegIdx >= NumOpRegs) 134 return true; 135 Reg = MI->getOperand(OpNum + RegIdx).getReg(); 136 137 if (BytesPerReg == 2) { 138 Reg = TRI.getSubReg(Reg, (ByteNumber % BytesPerReg) ? AVR::sub_hi 139 : AVR::sub_lo); 140 } 141 142 O << AVRInstPrinter::getPrettyRegisterName(Reg, MRI); 143 return false; 144 } 145 146 if (MO.getType() == MachineOperand::MO_GlobalAddress) 147 PrintSymbolOperand(MO, O); // Print global symbols. 148 else 149 printOperand(MI, OpNum, O); // Fallback to ordinary cases. 150 151 return false; 152 } 153 154 bool AVRAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, 155 unsigned OpNum, const char *ExtraCode, 156 raw_ostream &O) { 157 if (ExtraCode && ExtraCode[0]) 158 return true; // Unknown modifier 159 160 const MachineOperand &MO = MI->getOperand(OpNum); 161 (void)MO; 162 assert(MO.isReg() && "Unexpected inline asm memory operand"); 163 164 // TODO: We should be able to look up the alternative name for 165 // the register if it's given. 166 // TableGen doesn't expose a way of getting retrieving names 167 // for registers. 168 if (MI->getOperand(OpNum).getReg() == AVR::R31R30) { 169 O << "Z"; 170 } else if (MI->getOperand(OpNum).getReg() == AVR::R29R28) { 171 O << "Y"; 172 } else if (MI->getOperand(OpNum).getReg() == AVR::R27R26) { 173 O << "X"; 174 } else { 175 assert(false && "Wrong register class for memory operand."); 176 } 177 178 // If NumOpRegs == 2, then we assume it is product of a FrameIndex expansion 179 // and the second operand is an Imm. 180 const InlineAsm::Flag OpFlags(MI->getOperand(OpNum - 1).getImm()); 181 const unsigned NumOpRegs = OpFlags.getNumOperandRegisters(); 182 183 if (NumOpRegs == 2) { 184 assert(MI->getOperand(OpNum).getReg() != AVR::R27R26 && 185 "Base register X can not have offset/displacement."); 186 O << '+' << MI->getOperand(OpNum + 1).getImm(); 187 } 188 189 return false; 190 } 191 192 void AVRAsmPrinter::emitInstruction(const MachineInstr *MI) { 193 AVR_MC::verifyInstructionPredicates(MI->getOpcode(), 194 getSubtargetInfo().getFeatureBits()); 195 196 AVRMCInstLower MCInstLowering(OutContext, *this); 197 198 MCInst I; 199 MCInstLowering.lowerInstruction(*MI, I); 200 EmitToStreamer(*OutStreamer, I); 201 } 202 203 const MCExpr *AVRAsmPrinter::lowerConstant(const Constant *CV) { 204 MCContext &Ctx = OutContext; 205 206 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV)) { 207 bool IsProgMem = GV->getAddressSpace() == AVR::ProgramMemory; 208 if (IsProgMem) { 209 const MCExpr *Expr = MCSymbolRefExpr::create(getSymbol(GV), Ctx); 210 return AVRMCExpr::create(AVRMCExpr::VK_AVR_PM, Expr, false, Ctx); 211 } 212 } 213 214 return AsmPrinter::lowerConstant(CV); 215 } 216 217 void AVRAsmPrinter::emitXXStructor(const DataLayout &DL, const Constant *CV) { 218 if (!EmittedStructorSymbolAttrs) { 219 OutStreamer->emitRawComment( 220 " Emitting these undefined symbol references causes us to link the" 221 " libgcc code that runs our constructors/destructors"); 222 OutStreamer->emitRawComment(" This matches GCC's behavior"); 223 224 MCSymbol *CtorsSym = OutContext.getOrCreateSymbol("__do_global_ctors"); 225 OutStreamer->emitSymbolAttribute(CtorsSym, MCSA_Global); 226 227 MCSymbol *DtorsSym = OutContext.getOrCreateSymbol("__do_global_dtors"); 228 OutStreamer->emitSymbolAttribute(DtorsSym, MCSA_Global); 229 230 EmittedStructorSymbolAttrs = true; 231 } 232 233 AsmPrinter::emitXXStructor(DL, CV); 234 } 235 236 bool AVRAsmPrinter::doFinalization(Module &M) { 237 const TargetLoweringObjectFile &TLOF = getObjFileLowering(); 238 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget(); 