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 uint8_t OSABI; 110 public: 111 SystemZMCAsmBackend(uint8_t osABI) 112 : MCAsmBackend(support::big), OSABI(osABI) {} 113 114 // Override MCAsmBackend 115 unsigned getNumFixupKinds() const override { 116 return SystemZ::NumTargetFixupKinds; 117 } 118 std::optional<MCFixupKind> getFixupKind(StringRef Name) const override; 119 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override; 120 bool shouldForceRelocation(const MCAssembler &Asm, const MCFixup &Fixup, 121 const MCValue &Target) override; 122 void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup, 123 const MCValue &Target, MutableArrayRef<char> Data, 124 uint64_t Value, bool IsResolved, 125 const MCSubtargetInfo *STI) const override; 126 bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value, 127 const MCRelaxableFragment *Fragment, 128 const MCAsmLayout &Layout) const override { 129 return false; 130 } 131 bool writeNopData(raw_ostream &OS, uint64_t Count, 132 const MCSubtargetInfo *STI) const override; 133 std::unique_ptr<MCObjectTargetWriter> 134 createObjectTargetWriter() const override { 135 return createSystemZObjectWriter(OSABI); 136 } 137 }; 138 } // end anonymous namespace 139 140 std::optional<MCFixupKind> 141 SystemZMCAsmBackend::getFixupKind(StringRef Name) const { 142 unsigned Type = llvm::StringSwitch<unsigned>(Name) 143 #define ELF_RELOC(X, Y) .Case(#X, Y) 144 #include "llvm/BinaryFormat/ELFRelocs/SystemZ.def" 145 #undef ELF_RELOC 146 .Case("BFD_RELOC_NONE", ELF::R_390_NONE) 147 .Case("BFD_RELOC_8", ELF::R_390_8) 148 .Case("BFD_RELOC_16", ELF::R_390_16) 149 .Case("BFD_RELOC_32", ELF::R_390_32) 150 .Case("BFD_RELOC_64", ELF::R_390_64) 151 .Default(-1u); 152 if (Type != -1u) 153 return static_cast<MCFixupKind>(FirstLiteralRelocationKind + Type); 154 return std::nullopt; 155 } 156 157 const MCFixupKindInfo & 158 SystemZMCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const { 159 // Fixup kinds from .reloc directive are like R_390_NONE. They 160 // do not require any extra processing. 161 if (Kind >= FirstLiteralRelocationKind) 162 return MCAsmBackend::getFixupKindInfo(FK_NONE); 163 164 if (Kind < FirstTargetFixupKind) 165 return MCAsmBackend::getFixupKindInfo(Kind); 166 167 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && 168 "Invalid kind!"); 169 return SystemZ::MCFixupKindInfos[Kind - FirstTargetFixupKind]; 170 } 171 172 bool SystemZMCAsmBackend::shouldForceRelocation(const MCAssembler &, 173 const MCFixup &Fixup, 174 const MCValue &) { 175 return Fixup.getKind() >= FirstLiteralRelocationKind; 176 } 177 178 void SystemZMCAsmBackend::applyFixup(const MCAssembler &Asm, 179 const MCFixup &Fixup, 180 const MCValue &Target, 181 MutableArrayRef<char> Data, uint64_t Value, 182 bool IsResolved, 183 const MCSubtargetInfo *STI) const { 184 MCFixupKind Kind = Fixup.getKind(); 185 if (Kind >= FirstLiteralRelocationKind) 186 return; 187 unsigned Offset = Fixup.getOffset(); 188 unsigned BitSize = getFixupKindInfo(Kind).TargetSize; 189 unsigned Size = (BitSize + 7) / 8; 190 191 assert(Offset + Size <= Data.size() && "Invalid fixup offset!"); 192 193 // Big-endian insertion of Size bytes. 194 Value = extractBitsForFixup(Kind, Value, Fixup, Asm.getContext()); 195 if (BitSize < 64) 196 Value &= ((uint64_t)1 << BitSize) - 1; 197 unsigned ShiftValue = (Size * 8) - 8; 198 for (unsigned I = 0; I != Size; ++I) { 199 Data[Offset + I] |= uint8_t(Value >> ShiftValue); 200 ShiftValue -= 8; 201 } 202 } 203 204 bool SystemZMCAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count, 205 const MCSubtargetInfo *STI) const { 206 for (uint64_t I = 0; I != Count; ++I) 207 OS << '\x7'; 208 return true; 209 } 210 211 MCAsmBackend *llvm::createSystemZMCAsmBackend(const Target &T, 212 const MCSubtargetInfo &STI, 213 const MCRegisterInfo &MRI, 214 const MCTargetOptions &Options) { 215 uint8_t OSABI = 216 MCELFObjectTargetWriter::getOSABI(STI.getTargetTriple().getOS()); 217 return new SystemZMCAsmBackend(OSABI); 218 } 219