New try: Parser: Delay internalizing strings and values

src/ast-value-factory.h

+// Copyright 2014 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_AST_VALUE_FACTORY_H_
+#define V8_AST_VALUE_FACTORY_H_
+
+#include "src/api.h"
+#include "src/hashmap.h"
+#include "src/utils.h"
+
+// AstString, AstValue and AstValueFactory are for storing strings and values
+// independent of the V8 heap and internalizing them later. During parsing,
+// AstStrings and AstValues are created and stored outside the heap, in
+// AstValueFactory. After parsing, the strings and values are internalized
+// (moved into the V8 heap).
+namespace v8 {
+namespace internal {
+
+class AstString : public ZoneObject {
+ public:
+  AstString(bool is_one_byte, Vector<const byte> literal_bytes, int hash)
+      : type_(NORMAL),
+        is_one_byte_(is_one_byte),
+        literal_bytes_(literal_bytes),
+        hash_(hash),
+        left_(NULL),
+        right_(NULL) {}
+
+  AstString()
+      : type_(NORMAL),
+        is_one_byte_(true),
+        hash_(0),
+        left_(NULL),
+        right_(NULL) {}
+
+  // Creates a cons string. The only allowed operations for cons strings are
+  // is_one_byte(), length(), Internalize() and string().
+  AstString(const AstString* left, const AstString* right)
+      : type_(CONS),
+        is_one_byte_(left->is_one_byte_ && right->is_one_byte_),
+        hash_(0),
+        left_(left),
+        right_(right) {}
+
+  bool AsArrayIndex(uint32_t* index) const;
+
+  // The string is not null-terminated, use length() to find out the length.
+  const unsigned char* raw_data() const {
+    ASSERT(type_ == NORMAL);
+    return literal_bytes_.start();
+  }
+  int length() const {
+    if (type_ == CONS) {
+      return left_->length() + right_->length();
+    }
+    if (is_one_byte_)
+      return literal_bytes_.length();
+    return literal_bytes_.length() / 2;
+  }
+  bool is_one_byte() const { return is_one_byte_; }
+  bool IsEmpty() const { return length() == 0; }
+  bool IsOneByteEqualTo(const char* data) const;
+  uint16_t FirstCharacter() const {
+    ASSERT(type_ == NORMAL);
+    if (is_one_byte_)
+      return literal_bytes_[0];
+    const uint16_t* c =
+        reinterpret_cast<const uint16_t*>(literal_bytes_.start());
+    return *c;
+  }
+
+  // Puts the string into the V8 heap.
+  void Internalize(Isolate* isolate);
+
+  // This function can be called after internalizing.
+  V8_INLINE Handle<String> string() const {
+    ASSERT(!string_.is_null());
+    return string_;
+  }
+
+  // For storing AstStrings in a hash map.
+  int hash() const {
+    ASSERT(type_ == NORMAL);
+    return hash_;
+  }
+  static bool Compare(void* a, void* b);
+
+ private:
+  friend class AstValueFactory;
+
+  enum Type {
+    NORMAL,
+    CONS
+  };
+
+  Type type_;
+  bool is_one_byte_;
+
+  // For normal strings. Points to memory owned by Zone.
+  Vector<const byte> literal_bytes_;
+  int hash_;
+
+  // For cons strings.
+  const AstString* left_;
+  const AstString* right_;
+
+  // This is null until the string is internalized.
+  Handle<String> string_;
+};
+
+
+// AstValue is either a string, a number, a string array, a boolean, or a
+// special value (null, undefined, the hole).
+class AstValue : public ZoneObject {
+ public:
+  bool IsString() const {
+    return type_ == STRING;
+  }
+
+  bool IsNumber() const {
+    return type_ == NUMBER || type_ == SMI;
+  }
+
+  const AstString* AsString() const {
+    if (type_ == STRING)
+      return string_;
+    UNREACHABLE();
+    return 0;
+  }
+
+  double AsNumber() const {
+    if (type_ == NUMBER)
+      return number_;
+    if (type_ == SMI)
+      return smi_;
+    UNREACHABLE();
+    return 0;
+  }
+
+  bool EqualsString(const AstString* string) const {
+    return type_ == STRING && string_ == string;
+  }
+
+  bool IsPropertyName() const;
+
+  bool BooleanValue() const;
+
+  void Internalize(Isolate* isolate);
+
+  // Can be called after Internalize has been called.
+  V8_INLINE Handle<Object> value() const {
+    if (type_ == STRING) {
+      return string_->string();
+    }
+    ASSERT(!value_.is_null());
+    return value_;
+  }
+
+ private:
+  friend class AstValueFactory;
+
+  enum Type {
+    STRING,
+    SYMBOL,
+    NUMBER,
+    SMI,
+    BOOLEAN,
+    STRING_ARRAY,
+    NULL_TYPE,
+    UNDEFINED,
+    THE_HOLE
+  };
+
+  explicit AstValue(const AstString* s) : type_(STRING) { string_ = s; }
+
+  explicit AstValue(const char* name) : type_(SYMBOL) { symbol_name_ = name; }
+
+  explicit AstValue(double n) : type_(NUMBER) { number_ = n; }
+
+  AstValue(Type t, int i) : type_(t) {
+    ASSERT(type_ == SMI);
+    smi_ = i;
+  }
+
+  explicit AstValue(bool b) : type_(BOOLEAN) { bool_ = b; }
+
+  explicit AstValue(ZoneList<const AstString*>* s) : type_(STRING_ARRAY) {
+    strings_ = s;
+  }
+
+  explicit AstValue(Type t) : type_(t) {
+    ASSERT(t == NULL_TYPE || t == UNDEFINED || t == THE_HOLE);
+  }
+
+  Type type_;
+
+  // Uninternalized value.
+  union {
+    const AstString* string_;
+    double number_;
+    int smi_;
+    bool bool_;
+    ZoneList<const AstString*>* strings_;
+    const char* symbol_name_;
+  };
+
+  // Internalized value (empty before internalized).
+  Handle<Object> value_;
+};
+
+
+// For generating string constants.
+#define STRING_CONSTANTS(F) \
+  F(anonymous_function, "(anonymous function)") \
+  F(arguments, "arguments") \
+  F(done, "done") \
+  F(dot, ".") \
+  F(dot_for, ".for") \
+  F(dot_generator, ".generator") \
+  F(dot_generator_object, ".generator_object") \
+  F(dot_iterable, ".iterable") \
+  F(dot_iterator, ".iterator") \
+  F(dot_module, ".module") \
+  F(dot_result, ".result") \
+  F(empty, "") \
+  F(eval, "eval") \
+  F(initialize_const_global, "initializeConstGlobal") \
+  F(initialize_var_global, "initializeVarGlobal") \
+  F(make_reference_error, "MakeReferenceError") \
+  F(make_syntax_error, "MakeSyntaxError") \
+  F(make_type_error, "MakeTypeError") \
+  F(module, "module") \
+  F(native, "native") \
+  F(next, "next") \
+  F(proto, "__proto__") \
+  F(prototype, "prototype") \
+  F(this, "this") \
+  F(use_strict, "use strict") \
+  F(value, "value")
+
+class AstValueFactory {
+ public:
+  explicit AstValueFactory(Zone* zone)
+      : string_table_(AstString::Compare),
+        zone_(zone),
+        isolate_(NULL) {
+#define F(name, str) { \
+      const char* data = str; \
+      name##_string_ = GetOneByteString( \
+          Vector<const uint8_t>(reinterpret_cast<const uint8_t*>(data), \
+                                static_cast<int>(strlen(data)))); \
+    }
+    STRING_CONSTANTS(F)
+#undef F
+  }
+
+  const AstString* GetOneByteString(const Vector<const uint8_t>& literal);

