1 //===- lib/MC/AArch64ELFStreamer.cpp - ELF Object Output for AArch64 ------===// 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 assembles .s files and emits AArch64 ELF .o object files. Different 10 // from generic ELF streamer in emitting mapping symbols ($x and $d) to delimit 11 // regions of data and code. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "AArch64ELFStreamer.h" 16 #include "AArch64MCTargetDesc.h" 17 #include "AArch64TargetStreamer.h" 18 #include "AArch64WinCOFFStreamer.h" 19 #include "llvm/ADT/DenseMap.h" 20 #include "llvm/ADT/StringRef.h" 21 #include "llvm/ADT/Twine.h" 22 #include "llvm/BinaryFormat/ELF.h" 23 #include "llvm/MC/MCAsmBackend.h" 24 #include "llvm/MC/MCAssembler.h" 25 #include "llvm/MC/MCCodeEmitter.h" 26 #include "llvm/MC/MCContext.h" 27 #include "llvm/MC/MCELFStreamer.h" 28 #include "llvm/MC/MCExpr.h" 29 #include "llvm/MC/MCInst.h" 30 #include "llvm/MC/MCObjectWriter.h" 31 #include "llvm/MC/MCSection.h" 32 #include "llvm/MC/MCStreamer.h" 33 #include "llvm/MC/MCSubtargetInfo.h" 34 #include "llvm/MC/MCSymbolELF.h" 35 #include "llvm/MC/MCWinCOFFStreamer.h" 36 #include "llvm/Support/Casting.h" 37 #include "llvm/Support/FormattedStream.h" 38 #include "llvm/Support/raw_ostream.h" 39 #include "llvm/TargetParser/Triple.h" 40 41 using namespace llvm; 42 43 namespace { 44 45 class AArch64ELFStreamer; 46 47 class AArch64TargetAsmStreamer : public AArch64TargetStreamer { 48 formatted_raw_ostream &OS; 49 50 void emitInst(uint32_t Inst) override; 51 52 void emitDirectiveVariantPCS(MCSymbol *Symbol) override { 53 OS << "\t.variant_pcs\t" << Symbol->getName() << "\n"; 54 } 55 56 void emitARM64WinCFIAllocStack(unsigned Size) override { 57 OS << "\t.seh_stackalloc\t" << Size << "\n"; 58 } 59 void emitARM64WinCFISaveR19R20X(int Offset) override { 60 OS << "\t.seh_save_r19r20_x\t" << Offset << "\n"; 61 } 62 void emitARM64WinCFISaveFPLR(int Offset) override { 63 OS << "\t.seh_save_fplr\t" << Offset << "\n"; 64 } 65 void emitARM64WinCFISaveFPLRX(int Offset) override { 66 OS << "\t.seh_save_fplr_x\t" << Offset << "\n"; 67 } 68 void emitARM64WinCFISaveReg(unsigned Reg, int Offset) override { 69 OS << "\t.seh_save_reg\tx" << Reg << ", " << Offset << "\n"; 70 } 71 void emitARM64WinCFISaveRegX(unsigned Reg, int Offset) override { 72 OS << "\t.seh_save_reg_x\tx" << Reg << ", " << Offset << "\n"; 73 } 74 void emitARM64WinCFISaveRegP(unsigned Reg, int Offset) override { 75 OS << "\t.seh_save_regp\tx" << Reg << ", " << Offset << "\n"; 76 } 77 void emitARM64WinCFISaveRegPX(unsigned Reg, int Offset) override { 78 OS << "\t.seh_save_regp_x\tx" << Reg << ", " << Offset << "\n"; 79 } 80 void emitARM64WinCFISaveLRPair(unsigned Reg, int Offset) override { 81 OS << "\t.seh_save_lrpair\tx" << Reg << ", " << Offset << "\n"; 82 } 83 void emitARM64WinCFISaveFReg(unsigned Reg, int Offset) override { 84 OS << "\t.seh_save_freg\td" << Reg << ", " << Offset << "\n"; 85 } 86 void emitARM64WinCFISaveFRegX(unsigned Reg, int Offset) override { 87 OS << "\t.seh_save_freg_x\td" << Reg << ", " << Offset << "\n"; 88 } 89 void emitARM64WinCFISaveFRegP(unsigned Reg, int Offset) override { 90 OS << "\t.seh_save_fregp\td" << Reg << ", " << Offset << "\n"; 91 } 92 void emitARM64WinCFISaveFRegPX(unsigned Reg, int Offset) override { 93 OS << "\t.seh_save_fregp_x\td" << Reg << ", " << Offset << "\n"; 94 } 95 void emitARM64WinCFISetFP() override { OS << "\t.seh_set_fp\n"; } 96 void emitARM64WinCFIAddFP(unsigned Size) override { 97 OS << "\t.seh_add_fp\t" << Size << "\n"; 98 } 99 void emitARM64WinCFINop() override { OS << "\t.seh_nop\n"; } 100 void emitARM64WinCFISaveNext() override { OS << "\t.seh_save_next\n"; } 101 void emitARM64WinCFIPrologEnd() override { OS << "\t.seh_endprologue\n"; } 102 void emitARM64WinCFIEpilogStart() override { OS << "\t.seh_startepilogue\n"; } 103 void emitARM64WinCFIEpilogEnd() override { OS << "\t.seh_endepilogue\n"; } 104 void emitARM64WinCFITrapFrame() override { OS << "\t.seh_trap_frame\n"; } 105 void emitARM64WinCFIMachineFrame() override { OS << "\t.seh_pushframe\n"; } 106 void emitARM64WinCFIContext() override { OS << "\t.seh_context\n"; } 107 void emitARM64WinCFIECContext() override { OS << "\t.seh_ec_context\n"; } 108 void emitARM64WinCFIClearUnwoundToCall() override { 109 OS << "\t.seh_clear_unwound_to_call\n"; 110 } 111 void emitARM64WinCFIPACSignLR() override { 112 OS << "\t.seh_pac_sign_lr\n"; 113 } 114 115 void emitARM64WinCFISaveAnyRegI(unsigned Reg, int Offset) override { 116 OS << "\t.seh_save_any_reg\tx" << Reg << ", " << Offset << "\n"; 117 } 118 void emitARM64WinCFISaveAnyRegIP(unsigned Reg, int Offset) override { 119 OS << "\t.seh_save_any_reg_p\tx" << Reg << ", " << Offset << "\n"; 120 } 121 void emitARM64WinCFISaveAnyRegD(unsigned Reg, int Offset) override { 122 OS << "\t.seh_save_any_reg\td" << Reg << ", " << Offset << "\n"; 123 } 124 void emitARM64WinCFISaveAnyRegDP(unsigned Reg, int Offset) override { 125 OS << "\t.seh_save_any_reg_p\td" << Reg << ", " << Offset << "\n"; 126 } 127 void emitARM64WinCFISaveAnyRegQ(unsigned Reg, int Offset) override { 128 OS << "\t.seh_save_any_reg\tq" << Reg << ", " << Offset << "\n"; 129 } 130 void emitARM64WinCFISaveAnyRegQP(unsigned Reg, int Offset) override { 131 OS << "\t.seh_save_any_reg_p\tq" << Reg << ", " << Offset << "\n"; 132 } 133 void emitARM64WinCFISaveAnyRegIX(unsigned Reg, int Offset) override { 134 OS << "\t.seh_save_any_reg_x\tx" << Reg << ", " << Offset << "\n"; 135 } 136 void emitARM64WinCFISaveAnyRegIPX(unsigned Reg, int Offset) override { 137 OS << "\t.seh_save_any_reg_px\tx" << Reg << ", " << Offset << "\n"; 138 } 139 void emitARM64WinCFISaveAnyRegDX(unsigned Reg, int Offset) override { 140 OS << "\t.seh_save_any_reg_x\td" << Reg << ", " << Offset << "\n"; 141 } 142 void emitARM64WinCFISaveAnyRegDPX(unsigned Reg, int Offset) override { 143 OS << "\t.seh_save_any_reg_px\td" << Reg << ", " << Offset << "\n"; 144 } 145 void emitARM64WinCFISaveAnyRegQX(unsigned Reg, int Offset) override { 146 OS << "\t.seh_save_any_reg_x\tq" << Reg << ", " << Offset << "\n"; 147 } 148 void emitARM64WinCFISaveAnyRegQPX(unsigned Reg, int Offset) override { 149 OS << "\t.seh_save_any_reg_px\tq" << Reg << ", " << Offset << "\n"; 150 } 151 152 public: 153 AArch64TargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS); 154 }; 155 156 AArch64TargetAsmStreamer::AArch64TargetAsmStreamer(MCStreamer &S, 157 formatted_raw_ostream &OS) 158 : AArch64TargetStreamer(S), OS(OS) {} 159 160 void AArch64TargetAsmStreamer::emitInst(uint32_t Inst) { 161 OS << "\t.inst\t0x" << Twine::utohexstr(Inst) << "\n"; 162 } 163 164 /// Extend the generic ELFStreamer class so that it can emit mapping symbols at 165 /// the appropriate points in the object files. These symbols are defined in the 166 /// AArch64 ELF ABI: 167 /// infocenter.arm.com/help/topic/com.arm.doc.ihi0056a/IHI0056A_aaelf64.pdf 168 /// 169 /// In brief: $x or $d should be emitted at the start of each contiguous region 170 /// of A64 code or data in a section. In practice, this emission does not rely 171 /// on explicit assembler directives but on inherent properties of the 172 /// directives doing the emission (e.g. ".byte" is data, "add x0, x0, x0" an 173 /// instruction). 174 /// 175 /// As a result this system is orthogonal to the DataRegion infrastructure used 176 /// by MachO. Beware! 177 class AArch64ELFStreamer : public MCELFStreamer { 178 public: 179 AArch64ELFStreamer(MCContext &Context, std::unique_ptr<MCAsmBackend> TAB, 180 std::unique_ptr<MCObjectWriter> OW, 181 std::unique_ptr<MCCodeEmitter> Emitter) 182 : MCELFStreamer(Context, std::move(TAB), std::move(OW), 183 std::move(Emitter)), 184 MappingSymbolCounter(0), LastEMS(EMS_None) {} 185 186 void changeSection(MCSection *Section, const MCExpr *Subsection) override { 187 // We have to keep track of the mapping symbol state of any sections we 188 // use. Each one should start off as EMS_None, which is provided as the 189 // default constructor by DenseMap::lookup. 190 LastMappingSymbols[getPreviousSection().first] = LastEMS; 191 LastEMS = LastMappingSymbols.lookup(Section); 192 193 MCELFStreamer::changeSection(Section, Subsection); 194 } 195 196 // Reset state between object emissions 197 void reset() override { 198 MappingSymbolCounter = 0; 199 MCELFStreamer::reset(); 200 LastMappingSymbols.clear(); 201 LastEMS = EMS_None; 202 } 203 204 /// This function is the one used to emit instruction data into the ELF 205 /// streamer. We override it to add the appropriate mapping symbol if 206 /// necessary. 207 void emitInstruction(const MCInst &Inst, 208 const MCSubtargetInfo &STI) override { 209 emitA64MappingSymbol(); 210 MCELFStreamer::emitInstruction(Inst, STI); 211 } 212 213 /// Emit a 32-bit value as an instruction. This is only used for the .inst 214 /// directive, EmitInstruction should be used in other cases. 215 void emitInst(uint32_t Inst) { 216 char Buffer[4]; 217 218 // We can't just use EmitIntValue here, as that will emit a data mapping 219 // symbol, and swap the endianness on big-endian systems (instructions are 220 // always little-endian). 