Begins work on ARM64, first assembler test.

runtime/vm/disassembler_arm64.cc

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "vm/disassembler.h"
+
+#include "vm/globals.h"  // Needed here to get TARGET_ARCH_ARM64.
+#if defined(TARGET_ARCH_ARM64)
+#include "platform/assert.h"
+
+namespace dart {
+
+class ARM64Decoder : public ValueObject {
+ public:
+  ARM64Decoder(char* buffer, size_t buffer_size)
+      : buffer_(buffer),
+        buffer_size_(buffer_size),
+        buffer_pos_(0) {
+    buffer_[buffer_pos_] = '\0';
+  }
+
+  ~ARM64Decoder() {}
+
+  // Writes one disassembled instruction into 'buffer' (0-terminated).
+  // Returns true if the instruction was successfully decoded, false otherwise.
+  void InstructionDecode(uword pc);
+
+ private:
+  // Bottleneck functions to print into the out_buffer.
+  void Print(const char* str);
+
+  // Printing of common values.
+  void PrintRegister(int reg);
+  void PrintShiftExtendRm(Instr* instr);
+  void PrintS(Instr* instr);
+
+  // Handle formatting of instructions and their options.
+  int FormatRegister(Instr* instr, const char* option);
+  int FormatOption(Instr* instr, const char* format);
+  void Format(Instr* instr, const char* format);
+  void Unknown(Instr* instr);
+
+  // Decode instructions.
+  #define DECODE_OP(op)                                                        \
+    void Decode##op(Instr* instr);
+  APPLY_OP_LIST(DECODE_OP)
+  #undef DECODE_OP
+
+
+  // Convenience functions.
+  char* get_buffer() const { return buffer_; }
+  char* current_position_in_buffer() { return buffer_ + buffer_pos_; }
+  size_t remaining_size_in_buffer() { return buffer_size_ - buffer_pos_; }
+
+  char* buffer_;  // Decode instructions into this buffer.
+  size_t buffer_size_;  // The size of the character buffer.
+  size_t buffer_pos_;  // Current character position in buffer.
+
+  DISALLOW_ALLOCATION();
+  DISALLOW_COPY_AND_ASSIGN(ARM64Decoder);
+};
+
+
+// Support for assertions in the ARM64Decoder formatting functions.
+#define STRING_STARTS_WITH(string, compare_string) \
+  (strncmp(string, compare_string, strlen(compare_string)) == 0)
+
+
+// Append the str to the output buffer.
+void ARM64Decoder::Print(const char* str) {
+  char cur = *str++;
+  while (cur != '\0' && (buffer_pos_ < (buffer_size_ - 1))) {
+    buffer_[buffer_pos_++] = cur;
+    cur = *str++;
+  }
+  buffer_[buffer_pos_] = '\0';
+}
+
+
+// These register names are defined in a way to match the native disassembler
+// formatting, except for register aliases ctx (r9) and pp (r10).
+// See for example the command "objdump -d <binary file>".
+static const char* reg_names[kNumberOfCpuRegisters] = {
+  "r0",  "r1",  "r2",  "r3",  "r4",  "r5",  "r6",  "r7",
+  "r8",  "r9",  "r10", "r11", "r12", "r13", "r14", "r15",
+  "r16", "r17", "r18", "r19", "r20", "r21", "r22", "r23",
+  "r24", "ip0", "ip1", "pp",  "ctx", "fp",  "lr",  "r31",
+};
+
+
+// Print the register name according to the active name converter.
+void ARM64Decoder::PrintRegister(int reg) {
+  ASSERT(0 <= reg);
+  ASSERT(reg < kNumberOfCpuRegisters);
+  Print(reg_names[reg]);
+}
+
+
+// These shift names are defined in a way to match the native disassembler
+// formatting. See for example the command "objdump -d <binary file>".
+static const char* shift_names[kMaxShift] = {
+  "lsl", "lsr", "asr", "ror"
+};
+
+
+static const char* extend_names[kMaxExtend] = {
+  "uxtb", "uxth", "uxtw", "uxtx",
+  "sxtb", "sxth", "sxtw", "sxtx",
+};
+
+
+// Print the register shift operands for the instruction. Generally used for
+// data processing instructions.
