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/AVRMCAsmInfo.h" 20 #include "TargetInfo/AVRTargetInfo.h" 21 22 #include "llvm/CodeGen/AsmPrinter.h" 23 #include "llvm/CodeGen/MachineFunction.h" 24 #include "llvm/CodeGen/MachineInstr.h" 25 #include "llvm/CodeGen/MachineModuleInfo.h" 26 #include "llvm/CodeGen/TargetRegisterInfo.h" 27 #include "llvm/CodeGen/TargetSubtargetInfo.h" 28 #include "llvm/IR/Mangler.h" 29 #include "llvm/IR/Module.h" 30 #include "llvm/MC/MCContext.h" 31 #include "llvm/MC/MCInst.h" 32 #include "llvm/MC/MCSectionELF.h" 33 #include "llvm/MC/MCStreamer.h" 34 #include "llvm/MC/MCSymbol.h" 35 #include "llvm/MC/TargetRegistry.h" 36 #include "llvm/Support/Compiler.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 using namespace llvm; 44 45 namespace { 46 47 /// An AVR assembly code printer. 48 class AVRAsmPrinter : public AsmPrinter { 49 public: 50 AVRAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer) 51 : AsmPrinter(TM, std::move(Streamer), ID), MRI(*TM.getMCRegisterInfo()) {} 52 53 StringRef getPassName() const override { return "AVR Assembly Printer"; } 54 55 void printOperand(const MachineInstr *MI, unsigned OpNo, raw_ostream &O); 56 57 bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNum, 58 const char *ExtraCode, raw_ostream &O) override; 59 60 bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNum, 61 const char *ExtraCode, raw_ostream &O) override; 62 63 void emitInstruction(const MachineInstr *MI) override; 64 65 const MCExpr *lowerConstant(const Constant *CV, const Constant *BaseCV, 66 uint64_t Offset) override; 67 68 void emitXXStructor(const DataLayout &DL, const Constant *CV) override; 69 70 bool doFinalization(Module &M) override; 71 72 void emitStartOfAsmFile(Module &M) override; 73 74 static char ID; 75 76 private: 77 const MCRegisterInfo &MRI; 78 bool EmittedStructorSymbolAttrs = false; 79 }; 80 81 } // namespace 82 83 void AVRAsmPrinter::printOperand(const MachineInstr *MI, unsigned OpNo, 84 raw_ostream &O) { 85 const MachineOperand &MO = MI->getOperand(OpNo); 86 87 switch (MO.getType()) { 88 case MachineOperand::MO_Register: 89 O << AVRInstPrinter::getPrettyRegisterName(MO.getReg(), MRI); 90 break; 91 case MachineOperand::MO_Immediate: 92 O << MO.getImm(); 93 break; 94 case MachineOperand::MO_GlobalAddress: 95 O << getSymbol(MO.getGlobal()); 96 break; 97 case MachineOperand::MO_ExternalSymbol: 98 O << *GetExternalSymbolSymbol(MO.getSymbolName()); 99 break; 100 case MachineOperand::MO_MachineBasicBlock: 101 O << *MO.getMBB()->getSymbol(); 102 break; 103 default: 104 llvm_unreachable("Not implemented yet!"); 105 } 106 } 107 108 bool AVRAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum, 109 const char *ExtraCode, raw_ostream &O) { 110 // Default asm printer can only deal with some extra codes, 111 // so try it first. 112 if (!AsmPrinter::PrintAsmOperand(MI, OpNum, ExtraCode, O)) 113 return false; 114 115 const MachineOperand &MO = MI->getOperand(OpNum); 116 117 if (ExtraCode && ExtraCode[0]) { 118 // Unknown extra code. 119 if (ExtraCode[1] != 0 || ExtraCode[0] < 'A' || ExtraCode[0] > 'Z') 120 return true; 121 122 // Operand must be a register when using 'A' ~ 'Z' extra code. 123 if (!MO.isReg()) 124 return true; 125 126 Register Reg = MO.getReg(); 127 128 unsigned ByteNumber = ExtraCode[0] - 'A'; 129 const InlineAsm::Flag OpFlags(MI->getOperand(OpNum - 1).getImm()); 130 const unsigned NumOpRegs = OpFlags.getNumOperandRegisters(); 131 132 const AVRSubtarget &STI = MF->getSubtarget<AVRSubtarget>(); 133 const TargetRegisterInfo &TRI = *STI.getRegisterInfo(); 134 135 const TargetRegisterClass *RC = TRI.getMinimalPhysRegClass(Reg); 136 unsigned BytesPerReg = TRI.getRegSizeInBits(*RC) / 8; 137 assert(BytesPerReg <= 2 && "Only 8 and 16 bit regs are supported."); 138 139 unsigned RegIdx = ByteNumber / BytesPerReg; 140 if (RegIdx >= NumOpRegs) 141 return true; 142 Reg = MI->getOperand(OpNum + RegIdx).getReg(); 143 144 if (BytesPerReg == 2) { 145 Reg = TRI.getSubReg(Reg, (ByteNumber % BytesPerReg) ? AVR::sub_hi 146 : AVR::sub_lo); 147 } 148 149 O << AVRInstPrinter::getPrettyRegisterName(Reg, MRI); 150 return false; 151 } 152 153 if (MO.getType() == MachineOperand::MO_GlobalAddress) 154 PrintSymbolOperand(MO, O); // Print global symbols. 