1 //===-- MSP430AsmBackend.cpp - MSP430 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/MSP430FixupKinds.h" 11 #include "MCTargetDesc/MSP430MCTargetDesc.h" 12 #include "llvm/ADT/APInt.h" 13 #include "llvm/MC/MCAsmBackend.h" 14 #include "llvm/MC/MCAssembler.h" 15 #include "llvm/MC/MCContext.h" 16 #include "llvm/MC/MCDirectives.h" 17 #include "llvm/MC/MCELFObjectWriter.h" 18 #include "llvm/MC/MCExpr.h" 19 #include "llvm/MC/MCFixupKindInfo.h" 20 #include "llvm/MC/MCObjectWriter.h" 21 #include "llvm/MC/MCSubtargetInfo.h" 22 #include "llvm/MC/MCSymbol.h" 23 #include "llvm/MC/MCTargetOptions.h" 24 #include "llvm/Support/ErrorHandling.h" 25 #include "llvm/Support/raw_ostream.h" 26 27 using namespace llvm; 28 29 namespace { 30 class MSP430AsmBackend : public MCAsmBackend { 31 uint8_t OSABI; 32 33 uint64_t adjustFixupValue(const MCFixup &Fixup, uint64_t Value, 34 MCContext &Ctx) const; 35 36 public: 37 MSP430AsmBackend(const MCSubtargetInfo &STI, uint8_t OSABI) 38 : MCAsmBackend(support::little), OSABI(OSABI) {} 39 ~MSP430AsmBackend() override {} 40 41 void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup, 42 const MCValue &Target, MutableArrayRef<char> Data, 43 uint64_t Value, bool IsResolved, 44 const MCSubtargetInfo *STI) const override; 45 46 std::unique_ptr<MCObjectTargetWriter> 47 createObjectTargetWriter() const override { 48 return createMSP430ELFObjectWriter(OSABI); 49 } 50 51 bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value, 52 const MCRelaxableFragment *DF, 53 const MCAsmLayout &Layout) const override { 54 return false; 55 } 56 57 bool fixupNeedsRelaxationAdvanced(const MCFixup &Fixup, bool Resolved, 58 uint64_t Value, 59 const MCRelaxableFragment *DF, 60 const MCAsmLayout &Layout, 61 const bool WasForced) const override { 62 return false; 63 } 64 65 unsigned getNumFixupKinds() const override { 66 return MSP430::NumTargetFixupKinds; 67 } 68 69 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override { 70 const static MCFixupKindInfo Infos[MSP430::NumTargetFixupKinds] = { 71 // This table must be in the same order of enum in MSP430FixupKinds.h. 72 // 73 // name offset bits flags 74 {"fixup_32", 0, 32, 0}, 75 {"fixup_10_pcrel", 0, 10, MCFixupKindInfo::FKF_IsPCRel}, 76 {"fixup_16", 0, 16, 0}, 77 {"fixup_16_pcrel", 0, 16, MCFixupKindInfo::FKF_IsPCRel}, 78 {"fixup_16_byte", 0, 16, 0}, 79 {"fixup_16_pcrel_byte", 0, 16, MCFixupKindInfo::FKF_IsPCRel}, 80 {"fixup_2x_pcrel", 0, 10, MCFixupKindInfo::FKF_IsPCRel}, 81 {"fixup_rl_pcrel", 0, 16, MCFixupKindInfo::FKF_IsPCRel}, 82 {"fixup_8", 0, 8, 0}, 83 {"fixup_sym_diff", 0, 32, 0}, 84 }; 85 static_assert((array_lengthof(Infos)) == MSP430::NumTargetFixupKinds, 86 "Not all fixup kinds added to Infos array"); 87 88 if (Kind < FirstTargetFixupKind) 89 return MCAsmBackend::getFixupKindInfo(Kind); 90 91 return Infos[Kind - FirstTargetFixupKind]; 92 } 93 94 bool mayNeedRelaxation(const MCInst &Inst, 95 const MCSubtargetInfo &STI) const override { 96 return false; 97 } 98 99 void relaxInstruction(const MCInst &Inst, const MCSubtargetInfo &STI, 100 MCInst &Res) const override {} 101 102 bool writeNopData(raw_ostream &OS, uint64_t Count) const override; 103 }; 104 105 uint64_t MSP430AsmBackend::adjustFixupValue(const MCFixup &Fixup, 106 uint64_t Value, 107 MCContext &Ctx) const { 108 unsigned Kind = Fixup.getKind(); 109 switch (Kind) { 110 case MSP430::fixup_10_pcrel: { 111 if (Value & 0x1) 112 Ctx.reportError(Fixup.getLoc(), "fixup value must be 2-byte aligned"); 113 114 // Offset is signed 115 int16_t Offset = Value; 116 // Jumps are in words 117 Offset >>= 1; 118 // PC points to the next instruction so decrement by one 119 --Offset; 120 121 if (Offset < -512 || Offset > 511) 122 Ctx.reportError(Fixup.getLoc(), "fixup value out of range"); 123 124 // Mask 10 bits 125 Offset &= 0x3ff; 126 127 return Offset; 128 } 129 default: 130 return Value; 131 } 132 } 133 134 void MSP430AsmBackend::applyFixup(const MCAssembler &Asm, const MCFixup &Fixup, 135 const MCValue &Target, 136 MutableArrayRef<char> Data, 137 uint64_t Value, bool IsResolved, 138 const MCSubtargetInfo *STI) const { 139 Value = adjustFixupValue(Fixup, Value, Asm.getContext()); 140 MCFixupKindInfo Info = getFixupKindInfo(Fixup.getKind()); 141 if (!Value) 142 return; // Doesn't change encoding. 143 144 // Shift the value into position. 145 Value <<= Info.TargetOffset; 146 147 unsigned Offset = Fixup.getOffset(); 148 unsigned NumBytes = alignTo(Info.TargetSize + Info.TargetOffset, 8) / 8; 149 150 assert(Offset + NumBytes <= Data.size() && "Invalid fixup offset!"); 151 152 // For each byte of the fragment that the fixup touches, mask in the 153 // bits from the fixup value. 154 for (unsigned i = 0; i != NumBytes; ++i) { 155 Data[Offset + i] |= uint8_t((Value >> (i * 8)) & 0xff); 156 } 157 } 158 159 bool MSP430AsmBackend::writeNopData(raw_ostream &OS, uint64_t Count) const { 160 if ((Count % 2) != 0) 161 return false; 162 163 // The canonical nop on MSP430 is mov #0, r3 164 uint64_t NopCount = Count / 2; 165 while (NopCount--) 166 OS.write("\x03\x43", 2); 167 168 return true; 169 } 170 171 } // end anonymous namespace 172 173 MCAsmBackend *llvm::createMSP430MCAsmBackend(const Target &T, 174 const MCSubtargetInfo &STI, 175 const MCRegisterInfo &MRI, 176 const MCTargetOptions &Options) { 177 return new MSP430AsmBackend(STI, ELF::ELFOSABI_STANDALONE); 178 } 179