[rossberg, 2014/06/23 09:44:27]

Hm, isn't the idea of the Vector abstraction that this shouldn't be necessary?

[marja, 2014/06/23 11:46:45]

It's not a huge difference; this will copy the length and the data pointer (not
the actual data); I just got a comment in another code review that I should use
const Vector&; and why not... that's copying one pointer instead of 2.

[rossberg, 2014/06/23 13:30:52]

But you pay with an extra indirection for all uses. Consequently, this is not
only a micro optimisation, it's one that could actually cost micro performance.
;)

[marja, 2014/06/23 14:56:42]

As you wish. (Changed back to Vector.)

+  const AstString* GetTwoByteString(const Vector<const uint16_t>& literal);
+  const AstString* GetString(Handle<String> literal);
+  const AstString* NewConsString(const AstString* left, const AstString* right);
+
+  void Internalize(Isolate* isolate);
+  bool IsInternalized() {
+    return isolate_ != NULL;
+  }
+
+#define F(name, str) \
+  const AstString* name##_string() const { return name##_string_; }
+  STRING_CONSTANTS(F)
+#undef F
+
+  const AstValue* NewString(const AstString* string);
+  // A JavaScript symbol (ECMA-262 edition 6).
+  const AstValue* NewSymbol(const char* name);
+  const AstValue* NewNumber(double number);
+  const AstValue* NewSmi(int number);
+  const AstValue* NewBoolean(bool b);
+  const AstValue* NewStringList(ZoneList<const AstString*>* strings);
+  const AstValue* NewNull();
+  const AstValue* NewUndefined();
+  const AstValue* NewTheHole();
+
+ private:
+  const AstString* GetString(int hash, bool is_one_byte,
+                             const Vector<const byte>& literal_bytes);
+
+  // All strings are copied here, one after another (no NULLs inbetween).
+  HashMap string_table_;
+  // For keeping track of all AstValues and AstStrings we've created (so that
+  // they can be internalized later).
+  List<AstValue*> values_;
+  List<AstString*> strings_;
+  Zone* zone_;
+  Isolate* isolate_;
+
+#define F(name, str) \
+  const AstString* name##_string_;
+  STRING_CONSTANTS(F)
+#undef F
+};
+
+} }  // namespace v8::internal
+
+#undef STRING_CONSTANTS
+
+#endif  // V8_AST_VALUE_FACTORY_H_