1 //===-- SystemZMCAsmBackend.cpp - SystemZ 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/SystemZMCFixups.h" 10 #include "MCTargetDesc/SystemZMCTargetDesc.h" 11 #include "llvm/ADT/StringSwitch.h" 12 #include "llvm/MC/MCAsmBackend.h" 13 #include "llvm/MC/MCAssembler.h" 14 #include "llvm/MC/MCContext.h" 15 #include "llvm/MC/MCELFObjectWriter.h" 16 #include "llvm/MC/MCFixupKindInfo.h" 17 #include "llvm/MC/MCInst.h" 18 #include "llvm/MC/MCObjectWriter.h" 19 #include "llvm/MC/MCSubtargetInfo.h" 20 21 using namespace llvm; 22 23 // Value is a fully-resolved relocation value: Symbol + Addend [- Pivot]. 24 // Return the bits that should be installed in a relocation field for 25 // fixup kind Kind. 26 static uint64_t extractBitsForFixup(MCFixupKind Kind, uint64_t Value, 27 const MCFixup &Fixup, MCContext &Ctx) { 28 if (Kind < FirstTargetFixupKind) 29 return Value; 30 31 auto checkFixupInRange = [&](int64_t Min, int64_t Max) -> bool { 32 int64_t SVal = int64_t(Value); 33 if (SVal < Min || SVal > Max) { 34 Ctx.reportError(Fixup.getLoc(), "operand out of range (" + Twine(SVal) + 35 " not between " + Twine(Min) + 36 " and " + Twine(Max) + ")"); 37 return false; 38 } 39 return true; 40 }; 41 42 auto handlePCRelFixupValue = [&](unsigned W) -> uint64_t { 43 if (Value % 2 != 0) 44 Ctx.reportError(Fixup.getLoc(), "Non-even PC relative offset."); 45 if (!checkFixupInRange(minIntN(W) * 2, maxIntN(W) * 2)) 46 return 0; 47 return (int64_t)Value / 2; 48 }; 49 50 auto handleImmValue = [&](bool IsSigned, unsigned W) -> uint64_t { 51 if (!(IsSigned ? checkFixupInRange(minIntN(W), maxIntN(W)) 52 : checkFixupInRange(0, maxUIntN(W)))) 53 return 0; 54 return Value; 55 }; 56 57 switch (unsigned(Kind)) { 58 case SystemZ::FK_390_PC12DBL: 59 return handlePCRelFixupValue(12); 60 case SystemZ::FK_390_PC16DBL: 61 return handlePCRelFixupValue(16); 62 case SystemZ::FK_390_PC24DBL: 63 return handlePCRelFixupValue(24); 64 case SystemZ::FK_390_PC32DBL: 65 return handlePCRelFixupValue(32); 66 67 case SystemZ::FK_390_TLS_CALL: 68 return 0; 69 70 case SystemZ::FK_390_S8Imm: 71 return handleImmValue(true, 8); 72 case SystemZ::FK_390_S16Imm: 73 return handleImmValue(true, 16); 74 case SystemZ::FK_390_S20Imm: { 75 Value = handleImmValue(true, 20); 76 // S20Imm is used only for signed 20-bit displacements. 77 // The high byte of a 20 bit displacement value comes first. 78 uint64_t DLo = Value & 0xfff; 79 uint64_t DHi = (Value >> 12) & 0xff; 80 return (DLo << 8) | DHi; 81 } 82 case SystemZ::FK_390_S32Imm: 83 return handleImmValue(true, 32); 84 case SystemZ::FK_390_U1Imm: 85 return handleImmValue(false, 1); 86 case SystemZ::FK_390_U2Imm: 87 return handleImmValue(false, 2); 88 case SystemZ::FK_390_U3Imm: 89 return handleImmValue(false, 3); 90 case SystemZ::FK_390_U4Imm: 91 return handleImmValue(false, 4); 92 case SystemZ::FK_390_U8Imm: 93 return handleImmValue(false, 8); 94 case SystemZ::FK_390_U12Imm: 95 return handleImmValue(false, 12); 96 case SystemZ::FK_390_U16Imm: 97 return handleImmValue(false, 16); 98 case SystemZ::FK_390_U32Imm: 99 return handleImmValue(false, 32); 100 case SystemZ::FK_390_U48Imm: 101 return handleImmValue(false, 48); 102 } 103 104 llvm_unreachable("Unknown fixup kind!"); 105 } 106 107 namespace { 108 class SystemZMCAsmBackend : public MCAsmBackend { 109 public: 110 SystemZMCAsmBackend() : MCAsmBackend(llvm::endianness::big) {} 111 112 // Override MCAsmBackend 113 unsigned getNumFixupKinds() const override { 114 return SystemZ::NumTargetFixupKinds; 115 } 116 std::optional<MCFixupKind> getFixupKind(StringRef Name) const override; 117 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override; 118 bool shouldForceRelocation(const MCAssembler &Asm, const MCFixup &Fixup, 119 const MCValue &Target, 120 const MCSubtargetInfo *STI) override; 121 void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup, 