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/Support/ErrorHandling.h" 24 #include "llvm/Support/TargetRegistry.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 return Value & 0xfffc; 48 case PPC::fixup_ppc_pcrel34: 49 return Value & 0x3ffffffff; 50 } 51 } 52 53 static unsigned getFixupKindNumBytes(unsigned Kind) { 54 switch (Kind) { 55 default: 56 llvm_unreachable("Unknown fixup kind!"); 57 case FK_Data_1: 58 return 1; 59 case FK_Data_2: 60 case PPC::fixup_ppc_half16: 61 case PPC::fixup_ppc_half16ds: 62 return 2; 63 case FK_Data_4: 64 case PPC::fixup_ppc_brcond14: 65 case PPC::fixup_ppc_brcond14abs: 66 case PPC::fixup_ppc_br24: 67 case PPC::fixup_ppc_br24abs: 68 case PPC::fixup_ppc_br24_notoc: 69 return 4; 70 case PPC::fixup_ppc_pcrel34: 71 case FK_Data_8: 72 return 8; 73 case PPC::fixup_ppc_nofixup: 74 return 0; 75 } 76 } 77 78 namespace { 79 80 class PPCAsmBackend : public MCAsmBackend { 81 protected: 82 Triple TT; 83 public: 84 PPCAsmBackend(const Target &T, const Triple &TT) 85 : MCAsmBackend(TT.isLittleEndian() ? support::little : support::big), 86 TT(TT) {} 87 88 unsigned getNumFixupKinds() const override { 89 return PPC::NumTargetFixupKinds; 90 } 91 92 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override { 93 const static MCFixupKindInfo InfosBE[PPC::NumTargetFixupKinds] = { 94 // name offset bits flags 95 { "fixup_ppc_br24", 6, 24, MCFixupKindInfo::FKF_IsPCRel }, 96 { "fixup_ppc_br24_notoc", 6, 24, MCFixupKindInfo::FKF_IsPCRel }, 97 { "fixup_ppc_brcond14", 16, 14, MCFixupKindInfo::FKF_IsPCRel }, 98 { "fixup_ppc_br24abs", 6, 24, 0 }, 99 { "fixup_ppc_brcond14abs", 16, 14, 0 }, 100 { "fixup_ppc_half16", 0, 16, 0 }, 101 { "fixup_ppc_half16ds", 0, 14, 0 }, 102 { "fixup_ppc_pcrel34", 0, 34, MCFixupKindInfo::FKF_IsPCRel }, 103 { "fixup_ppc_nofixup", 0, 0, 0 } 104 }; 105 const static MCFixupKindInfo InfosLE[PPC::NumTargetFixupKinds] = { 106 // name offset bits flags 107 { "fixup_ppc_br24", 2, 24, MCFixupKindInfo::FKF_IsPCRel }, 108 { "fixup_ppc_br24_notoc", 2, 24, MCFixupKindInfo::FKF_IsPCRel }, 109 { "fixup_ppc_brcond14", 2, 14, MCFixupKindInfo::FKF_IsPCRel }, 110 { "fixup_ppc_br24abs", 2, 24, 0 }, 111 { "fixup_ppc_brcond14abs", 2, 14, 0 }, 112 { "fixup_ppc_half16", 0, 16, 0 }, 113 { "fixup_ppc_half16ds", 2, 14, 0 }, 114 { "fixup_ppc_pcrel34", 0, 34, MCFixupKindInfo::FKF_IsPCRel }, 115 { "fixup_ppc_nofixup", 0, 0, 0 } 116 }; 117 118 // Fixup kinds from .reloc directive are like R_PPC_NONE/R_PPC64_NONE. They 119 // do not require any extra processing. 120 if (Kind >= FirstLiteralRelocationKind) 121 return MCAsmBackend::getFixupKindInfo(FK_NONE); 122 123 if (Kind < FirstTargetFixupKind) 124 return MCAsmBackend::getFixupKindInfo(Kind); 125 126 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && 127 "Invalid kind!"); 128 return (Endian == support::little 129 ? InfosLE 130 : InfosBE)[Kind - FirstTargetFixupKind]; 131 } 132 133 void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup, 134 const MCValue &Target, MutableArrayRef<char> Data, 135 uint64_t Value, bool IsResolved, 136 const MCSubtargetInfo *STI) const override { 137 MCFixupKind Kind = Fixup.getKind(); 138 if (Kind >= FirstLiteralRelocationKind) 139 return; 140 Value = adjustFixupValue(Kind, Value); 141 if (!Value) return; // Doesn't change encoding. 142 143 unsigned Offset = Fixup.getOffset(); 144 unsigned NumBytes = getFixupKindNumBytes(Kind); 145 146 // For each byte of the fragment that the fixup touches, mask in the bits 147 // from the fixup value. The Value has been "split up" into the appropriate 148 // bitfields above. 