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/MCInst.h" 17 #include "llvm/MC/MCObjectWriter.h" 18 #include "llvm/MC/MCSubtargetInfo.h" 19 #include "llvm/MC/MCValue.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 std::optional<MCFixupKind> getFixupKind(StringRef Name) const override; 114 MCFixupKindInfo getFixupKindInfo(MCFixupKind Kind) const override; 115 void applyFixup(const MCFragment &, const MCFixup &, const MCValue &Target, 116 MutableArrayRef<char> Data, uint64_t Value, 117 bool IsResolved) override; 118 bool writeNopData(raw_ostream &OS, uint64_t Count, 119 const MCSubtargetInfo *STI) const override; 120 }; 121 } // end anonymous namespace 122 123 std::optional<MCFixupKind> 124 SystemZMCAsmBackend::getFixupKind(StringRef Name) const { 125 unsigned Type = llvm::StringSwitch<unsigned>(Name) 126 #define ELF_RELOC(X, Y) .Case(#X, Y) 127 #include "llvm/BinaryFormat/ELFRelocs/SystemZ.def" 128 #undef ELF_RELOC 129 .Case("BFD_RELOC_NONE", ELF::R_390_NONE) 130 .Case("BFD_RELOC_8", ELF::R_390_8) 131 .Case("BFD_RELOC_16", ELF::R_390_16) 132 .Case("BFD_RELOC_32", ELF::R_390_32) 133 .Case("BFD_RELOC_64", ELF::R_390_64) 134 .Default(-1u); 135 if (Type != -1u) 136 return static_cast<MCFixupKind>(FirstLiteralRelocationKind + Type); 137 return std::nullopt; 138 } 139 140 MCFixupKindInfo SystemZMCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const { 141 // Fixup kinds from .reloc directive are like R_390_NONE. They 142 // do not require any extra processing. 143 if (mc::isRelocation(Kind)) 144 return {}; 145 146 if (Kind < FirstTargetFixupKind) 147 return MCAsmBackend::getFixupKindInfo(Kind); 148 149 assert(unsigned(Kind - FirstTargetFixupKind) < SystemZ::NumTargetFixupKinds && 150 "Invalid kind!"); 151 return SystemZ::MCFixupKindInfos[Kind - FirstTargetFixupKind]; 152 } 153 154 void SystemZMCAsmBackend::applyFixup(const MCFragment &F, const MCFixup &Fixup, 155 const MCValue &Target, 156 MutableArrayRef<char> Data, uint64_t Value, 157 bool IsResolved) { 158 if (Target.getSpecifier()) 159 IsResolved = false; 160 maybeAddReloc(F, Fixup, Target, Value, IsResolved); 161 MCFixupKind Kind = Fixup.getKind(); 162 if (mc::isRelocation(Kind)) 163 return; 164 unsigned Offset = Fixup.getOffset(); 165 unsigned BitSize = getFixupKindInfo(Kind).TargetSize; 166 unsigned Size = (BitSize + 7) / 8; 167 168 assert(Offset + Size <= Data.size() && "Invalid fixup offset!"); 169 170 // Big-endian insertion of Size bytes. 171 Value = extractBitsForFixup(Kind, Value, Fixup, getContext()); 172 if (BitSize < 64) 173 Value &= ((uint64_t)1 << BitSize) - 1; 174 unsigned ShiftValue = (Size * 8) - 8; 175 for (unsigned I = 0; I != Size; ++I) { 176 Data[Offset + I] |= uint8_t(Value >> ShiftValue); 177 ShiftValue -= 8; 178 } 179 } 180 181 bool SystemZMCAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count, 182 const MCSubtargetInfo *STI) const { 183 for (uint64_t I = 0; I != Count; ++I) 184 OS << '\x7'; 185 return true; 186 } 187 188 namespace { 189 class ELFSystemZAsmBackend : public SystemZMCAsmBackend { 190 uint8_t OSABI; 191 192 public: 193 ELFSystemZAsmBackend(uint8_t OsABI) : SystemZMCAsmBackend(), OSABI(OsABI){}; 194 195 std::unique_ptr<MCObjectTargetWriter> 196 createObjectTargetWriter() const override { 197 return createSystemZELFObjectWriter(OSABI); 198 } 199 }; 200 201 class GOFFSystemZAsmBackend : public SystemZMCAsmBackend { 202 public: 203 GOFFSystemZAsmBackend() : SystemZMCAsmBackend(){}; 204 205 std::unique_ptr<MCObjectTargetWriter> 206 createObjectTargetWriter() const override { 207 return createSystemZGOFFObjectWriter(); 208 } 209 }; 210 } // namespace 211 212 MCAsmBackend *llvm::createSystemZMCAsmBackend(const Target &T, 213 const MCSubtargetInfo &STI, 214 const MCRegisterInfo &MRI, 215 const MCTargetOptions &Options) { 216 if (STI.getTargetTriple().isOSzOS()) { 217 return new GOFFSystemZAsmBackend(); 218 } 219 220 uint8_t OSABI = 221 MCELFObjectTargetWriter::getOSABI(STI.getTargetTriple().getOS()); 222 return new ELFSystemZAsmBackend(OSABI); 223 } 224