1 //===-- SystemZMCAsmBackend.cpp - SystemZ assembler backend ---------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 #include "MCTargetDesc/SystemZMCFixups.h" 11 #include "MCTargetDesc/SystemZMCTargetDesc.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 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override; 54 void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup, 55 const MCValue &Target, MutableArrayRef<char> Data, 56 uint64_t Value, bool IsResolved, 57 const MCSubtargetInfo *STI) const override; 58 bool mayNeedRelaxation(const MCInst &Inst, 59 const MCSubtargetInfo &STI) const override { 60 return false; 61 } 62 bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value, 63 const MCRelaxableFragment *Fragment, 64 const MCAsmLayout &Layout) const override { 65 return false; 66 } 67 void relaxInstruction(const MCInst &Inst, const MCSubtargetInfo &STI, 68 MCInst &Res) const override { 69 llvm_unreachable("SystemZ does do not have assembler relaxation"); 70 } 71 bool writeNopData(raw_ostream &OS, uint64_t Count) const override; 72 std::unique_ptr<MCObjectTargetWriter> 73 createObjectTargetWriter() const override { 74 return createSystemZObjectWriter(OSABI); 75 } 76 }; 77 } // end anonymous namespace 78 79 const MCFixupKindInfo & 80 SystemZMCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const { 81 const static MCFixupKindInfo Infos[SystemZ::NumTargetFixupKinds] = { 82 { "FK_390_PC12DBL", 4, 12, MCFixupKindInfo::FKF_IsPCRel }, 83 { "FK_390_PC16DBL", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 84 { "FK_390_PC24DBL", 0, 24, MCFixupKindInfo::FKF_IsPCRel }, 85 { "FK_390_PC32DBL", 0, 32, MCFixupKindInfo::FKF_IsPCRel }, 86 { "FK_390_TLS_CALL", 0, 0, 0 } 87 }; 88 89 if (Kind < FirstTargetFixupKind) 90 return MCAsmBackend::getFixupKindInfo(Kind); 91 92 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && 93 "Invalid kind!"); 94 return Infos[Kind - FirstTargetFixupKind]; 95 } 96 97 void SystemZMCAsmBackend::applyFixup(const MCAssembler &Asm, 98 const MCFixup &Fixup, 99 const MCValue &Target, 100 MutableArrayRef<char> Data, uint64_t Value, 101 bool IsResolved, 102 const MCSubtargetInfo *STI) const { 103 MCFixupKind Kind = Fixup.getKind(); 104 unsigned Offset = Fixup.getOffset(); 105 unsigned BitSize = getFixupKindInfo(Kind).TargetSize; 106 unsigned Size = (BitSize + 7) / 8; 107 108 assert(Offset + Size <= Data.size() && "Invalid fixup offset!"); 109 110 // Big-endian insertion of Size bytes. 111 Value = extractBitsForFixup(Kind, Value); 112 if (BitSize < 64) 113 Value &= ((uint64_t)1 << BitSize) - 1; 114 unsigned ShiftValue = (Size * 8) - 8; 115 for (unsigned I = 0; I != Size; ++I) { 116 Data[Offset + I] |= uint8_t(Value >> ShiftValue); 117 ShiftValue -= 8; 118 } 119 } 120 121 bool SystemZMCAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count) const { 122 for (uint64_t I = 0; I != Count; ++I) 123 OS << '\x7'; 124 return true; 125 } 126 127 MCAsmBackend *llvm::createSystemZMCAsmBackend(const Target &T, 128 const MCSubtargetInfo &STI, 129 const MCRegisterInfo &MRI, 130 const MCTargetOptions &Options) { 131 uint8_t OSABI = 132 MCELFObjectTargetWriter::getOSABI(STI.getTargetTriple().getOS()); 133 return new SystemZMCAsmBackend(OSABI); 134 } 135