1 //===-- PPCAsmBackend.cpp - PPC Assembler Backend -------------------------===// 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 #include "MCTargetDesc/PPCFixupKinds.h" 10 #include "MCTargetDesc/PPCMCTargetDesc.h" 11 #include "llvm/BinaryFormat/ELF.h" 12 #include "llvm/BinaryFormat/MachO.h" 13 #include "llvm/MC/MCAsmBackend.h" 14 #include "llvm/MC/MCAssembler.h" 15 #include "llvm/MC/MCELFObjectWriter.h" 16 #include "llvm/MC/MCFixupKindInfo.h" 17 #include "llvm/MC/MCMachObjectWriter.h" 18 #include "llvm/MC/MCObjectWriter.h" 19 #include "llvm/MC/MCSectionMachO.h" 20 #include "llvm/MC/MCSubtargetInfo.h" 21 #include "llvm/MC/MCSymbolELF.h" 22 #include "llvm/MC/MCValue.h" 23 #include "llvm/MC/TargetRegistry.h" 24 #include "llvm/Support/ErrorHandling.h" 25 using namespace llvm; 26 27 static uint64_t adjustFixupValue(unsigned Kind, uint64_t Value) { 28 switch (Kind) { 29 default: 30 llvm_unreachable("Unknown fixup kind!"); 31 case FK_Data_1: 32 case FK_Data_2: 33 case FK_Data_4: 34 case FK_Data_8: 35 case PPC::fixup_ppc_nofixup: 36 return Value; 37 case PPC::fixup_ppc_brcond14: 38 case PPC::fixup_ppc_brcond14abs: 39 return Value & 0xfffc; 40 case PPC::fixup_ppc_br24: 41 case PPC::fixup_ppc_br24abs: 42 case PPC::fixup_ppc_br24_notoc: 43 return Value & 0x3fffffc; 44 case PPC::fixup_ppc_half16: 45 return Value & 0xffff; 46 case PPC::fixup_ppc_half16ds: 47 case PPC::fixup_ppc_half16dq: 48 return Value & 0xfffc; 49 case PPC::fixup_ppc_pcrel34: 50 case PPC::fixup_ppc_imm34: 51 return Value & 0x3ffffffff; 52 } 53 } 54 55 static unsigned getFixupKindNumBytes(unsigned Kind) { 56 switch (Kind) { 57 default: 58 llvm_unreachable("Unknown fixup kind!"); 59 case FK_Data_1: 60 return 1; 61 case FK_Data_2: 62 case PPC::fixup_ppc_half16: 63 case PPC::fixup_ppc_half16ds: 64 case PPC::fixup_ppc_half16dq: 65 return 2; 66 case FK_Data_4: 67 case PPC::fixup_ppc_brcond14: 68 case PPC::fixup_ppc_brcond14abs: 69 case PPC::fixup_ppc_br24: 70 case PPC::fixup_ppc_br24abs: 71 case PPC::fixup_ppc_br24_notoc: 72 return 4; 73 case PPC::fixup_ppc_pcrel34: 74 case PPC::fixup_ppc_imm34: 75 case FK_Data_8: 76 return 8; 77 case PPC::fixup_ppc_nofixup: 78 return 0; 79 } 80 } 81 82 namespace { 83 84 class PPCAsmBackend : public MCAsmBackend { 85 protected: 86 Triple TT; 87 public: 88 PPCAsmBackend(const Target &T, const Triple &TT) 89 : MCAsmBackend(TT.isLittleEndian() ? support::little : support::big), 90 TT(TT) {} 91 92 unsigned getNumFixupKinds() const override { 93 return PPC::NumTargetFixupKinds; 94 } 95 96 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override { 97 const static MCFixupKindInfo InfosBE[PPC::NumTargetFixupKinds] = { 98 // name offset bits flags 99 { "fixup_ppc_br24", 6, 24, MCFixupKindInfo::FKF_IsPCRel }, 100 { "fixup_ppc_br24_notoc", 6, 24, MCFixupKindInfo::FKF_IsPCRel }, 101 { "fixup_ppc_brcond14", 16, 14, MCFixupKindInfo::FKF_IsPCRel }, 102 { "fixup_ppc_br24abs", 6, 24, 0 }, 103 { "fixup_ppc_brcond14abs", 16, 14, 0 }, 104 { "fixup_ppc_half16", 0, 16, 0 }, 105 { "fixup_ppc_half16ds", 0, 14, 0 }, 106 { "fixup_ppc_pcrel34", 