[assembler] Introduce proper AssemblerBase::Print() for improved debuggability.

src/disassembler.cc

 // Copyright 2011 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/disassembler.h"
 
 #include "src/code-stubs.h"
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
@@ skipping 14 matching lines @@
   virtual const char* NameInCode(byte* addr) const;
   Code* code() const { return code_; }
  private:
   Code* code_;
 
   EmbeddedVector<char, 128> v8_buffer_;
 };
 
 
 const char* V8NameConverter::NameOfAddress(byte* pc) const {
-  const char* name = code_->GetIsolate()->builtins()->Lookup(pc);
+  const char* name =
+      code_ == NULL ? NULL : code_->GetIsolate()->builtins()->Lookup(pc);
+
   if (name != NULL) {
     SNPrintF(v8_buffer_, "%s  (%p)", name, pc);
     return v8_buffer_.start();
   }
 
   if (code_ != NULL) {
     int offs = static_cast<int>(pc - code_->instruction_start());
     // print as code offset, if it seems reasonable
     if (0 <= offs && offs < code_->instruction_size()) {
       SNPrintF(v8_buffer_, "%d  (%p)", offs, pc);
@@ skipping 235 matching lines @@
 
 int Disassembler::Decode(Isolate* isolate, std::ostream* os, byte* begin,
                          byte* end, Code* code) {
   return 0;
 }
 
 #endif  // ENABLE_DISASSEMBLER
 
 }  // namespace internal
 }  // namespace v8