239 const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl(); 240 241 bool NeedsCopyData = false; 242 bool NeedsClearBSS = false; 243 for (const auto &GO : M.globals()) { 244 if (!GO.hasInitializer() || GO.hasAvailableExternallyLinkage()) 245 // These globals aren't defined in the current object file. 246 continue; 247 248 if (GO.hasCommonLinkage()) { 249 // COMMON symbols are put in .bss. 250 NeedsClearBSS = true; 251 continue; 252 } 253 254 auto *Section = cast<MCSectionELF>(TLOF.SectionForGlobal(&GO, TM)); 255 if (Section->getName().starts_with(".data")) 256 NeedsCopyData = true; 257 else if (Section->getName().starts_with(".rodata") && SubTM->hasLPM()) 258 // AVRs that have a separate program memory (that's most AVRs) store 259 // .rodata sections in RAM. 260 NeedsCopyData = true; 261 else if (Section->getName().starts_with(".bss")) 262 NeedsClearBSS = true; 263 } 264 265 MCSymbol *DoCopyData = OutContext.getOrCreateSymbol("__do_copy_data"); 266 MCSymbol *DoClearBss = OutContext.getOrCreateSymbol("__do_clear_bss"); 267 268 if (NeedsCopyData) { 269 OutStreamer->emitRawComment( 270 " Declaring this symbol tells the CRT that it should"); 271 OutStreamer->emitRawComment( 272 "copy all variables from program memory to RAM on startup"); 273 OutStreamer->emitSymbolAttribute(DoCopyData, MCSA_Global); 274 } 275 276 if (NeedsClearBSS) { 277 OutStreamer->emitRawComment( 278 " Declaring this symbol tells the CRT that it should"); 279 OutStreamer->emitRawComment("clear the zeroed data section on startup"); 280 OutStreamer->emitSymbolAttribute(DoClearBss, MCSA_Global); 281 } 282 283 return AsmPrinter::doFinalization(M); 284 } 285 286 void AVRAsmPrinter::emitStartOfAsmFile(Module &M) { 287 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget(); 288 const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl(); 289 if (!SubTM) 290 return; 291 292 // Emit __tmp_reg__. 293 OutStreamer->emitAssignment( 294 MMI->getContext().getOrCreateSymbol(StringRef("__tmp_reg__")), 295 MCConstantExpr::create(SubTM->getRegTmpIndex(), MMI->getContext())); 296 // Emit __zero_reg__. 297 OutStreamer->emitAssignment( 298 MMI->getContext().getOrCreateSymbol(StringRef("__zero_reg__")), 299 MCConstantExpr::create(SubTM->getRegZeroIndex(), MMI->getContext())); 300 // Emit __SREG__. 301 OutStreamer->emitAssignment( 302 MMI->getContext().getOrCreateSymbol(StringRef("__SREG__")), 303 MCConstantExpr::create(SubTM->getIORegSREG(), MMI->getContext())); 304 // Emit __SP_H__ if available. 305 if (!SubTM->hasSmallStack()) 306 OutStreamer->emitAssignment( 307 MMI->getContext().getOrCreateSymbol(StringRef("__SP_H__")), 308 MCConstantExpr::create(SubTM->getIORegSPH(), MMI->getContext())); 309 // Emit __SP_L__. 310 OutStreamer->emitAssignment( 311 MMI->getContext().getOrCreateSymbol(StringRef("__SP_L__")), 312 MCConstantExpr::create(SubTM->getIORegSPL(), MMI->getContext())); 313 // Emit __EIND__ if available. 314 if (SubTM->hasEIJMPCALL()) 315 OutStreamer->emitAssignment( 316 MMI->getContext().getOrCreateSymbol(StringRef("__EIND__")), 317 MCConstantExpr::create(SubTM->getIORegEIND(), MMI->getContext())); 318 // Emit __RAMPZ__ if available. 319 if (SubTM->hasELPM()) 320 OutStreamer->emitAssignment( 321 MMI->getContext().getOrCreateSymbol(StringRef("__RAMPZ__")), 322 MCConstantExpr::create(SubTM->getIORegRAMPZ(), MMI->getContext())); 323 } 324 325 } // end of namespace llvm 326 327 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeAVRAsmPrinter() { 328 llvm::RegisterAsmPrinter<llvm::AVRAsmPrinter> X(llvm::getTheAVRTarget()); 329 } 330