lib/Target/ARC/Disassembler/ARCDisassembler.cpp

   1 //===- ARCDisassembler.cpp - Disassembler for ARC ---------------*- C++ -*-===//
   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 /// \file
  10 /// This file is part of the ARC Disassembler.
  11 ///
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "ARC.h"
  15 #include "ARCRegisterInfo.h"
  16 #include "MCTargetDesc/ARCMCTargetDesc.h"
  17 #include "TargetInfo/ARCTargetInfo.h"
  18 #include "llvm/MC/MCContext.h"
  19 #include "llvm/MC/MCDisassembler/MCDisassembler.h"
  20 #include "llvm/MC/MCFixedLenDisassembler.h"
  21 #include "llvm/MC/MCInst.h"
  22 #include "llvm/MC/MCInstrInfo.h"
  23 #include "llvm/MC/MCSubtargetInfo.h"
  24 #include "llvm/Support/TargetRegistry.h"
  25
  26 using namespace llvm;
  27
  28 #define DEBUG_TYPE "arc-disassembler"
  29
  30 using DecodeStatus = MCDisassembler::DecodeStatus;
  31
  32 namespace {
  33
  34 /// A disassembler class for ARC.
  35 class ARCDisassembler : public MCDisassembler {
  36 public:
  37   std::unique_ptr<MCInstrInfo const> const MCII;
  38
  39   ARCDisassembler(const MCSubtargetInfo &STI, MCContext &Ctx,
  40                   MCInstrInfo const *MCII)
  41       : MCDisassembler(STI, Ctx), MCII(MCII) {}
  42
  43   DecodeStatus getInstruction(MCInst &Instr, uint64_t &Size,
  44                               ArrayRef<uint8_t> Bytes, uint64_t Address,
  45                               raw_ostream &VStream,
  46                               raw_ostream &CStream) const override;
  47 };
  48
  49 } // end anonymous namespace
  50
  51 static bool readInstruction32(ArrayRef<uint8_t> Bytes, uint64_t Address,
  52                               uint64_t &Size, uint32_t &Insn) {
  53   Size = 4;
  54   // Read 2 16-bit values, but swap hi/lo parts.
  55   Insn =
  56       (Bytes[0] << 16) | (Bytes[1] << 24) | (Bytes[2] << 0) | (Bytes[3] << 8);
  57   return true;
  58 }
  59
  60 static bool readInstruction64(ArrayRef<uint8_t> Bytes, uint64_t Address,
  61                               uint64_t &Size, uint64_t &Insn) {
  62   Size = 8;
  63   Insn = ((uint64_t)Bytes[0] << 16) | ((uint64_t)Bytes[1] << 24) |
  64          ((uint64_t)Bytes[2] << 0) | ((uint64_t)Bytes[3] << 8) |
  65          ((uint64_t)Bytes[4] << 48) | ((uint64_t)Bytes[5] << 56) |
  66          ((uint64_t)Bytes[6] << 32) | ((uint64_t)Bytes[7] << 40);
  67   return true;
  68 }
  69
  70 static bool readInstruction48(ArrayRef<uint8_t> Bytes, uint64_t Address,
  71                               uint64_t &Size, uint64_t &Insn) {
  72   Size = 6;
  73   Insn = ((uint64_t)Bytes[0] << 0) | ((uint64_t)Bytes[1] << 8) |
  74          ((uint64_t)Bytes[2] << 32) | ((uint64_t)Bytes[3] << 40) |
  75          ((uint64_t)Bytes[4] << 16) | ((uint64_t)Bytes[5] << 24);
  76   return true;
  77 }
  78
  79 static bool readInstruction16(ArrayRef<uint8_t> Bytes, uint64_t Address,
  80                               uint64_t &Size, uint32_t &Insn) {
  81   Size = 2;
  82   Insn = (Bytes[0] << 0) | (Bytes[1] << 8);
  83   return true;
  84 }
  85
  86 template <unsigned B>
  87 static DecodeStatus DecodeSignedOperand(MCInst &Inst, unsigned InsnS,
  88                                         uint64_t Address = 0,
  89                                         const void *Decoder = nullptr);
  90
  91 template <unsigned B>
  92 static DecodeStatus DecodeFromCyclicRange(MCInst &Inst, unsigned InsnS,
  93                                         uint64_t Address = 0,
