Reapply "Support for precise stepping in functions compiled before debugging was started (step 2)"

src/compiler.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 102 matching lines @@
     pre_parse_data_ = pre_parse_data;
   }
   void SetCallingContext(Handle<Context> context) {
     ASSERT(is_eval());
     calling_context_ = context;
   }
   void SetOsrAstId(int osr_ast_id) {
     ASSERT(IsOptimizing());
     osr_ast_id_ = osr_ast_id;
   }
+  void MarkCompilingForDebugging(Handle<Code> current_code) {
+    ASSERT(mode_ != OPTIMIZE);
+    ASSERT(current_code->kind() == Code::FUNCTION);
+    flags_ |= IsCompilingForDebugging::encode(true);
+    if (current_code->is_compiled_optimizable()) {
+      EnableDeoptimizationSupport();
+    } else {
+      mode_ = CompilationInfo::NONOPT;
+    }
+  }
+  bool IsCompilingForDebugging() {
+    return IsCompilingForDebugging::decode(flags_);
+  }
 
   bool has_global_object() const {
     return !closure().is_null() && (closure()->context()->global() != NULL);
   }
 
   GlobalObject* global_object() const {
     return has_global_object() ? closure()->context()->global() : NULL;
   }
 
   // Accessors for the different compilation modes.
   bool IsOptimizing() const { return mode_ == OPTIMIZE; }
   bool IsOptimizable() const { return mode_ == BASE; }
   void SetOptimizing(int osr_ast_id) {
     SetMode(OPTIMIZE);
     osr_ast_id_ = osr_ast_id;
   }
   void DisableOptimization();
 
   // Deoptimization support.
-  bool HasDeoptimizationSupport() const { return supports_deoptimization_; }
+  bool HasDeoptimizationSupport() const {
+    return SupportsDeoptimization::decode(flags_);
+  }
   void EnableDeoptimizationSupport() {
     ASSERT(IsOptimizable());
-    supports_deoptimization_ = true;
+    flags_ |= SupportsDeoptimization::encode(true);
   }
 
   // Determine whether or not we can adaptively optimize.
   bool AllowOptimize() {
     return V8::UseCrankshaft() && !closure_.is_null();
   }
 
   // Disable all optimization attempts of this info for the rest of the
   // current compilation pipeline.
   void AbortOptimization();
@@ skipping 40 matching lines @@
   class IsEval:   public BitField<bool, 1, 1> {};
   class IsGlobal: public BitField<bool, 2, 1> {};
   // Flags that can be set for lazy compilation.
   class IsInLoop: public BitField<bool, 3, 1> {};
   // Strict mode - used in eager compilation.
   class IsStrictMode: public BitField<bool, 4, 1> {};
   // Native syntax (%-stuff) allowed?
   class IsNativesSyntaxAllowed: public BitField<bool, 5, 1> {};
   // Is this a function from our natives.
   class IsNative: public BitField<bool, 6, 1> {};
+  // Is this code being compiled with support for deoptimization..
+  class SupportsDeoptimization: public BitField<bool, 7, 1> {};
+  // If compiling for debugging produce just full code matching the
+  // initial mode setting.
+  class IsCompilingForDebugging: public BitField<bool, 8, 1> {};
 
 
   unsigned flags_;
 
   // Fields filled in by the compilation pipeline.
   // AST filled in by the parser.
   FunctionLiteral* function_;
   // The scope of the function literal as a convenience.  Set to indicate
   // that scopes have been analyzed.
   Scope* scope_;
   // The compiled code.
   Handle<Code> code_;
 
   // Possible initial inputs to the compilation process.
   Handle<JSFunction> closure_;
   Handle<SharedFunctionInfo> shared_info_;
   Handle<Script> script_;
 
   // Fields possibly needed for eager compilation, NULL by default.
   v8::Extension* extension_;
   ScriptDataImpl* pre_parse_data_;
 
   // The context of the caller is needed for eval code, and will be a null
   // handle otherwise.
   Handle<Context> calling_context_;
 
   // Compilation mode flag and whether deoptimization is allowed.
   Mode mode_;
-  bool supports_deoptimization_;
   int osr_ast_id_;
 
   DISALLOW_COPY_AND_ASSIGN(CompilationInfo);
 };
 
 
 // The V8 compiler
 //
 // General strategy: Source code is translated into an anonymous function w/o
 // parameters which then can be executed. If the source code contains other
@@ skipping 53 matching lines @@
 
   static void RecordFunctionCompilation(Logger::LogEventsAndTags tag,
                                         CompilationInfo* info,
                                         Handle<SharedFunctionInfo> shared);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_COMPILER_H_