122 const MCValue &Target, MutableArrayRef<char> Data, 123 uint64_t Value, bool IsResolved, 124 const MCSubtargetInfo *STI) const override; 125 bool writeNopData(raw_ostream &OS, uint64_t Count, 126 const MCSubtargetInfo *STI) const override; 127 }; 128 } // end anonymous namespace 129 130 std::optional<MCFixupKind> 131 SystemZMCAsmBackend::getFixupKind(StringRef Name) const { 132 unsigned Type = llvm::StringSwitch<unsigned>(Name) 133 #define ELF_RELOC(X, Y) .Case(#X, Y) 134 #include "llvm/BinaryFormat/ELFRelocs/SystemZ.def" 135 #undef ELF_RELOC 136 .Case("BFD_RELOC_NONE", ELF::R_390_NONE) 137 .Case("BFD_RELOC_8", ELF::R_390_8) 138 .Case("BFD_RELOC_16", ELF::R_390_16) 139 .Case("BFD_RELOC_32", ELF::R_390_32) 140 .Case("BFD_RELOC_64", ELF::R_390_64) 141 .Default(-1u); 142 if (Type != -1u) 143 return static_cast<MCFixupKind>(FirstLiteralRelocationKind + Type); 144 return std::nullopt; 145 } 146 147 const MCFixupKindInfo & 148 SystemZMCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const { 149 // Fixup kinds from .reloc directive are like R_390_NONE. They 150 // do not require any extra processing. 151 if (Kind >= FirstLiteralRelocationKind) 152 return MCAsmBackend::getFixupKindInfo(FK_NONE); 153 154 if (Kind < FirstTargetFixupKind) 155 return MCAsmBackend::getFixupKindInfo(Kind); 156 157 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && 158 "Invalid kind!"); 159 return SystemZ::MCFixupKindInfos[Kind - FirstTargetFixupKind]; 160 } 161 162 bool SystemZMCAsmBackend::shouldForceRelocation(const MCAssembler &, 163 const MCFixup &Fixup, 164 const MCValue &, 165 const MCSubtargetInfo *STI) { 166 return Fixup.getKind() >= FirstLiteralRelocationKind; 167 } 168 169 void SystemZMCAsmBackend::applyFixup(const MCAssembler &Asm, 170 const MCFixup &Fixup, 171 const MCValue &Target, 172 MutableArrayRef<char> Data, uint64_t Value, 173 bool IsResolved, 174 const MCSubtargetInfo *STI) const { 175 MCFixupKind Kind = Fixup.getKind(); 176 if (Kind >= FirstLiteralRelocationKind) 177 return; 178 unsigned Offset = Fixup.getOffset(); 179 unsigned BitSize = getFixupKindInfo(Kind).TargetSize; 180 unsigned Size = (BitSize + 7) / 8; 181 182 assert(Offset + Size <= Data.size() && "Invalid fixup offset!"); 183 184 // Big-endian insertion of Size bytes. 185 Value = extractBitsForFixup(Kind, Value, Fixup, Asm.getContext()); 186 if (BitSize < 64) 187 Value &= ((uint64_t)1 << BitSize) - 1; 188 unsigned ShiftValue = (Size * 8) - 8; 189 for (unsigned I = 0; I != Size; ++I) { 190 Data[Offset + I] |= uint8_t(Value >> ShiftValue); 191 ShiftValue -= 8; 192 } 193 } 194 195 bool SystemZMCAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count, 196 const MCSubtargetInfo *STI) const { 197 for (uint64_t I = 0; I != Count; ++I) 198 OS << '\x7'; 199 return true; 200 } 201 202 namespace { 203 class ELFSystemZAsmBackend : public SystemZMCAsmBackend { 204 uint8_t OSABI; 205 206 public: 207 ELFSystemZAsmBackend(uint8_t OsABI) : SystemZMCAsmBackend(), OSABI(OsABI){}; 208 209 std::unique_ptr<MCObjectTargetWriter> 210 createObjectTargetWriter() const override { 211 return createSystemZELFObjectWriter(OSABI); 212 } 213 }; 214 215 class GOFFSystemZAsmBackend : public SystemZMCAsmBackend { 216 public: 217 GOFFSystemZAsmBackend() : SystemZMCAsmBackend(){}; 218 219 std::unique_ptr<MCObjectTargetWriter> 220 createObjectTargetWriter() const override { 221 return createSystemZGOFFObjectWriter(); 222 } 223 }; 224 } // namespace 225 226 MCAsmBackend *llvm::createSystemZMCAsmBackend(const Target &T, 227 const MCSubtargetInfo &STI, 228 const MCRegisterInfo &MRI, 229 const MCTargetOptions &Options) { 230 if (STI.getTargetTriple().isOSzOS()) { 231 return new GOFFSystemZAsmBackend(); 232 } 233 234 uint8_t OSABI = 235 MCELFObjectTargetWriter::getOSABI(STI.getTargetTriple().getOS()); 236 return new ELFSystemZAsmBackend(OSABI); 237 } 238