+void ARM64Decoder::PrintShiftExtendRm(Instr* instr) {
+  int rm = instr->RmField();
+  Shift shift = instr->ShiftTypeField();
+  int shift_amount = instr->ShiftAmountField();
+  Extend extend = instr->ExtendTypeField();
+  int extend_shift_amount = instr->ExtShiftAmountField();
+
+  PrintRegister(rm);
+
+  if (instr->IsShift() && (shift == LSL) && (shift_amount == 0)) {
+    // Special case for using rm only.
+    return;
+  }
+  if (instr->IsShift()) {
+    // by immediate
+    if ((shift == ROR) && (shift_amount == 0)) {
+      Print(", RRX");
+      return;
+    } else if (((shift == LSR) || (shift == ASR)) && (shift_amount == 0)) {
+      shift_amount = 32;
+    }
+    buffer_pos_ += OS::SNPrint(current_position_in_buffer(),
+                               remaining_size_in_buffer(),
+                               ", %s #%d",
+                               shift_names[shift],
+                               shift_amount);
+  } else {
+    ASSERT(instr->IsExtend());
+    // by register
+    buffer_pos_ += OS::SNPrint(current_position_in_buffer(),
+                               remaining_size_in_buffer(),
+                               ", %s",
+                               extend_names[extend]);
+    if (((instr->SFField() == 1) && (extend == UXTX)) ||
+        ((instr->SFField() == 0) && (extend == UXTW))) {
+      // Shift amount.
+      buffer_pos_ += OS::SNPrint(current_position_in_buffer(),
+                                 remaining_size_in_buffer(),
+                                 " %d",
+                                 extend_shift_amount);
+    }
+  }
+}
+
+
+// Handle all register based formatting in these functions to reduce the
+// complexity of FormatOption.
+int ARM64Decoder::FormatRegister(Instr* instr, const char* format) {
+  ASSERT(format[0] == 'r');
+  if (format[1] == 'n') {  // 'rn: Rn register
+    int reg = instr->RnField();
+    PrintRegister(reg);
+    return 2;
+  } else if (format[1] == 'd') {  // 'rd: Rd register
+    int reg = instr->RdField();
+    PrintRegister(reg);
+    return 2;
+  } else if (format[1] == 'm') {  // 'rm: Rm register
+    int reg = instr->RmField();
+    PrintRegister(reg);
+    return 2;
+  }
+  UNREACHABLE();
+  return -1;
+}
+
+
+// FormatOption takes a formatting string and interprets it based on
+// the current instructions. The format string points to the first
+// character of the option string (the option escape has already been
+// consumed by the caller.)  FormatOption returns the number of
+// characters that were consumed from the formatting string.
+int ARM64Decoder::FormatOption(Instr* instr, const char* format) {
+  switch (format[0]) {
+    case 'i': {  // 'imm12, imm16
+      uint64_t imm;
+      int ret = 5;
+      if (format[4] == '2') {
+        ASSERT(STRING_STARTS_WITH(format, "imm12"));
+        imm = instr->Imm12Field();
+        if (format[5] == 's') {
+          // shifted immediate.
+          if (instr->Imm12ShiftField() == 1) {
+            imm = imm << 12;
+          } else if ((instr->Imm12ShiftField() & 0x2) != 0) {
+            Print("Unknown Shift");
+          }
+          ret = 6;
+        }
+      } else {
+        ASSERT(STRING_STARTS_WITH(format, "imm16"));
+        imm = instr->Imm16Field();
+      }
+      buffer_pos_ += OS::SNPrint(current_position_in_buffer(),
+                                 remaining_size_in_buffer(),
+                                 "0x%"Px64,
+                                 imm);
+      return ret;
+    }
+    case 's': {  // 's: S flag.
+      if (format[1] == 'h') {
+        ASSERT(STRING_STARTS_WITH(format, "shift_op"));
+        PrintShiftExtendRm(instr);
+        return 8;
+      } else if (format[1] == 'f') {
+        ASSERT(STRING_STARTS_WITH(format, "sf"));
+        if (instr->SFField() == 1) {
+          // TODO(zra): If we don't use the w form much, we can omit printing
+          // this x.