149 for (unsigned i = 0; i != NumBytes; ++i) { 150 unsigned Idx = Endian == support::little ? i : (NumBytes - 1 - i); 151 Data[Offset + i] |= uint8_t((Value >> (Idx * 8)) & 0xff); 152 } 153 } 154 155 bool shouldForceRelocation(const MCAssembler &Asm, const MCFixup &Fixup, 156 const MCValue &Target) override { 157 MCFixupKind Kind = Fixup.getKind(); 158 switch ((unsigned)Kind) { 159 default: 160 return Kind >= FirstLiteralRelocationKind; 161 case PPC::fixup_ppc_br24: 162 case PPC::fixup_ppc_br24abs: 163 case PPC::fixup_ppc_br24_notoc: 164 // If the target symbol has a local entry point we must not attempt 165 // to resolve the fixup directly. Emit a relocation and leave 166 // resolution of the final target address to the linker. 167 if (const MCSymbolRefExpr *A = Target.getSymA()) { 168 if (const auto *S = dyn_cast<MCSymbolELF>(&A->getSymbol())) { 169 // The "other" values are stored in the last 6 bits of the second 170 // byte. The traditional defines for STO values assume the full byte 171 // and thus the shift to pack it. 172 unsigned Other = S->getOther() << 2; 173 if ((Other & ELF::STO_PPC64_LOCAL_MASK) != 0) 174 return true; 175 } 176 } 177 return false; 178 } 179 } 180 181 bool mayNeedRelaxation(const MCInst &Inst, 182 const MCSubtargetInfo &STI) const override { 183 // FIXME. 184 return false; 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) const override { 202 uint64_t NumNops = Count / 4; 203 for (uint64_t i = 0; i != NumNops; ++i) 204 support::endian::write<uint32_t>(OS, 0x60000000, Endian); 205 206 OS.write_zeros(Count % 4); 207 208 return true; 209 } 210 }; 211 } // end anonymous namespace 212 213 214 // FIXME: This should be in a separate file. 215 namespace { 216 217 class ELFPPCAsmBackend : public PPCAsmBackend { 218 public: 219 ELFPPCAsmBackend(const Target &T, const Triple &TT) : PPCAsmBackend(T, TT) {} 220 221 std::unique_ptr<MCObjectTargetWriter> 222 createObjectTargetWriter() const override { 223 uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(TT.getOS()); 224 bool Is64 = TT.isPPC64(); 225 return createPPCELFObjectWriter(Is64, OSABI); 226 } 227 228 Optional<MCFixupKind> getFixupKind(StringRef Name) const override; 229 }; 230 231 class XCOFFPPCAsmBackend : public PPCAsmBackend { 232 public: 233 XCOFFPPCAsmBackend(const Target &T, const Triple &TT) 234 : PPCAsmBackend(T, TT) {} 235 236 std::unique_ptr<MCObjectTargetWriter> 237 createObjectTargetWriter() const override { 238 return createPPCXCOFFObjectWriter(TT.isArch64Bit()); 239 } 240 }; 241 242 } // end anonymous namespace 243 244 Optional<MCFixupKind> ELFPPCAsmBackend::getFixupKind(StringRef Name) const { 245 if (TT.isOSBinFormatELF()) { 246 unsigned Type; 247 if (TT.isPPC64()) { 248 Type = llvm::StringSwitch<unsigned>(Name) 249 #define ELF_RELOC(X, Y) .Case(#X, Y) 250 #include "llvm/BinaryFormat/ELFRelocs/PowerPC64.def" 251 #undef ELF_RELOC 252 .Default(-1u); 253 } else { 254 Type = llvm::StringSwitch<unsigned>(Name) 255 #define ELF_RELOC(X, Y) .Case(#X, Y) 256 #include "llvm/BinaryFormat/ELFRelocs/PowerPC.def" 257 #undef ELF_RELOC 258 .Default(-1u); 259 } 260 if (Type != -1u) 261 return static_cast<MCFixupKind>(FirstLiteralRelocationKind + Type); 262 } 263 return None; 264 } 265 266 MCAsmBackend *llvm::createPPCAsmBackend(const Target &T, 267 const MCSubtargetInfo &STI, 268 const MCRegisterInfo &MRI, 269 const MCTargetOptions &Options) { 270 const Triple &TT = STI.getTargetTriple(); 271 if (TT.isOSBinFormatXCOFF()) 272 return new XCOFFPPCAsmBackend(T, TT); 273 274 return new ELFPPCAsmBackend(T, TT); 275 } 276