155 else 156 printOperand(MI, OpNum, O); // Fallback to ordinary cases. 157 158 return false; 159 } 160 161 bool AVRAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, 162 unsigned OpNum, const char *ExtraCode, 163 raw_ostream &O) { 164 if (ExtraCode && ExtraCode[0]) 165 return true; // Unknown modifier 166 167 const MachineOperand &MO = MI->getOperand(OpNum); 168 (void)MO; 169 assert(MO.isReg() && "Unexpected inline asm memory operand"); 170 171 // TODO: We should be able to look up the alternative name for 172 // the register if it's given. 173 // TableGen doesn't expose a way of getting retrieving names 174 // for registers. 175 if (MI->getOperand(OpNum).getReg() == AVR::R31R30) { 176 O << "Z"; 177 } else if (MI->getOperand(OpNum).getReg() == AVR::R29R28) { 178 O << "Y"; 179 } else if (MI->getOperand(OpNum).getReg() == AVR::R27R26) { 180 O << "X"; 181 } else { 182 assert(false && "Wrong register class for memory operand."); 183 } 184 185 // If NumOpRegs == 2, then we assume it is product of a FrameIndex expansion 186 // and the second operand is an Imm. 187 const InlineAsm::Flag OpFlags(MI->getOperand(OpNum - 1).getImm()); 188 const unsigned NumOpRegs = OpFlags.getNumOperandRegisters(); 189 190 if (NumOpRegs == 2) { 191 assert(MI->getOperand(OpNum).getReg() != AVR::R27R26 && 192 "Base register X can not have offset/displacement."); 193 O << '+' << MI->getOperand(OpNum + 1).getImm(); 194 } 195 196 return false; 197 } 198 199 void AVRAsmPrinter::emitInstruction(const MachineInstr *MI) { 200 AVR_MC::verifyInstructionPredicates(MI->getOpcode(), 201 getSubtargetInfo().getFeatureBits()); 202 203 AVRMCInstLower MCInstLowering(OutContext, *this); 204 205 MCInst I; 206 MCInstLowering.lowerInstruction(*MI, I); 207 EmitToStreamer(*OutStreamer, I); 208 } 209 210 const MCExpr *AVRAsmPrinter::lowerConstant(const Constant *CV, 211 const Constant *BaseCV, 212 uint64_t Offset) { 213 MCContext &Ctx = OutContext; 214 215 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV)) { 216 bool IsProgMem = GV->getAddressSpace() == AVR::ProgramMemory; 217 if (IsProgMem) { 218 const MCExpr *Expr = MCSymbolRefExpr::create(getSymbol(GV), Ctx); 219 return AVRMCExpr::create(AVR::S_PM, Expr, false, Ctx); 220 } 221 } 222 223 return AsmPrinter::lowerConstant(CV, BaseCV, Offset); 224 } 225 226 void AVRAsmPrinter::emitXXStructor(const DataLayout &DL, const Constant *CV) { 227 if (!EmittedStructorSymbolAttrs) { 228 OutStreamer->emitRawComment( 229 " Emitting these undefined symbol references causes us to link the" 230 " libgcc code that runs our constructors/destructors"); 231 OutStreamer->emitRawComment(" This matches GCC's behavior"); 232 233 MCSymbol *CtorsSym = OutContext.getOrCreateSymbol("__do_global_ctors"); 234 OutStreamer->emitSymbolAttribute(CtorsSym, MCSA_Global); 235 236 MCSymbol *DtorsSym = OutContext.getOrCreateSymbol("__do_global_dtors"); 237 OutStreamer->emitSymbolAttribute(DtorsSym, MCSA_Global); 238 239 EmittedStructorSymbolAttrs = true; 240 } 241 242 AsmPrinter::emitXXStructor(DL, CV); 243 } 244 245 bool AVRAsmPrinter::doFinalization(Module &M) { 246 const TargetLoweringObjectFile &TLOF = getObjFileLowering(); 247 