[Hexagon] Adding basic disassembler.
Marking all instructions as CodeGenOnly since encoding bits are not set yet.
http://reviews.llvm.org/D5829?vs=on&id=15023&whitespace=ignore-all#toc

llvm-svn: 220393
diff --git a/llvm/lib/Target/Hexagon/Disassembler/HexagonDisassembler.cpp b/llvm/lib/Target/Hexagon/Disassembler/HexagonDisassembler.cpp
new file mode 100644
index 0000000..688b8e6
--- /dev/null
+++ b/llvm/lib/Target/Hexagon/Disassembler/HexagonDisassembler.cpp
@@ -0,0 +1,131 @@
+//===-- HexagonDisassembler.cpp - Disassembler for Hexagon ISA ------------===//

+//

+//                     The LLVM Compiler Infrastructure

+//

+// This file is distributed under the University of Illinois Open Source

+// License. See LICENSE.TXT for details.

+//

+//===----------------------------------------------------------------------===//

+

+#include "MCTargetDesc/HexagonBaseInfo.h"

+#include "MCTargetDesc/HexagonMCTargetDesc.h"

+

+#include "llvm/MC/MCContext.h"

+#include "llvm/MC/MCDisassembler.h"

+#include "llvm/MC/MCExpr.h"

+#include "llvm/MC/MCFixedLenDisassembler.h"

+#include "llvm/MC/MCInst.h"

+#include "llvm/MC/MCInstrDesc.h"

+#include "llvm/MC/MCSubtargetInfo.h"

+#include "llvm/Support/Debug.h"

+#include "llvm/Support/ErrorHandling.h"

+#include "llvm/Support/LEB128.h"

+#include "llvm/Support/MemoryObject.h"

+#include "llvm/Support/raw_ostream.h"

+#include "llvm/Support/TargetRegistry.h"

+#include "llvm/Support/Endian.h"

+

+#include <vector>

+#include <array>

+

+using namespace llvm;

+

+#define DEBUG_TYPE "hexagon-disassembler"

+

+using DecodeStatus = MCDisassembler::DecodeStatus;

+

+namespace {

+/// \brief Hexagon disassembler for all Hexagon platforms.

+class HexagonDisassembler : public MCDisassembler {

+public:

+  HexagonDisassembler(MCSubtargetInfo const &STI, MCContext &Ctx)

+      : MCDisassembler(STI, Ctx) {}

+

+  DecodeStatus getInstruction(MCInst &instr, uint64_t &size,

+                              MemoryObject const &region, uint64_t address,

+                              raw_ostream &vStream, raw_ostream &cStream) const override;

+};

+}

+

+static const uint16_t IntRegDecoderTable[] = {

+    Hexagon::R0,  Hexagon::R1,  Hexagon::R2,  Hexagon::R3,  Hexagon::R4,

+    Hexagon::R5,  Hexagon::R6,  Hexagon::R7,  Hexagon::R8,  Hexagon::R9,

+    Hexagon::R10, Hexagon::R11, Hexagon::R12, Hexagon::R13, Hexagon::R14,

+    Hexagon::R15, Hexagon::R16, Hexagon::R17, Hexagon::R18, Hexagon::R19,

+    Hexagon::R20, Hexagon::R21, Hexagon::R22, Hexagon::R23, Hexagon::R24,

+    Hexagon::R25, Hexagon::R26, Hexagon::R27, Hexagon::R28, Hexagon::R29,

+    Hexagon::R30, Hexagon::R31};

+

+static const uint16_t DoubleRegDecoderTable[] = {

+    Hexagon::D0,  Hexagon::D1,  Hexagon::D2,  Hexagon::D3,

+    Hexagon::D4,  Hexagon::D5,  Hexagon::D6,  Hexagon::D7,

+    Hexagon::D8,  Hexagon::D9,  Hexagon::D10, Hexagon::D11,

+    Hexagon::D12, Hexagon::D13, Hexagon::D14, Hexagon::D15};

+

+static const uint16_t PredRegDecoderTable[] = {Hexagon::P0, Hexagon::P1,

+                                               Hexagon::P2, Hexagon::P3};

+

+static DecodeStatus DecodeIntRegsRegisterClass(MCInst &Inst, unsigned RegNo,

+                                               uint64_t /*Address*/,

+                                               void const *Decoder) {

+  if (RegNo > 31)

+    return MCDisassembler::Fail;

+

+  unsigned Register = IntRegDecoderTable[RegNo];

+  Inst.addOperand(MCOperand::CreateReg(Register));

+  return MCDisassembler::Success;

+}

+

+static DecodeStatus DecodeDoubleRegsRegisterClass(MCInst &Inst, unsigned RegNo,

+                                                  uint64_t /*Address*/,

+                                                  void const *Decoder) {

+  if (RegNo > 15)

+    return MCDisassembler::Fail;

+

+  unsigned Register = DoubleRegDecoderTable[RegNo];

+  Inst.addOperand(MCOperand::CreateReg(Register));

+  return MCDisassembler::Success;

+}

+

+static DecodeStatus DecodePredRegsRegisterClass(MCInst &Inst, unsigned RegNo,

+                                                uint64_t /*Address*/,

+                                                void const *Decoder) {

+  if (RegNo > 3)

+    return MCDisassembler::Fail;

+

+  unsigned Register = PredRegDecoderTable[RegNo];

+  Inst.addOperand(MCOperand::CreateReg(Register));

+  return MCDisassembler::Success;

+}

+

+#include "HexagonGenDisassemblerTables.inc"

+

+static MCDisassembler *createHexagonDisassembler(Target const &T,

+                                                 MCSubtargetInfo const &STI,

+                                                 MCContext &Ctx) {

+  return new HexagonDisassembler(STI, Ctx);

+}

+

+extern "C" void LLVMInitializeHexagonDisassembler() {

+  TargetRegistry::RegisterMCDisassembler(TheHexagonTarget,

+                                         createHexagonDisassembler);

+}

+

+DecodeStatus HexagonDisassembler::getInstruction(MCInst &MI, uint64_t &Size,

+                                                 MemoryObject const &Region,

+                                                 uint64_t Address,

+                                                 raw_ostream &os,

+                                                 raw_ostream &cs) const {

+  std::array<uint8_t, 4> Bytes;

+  Size = 4;

+  if (Region.readBytes(Address, Bytes.size(), Bytes.data()) == -1) {

+    return MCDisassembler::Fail;

+  }

+  uint32_t insn =

+      llvm::support::endian::read<uint32_t, llvm::support::little,

+                                  llvm::support::unaligned>(Bytes.data());

+

+  // Remove parse bits.

+  insn &= ~static_cast<uint32_t>(HexagonII::InstParseBits::INST_PARSE_MASK);

+  return decodeInstruction(DecoderTable32, MI, insn, Address, this, STI);

+}