[interpreter] Ensure --debug-code works with snapshots.

src/interpreter/interpreter.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/interpreter.h"
 
 #include <fstream>
 #include <memory>
 
 #include "src/ast/prettyprinter.h"
@@ skipping 35 matching lines @@
   BytecodeGenerator generator_;
 
   DISALLOW_COPY_AND_ASSIGN(InterpreterCompilationJob);
 };
 
 Interpreter::Interpreter(Isolate* isolate) : isolate_(isolate) {
   memset(dispatch_table_, 0, sizeof(dispatch_table_));
 }
 
 void Interpreter::Initialize() {
-  if (IsDispatchTableInitialized()) return;
+  if (!ShouldInitializeDispatchTable()) return;
   Zone zone(isolate_->allocator(), ZONE_NAME);
   HandleScope scope(isolate_);
 
   if (FLAG_trace_ignition_dispatches) {
     static const int kBytecodeCount = static_cast<int>(Bytecode::kLast) + 1;
     bytecode_dispatch_counters_table_.reset(
         new uintptr_t[kBytecodeCount * kBytecodeCount]);
     memset(bytecode_dispatch_counters_table_.get(), 0,
            sizeof(uintptr_t) * kBytecodeCount * kBytecodeCount);
   }
@@ skipping 29 matching lines @@
   }
 
   // Fill unused entries will the illegal bytecode handler.
   size_t illegal_index =
       GetDispatchTableIndex(Bytecode::kIllegal, OperandScale::kSingle);
   for (size_t index = 0; index < arraysize(dispatch_table_); ++index) {
     if (dispatch_table_[index] == nullptr) {
       dispatch_table_[index] = dispatch_table_[illegal_index];
     }
   }
+
+  // Initialization should have been successful.
+  DCHECK(IsDispatchTableInitialized());
 }
 
 Code* Interpreter::GetBytecodeHandler(Bytecode bytecode,
                                       OperandScale operand_scale) {
   DCHECK(IsDispatchTableInitialized());
   DCHECK(Bytecodes::BytecodeHasHandler(bytecode, operand_scale));
   size_t index = GetDispatchTableIndex(bytecode, operand_scale);
   Address code_entry = dispatch_table_[index];
   return Code::GetCodeFromTargetAddress(code_entry);
 }
@@ skipping 90 matching lines @@
   info()->SetBytecodeArray(bytecodes);
   info()->SetCode(info()->isolate()->builtins()->InterpreterEntryTrampoline());
   return SUCCEEDED;
 }
 
 CompilationJob* Interpreter::NewCompilationJob(CompilationInfo* info) {
   return new InterpreterCompilationJob(info);
 }
 
 bool Interpreter::IsDispatchTableInitialized() {
-  if (FLAG_trace_ignition || FLAG_trace_ignition_codegen ||
-      FLAG_trace_ignition_dispatches) {
-    // Regenerate table to add bytecode tracing operations, print the assembly
-    // code generated by TurboFan or instrument handlers with dispatch counters.
-    return false;
-  }
   return dispatch_table_[0] != nullptr;
 }
 
+bool Interpreter::ShouldInitializeDispatchTable() {
+  if (FLAG_trace_ignition || FLAG_trace_ignition_codegen ||
+      FLAG_trace_ignition_dispatches || FLAG_debug_code) {
+    // Regenerate table to add bytecode tracing operations, print the assembly
+    // code generated by TurboFan, instrument handlers with dispatch counters,
+    // or insert debugging code into the bytecode handlers.
+    return true;
+  }
+  return !IsDispatchTableInitialized();
+}
+
 void Interpreter::TraceCodegen(Handle<Code> code) {
 #ifdef ENABLE_DISASSEMBLER
   if (FLAG_trace_ignition_codegen) {
     OFStream os(stdout);
     code->Disassemble(nullptr, os);
     os << std::flush;
   }
 #endif  // ENABLE_DISASSEMBLER
 }
 
@@ skipping 2402 matching lines @@
   __ StoreObjectField(generator, JSGeneratorObject::kContinuationOffset,
       __ SmiTag(new_state));
   __ SetAccumulator(old_state);
 
   __ Dispatch();
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8