1 //===-- LanaiAsmBackend.cpp - Lanai 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 "LanaiFixupKinds.h" 10 #include "MCTargetDesc/LanaiMCTargetDesc.h" 11 #include "llvm/MC/MCAsmBackend.h" 12 #include "llvm/MC/MCAssembler.h" 13 #include "llvm/MC/MCDirectives.h" 14 #include "llvm/MC/MCELFObjectWriter.h" 15 #include "llvm/MC/MCFixupKindInfo.h" 16 #include "llvm/MC/MCObjectWriter.h" 17 #include "llvm/MC/MCSubtargetInfo.h" 18 #include "llvm/Support/ErrorHandling.h" 19 #include "llvm/Support/raw_ostream.h" 20 21 using namespace llvm; 22 23 // Prepare value for the target space 24 static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) { 25 switch (Kind) { 26 case FK_Data_1: 27 case FK_Data_2: 28 case FK_Data_4: 29 case FK_Data_8: 30 return Value; 31 case Lanai::FIXUP_LANAI_21: 32 case Lanai::FIXUP_LANAI_21_F: 33 case Lanai::FIXUP_LANAI_25: 34 case Lanai::FIXUP_LANAI_32: 35 case Lanai::FIXUP_LANAI_HI16: 36 case Lanai::FIXUP_LANAI_LO16: 37 return Value; 38 default: 39 llvm_unreachable("Unknown fixup kind!"); 40 } 41 } 42 43 namespace { 44 class LanaiAsmBackend : public MCAsmBackend { 45 Triple::OSType OSType; 46 47 public: 48 LanaiAsmBackend(const Target &T, Triple::OSType OST) 49 : MCAsmBackend(support::big), OSType(OST) {} 50 51 void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup, 52 const MCValue &Target, MutableArrayRef<char> Data, 53 uint64_t Value, bool IsResolved, 54 const MCSubtargetInfo *STI) const override; 55 56 std::unique_ptr<MCObjectTargetWriter> 57 createObjectTargetWriter() const override; 58 59 // No instruction requires relaxation 60 bool fixupNeedsRelaxation(const MCFixup & /*Fixup*/, uint64_t /*Value*/, 61 const MCRelaxableFragment * /*DF*/, 62 const MCAsmLayout & /*Layout*/) const override { 63 return false; 64 } 65 66 const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override; 67 68 unsigned getNumFixupKinds() const override { 69 return Lanai::NumTargetFixupKinds; 70 } 71 72 bool mayNeedRelaxation(const MCInst & /*Inst*/, 73 const MCSubtargetInfo &STI) const override { 74 return false; 75 } 76 77 bool writeNopData(raw_ostream &OS, uint64_t Count) const override; 78 }; 79 80 bool LanaiAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count) const { 81 if ((Count % 4) != 0) 82 return false; 83 84 for (uint64_t i = 0; i < Count; i += 4) 85 OS.write("\x15\0\0\0", 4); 86 87 return true; 88 } 89 90 void LanaiAsmBackend::applyFixup(const MCAssembler &Asm, const MCFixup &Fixup, 91 const MCValue &Target, 92 MutableArrayRef<char> Data, uint64_t Value, 93 bool /*IsResolved*/, 94 const MCSubtargetInfo * /*STI*/) const { 95 MCFixupKind Kind = Fixup.getKind(); 96 Value = adjustFixupValue(static_cast<unsigned>(Kind), Value); 97 98 if (!Value) 99 return; // This value doesn't change the encoding 100 101 // Where in the object and where the number of bytes that need 102 // fixing up 103 unsigned Offset = Fixup.getOffset(); 104 unsigned NumBytes = (getFixupKindInfo(Kind).TargetSize + 7) / 8; 105 unsigned FullSize = 4; 106 107 // Grab current value, if any, from bits. 108 uint64_t CurVal = 0; 109 110 // Load instruction and apply value 111 for (unsigned i = 0; i != NumBytes; ++i) { 112 unsigned Idx = (FullSize - 1 - i); 113 CurVal |= static_cast<uint64_t>(static_cast<uint8_t>(Data[Offset + Idx])) 114 << (i * 8); 115 } 116 117 uint64_t Mask = 118 (static_cast<uint64_t>(-1) >> (64 - getFixupKindInfo(Kind).TargetSize)); 119 CurVal |= Value & Mask; 120 121 // Write out the fixed up bytes back to the code/data bits. 122 for (unsigned i = 0; i != NumBytes; ++i) { 123 unsigned Idx = (FullSize - 1 - i); 124 Data[Offset + Idx] = static_cast<uint8_t>((CurVal >> (i * 8)) & 0xff); 125 } 126 } 127 128 std::unique_ptr<MCObjectTargetWriter> 129 LanaiAsmBackend::createObjectTargetWriter() const { 130 return createLanaiELFObjectWriter(MCELFObjectTargetWriter::getOSABI(OSType)); 131 } 132 133 const MCFixupKindInfo & 134 LanaiAsmBackend::getFixupKindInfo(MCFixupKind Kind) const { 135 static const MCFixupKindInfo Infos[Lanai::NumTargetFixupKinds] = { 136 // This table *must* be in same the order of fixup_* kinds in 137 // LanaiFixupKinds.h. 138 // Note: The number of bits indicated here are assumed to be contiguous. 139 // This does not hold true for LANAI_21 and LANAI_21_F which are applied 140 // to bits 0x7cffff and 0x7cfffc, respectively. Since the 'bits' counts 141 // here are used only for cosmetic purposes, we set the size to 16 bits 142 // for these 21-bit relocation as llvm/lib/MC/MCAsmStreamer.cpp checks 143 // no bits are set in the fixup range. 144 // 145 // name offset bits flags 146 {"FIXUP_LANAI_NONE", 0, 32, 0}, 147 {"FIXUP_LANAI_21", 16, 16 /*21*/, 0}, 148 {"FIXUP_LANAI_21_F", 16, 16 /*21*/, 0}, 149 {"FIXUP_LANAI_25", 7, 25, 0}, 150 {"FIXUP_LANAI_32", 0, 32, 0}, 151 {"FIXUP_LANAI_HI16", 16, 16, 0}, 152 {"FIXUP_LANAI_LO16", 16, 16, 0}}; 153 154 if (Kind < FirstTargetFixupKind) 155 return MCAsmBackend::getFixupKindInfo(Kind); 156 157 assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && 158 "Invalid kind!"); 159 return Infos[Kind - FirstTargetFixupKind]; 160 } 161 162 } // namespace 163 164 MCAsmBackend *llvm::createLanaiAsmBackend(const Target &T, 165 const MCSubtargetInfo &STI, 166 const MCRegisterInfo & /*MRI*/, 167 const MCTargetOptions & /*Options*/) { 168 const Triple &TT = STI.getTargetTriple(); 169 if (!TT.isOSBinFormatELF()) 170 llvm_unreachable("OS not supported"); 171 172 return new LanaiAsmBackend(T, TT.getOS()); 173 } 174