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