Copies Simulator Debugger from ARM to MIPS.

runtime/vm/disassembler_arm.cc

Index: runtime/vm/disassembler_arm.cc
===================================================================
--- runtime/vm/disassembler_arm.cc	(revision 19939)
+++ runtime/vm/disassembler_arm.cc	(working copy)
@@ -15,15 +15,20 @@
   ARMDecoder(char* buffer, size_t buffer_size)
       : buffer_(buffer),
         buffer_size_(buffer_size),
-        buffer_pos_(0) {
+        buffer_pos_(0),
+        decode_failure_(false) {
     buffer_[buffer_pos_] = '\0';
   }
 
   ~ARMDecoder() {}
 
   // Writes one disassembled instruction into 'buffer' (0-terminated).
+  // Returns true if the instruction was successfully decoded, false otherwise.
   void InstructionDecode(uword pc);
 
+  void DetectedDecodeFailure() { decode_failure_ = true; }
+  bool GetDecodeFailure() const { return decode_failure_; }
+
  private:
   // Bottleneck functions to print into the out_buffer.
   void Print(const char* str);
@@ -66,6 +71,8 @@
   size_t buffer_size_;  // The size of the character buffer.
   size_t buffer_pos_;  // Current character position in buffer.
 
+  bool decode_failure_;  // Set to true when a failure to decode is detected.
+
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(ARMDecoder);
 };
@@ -572,6 +579,7 @@
 // which will just print "unknown" of the instruction bits.
 void ARMDecoder::Unknown(Instr* instr) {
   Format(instr, "unknown");
+  DetectedDecodeFailure();
 }
 
 
@@ -1210,7 +1218,8 @@
 
 
 void ARMDecoder::InstructionDecode(uword pc) {
-Instr* instr = Instr::At(pc);
+  Instr* instr = Instr::At(pc);
+
   if (instr->ConditionField() == kSpecialCondition) {
     if (instr->InstructionBits() == static_cast<int32_t>(0xf57ff01f)) {
       Format(instr, "clrex");
@@ -1258,22 +1267,26 @@
 }
 
 
-int Disassembler::DecodeInstruction(char* hex_buffer, intptr_t hex_size,
+bool Disassembler::DecodeInstruction(char* hex_buffer, intptr_t hex_size,
                                     char* human_buffer, intptr_t human_size,
-                                    uword pc) {
+                                    int* out_instr_size, uword pc) {
   ARMDecoder 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);
-  return Instr::kInstrSize;
+  if (out_instr_size) {
+    *out_instr_size = Instr::kInstrSize;
+  }
+  return !decoder.GetDecodeFailure();
 }
 
 
-void Disassembler::Disassemble(uword start,
+bool Disassembler::Disassemble(uword start,
                                uword end,
                                DisassemblyFormatter* formatter,
                                const Code::Comments& comments) {
   ASSERT(formatter != NULL);
+  bool success = true;
   char hex_buffer[kHexadecimalBufferSize];  // Instruction in hexadecimal form.
   char human_buffer[kUserReadableBufferSize];  // Human-readable instruction.
   uword pc = start;
@@ -1287,11 +1300,13 @@
           String::Handle(comments.CommentAt(comment_finger)).ToCString());
       comment_finger++;
     }
-    int instruction_length = DecodeInstruction(hex_buffer,
-                                               sizeof(hex_buffer),
-                                               human_buffer,
-                                               sizeof(human_buffer),
-                                               pc);
+    int instruction_length;
+    bool res = DecodeInstruction(hex_buffer, sizeof(hex_buffer),
+                                 human_buffer, sizeof(human_buffer),
+                                 &instruction_length, pc);
+    if (!res) {
+      success = false;
+    }
     formatter->ConsumeInstruction(hex_buffer,
                                   sizeof(hex_buffer),
                                   human_buffer,
@@ -1299,6 +1314,8 @@
                                   pc);
     pc += instruction_length;
   }
+
+  return success;
 }
 
 }  // namespace dart