  94                                         const void *Decoder = nullptr);
  95
  96 template <unsigned B>
  97 static DecodeStatus DecodeBranchTargetS(MCInst &Inst, unsigned InsnS,
  98                                         uint64_t Address, const void *Decoder);
  99
 100 static DecodeStatus DecodeMEMrs9(MCInst &, unsigned, uint64_t, const void *);
 101
 102 static DecodeStatus DecodeLdLImmInstruction(MCInst &, uint64_t, uint64_t,
 103                                             const void *);
 104
 105 static DecodeStatus DecodeStLImmInstruction(MCInst &, uint64_t, uint64_t,
 106                                             const void *);
 107
 108 static DecodeStatus DecodeLdRLImmInstruction(MCInst &, uint64_t, uint64_t,
 109                                              const void *);
 110
 111 static DecodeStatus DecodeMoveHRegInstruction(MCInst &Inst, uint64_t, uint64_t,
 112                                               const void *);
 113
 114 static const uint16_t GPR32DecoderTable[] = {
 115     ARC::R0,  ARC::R1,    ARC::R2,  ARC::R3,   ARC::R4,  ARC::R5,  ARC::R6,
 116     ARC::R7,  ARC::R8,    ARC::R9,  ARC::R10,  ARC::R11, ARC::R12, ARC::R13,
 117     ARC::R14, ARC::R15,   ARC::R16, ARC::R17,  ARC::R18, ARC::R19, ARC::R20,
 118     ARC::R21, ARC::R22,   ARC::R23, ARC::R24,  ARC::R25, ARC::GP,  ARC::FP,
 119     ARC::SP,  ARC::ILINK, ARC::R30, ARC::BLINK};
 120
 121 static DecodeStatus DecodeGPR32RegisterClass(MCInst &Inst, unsigned RegNo,
 122                                              uint64_t Address,
 123                                              const void *Decoder) {
 124   if (RegNo >= 32) {
 125     LLVM_DEBUG(dbgs() << "Not a GPR32 register.");
 126     return MCDisassembler::Fail;
 127   }
 128
 129   unsigned Reg = GPR32DecoderTable[RegNo];
 130   Inst.addOperand(MCOperand::createReg(Reg));
 131   return MCDisassembler::Success;
 132 }
 133
 134 static DecodeStatus DecodeGBR32ShortRegister(MCInst &Inst, unsigned RegNo,
 135                                                uint64_t Address,
 136                                                const void *Decoder) {
 137   // Enumerates registers from ranges [r0-r3],[r12-r15].
 138   if (RegNo > 3)
 139     RegNo += 8; // 4 for r12, etc...
 140
 141   return DecodeGPR32RegisterClass(Inst, RegNo, Address, Decoder);
 142 }
 143
 144 #include "ARCGenDisassemblerTables.inc"
 145
 146 static unsigned decodeCField(unsigned Insn) {
 147   return fieldFromInstruction(Insn, 6, 6);
 148 }
 149
 150 static unsigned decodeBField(unsigned Insn) {
 151   return (fieldFromInstruction(Insn, 12, 3) << 3) |
 152          fieldFromInstruction(Insn, 24, 3);
 153 }
 154
 155 static unsigned decodeAField(unsigned Insn) {
 156   return fieldFromInstruction(Insn, 0, 6);
 157 }
 158
 159 static DecodeStatus DecodeMEMrs9(MCInst &Inst, unsigned Insn, uint64_t Address,
 160                                  const void *Dec) {
 161   // We have the 9-bit immediate in the low bits, 6-bit register in high bits.
 162   unsigned S9 = Insn & 0x1ff;
 163   unsigned R = (Insn & (0x7fff & ~0x1ff)) >> 9;
 164   DecodeGPR32RegisterClass(Inst, R, Address, Dec);
 165   Inst.addOperand(MCOperand::createImm(SignExtend32<9>(S9)));
 166   return MCDisassembler::Success;
 167 }
 168
 169 static bool DecodeSymbolicOperand(MCInst &Inst, uint64_t Address,
 170                                   uint64_t Value, const void *Decoder) {
 171   static const uint64_t atLeast = 2;
 172   // TODO: Try to force emitter to use MCDisassembler* instead of void*.
