A64: Hardwire the decoder and the simulator

If one of --trace-sim --debug-sim or --log-instruction-stats flags is
given, we use the decoder dispatcher instead.

BUG=none
R=rodolph.perfetta@arm.com, ulan@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/177533023

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19564 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/a64/decoder-a64.h

@@ -146,10 +146,11 @@ template<typename V>
 class Decoder : public V {
  public:
   Decoder() {}
+  virtual ~Decoder() {}
 
   // Top-level instruction decoder function. Decodes an instruction and calls
   // the visitor functions registered with the Decoder class.
-  void Decode(Instruction *instr);
+  virtual void Decode(Instruction *instr);
 
  private:
   // Decode the PC relative addressing instruction, and call the corresponding

src/a64/simulator-a64.cc

@@ -105,8 +105,12 @@ Simulator* Simulator::current(Isolate* isolate) {
 
   Simulator* sim = isolate_data->simulator();
   if (sim == NULL) {
-    // TODO(146): delete the simulator object when a thread/isolate goes away.
-    sim = new Simulator(new Decoder<DispatchingDecoderVisitor>(), isolate);
+    if (FLAG_trace_sim || FLAG_log_instruction_stats || FLAG_debug_sim) {
+      sim = new Simulator(new Decoder<DispatchingDecoderVisitor>(), isolate);
+    } else {
+      sim = new Decoder<Simulator>();
+      sim->isolate_ = isolate;
+    }
     isolate_data->set_simulator(sim);
   }
   return sim;
@@ -343,6 +347,32 @@ Simulator::Simulator(Decoder<DispatchingDecoderVisitor>* decoder,
   // Setup the decoder.
   decoder_->AppendVisitor(this);
 
+  Init(stream);
+
+  if (FLAG_trace_sim) {
+    decoder_->InsertVisitorBefore(print_disasm_, this);
+    log_parameters_ = LOG_ALL;
+  }
+
+  if (FLAG_log_instruction_stats) {
+    instrument_ = new Instrument(FLAG_log_instruction_file,
+                                 FLAG_log_instruction_period);
+    decoder_->AppendVisitor(instrument_);
+  }
+}
+
+
+Simulator::Simulator()
+    : decoder_(NULL),
+      last_debugger_input_(NULL),
+      log_parameters_(NO_PARAM),
+      isolate_(NULL) {
+  Init(NULL);
+  CHECK(!FLAG_trace_sim && !FLAG_log_instruction_stats);
+}
+
+
+void Simulator::Init(FILE* stream) {
   ResetState();
 
   // Allocate and setup the simulator stack.
@@ -356,21 +386,10 @@ Simulator::Simulator(Decoder<DispatchingDecoderVisitor>* decoder,
   stream_ = stream;
   print_disasm_ = new PrintDisassembler(stream_);
 
-  if (FLAG_trace_sim) {
-    decoder_->InsertVisitorBefore(print_disasm_, this);
-    log_parameters_ = LOG_ALL;
-  }
-
   // The debugger needs to disassemble code without the simulator executing an
   // instruction, so we create a dedicated decoder.
   disassembler_decoder_ = new Decoder<DispatchingDecoderVisitor>();
   disassembler_decoder_->AppendVisitor(print_disasm_);
-
-  if (FLAG_log_instruction_stats) {
-    instrument_ = new Instrument(FLAG_log_instruction_file,
-                                 FLAG_log_instruction_period);
-    decoder_->AppendVisitor(instrument_);
-  }
 }
 
 
@@ -405,6 +424,7 @@ Simulator::~Simulator() {
   delete disassembler_decoder_;
   delete print_disasm_;
   DeleteArray(last_debugger_input_);
+  delete decoder_;
 }
 
 

src/a64/simulator-a64.h

@@ -195,6 +195,7 @@ class Simulator : public DecoderVisitor {
   explicit Simulator(Decoder<DispatchingDecoderVisitor>* decoder,
                      Isolate* isolate = NULL,
                      FILE* stream = stderr);
+  Simulator();
   ~Simulator();
 
   // System functions.
@@ -334,10 +335,14 @@ class Simulator : public DecoderVisitor {
     pc_modified_ = false;
   }
 
+  virtual void Decode(Instruction* instr) {
+    decoder_->Decode(instr);
+  }
+
   void ExecuteInstruction() {
     ASSERT(IsAligned(reinterpret_cast<uintptr_t>(pc_), kInstructionSize));
     CheckBreakNext();
-    decoder_->Decode(pc_);
+    Decode(pc_);
     LogProcessorState();
     increment_pc();
     CheckBreakpoints();
@@ -582,12 +587,18 @@ class Simulator : public DecoderVisitor {
 
   int log_parameters() { return log_parameters_; }
   void set_log_parameters(int new_parameters) {
+    log_parameters_ = new_parameters;
+    if (!decoder_) {
+      if (new_parameters & LOG_DISASM) {
+        PrintF("Run --debug-sim to dynamically turn on disassembler\n");
+      }
+      return;
+    }
     if (new_parameters & LOG_DISASM) {
       decoder_->InsertVisitorBefore(print_disasm_, this);
     } else {
       decoder_->RemoveVisitor(print_disasm_);
     }
-    log_parameters_ = new_parameters;
   }
 
   static inline const char* WRegNameForCode(unsigned code,
@@ -819,6 +830,8 @@ class Simulator : public DecoderVisitor {
   char* last_debugger_input_;
 
  private:
+  void Init(FILE* stream);
+
   int  log_parameters_;
   Isolate* isolate_;
 };

src/flag-definitions.h

@@ -585,6 +585,7 @@ DEFINE_bool(trace_parse, false, "trace parsing and preparsing")
 
 // simulator-arm.cc, simulator-a64.cc and simulator-mips.cc
 DEFINE_bool(trace_sim, false, "Trace simulator execution")
+DEFINE_bool(debug_sim, false, "Enable debugging the simulator")
 DEFINE_bool(check_icache, false,
             "Check icache flushes in ARM and MIPS simulator")
 DEFINE_int(stop_sim_at, 0, "Simulator stop after x number of instructions")