0, 34, MCFixupKindInfo::FKF_IsPCRel }, 107 { "fixup_ppc_imm34", 0, 34, 0 }, 108 { "fixup_ppc_nofixup", 0, 0, 0 } 109 }; 110 const static MCFixupKindInfo InfosLE[PPC::NumTargetFixupKinds] = { 111 // name offset bits flags 112 { "fixup_ppc_br24", 2, 24, MCFixupKindInfo::FKF_IsPCRel }, 113 { "fixup_ppc_br24_notoc", 2, 24, MCFixupKindInfo::FKF_IsPCRel }, 114 { "fixup_ppc_brcond14", 2, 14, MCFixupKindInfo::FKF_IsPCRel }, 115 { "fixup_ppc_br24abs", 2, 24, 0 }, 116 { "fixup_ppc_brcond14abs", 2, 14, 0 }, 117 { "fixup_ppc_half16", 0, 16, 0 }, 118 { "fixup_ppc_half16ds", 2, 14, 0 }, 119 { "fixup_ppc_pcrel34", 0, 34, MCFixupKindInfo::FKF_IsPCRel }, 120 { "fixup_ppc_imm34", 0, 34, 0 }, 121 { "fixup_ppc_nofixup", 0, 0, 0 } 122 }; 123 124 // Fixup kinds from .reloc directive are like R_PPC_NONE/R_PPC64_NONE. They 125 // do not require any extra processing. 126 if (Kind >= FirstLiteralRelocationKind) 127 return MCAsmBackend::getFixupKindInfo(FK_NONE); 128 129 if (Kind < FirstTargetFixupKind) 130 return MCAsmBackend::getFixupKindInfo(Kind); 131 132 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && 133 "Invalid kind!"); 134 return (Endian == support::little 135 ? InfosLE 136 : InfosBE)[Kind - FirstTargetFixupKind]; 137 } 138 139 void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup, 140 const MCValue &Target, MutableArrayRef<char> Data, 141 uint64_t Value, bool IsResolved, 142 const MCSubtargetInfo *STI) const override { 143 MCFixupKind Kind = Fixup.getKind(); 144 if (Kind >= FirstLiteralRelocationKind) 145 return; 146 Value = adjustFixupValue(Kind, Value); 147 if (!Value) return; // Doesn't change encoding. 148 149 unsigned Offset = Fixup.getOffset(); 150 unsigned NumBytes = getFixupKindNumBytes(Kind); 151 152 // For each byte of the fragment that the fixup touches, mask in the bits 153 // from the fixup value. The Value has been "split up" into the appropriate 154 // bitfields above. 155 for (unsigned i = 0; i != NumBytes; ++i) { 156 unsigned Idx = Endian == support::little ? i : (NumBytes - 1 - i); 157 Data[Offset + i] |= uint8_t((Value >> (Idx * 8)) & 0xff); 158 } 159 } 160 161 bool shouldForceRelocation(const MCAssembler &Asm, const MCFixup &Fixup, 162 const MCValue &Target) override { 163 MCFixupKind Kind = Fixup.getKind(); 164 switch ((unsigned)Kind) { 165 default: 166 return Kind >= FirstLiteralRelocationKind; 167 case PPC::fixup_ppc_br24: 168 case PPC::fixup_ppc_br24abs: 169 case PPC::fixup_ppc_br24_notoc: 170 // If the target symbol has a local entry point we must not attempt 171 // to resolve the fixup directly. Emit a relocation and leave 172 // resolution of the final target address to the linker. 173 if (const MCSymbolRefExpr *A = Target.getSymA()) { 174 if (const auto *S = dyn_cast<MCSymbolELF>(&A->getSymbol())) { 175 // The "other" values are stored in the last 6 bits of the second 176 // byte. The traditional defines for STO values assume the full byte 177 // and thus the shift to pack it. 178 unsigned Other = S->getOther() << 2; 179 if ((Other & ELF::STO_PPC64_LOCAL_MASK) != 0) 180 return true; 181 } 182 } 183 return false; 184 } 185 } 186 187 bool fixupNeedsRelaxation(const MCFixup &Fixup, 188 uint64_t Value, 189 const MCRelaxableFragment *DF, 190 const MCAsmLayout &Layout) const override { 191 // FIXME. 