221 for (char &C : Buffer) { 222 C = uint8_t(Inst); 223 Inst >>= 8; 224 } 225 226 emitA64MappingSymbol(); 227 MCELFStreamer::emitBytes(StringRef(Buffer, 4)); 228 } 229 230 /// This is one of the functions used to emit data into an ELF section, so the 231 /// AArch64 streamer overrides it to add the appropriate mapping symbol ($d) 232 /// if necessary. 233 void emitBytes(StringRef Data) override { 234 emitDataMappingSymbol(); 235 MCELFStreamer::emitBytes(Data); 236 } 237 238 /// This is one of the functions used to emit data into an ELF section, so the 239 /// AArch64 streamer overrides it to add the appropriate mapping symbol ($d) 240 /// if necessary. 241 void emitValueImpl(const MCExpr *Value, unsigned Size, SMLoc Loc) override { 242 emitDataMappingSymbol(); 243 MCELFStreamer::emitValueImpl(Value, Size, Loc); 244 } 245 246 void emitFill(const MCExpr &NumBytes, uint64_t FillValue, 247 SMLoc Loc) override { 248 emitDataMappingSymbol(); 249 MCObjectStreamer::emitFill(NumBytes, FillValue, Loc); 250 } 251 private: 252 enum ElfMappingSymbol { 253 EMS_None, 254 EMS_A64, 255 EMS_Data 256 }; 257 258 void emitDataMappingSymbol() { 259 if (LastEMS == EMS_Data) 260 return; 261 emitMappingSymbol("$d"); 262 LastEMS = EMS_Data; 263 } 264 265 void emitA64MappingSymbol() { 266 if (LastEMS == EMS_A64) 267 return; 268 emitMappingSymbol("$x"); 269 LastEMS = EMS_A64; 270 } 271 272 void emitMappingSymbol(StringRef Name) { 273 auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol( 274 Name + "." + Twine(MappingSymbolCounter++))); 275 emitLabel(Symbol); 276 Symbol->setType(ELF::STT_NOTYPE); 277 Symbol->setBinding(ELF::STB_LOCAL); 278 Symbol->setExternal(false); 279 } 280 281 int64_t MappingSymbolCounter; 282 283 DenseMap<const MCSection *, ElfMappingSymbol> LastMappingSymbols; 284 ElfMappingSymbol LastEMS; 285 }; 286 287 } // end anonymous namespace 288 289 AArch64ELFStreamer &AArch64TargetELFStreamer::getStreamer() { 290 return static_cast<AArch64ELFStreamer &>(Streamer); 291 } 292 293 void AArch64TargetELFStreamer::emitInst(uint32_t Inst) { 294 getStreamer().emitInst(Inst); 295 } 296 297 void AArch64TargetELFStreamer::emitDirectiveVariantPCS(MCSymbol *Symbol) { 298 getStreamer().getAssembler().registerSymbol(*Symbol); 299 cast<MCSymbolELF>(Symbol)->setOther(ELF::STO_AARCH64_VARIANT_PCS); 300 } 301 302 MCTargetStreamer * 303 llvm::createAArch64AsmTargetStreamer(MCStreamer &S, formatted_raw_ostream &OS, 304 MCInstPrinter *InstPrint, 305 bool isVerboseAsm) { 306 return new AArch64TargetAsmStreamer(S, OS); 307 } 308 309 MCELFStreamer *llvm::createAArch64ELFStreamer( 310 MCContext &Context, std::unique_ptr<MCAsmBackend> TAB, 311 std::unique_ptr<MCObjectWriter> OW, std::unique_ptr<MCCodeEmitter> Emitter, 312 bool RelaxAll) { 313 AArch64ELFStreamer *S = new AArch64ELFStreamer( 314 Context, std::move(TAB), std::move(OW), std::move(Emitter)); 315 if (RelaxAll) 316 S->getAssembler().setRelaxAll(true); 317 return S; 318 } 319