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/MCELFObjectWriter.h" 14 #include "llvm/MC/MCFixupKindInfo.h" 15 #include "llvm/MC/MCInst.h" 16 #include "llvm/MC/MCObjectWriter.h" 17 #include "llvm/MC/MCSubtargetInfo.h" 18 19 using namespace llvm; 20 21 // Value is a fully-resolved relocation value: Symbol + Addend [- Pivot]. 22 // Return the bits that should be installed in a relocation field for 23 // fixup kind Kind. 24 static uint64_t extractBitsForFixup(MCFixupKind Kind, uint64_t Value) { 25 if (Kind < FirstTargetFixupKind) 26 return Value; 27 28 switch (unsigned(Kind)) { 29 case SystemZ::FK_390_PC12DBL: 30 case SystemZ::FK_390_PC16DBL: 31 case SystemZ::FK_390_PC24DBL: 32 case SystemZ::FK_390_PC32DBL: 33 return (int64_t)Value / 2; 34 35 case SystemZ::FK_390_TLS_CALL: 36 return 0; 37 } 38 39 llvm_unreachable("Unknown fixup kind!"); 40 } 41 42 namespace { 43 class SystemZMCAsmBackend : public MCAsmBackend { 44 uint8_t OSABI; 45 public: 46 SystemZMCAsmBackend(uint8_t osABI) 47 : MCAsmBackend(support::big), OSABI(osABI) {} 48 49 // Override MCAsmBackend 50 unsigned getNumFixupKinds() const override { 51 return SystemZ::NumTargetFixupKinds; 52 } 53 Optional<MCFixupKind> getFixupKind(StringRef Name) const override; 54 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override; 55 bool shouldForceRelocation(const MCAssembler &Asm, const MCFixup &Fixup, 56 const MCValue &Target) override; 57 void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup, 58 const MCValue &Target, MutableArrayRef<char> Data, 59 uint64_t Value, bool IsResolved, 60 const MCSubtargetInfo *STI) const override; 61 bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value, 62 const MCRelaxableFragment *Fragment, 63 const MCAsmLayout &Layout) const override { 64 return false; 65 } 66 bool writeNopData(raw_ostream &OS, uint64_t Count, 67 const MCSubtargetInfo *STI) const override; 68 std::unique_ptr<MCObjectTargetWriter> 69 createObjectTargetWriter() const override { 70 return createSystemZObjectWriter(OSABI); 71 } 72 }; 73 } // end anonymous namespace 74 75 Optional<MCFixupKind> SystemZMCAsmBackend::getFixupKind(StringRef Name) const { 76 unsigned Type = llvm::StringSwitch<unsigned>(Name) 77 #define ELF_RELOC(X, Y) .Case(#X, Y) 78 #include "llvm/BinaryFormat/ELFRelocs/SystemZ.def" 79 #undef ELF_RELOC 80 .Case("BFD_RELOC_NONE", ELF::R_390_NONE) 81 .Case("BFD_RELOC_8", ELF::R_390_8) 82 .Case("BFD_RELOC_16", ELF::R_390_16) 83 .Case("BFD_RELOC_32", ELF::R_390_32) 84 .Case("BFD_RELOC_64", ELF::R_390_64) 85 .Default(-1u); 86 if (Type != -1u) 87 return static_cast<MCFixupKind>(FirstLiteralRelocationKind + Type); 88 return None; 89 } 90 91 const MCFixupKindInfo & 92 SystemZMCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const { 93 const static MCFixupKindInfo Infos[SystemZ::NumTargetFixupKinds] = { 94 { "FK_390_PC12DBL", 4, 12, MCFixupKindInfo::FKF_IsPCRel }, 95 { "FK_390_PC16DBL", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 96 { "FK_390_PC24DBL", 0, 24, MCFixupKindInfo::FKF_IsPCRel }, 97 { "FK_390_PC32DBL", 0, 32, MCFixupKindInfo::FKF_IsPCRel }, 98 { "FK_390_TLS_CALL", 0, 0, 0 } 99 }; 100 101 // Fixup kinds from .reloc directive are like R_390_NONE. They 102 // do not require any extra processing. 103 if (Kind >= FirstLiteralRelocationKind) 104 return MCAsmBackend::getFixupKindInfo(FK_NONE); 105 106 if (Kind < FirstTargetFixupKind) 107 return MCAsmBackend::getFixupKindInfo(Kind); 108 109 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && 110 "Invalid kind!"); 111 return Infos[Kind - FirstTargetFixupKind]; 112 } 113 114 bool SystemZMCAsmBackend::shouldForceRelocation(const MCAssembler &, 115 const MCFixup &Fixup, 116 const MCValue &) { 117 return Fixup.getKind() >= FirstLiteralRelocationKind; 118 } 119 120 void SystemZMCAsmBackend::applyFixup(const MCAssembler &Asm, 121 const MCFixup &Fixup, 122 const MCValue &Target, 123 MutableArrayRef<char> Data, uint64_t Value, 124 bool IsResolved, 125 const MCSubtargetInfo *STI) const { 126 MCFixupKind Kind = Fixup.getKind(); 127 if (Kind >= FirstLiteralRelocationKind) 128 return; 129 unsigned Offset = Fixup.getOffset(); 130 unsigned BitSize = getFixupKindInfo(Kind).TargetSize; 131 unsigned Size = (BitSize + 7) / 8; 132 133 assert(Offset + Size <= Data.size() && "Invalid fixup offset!"); 134 135 // Big-endian insertion of Size bytes. 136 Value = extractBitsForFixup(Kind, Value); 137 if (BitSize < 64) 138 Value &= ((uint64_t)1 << BitSize) - 1; 139 unsigned ShiftValue = (Size * 8) - 8; 140 for (unsigned I = 0; I != Size; ++I) { 141 Data[Offset + I] |= uint8_t(Value >> ShiftValue); 142 ShiftValue -= 8; 143 } 144 } 145 146 bool SystemZMCAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count, 147 const MCSubtargetInfo *STI) const { 148 for (uint64_t I = 0; I != Count; ++I) 149 OS << '\x7'; 150 return true; 151 } 152 153 MCAsmBackend *llvm::createSystemZMCAsmBackend(const Target &T, 154 const MCSubtargetInfo &STI, 155 const MCRegisterInfo &MRI, 156 const MCTargetOptions &Options) { 157 uint8_t OSABI = 158 MCELFObjectTargetWriter::getOSABI(STI.getTargetTriple().getOS()); 159 return new SystemZMCAsmBackend(OSABI); 160 } 161