192 llvm_unreachable("relaxInstruction() unimplemented"); 193 } 194 195 void relaxInstruction(MCInst &Inst, 196 const MCSubtargetInfo &STI) const override { 197 // FIXME. 198 llvm_unreachable("relaxInstruction() unimplemented"); 199 } 200 201 bool writeNopData(raw_ostream &OS, uint64_t Count, 202 const MCSubtargetInfo *STI) const override { 203 uint64_t NumNops = Count / 4; 204 for (uint64_t i = 0; i != NumNops; ++i) 205 support::endian::write<uint32_t>(OS, 0x60000000, Endian); 206 207 OS.write_zeros(Count % 4); 208 209 return true; 210 } 211 }; 212 } // end anonymous namespace 213 214 215 // FIXME: This should be in a separate file. 216 namespace { 217 218 class ELFPPCAsmBackend : public PPCAsmBackend { 219 public: 220 ELFPPCAsmBackend(const Target &T, const Triple &TT) : PPCAsmBackend(T, TT) {} 221 222 std::unique_ptr<MCObjectTargetWriter> 223 createObjectTargetWriter() const override { 224 uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(TT.getOS()); 225 bool Is64 = TT.isPPC64(); 226 return createPPCELFObjectWriter(Is64, OSABI); 227 } 228 229 std::optional<MCFixupKind> getFixupKind(StringRef Name) const override; 230 }; 231 232 class XCOFFPPCAsmBackend : public PPCAsmBackend { 233 public: 234 XCOFFPPCAsmBackend(const Target &T, const Triple &TT) 235 : PPCAsmBackend(T, TT) {} 236 237 std::unique_ptr<MCObjectTargetWriter> 238 createObjectTargetWriter() const override { 239 return createPPCXCOFFObjectWriter(TT.isArch64Bit()); 240 } 241 }; 242 243 } // end anonymous namespace 244 245 std::optional<MCFixupKind> 246 ELFPPCAsmBackend::getFixupKind(StringRef Name) const { 247 if (TT.isOSBinFormatELF()) { 248 unsigned Type; 249 if (TT.isPPC64()) { 250 Type = llvm::StringSwitch<unsigned>(Name) 251 #define ELF_RELOC(X, Y) .Case(#X, Y) 252 #include "llvm/BinaryFormat/ELFRelocs/PowerPC64.def" 253 #undef ELF_RELOC 254 .Case("BFD_RELOC_NONE", ELF::R_PPC64_NONE) 255 .Case("BFD_RELOC_16", ELF::R_PPC64_ADDR16) 256 .Case("BFD_RELOC_32", ELF::R_PPC64_ADDR32) 257 .Case("BFD_RELOC_64", ELF::R_PPC64_ADDR64) 258 .Default(-1u); 259 } else { 260 Type = llvm::StringSwitch<unsigned>(Name) 261 #define ELF_RELOC(X, Y) .Case(#X, Y) 262 #include "llvm/BinaryFormat/ELFRelocs/PowerPC.def" 263 #undef ELF_RELOC 264 .Case("BFD_RELOC_NONE", ELF::R_PPC_NONE) 265 .Case("BFD_RELOC_16", ELF::R_PPC_ADDR16) 266 .Case("BFD_RELOC_32", ELF::R_PPC_ADDR32) 267 .Default(-1u); 268 } 269 if (Type != -1u) 270 return static_cast<MCFixupKind>(FirstLiteralRelocationKind + Type); 271 } 272 return std::nullopt; 273 } 274 275 MCAsmBackend *llvm::createPPCAsmBackend(const Target &T, 276 const MCSubtargetInfo &STI, 277 const MCRegisterInfo &MRI, 278 const MCTargetOptions &Options) { 279 const Triple &TT = STI.getTargetTriple(); 280 if (TT.isOSBinFormatXCOFF()) 281 return new XCOFFPPCAsmBackend(T, TT); 282 283 return new ELFPPCAsmBackend(T, TT); 284 } 285