+          Print("x");
+        } else {
+          Print("w");
+        }
+        return 2;
+      } else if (format[1] == ' ') {
+        if (instr->HasS()) {
+          Print("s");
+        }
+        return 1;
+      } else {
+        UNREACHABLE();
+      }
+    }
+    case 'r': {
+      return FormatRegister(instr, format);
+    }
+    default: {
+      UNREACHABLE();
+      break;
+    }
+  }
+  UNREACHABLE();
+  return -1;
+}
+
+
+// Format takes a formatting string for a whole instruction and prints it into
+// the output buffer. All escaped options are handed to FormatOption to be
+// parsed further.
+void ARM64Decoder::Format(Instr* instr, const char* format) {
+  char cur = *format++;
+  while ((cur != 0) && (buffer_pos_ < (buffer_size_ - 1))) {
+    if (cur == '\'') {  // Single quote is used as the formatting escape.
+      format += FormatOption(instr, format);
+    } else {
+      buffer_[buffer_pos_++] = cur;
+    }
+    cur = *format++;
+  }
+  buffer_[buffer_pos_]  = '\0';
+}
+
+
+// For currently unimplemented decodings the disassembler calls Unknown(instr)
+// which will just print "unknown" of the instruction bits.
+void ARM64Decoder::Unknown(Instr* instr) {
+  Format(instr, "unknown");
+}
+
+
+void ARM64Decoder::DecodeMoveWide(Instr* instr) {
+  switch (instr->Bits(29, 2)) {
+    case 0:
+      Format(instr, "movn'sf 'rd, 'imm16");
+      break;
+    case 2:
+      Format(instr, "movz'sf 'rd, 'imm16");
+      break;
+    case 3:
+      Format(instr, "movk'sf 'rd, 'imm16");
+      break;
+    default:
+      Unknown(instr);
+      break;
+  }
+}
+
+
+void ARM64Decoder::DecodeAddSubImm(Instr* instr) {
+  switch (instr->Bit(30)) {
+    case 0:
+      Format(instr, "addi'sf's 'rd, 'rn, 'imm12s");
+      break;
+    case 1:
+      Format(instr, "subi'sf's 'rd, 'rn, 'imm12s");
+      break;
+    default:
+      Unknown(instr);
+      break;
+  }
+}
+
+void ARM64Decoder::DecodeDPImmediate(Instr* instr) {
+  if (instr->IsMoveWideOp()) {
+    DecodeMoveWide(instr);
+  } else if (instr->IsAddSubImmOp()) {
+    DecodeAddSubImm(instr);
+  } else {
+    Unknown(instr);
+  }
+}
+
+
+void ARM64Decoder::DecodeExceptionGen(Instr* instr) {
+  if ((instr->Bits(0, 2) == 1) && (instr->Bits(2, 3) == 0) &&
+      (instr->Bits(21, 3) == 0)) {
+    Format(instr, "svc 'imm16");
+  } else if ((instr->Bits(0, 2) == 0) && (instr->Bits(2, 3) == 0) &&
+             (instr->Bits(21, 3) == 1)) {
+    Format(instr, "brk 'imm16");
+  } else if ((instr->Bits(0, 2) == 0) && (instr->Bits(2, 3) == 0) &&
+             (instr->Bits(21, 3) == 2)) {
+    Format(instr, "hlt 'imm16");
+  }
+}
+
+
+void ARM64Decoder::DecodeSystem(Instr* instr) {
+  if ((instr->Bits(0, 8) == 0x5f) && (instr->Bits(12, 4) == 2) &&
+      (instr->Bits(16, 3) == 3) && (instr->Bits(19, 2) == 0) &&
+      (instr->Bit(21) == 0)) {
+    if (instr->Bits(8, 4) == 0) {
+      Format(instr, "nop");
+    } else {
+      Unknown(instr);
+    }
+  } else {
+    Unknown(instr);
+  }
+}
+
+
+void ARM64Decoder::DecodeUnconditionalBranchReg(Instr* instr) {
+  if ((instr->Bits(0, 5) == 0) && (instr->Bits(10, 5) == 0) &&
+      (instr->Bits(16, 5) == 0x1f)) {
+    switch (instr->Bits(21, 4)) {
+      case 0:
+        Format(instr, "br 'rn");
+        break;
+      case 1:
+        Format(instr, "blr 'rn");
+        break;
+      case 2:
+        Format(instr, "ret 'rn");
+        break;
+      default:
+        Unknown(instr);
+        break;
