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/SystemZMCTargetDesc.h" 11 #include "MCTargetDesc/SystemZMCFixups.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 18 using namespace llvm; 19 20 // Value is a fully-resolved relocation value: Symbol + Addend [- Pivot]. 21 // Return the bits that should be installed in a relocation field for 22 // fixup kind Kind. 23 static uint64_t extractBitsForFixup(MCFixupKind Kind, uint64_t Value) { 24 if (Kind < FirstTargetFixupKind) 25 return Value; 26 27 switch (unsigned(Kind)) { 28 case SystemZ::FK_390_PC16DBL: 29 case SystemZ::FK_390_PC32DBL: 30 case SystemZ::FK_390_PLT16DBL: 31 case SystemZ::FK_390_PLT32DBL: 32 return (int64_t)Value / 2; 33 } 34 35 llvm_unreachable("Unknown fixup kind!"); 36 } 37 38 namespace { 39 class SystemZMCAsmBackend : public MCAsmBackend { 40 uint8_t OSABI; 41 public: 42 SystemZMCAsmBackend(uint8_t osABI) 43 : OSABI(osABI) {} 44 45 // Override MCAsmBackend 46 virtual unsigned getNumFixupKinds() const LLVM_OVERRIDE { 47 return SystemZ::NumTargetFixupKinds; 48 } 49 virtual const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const 50 LLVM_OVERRIDE; 51 virtual void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize, 52 uint64_t Value) const LLVM_OVERRIDE; 53 virtual bool mayNeedRelaxation(const MCInst &Inst) const LLVM_OVERRIDE { 54 return false; 55 } 56 virtual bool fixupNeedsRelaxation(const MCFixup &Fixup, 57 uint64_t Value, 58 const MCRelaxableFragment *Fragment, 59 const MCAsmLayout &Layout) const 60 LLVM_OVERRIDE { 61 return false; 62 } 63 virtual void relaxInstruction(const MCInst &Inst, 64 MCInst &Res) const LLVM_OVERRIDE { 65 llvm_unreachable("SystemZ does do not have assembler relaxation"); 66 } 67 virtual bool writeNopData(uint64_t Count, 68 MCObjectWriter *OW) const LLVM_OVERRIDE; 69 virtual MCObjectWriter *createObjectWriter(raw_ostream &OS) const 70 LLVM_OVERRIDE { 71 return createSystemZObjectWriter(OS, OSABI); 72 } 73 virtual bool doesSectionRequireSymbols(const MCSection &Section) const 74 LLVM_OVERRIDE { 75 return false; 76 } 77 }; 78 } // end anonymous namespace 79 80 const MCFixupKindInfo & 81 SystemZMCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const { 82 const static MCFixupKindInfo Infos[SystemZ::NumTargetFixupKinds] = { 83 { "FK_390_PC16DBL", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 84 { "FK_390_PC32DBL", 0, 32, MCFixupKindInfo::FKF_IsPCRel }, 85 { "FK_390_PLT16DBL", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 86 { "FK_390_PLT32DBL", 0, 32, MCFixupKindInfo::FKF_IsPCRel } 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 MCFixup &Fixup, char *Data, 98 unsigned DataSize, uint64_t Value) const { 99 MCFixupKind Kind = Fixup.getKind(); 100 unsigned Offset = Fixup.getOffset(); 101 unsigned Size = (getFixupKindInfo(Kind).TargetSize + 7) / 8; 102 103 assert(Offset + Size <= DataSize && "Invalid fixup offset!"); 104 105 // Big-endian insertion of Size bytes. 106 Value = extractBitsForFixup(Kind, Value); 107 unsigned ShiftValue = (Size * 8) - 8; 108 for (unsigned I = 0; I != Size; ++I) { 109 Data[Offset + I] |= uint8_t(Value >> ShiftValue); 110 ShiftValue -= 8; 111 } 112 } 113 114 bool SystemZMCAsmBackend::writeNopData(uint64_t Count, 115 MCObjectWriter *OW) const { 116 for (uint64_t I = 0; I != Count; ++I) 117 OW->Write8(7); 118 return true; 119 } 120 121 MCAsmBackend *llvm::createSystemZMCAsmBackend(const Target &T, 122 const MCRegisterInfo &MRI, 123 StringRef TT, StringRef CPU) { 124 uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(Triple(TT).getOS()); 125 return new SystemZMCAsmBackend(OSABI); 126 } 127