 173   auto Disassembler = static_cast<const MCDisassembler *>(Decoder);
 174   return (nullptr != Disassembler &&
 175           Disassembler->tryAddingSymbolicOperand(Inst, Value, Address, true, 0,
 176                                                  atLeast));
 177 }
 178
 179 static void DecodeSymbolicOperandOff(MCInst &Inst, uint64_t Address,
 180                                      uint64_t Offset, const void *Decoder) {
 181   uint64_t nextAddress = Address + Offset;
 182
 183   if (!DecodeSymbolicOperand(Inst, Address, nextAddress, Decoder))
 184     Inst.addOperand(MCOperand::createImm(Offset));
 185 }
 186
 187 template <unsigned B>
 188 static DecodeStatus DecodeBranchTargetS(MCInst &Inst, unsigned InsnS,
 189                                         uint64_t Address, const void *Decoder) {
 190
 191   static_assert(B > 0, "field is empty");
 192   DecodeSymbolicOperandOff(Inst, Address, SignExtend32<B>(InsnS), Decoder);
 193   return MCDisassembler::Success;
 194 }
 195
 196 template <unsigned B>
 197 static DecodeStatus DecodeSignedOperand(MCInst &Inst, unsigned InsnS,
 198                                         uint64_t /*Address*/,
 199                                         const void * /*Decoder*/) {
 200
 201   static_assert(B > 0, "field is empty");
 202   Inst.addOperand(MCOperand::createImm(
 203       SignExtend32<B>(maskTrailingOnes<decltype(InsnS)>(B) & InsnS)));
 204   return MCDisassembler::Success;
 205 }
 206
 207 template <unsigned B>
 208 static DecodeStatus DecodeFromCyclicRange(MCInst &Inst, unsigned InsnS,
 209                                           uint64_t /*Address*/,
 210                                           const void * /*Decoder*/) {
 211
 212   static_assert(B > 0, "field is empty");
 213   const unsigned max = (1u << B) - 1;
 214   Inst.addOperand(
 215       MCOperand::createImm(InsnS < max ? static_cast<int>(InsnS) : -1));
 216   return MCDisassembler::Success;
 217 }
 218
 219 static DecodeStatus DecodeStLImmInstruction(MCInst &Inst, uint64_t Insn,
 220                                             uint64_t Address,
 221                                             const void *Decoder) {
 222   unsigned SrcC, DstB, LImm;
 223   DstB = decodeBField(Insn);
 224   if (DstB != 62) {
 225     LLVM_DEBUG(dbgs() << "Decoding StLImm found non-limm register.");
 226     return MCDisassembler::Fail;
 227   }
 228   SrcC = decodeCField(Insn);
 229   DecodeGPR32RegisterClass(Inst, SrcC, Address, Decoder);
 230   LImm = (Insn >> 32);
 231   Inst.addOperand(MCOperand::createImm(LImm));
 232   Inst.addOperand(MCOperand::createImm(0));
 233   return MCDisassembler::Success;
 234 }
 235
 236 static DecodeStatus DecodeLdLImmInstruction(MCInst &Inst, uint64_t Insn,
 237                                             uint64_t Address,
 238                                             const void *Decoder) {
 239   unsigned DstA, SrcB, LImm;
 240   LLVM_DEBUG(dbgs() << "Decoding LdLImm:\n");
 241   SrcB = decodeBField(Insn);
 242   if (SrcB != 62) {
 243     LLVM_DEBUG(dbgs() << "Decoding LdLImm found non-limm register.");
 244     return MCDisassembler::Fail;
 245   }
 246   DstA = decodeAField(Insn);
 247   DecodeGPR32RegisterClass(Inst, DstA, Address, Decoder);
 248   LImm = (Insn >> 32);
 249   Inst.addOperand(MCOperand::createImm(LImm));
 250   Inst.addOperand(MCOperand::createImm(0));
 251   return MCDisassembler::Success;
 252 }
 253
 254 static DecodeStatus DecodeLdRLImmInstruction(MCInst &Inst, uint64_t Insn,
 255                                              uint64_t Address,
 256                                              const void *Decoder) {
 257   unsigned DstA, SrcB;
 258   LLVM_DEBUG(dbgs() << "Decoding LdRLimm\n");
 259   DstA = decodeAField(Insn);
 260   DecodeGPR32RegisterClass(Inst, DstA, Address, Decoder);
 261   SrcB = decodeBField(Insn);
 262   DecodeGPR32RegisterClass(Inst, SrcB, Address, Decoder);
 263   if (decodeCField(Insn) != 62) {
 264     LLVM_DEBUG(dbgs() << "Decoding LdRLimm found non-limm register.");
 265     return MCDisassembler::Fail;
 266   }
 267   Inst.addOperand(MCOperand::createImm((uint32_t)(Insn >> 32)));
 268   return MCDisassembler::Success;
 269 }
 270
