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