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 : 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) const override; 57 bool mayNeedRelaxation(const MCInst &Inst) const override { 58 return false; 59 } 60 bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value, 61 const MCRelaxableFragment *Fragment, 62 const MCAsmLayout &Layout) const override { 63 return false; 64 } 65 void relaxInstruction(const MCInst &Inst, const MCSubtargetInfo &STI, 66 MCInst &Res) const override { 67 llvm_unreachable("SystemZ does do not have assembler relaxation"); 68 } 69 bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override; 70 std::unique_ptr<MCObjectWriter> 71 createObjectWriter(raw_pwrite_stream &OS) const override { 72 return createSystemZObjectWriter(OS, OSABI); 73 } 74 }; 75 } // end anonymous namespace 76 77 const MCFixupKindInfo & 78 SystemZMCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const { 79 const static MCFixupKindInfo Infos[SystemZ::NumTargetFixupKinds] = { 80 { "FK_390_PC12DBL", 4, 12, MCFixupKindInfo::FKF_IsPCRel }, 81 { "FK_390_PC16DBL", 0, 16, MCFixupKindInfo::FKF_IsPCRel }, 82 { "FK_390_PC24DBL", 0, 24, MCFixupKindInfo::FKF_IsPCRel }, 83 { "FK_390_PC32DBL", 0, 32, MCFixupKindInfo::FKF_IsPCRel }, 84 { "FK_390_TLS_CALL", 0, 0, 0 } 85 }; 86 87 if (Kind < FirstTargetFixupKind) 88 return MCAsmBackend::getFixupKindInfo(Kind); 89 90 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && 91 "Invalid kind!"); 92 return Infos[Kind - FirstTargetFixupKind]; 93 } 94 95 void SystemZMCAsmBackend::applyFixup(const MCAssembler &Asm, 96 const MCFixup &Fixup, 97 const MCValue &Target, 98 MutableArrayRef<char> Data, uint64_t Value, 99 bool IsResolved) const { 100 MCFixupKind Kind = Fixup.getKind(); 101 unsigned Offset = Fixup.getOffset(); 102 unsigned BitSize = getFixupKindInfo(Kind).TargetSize; 103 unsigned Size = (BitSize + 7) / 8; 104 105 assert(Offset + Size <= Data.size() && "Invalid fixup offset!"); 106 107 // Big-endian insertion of Size bytes. 108 Value = extractBitsForFixup(Kind, Value); 109 if (BitSize < 64) 110 Value &= ((uint64_t)1 << BitSize) - 1; 111 unsigned ShiftValue = (Size * 8) - 8; 112 for (unsigned I = 0; I != Size; ++I) { 113 Data[Offset + I] |= uint8_t(Value >> ShiftValue); 114 ShiftValue -= 8; 115 } 116 } 117 118 bool SystemZMCAsmBackend::writeNopData(uint64_t Count, 119 MCObjectWriter *OW) const { 120 for (uint64_t I = 0; I != Count; ++I) 121 OW->write8(7); 122 return true; 123 } 124 125 MCAsmBackend *llvm::createSystemZMCAsmBackend(const Target &T, 126 const MCSubtargetInfo &STI, 127 const MCRegisterInfo &MRI, 128 const MCTargetOptions &Options) { 129 uint8_t OSABI = 130 MCELFObjectTargetWriter::getOSABI(STI.getTargetTriple().getOS()); 131 return new SystemZMCAsmBackend(OSABI); 132 } 133