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 switch (unsigned(Kind)) { 51 case SystemZ::FK_390_PC12DBL: 52 return handlePCRelFixupValue(12); 53 case SystemZ::FK_390_PC16DBL: 54 return handlePCRelFixupValue(16); 55 case SystemZ::FK_390_PC24DBL: 56 return handlePCRelFixupValue(24); 57 case SystemZ::FK_390_PC32DBL: 58 return handlePCRelFixupValue(32); 59 60 case SystemZ::FK_390_12: 61 if (!checkFixupInRange(0, maxUIntN(12))) 62 return 0; 63 return Value; 64 65 case SystemZ::FK_390_20: { 66 if (!checkFixupInRange(minIntN(20), maxIntN(20))) 67 return 0; 68 // The high byte of a 20 bit displacement value comes first. 69 uint64_t DLo = Value & 0xfff; 70 uint64_t DHi = (Value >> 12) & 0xff; 71 return (DLo << 8) | DHi; 72 } 73 74 case SystemZ::FK_390_TLS_CALL: 75 return 0; 76 } 77 78 llvm_unreachable("Unknown fixup kind!"); 79 } 80 81 namespace { 82 class SystemZMCAsmBackend : public MCAsmBackend { 83 uint8_t OSABI; 84 public: 85 SystemZMCAsmBackend(uint8_t osABI) 86 : MCAsmBackend(support::big), OSABI(osABI) {} 87 88 // Override MCAsmBackend 89 unsigned getNumFixupKinds() const override { 90 return SystemZ::NumTargetFixupKinds; 91 } 92 std::optional<MCFixupKind> getFixupKind(StringRef Name) const override; 93 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override; 94 bool shouldForceRelocation(const MCAssembler &Asm, const MCFixup &Fixup, 95 const MCValue &Target) override; 96 void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup, 97 const MCValue &Target, MutableArrayRef<char> Data, 98 uint64_t Value, bool IsResolved, 99 const MCSubtargetInfo *STI) const override; 100 bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value, 101 const MCRelaxableFragment *Fragment, 102 const MCAsmLayout &Layout) const override { 103 return false; 104 } 105 bool writeNopData(raw_ostream &OS, uint64_t Count, 106 const MCSubtargetInfo *STI) const override; 107 std::unique_ptr<MCObjectTargetWriter> 108 createObjectTargetWriter() const override { 109 return createSystemZObjectWriter(OSABI); 110 } 111 }; 112 } // end anonymous namespace 113 114 std::optional<MCFixupKind> 115 SystemZMCAsmBackend::getFixupKind(StringRef Name) const { 116 unsigned Type = llvm::StringSwitch<unsigned>(Name) 117 #define ELF_RELOC(X, Y) .Case(#X, Y) 118 #include "llvm/BinaryFormat/ELFRelocs/SystemZ.def" 119 #undef ELF_RELOC 120 .Case("BFD_RELOC_NONE", ELF::R_390_NONE) 121 .Case("BFD_RELOC_8", ELF::R_390_8) 122 .Case("BFD_RELOC_16", ELF::R_390_16) 123 .Case("BFD_RELOC_32", ELF::R_390_32) 124 .Case("BFD_RELOC_64", ELF::R_390_64) 125 .Default(-1u); 126 if (Type != -1u) 127 return static_cast<MCFixupKind>(FirstLiteralRelocationKind + Type); 128 return std::nullopt; 129 } 130 131 const MCFixupKindInfo & 132 SystemZMCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const { 133 const static MCFixupKindInfo Infos[SystemZ::NumTargetFixupKinds] = { 134 { "FK_390_PC12DBL", 4, 12, MCFixupKindInfo::FKF_IsPCRel }, 135 { "FK_390_PC16DBL", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 136 { "FK_390_PC24DBL", 0, 24, MCFixupKindInfo::FKF_IsPCRel }, 137 { "FK_390_PC32DBL", 0, 32, MCFixupKindInfo::FKF_IsPCRel }, 138 { "FK_390_TLS_CALL", 0, 0, 0 }, 139 { "FK_390_12", 4, 12, 0 }, 140 { "FK_390_20", 4, 20, 0 } 141 }; 142 143 // Fixup kinds from .reloc directive are like R_390_NONE. They 144 // do not require any extra processing. 145 if (Kind >= FirstLiteralRelocationKind) 146 return MCAsmBackend::getFixupKindInfo(FK_NONE); 147 148 if (Kind < FirstTargetFixupKind) 149 return MCAsmBackend::getFixupKindInfo(Kind); 150 151 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && 152 "Invalid kind!"); 153 return Infos[Kind - FirstTargetFixupKind]; 154 } 155 156 bool SystemZMCAsmBackend::shouldForceRelocation(const MCAssembler &, 157 const MCFixup &Fixup, 158 const MCValue &) { 159 return Fixup.getKind() >= FirstLiteralRelocationKind; 160 } 161 162 void SystemZMCAsmBackend::applyFixup(const MCAssembler &Asm, 163 const MCFixup &Fixup, 164 const MCValue &Target, 165 MutableArrayRef<char> Data, uint64_t Value, 166 bool IsResolved, 167 const MCSubtargetInfo *STI) const { 168 MCFixupKind Kind = Fixup.getKind(); 169 if (Kind >= FirstLiteralRelocationKind) 170 return; 171 unsigned Offset = Fixup.getOffset(); 172 unsigned BitSize = getFixupKindInfo(Kind).TargetSize; 173 unsigned Size = (BitSize + 7) / 8; 174 175 assert(Offset + Size <= Data.size() && "Invalid fixup offset!"); 176 177 // Big-endian insertion of Size bytes. 178 Value = extractBitsForFixup(Kind, Value, Fixup, Asm.getContext()); 179 if (BitSize < 64) 180 Value &= ((uint64_t)1 << BitSize) - 1; 181 unsigned ShiftValue = (Size * 8) - 8; 182 for (unsigned I = 0; I != Size; ++I) { 183 Data[Offset + I] |= uint8_t(Value >> ShiftValue); 184 ShiftValue -= 8; 185 } 186 } 187 188 bool SystemZMCAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count, 189 const MCSubtargetInfo *STI) const { 190 for (uint64_t I = 0; I != Count; ++I) 191 OS << '\x7'; 192 return true; 193 } 194 195 MCAsmBackend *llvm::createSystemZMCAsmBackend(const Target &T, 196 const MCSubtargetInfo &STI, 197 const MCRegisterInfo &MRI, 198 const MCTargetOptions &Options) { 199 uint8_t OSABI = 200 MCELFObjectTargetWriter::getOSABI(STI.getTargetTriple().getOS()); 201 return new SystemZMCAsmBackend(OSABI); 202 } 203