1 //===-- HexagonDisassembler.cpp - Disassembler for Hexagon ISA ------------===//
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/HexagonBaseInfo.h"
11 #include "MCTargetDesc/HexagonMCTargetDesc.h"
12 
13 #include "llvm/MC/MCContext.h"
14 #include "llvm/MC/MCDisassembler.h"
15 #include "llvm/MC/MCExpr.h"
16 #include "llvm/MC/MCFixedLenDisassembler.h"
17 #include "llvm/MC/MCInst.h"
18 #include "llvm/MC/MCInstrDesc.h"
19 #include "llvm/MC/MCSubtargetInfo.h"
20 #include "llvm/Support/Debug.h"
21 #include "llvm/Support/ErrorHandling.h"
22 #include "llvm/Support/LEB128.h"
23 #include "llvm/Support/MemoryObject.h"
24 #include "llvm/Support/raw_ostream.h"
25 #include "llvm/Support/TargetRegistry.h"
26 #include "llvm/Support/Endian.h"
27 
28 #include <vector>
29 #include <array>
30 
31 using namespace llvm;
32 
33 #define DEBUG_TYPE "hexagon-disassembler"
34 
35 // Pull DecodeStatus and its enum values into the global namespace.
36 typedef llvm::MCDisassembler::DecodeStatus DecodeStatus;
37 
38 namespace {
39 /// \brief Hexagon disassembler for all Hexagon platforms.
40 class HexagonDisassembler : public MCDisassembler {
41 public:
42   HexagonDisassembler(MCSubtargetInfo const &STI, MCContext &Ctx)
43       : MCDisassembler(STI, Ctx) {}
44 
45   DecodeStatus getInstruction(MCInst &instr, uint64_t &size,
46                               MemoryObject const &region, uint64_t address,
47                               raw_ostream &vStream, raw_ostream &cStream) const override;
48 };
49 }
50 
51 static const uint16_t IntRegDecoderTable[] = {
52     Hexagon::R0,  Hexagon::R1,  Hexagon::R2,  Hexagon::R3,  Hexagon::R4,
53     Hexagon::R5,  Hexagon::R6,  Hexagon::R7,  Hexagon::R8,  Hexagon::R9,
54     Hexagon::R10, Hexagon::R11, Hexagon::R12, Hexagon::R13, Hexagon::R14,
55     Hexagon::R15, Hexagon::R16, Hexagon::R17, Hexagon::R18, Hexagon::R19,
56     Hexagon::R20, Hexagon::R21, Hexagon::R22, Hexagon::R23, Hexagon::R24,
57     Hexagon::R25, Hexagon::R26, Hexagon::R27, Hexagon::R28, Hexagon::R29,
58     Hexagon::R30, Hexagon::R31};
59 
60 static const uint16_t PredRegDecoderTable[] = {Hexagon::P0, Hexagon::P1,
61                                                Hexagon::P2, Hexagon::P3};
62 
63 static DecodeStatus DecodeIntRegsRegisterClass(MCInst &Inst, unsigned RegNo,
64                                                uint64_t /*Address*/,
65                                                void const *Decoder) {
66   if (RegNo > 31)
67     return MCDisassembler::Fail;
68 
69   unsigned Register = IntRegDecoderTable[RegNo];
70   Inst.addOperand(MCOperand::CreateReg(Register));
71   return MCDisassembler::Success;
72 }
73 
74 static DecodeStatus DecodePredRegsRegisterClass(MCInst &Inst, unsigned RegNo,
75                                                 uint64_t /*Address*/,
76                                                 void const *Decoder) {
77   if (RegNo > 3)
78     return MCDisassembler::Fail;
79 
80   unsigned Register = PredRegDecoderTable[RegNo];
81   Inst.addOperand(MCOperand::CreateReg(Register));
82   return MCDisassembler::Success;
83 }
84 
85 #include "HexagonGenDisassemblerTables.inc"
86 
87 static MCDisassembler *createHexagonDisassembler(Target const &T,
88                                                  MCSubtargetInfo const &STI,
89                                                  MCContext &Ctx) {
90   return new HexagonDisassembler(STI, Ctx);
91 }
92 
93 extern "C" void LLVMInitializeHexagonDisassembler() {
94   TargetRegistry::RegisterMCDisassembler(TheHexagonTarget,
95                                          createHexagonDisassembler);
96 }
97 
98 DecodeStatus HexagonDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
99                                                  MemoryObject const &Region,
100                                                  uint64_t Address,
101                                                  raw_ostream &os,
102                                                  raw_ostream &cs) const {
103   std::array<uint8_t, 4> Bytes;
104   Size = 4;
105   if (Region.readBytes(Address, Bytes.size(), Bytes.data()) == -1) {
106     return MCDisassembler::Fail;
107   }
108   uint32_t insn =
109       llvm::support::endian::read<uint32_t, llvm::support::little,
110                                   llvm::support::unaligned>(Bytes.data());
111 
112   // Remove parse bits.
113   insn &= ~static_cast<uint32_t>(HexagonII::InstParseBits::INST_PARSE_MASK);
114   return decodeInstruction(DecoderTable32, MI, insn, Address, this, STI);
115 }
116