 271 static DecodeStatus DecodeMoveHRegInstruction(MCInst &Inst, uint64_t Insn,
 272                                               uint64_t Address,
 273                                               const void *Decoder) {
 274   LLVM_DEBUG(dbgs() << "Decoding MOV_S h-register\n");
 275   using Field = decltype(Insn);
 276   Field h = fieldFromInstruction(Insn, 5, 3) |
 277             (fieldFromInstruction(Insn, 0, 2) << 3);
 278   Field g = fieldFromInstruction(Insn, 8, 3) |
 279             (fieldFromInstruction(Insn, 3, 2) << 3);
 280
 281   auto DecodeRegisterOrImm = [&Inst, Address, Decoder](Field RegNum,
 282                                                        Field Value) {
 283     if (30 == RegNum) {
 284       Inst.addOperand(MCOperand::createImm(Value));
 285       return MCDisassembler::Success;
 286     }
 287
 288     return DecodeGPR32RegisterClass(Inst, RegNum, Address, Decoder);
 289   };
 290
 291   if (MCDisassembler::Success != DecodeRegisterOrImm(g, 0))
 292     return MCDisassembler::Fail;
 293
 294   return DecodeRegisterOrImm(h, Insn >> 16u);
 295 }
 296
 297 DecodeStatus ARCDisassembler::getInstruction(MCInst &Instr, uint64_t &Size,
 298                                              ArrayRef<uint8_t> Bytes,
 299                                              uint64_t Address,
 300                                              raw_ostream &vStream,
 301                                              raw_ostream &cStream) const {
 302   MCDisassembler::DecodeStatus Result;
 303   if (Bytes.size() < 2) {
 304     Size = 0;
 305     return Fail;
 306   }
 307   uint8_t DecodeByte = (Bytes[1] & 0xF7) >> 3;
 308   // 0x00 -> 0x07 are 32-bit instructions.
 309   // 0x08 -> 0x1F are 16-bit instructions.
 310   if (DecodeByte < 0x08) {
 311     // 32-bit instruction.
 312     if (Bytes.size() < 4) {
 313       // Did we decode garbage?
 314       Size = 0;
 315       return Fail;
 316     }
 317     if (Bytes.size() >= 8) {
 318       // Attempt to decode 64-bit instruction.
 319       uint64_t Insn64;
 320       if (!readInstruction64(Bytes, Address, Size, Insn64))
 321         return Fail;
 322       Result =
 323           decodeInstruction(DecoderTable64, Instr, Insn64, Address, this, STI);
 324       if (Success == Result) {
 325         LLVM_DEBUG(dbgs() << "Successfully decoded 64-bit instruction.");
 326         return Result;
 327       }
 328       LLVM_DEBUG(dbgs() << "Not a 64-bit instruction, falling back to 32-bit.");
 329     }
 330     uint32_t Insn32;
 331     if (!readInstruction32(Bytes, Address, Size, Insn32)) {
 332       return Fail;
 333     }
 334     // Calling the auto-generated decoder function.
 335     return decodeInstruction(DecoderTable32, Instr, Insn32, Address, this, STI);
 336   } else {
 337     if (Bytes.size() >= 6) {
 338       // Attempt to treat as instr. with limm data.
 339       uint64_t Insn48;
 340       if (!readInstruction48(Bytes, Address, Size, Insn48))
 341         return Fail;
 342       Result =
 343           decodeInstruction(DecoderTable48, Instr, Insn48, Address, this, STI);
 344       if (Success == Result) {
 345         LLVM_DEBUG(
 346             dbgs() << "Successfully decoded 16-bit instruction with limm.");
 347         return Result;
 348       }
 349       LLVM_DEBUG(
 350           dbgs() << "Not a 16-bit instruction with limm, try without it.");
 351     }
 352
 353     uint32_t Insn16;
 354     if (!readInstruction16(Bytes, Address, Size, Insn16))
 355       return Fail;
 356
 357     // Calling the auto-generated decoder function.
 358     return decodeInstruction(DecoderTable16, Instr, Insn16, Address, this, STI);
 359   }
 360 }
 361
 362 static MCDisassembler *createARCDisassembler(const Target &T,
 363                                              const MCSubtargetInfo &STI,
 364                                              MCContext &Ctx) {
 365   return new ARCDisassembler(STI, Ctx, T.createMCInstrInfo());
 366 }
 367
 368 extern "C" void LLVMInitializeARCDisassembler() {
 369   // Register the disassembler.
 370   TargetRegistry::RegisterMCDisassembler(getTheARCTarget(),
 371                                          createARCDisassembler);
 372 }