343 lines · cpp
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-exception6//7//===----------------------------------------------------------------------===//8//9// This file contains a printer that converts from our internal representation10// 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 43using namespace llvm;44 45namespace {46 47/// An AVR assembly code printer.48class AVRAsmPrinter : public AsmPrinter {49public: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 76private:77 const MCRegisterInfo &MRI;78 bool EmittedStructorSymbolAttrs = false;79};80 81} // namespace82 83void 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 108bool 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_hi146 : 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 else156 printOperand(MI, OpNum, O); // Fallback to ordinary cases.157 158 return false;159}160 161bool AVRAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,162 unsigned OpNum, const char *ExtraCode,163 raw_ostream &O) {164 if (ExtraCode && ExtraCode[0])165 return true; // Unknown modifier166 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 for172 // the register if it's given.173 // TableGen doesn't expose a way of getting retrieving names174 // 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 expansion186 // 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 199void 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 210const 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 226void 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 245bool AVRAsmPrinter::doFinalization(Module &M) {246 const TargetLoweringObjectFile &TLOF = getObjFileLowering();247 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();248 const AVRSubtarget *SubTM = 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 = static_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) store268 // .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 295void AVRAsmPrinter::emitStartOfAsmFile(Module &M) {296 const AVRTargetMachine &TM = (const AVRTargetMachine &)MMI->getTarget();297 const AVRSubtarget *SubTM = 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 334char AVRAsmPrinter::ID = 0;335 336INITIALIZE_PASS(AVRAsmPrinter, "avr-asm-printer", "AVR Assembly Printer", false,337 false)338 339extern "C" LLVM_ABI LLVM_EXTERNAL_VISIBILITY void340LLVMInitializeAVRAsmPrinter() {341 llvm::RegisterAsmPrinter<AVRAsmPrinter> X(getTheAVRTarget());342}343