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget(); 248 const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl(); 249 250 bool NeedsCopyData = false; 251 bool NeedsClearBSS = false; 252 for (const auto &GO : M.globals()) { 253 if (!GO.hasInitializer() || GO.hasAvailableExternallyLinkage()) 254 // These globals aren't defined in the current object file. 255 continue; 256 257 if (GO.hasCommonLinkage()) { 258 // COMMON symbols are put in .bss. 259 NeedsClearBSS = true; 260 continue; 261 } 262 263 auto *Section = cast<MCSectionELF>(TLOF.SectionForGlobal(&GO, TM)); 264 if (Section->getName().starts_with(".data")) 265 NeedsCopyData = true; 266 else if (Section->getName().starts_with(".rodata") && SubTM->hasLPM()) 267 // AVRs that have a separate program memory (that's most AVRs) store 268 // .rodata sections in RAM. 269 NeedsCopyData = true; 270 else if (Section->getName().starts_with(".bss")) 271 NeedsClearBSS = true; 272 } 273 274 MCSymbol *DoCopyData = OutContext.getOrCreateSymbol("__do_copy_data"); 275 MCSymbol *DoClearBss = OutContext.getOrCreateSymbol("__do_clear_bss"); 276 277 if (NeedsCopyData) { 278 OutStreamer->emitRawComment( 279 " Declaring this symbol tells the CRT that it should"); 280 OutStreamer->emitRawComment( 281 "copy all variables from program memory to RAM on startup"); 282 OutStreamer->emitSymbolAttribute(DoCopyData, MCSA_Global); 283 } 284 285 if (NeedsClearBSS) { 286 OutStreamer->emitRawComment( 287 " Declaring this symbol tells the CRT that it should"); 288 OutStreamer->emitRawComment("clear the zeroed data section on startup"); 289 OutStreamer->emitSymbolAttribute(DoClearBss, MCSA_Global); 290 } 291 292 return AsmPrinter::doFinalization(M); 293 } 294 295 void AVRAsmPrinter::emitStartOfAsmFile(Module &M) { 296 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget(); 297 const AVRSubtarget *SubTM = (const AVRSubtarget *)TM.getSubtargetImpl(); 298 if (!SubTM) 299 return; 300 301 // Emit __tmp_reg__. 302 OutStreamer->emitAssignment( 303 MMI->getContext().getOrCreateSymbol(StringRef("__tmp_reg__")), 304 MCConstantExpr::create(SubTM->getRegTmpIndex(), MMI->getContext())); 305 // Emit __zero_reg__. 306 OutStreamer->emitAssignment( 307 MMI->getContext().getOrCreateSymbol(StringRef("__zero_reg__")), 308 MCConstantExpr::create(SubTM->getRegZeroIndex(), MMI->getContext())); 309 // Emit __SREG__. 310 OutStreamer->emitAssignment( 311 MMI->getContext().getOrCreateSymbol(StringRef("__SREG__")), 312 MCConstantExpr::create(SubTM->getIORegSREG(), MMI->getContext())); 313 // Emit __SP_H__ if available. 314 if (!SubTM->hasSmallStack()) 315 OutStreamer->emitAssignment( 316 MMI->getContext().getOrCreateSymbol(StringRef("__SP_H__")), 317 MCConstantExpr::create(SubTM->getIORegSPH(), MMI->getContext())); 318 // Emit __SP_L__. 319 OutStreamer->emitAssignment( 320 MMI->getContext().getOrCreateSymbol(StringRef("__SP_L__")), 321 MCConstantExpr::create(SubTM->getIORegSPL(), MMI->getContext())); 322 // Emit __EIND__ if available. 323 if (SubTM->hasEIJMPCALL()) 324 OutStreamer->emitAssignment( 325 MMI->getContext().getOrCreateSymbol(StringRef("__EIND__")), 326 MCConstantExpr::create(SubTM->getIORegEIND(), MMI->getContext())); 327 // Emit __RAMPZ__ if available. 328 if (SubTM->hasELPM()) 329 OutStreamer->emitAssignment( 330 MMI->getContext().getOrCreateSymbol(StringRef("__RAMPZ__")), 331 MCConstantExpr::create(SubTM->getIORegRAMPZ(), MMI->getContext())); 332 } 333 334 char AVRAsmPrinter::ID = 0; 335 336 INITIALIZE_PASS(AVRAsmPrinter, "avr-asm-printer", "AVR Assembly Printer", false, 337 false) 338 339 extern "C" LLVM_ABI LLVM_EXTERNAL_VISIBILITY void 340 LLVMInitializeAVRAsmPrinter() { 341 llvm::RegisterAsmPrinter<AVRAsmPrinter> X(getTheAVRTarget()); 342 } 343