+    }
+  }
+}
+
+
+void ARM64Decoder::DecodeCompareBranch(Instr* instr) {
+  if (instr->IsExceptionGenOp()) {
+    DecodeExceptionGen(instr);
+  } else if (instr->IsSystemOp()) {
+    DecodeSystem(instr);
+  } else if (instr->IsUnconditionalBranchRegOp()) {
+    DecodeUnconditionalBranchReg(instr);
+  } else {
+    Unknown(instr);
+  }
+}
+
+
+void ARM64Decoder::DecodeLoadStore(Instr* instr) {
+  Unknown(instr);
+}
+
+
+void ARM64Decoder::DecodeAddSubShiftExt(Instr* instr) {
+  switch (instr->Bit(30)) {
+    case 0:
+      Format(instr, "add'sf's 'rd, 'rn, 'shift_op");
+      break;
+    case 1:
+      Format(instr, "sub'sf's 'rd, 'rn, 'shift_op");
+      break;
+    default:
+      UNREACHABLE();
+      break;
+  }
+}
+
+
+void ARM64Decoder::DecodeDPRegister(Instr* instr) {
+  if (instr->IsAddSubShiftExtOp()) {
+    DecodeAddSubShiftExt(instr);
+  } else {
+    Unknown(instr);
+  }
+}
+
+
+void ARM64Decoder::DecodeDPSimd1(Instr* instr) {
+  Unknown(instr);
+}
+
+
+void ARM64Decoder::DecodeDPSimd2(Instr* instr) {
+  Unknown(instr);
+}
+
+
+void ARM64Decoder::InstructionDecode(uword pc) {
+  Instr* instr = Instr::At(pc);
+
+  if (instr->IsDPImmediateOp()) {
+    DecodeDPImmediate(instr);
+  } else if (instr->IsCompareBranchOp()) {
+    DecodeCompareBranch(instr);
+  } else if (instr->IsLoadStoreOp()) {
+    DecodeLoadStore(instr);
+  } else if (instr->IsDPRegisterOp()) {
+    DecodeDPRegister(instr);
+  } else if (instr->IsDPSimd1Op()) {
+    DecodeDPSimd1(instr);
+  } else {
+    ASSERT(instr->IsDPSimd2Op());
+    DecodeDPSimd2(instr);
+  }
+}
+
+
+void Disassembler::DecodeInstruction(char* hex_buffer, intptr_t hex_size,
+                                     char* human_buffer, intptr_t human_size,
+                                     int* out_instr_size, uword pc) {
+  ARM64Decoder decoder(human_buffer, human_size);
+  decoder.InstructionDecode(pc);
+  int32_t instruction_bits = Instr::At(pc)->InstructionBits();
+  OS::SNPrint(hex_buffer, hex_size, "%08x", instruction_bits);
+  if (out_instr_size) {
+    *out_instr_size = Instr::kInstrSize;
+  }
+}
+
+
+void Disassembler::Disassemble(uword start,
+                               uword end,
+                               DisassemblyFormatter* formatter,
+                               const Code::Comments& comments) {
+  ASSERT(formatter != NULL);
+  char hex_buffer[kHexadecimalBufferSize];  // Instruction in hexadecimal form.
+  char human_buffer[kUserReadableBufferSize];  // Human-readable instruction.
+  uword pc = start;
+  intptr_t comment_finger = 0;
+  while (pc < end) {
+    const intptr_t offset = pc - start;
+    while (comment_finger < comments.Length() &&
+           comments.PCOffsetAt(comment_finger) <= offset) {
+      formatter->Print(
+          "        ;; %s\n",
+          String::Handle(comments.CommentAt(comment_finger)).ToCString());
+      comment_finger++;
+    }
+    int instruction_length;
+    DecodeInstruction(hex_buffer, sizeof(hex_buffer),
+                      human_buffer, sizeof(human_buffer),
+                      &instruction_length, pc);
+
+    formatter->ConsumeInstruction(hex_buffer,
+                                  sizeof(hex_buffer),
+                                  human_buffer,
+                                  sizeof(human_buffer),
+                                  pc);
+    pc += instruction_length;
+  }
+}
+
+}  // namespace dart
+
+#endif  // defined TARGET_ARCH_ARM