Parser: Delay internalizing strings and values.

src/ast-value-factory.cc

+// 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.
+
+#include "src/ast-value-factory.h"
+
+#include "src/api.h"
+#include "src/objects.h"
+
+namespace v8 {
+namespace internal {
+
+namespace {
+
+template <typename Char>
+int vector_hash(Vector<const Char> string) {
+  int hash = 0;
+  for (int i = 0; i < string.length(); i++) {
+    int c = static_cast<int>(string[i]);
+    hash += c;
+    hash += (hash << 10);
+    hash ^= (hash >> 6);
+  }
+  return hash;
+}
+
+
+// For using StringToArrayIndex.
+class OneByteStringStream {
+ public:
+  explicit OneByteStringStream(Vector<const byte> lb) :
+      literal_bytes_(lb), pos_(0) {}
+
+  bool HasMore() { return pos_ < literal_bytes_.length(); }
+  uint16_t GetNext() { return literal_bytes_[pos_++]; }
+
+ private:
+  Vector<const byte> literal_bytes_;
+  int pos_;
+};
+
+}
+
+
+bool AstString::AsArrayIndex(uint32_t* index) const {
+  if (!string_.is_null())
+    return string_->AsArrayIndex(index);
+  if (!is_one_byte_ || literal_bytes_.length() == 0 ||
+      literal_bytes_.length() > String::kMaxArrayIndexSize)
+    return false;
+  OneByteStringStream stream(literal_bytes_);
+  return StringToArrayIndex(&stream, index);
+}
+
+
+bool AstString::IsOneByteEqualTo(const char* data) const {
+  int length = strlen(data);
+  if (is_one_byte_ && literal_bytes_.length() == length) {
+    const char* token = reinterpret_cast<const char*>(literal_bytes_.start());
+    return !strncmp(token, data, length);
+  }
+  return false;
+}
+
+
+void AstString::Internalize(Isolate* isolate) {
+  if (!string_.is_null()) return;
+  if (literal_bytes_.length() == 0) {
+    string_ = isolate->factory()->empty_string();
+  } else if (is_one_byte_) {
+    string_ = isolate->factory()->InternalizeOneByteString(literal_bytes_);
+  } else {
+    string_ = isolate->factory()->InternalizeTwoByteString(
+        Vector<const uint16_t>::cast(literal_bytes_));
+  }
+}
+
+
+bool AstString::Compare(void* a, void* b) {
+  AstString* string1 = reinterpret_cast<AstString*>(a);
+  AstString* string2 = reinterpret_cast<AstString*>(b);
+  if (string1->is_one_byte_ != string2->is_one_byte_) return false;
+  if (string1->hash_ != string2->hash_) return false;
+  int length = string1->literal_bytes_.length();
+  if (string2->literal_bytes_.length() != length) return false;
+  return memcmp(string1->literal_bytes_.start(),
+                string2->literal_bytes_.start(), length) == 0;
+}
+
+
+bool AstValue::IsPropertyName() const {
+  if (type_ == STRING) {
+    uint32_t index;
+    return !string_->AsArrayIndex(&index);
+  }
+  return false;
+}
+
+
+bool AstValue::BooleanValue() const {
+  switch (type_) {
+    case STRING:
+      ASSERT(string_ != NULL);
+      return !string_->IsEmpty();
+    case NUMBER:
+      return DoubleToBoolean(number_);
+    case SMI:
+      return smi_ != 0;
+    case STRING_ARRAY:
+      UNREACHABLE();
+      break;
+    case BOOLEAN:
+      return bool_;
+    case NULL_TYPE:
+      return false;
+    case THE_HOLE:
+      UNREACHABLE();
+      break;
+    case UNDEFINED:
+      return false;
+    case SYMBOL:
+      UNREACHABLE();
+      break;
+  }
+  UNREACHABLE();
+  return false;
+}
+
+
+void AstValue::Internalize(Isolate* isolate) {
+  switch (type_) {
+    case STRING:
+      ASSERT(string_ != NULL);
+      // Strings are already internalized.
+      ASSERT(!string_->string().is_null());
+      break;
+    case NUMBER:
+      value_ = isolate->factory()->NewNumber(number_, TENURED);
+      break;
+    case SMI:
+      value_ = handle(Smi::FromInt(smi_), isolate);
+      break;
+    case BOOLEAN:
+      if (bool_) {
+        value_ = isolate->factory()->true_value();
+      } else {
+        value_ = isolate->factory()->false_value();
+      }
+      break;
+    case STRING_ARRAY: {
+      ASSERT(strings_ != NULL);
+      Factory* factory = isolate->factory();
+      int len = strings_->length();
+      Handle<FixedArray> elements = factory->NewFixedArray(len, TENURED);
+      for (int i = 0; i < len; i++) {
+        const AstString* string = (*strings_)[i];
+        Handle<Object> element = string->string();
+        // Strings are already internalized.
+        ASSERT(!element.is_null());
+        elements->set(i, *element);
+      }
+      value_ =
+          factory->NewJSArrayWithElements(elements, FAST_ELEMENTS, TENURED);
+      break;
+    }
+    case NULL_TYPE:
+      value_ = isolate->factory()->null_value();
+      break;
+    case THE_HOLE:
+      value_ = isolate->factory()->the_hole_value();
+      break;
+    case UNDEFINED:
+      value_ = isolate->factory()->undefined_value();
+      break;
+    case SYMBOL:
+      value_ = Object::GetProperty(

[rossberg, 2014/06/13 13:00:42]

Yeah, I suppose that's fine. I had hoped to keep those variables an
implementation detail of the symbol module (and an unfortunate artefact that
they are actually exposed). But re-calling InternalSymbol instead probably isn't
any nicer.

+                   isolate, handle(isolate->native_context()->builtins()),
+                   symbol_name_).ToHandleChecked();
+      break;
+  }
+}
+
+
+const AstString* AstValueFactory::GetOneByteString(
+    Vector<const uint8_t> literal) {
+  return GetString(vector_hash(literal), true, literal);
+}
+
+
+const AstString* AstValueFactory::GetTwoByteString(
+    Vector<const uint16_t> literal) {
+  return GetString(vector_hash(literal), false,
+                   Vector<const byte>::cast(literal));
+}
+
+
+const AstString* AstValueFactory::GetString(Handle<String> literal) {
+  DisallowHeapAllocation no_gc;
+  String::FlatContent content = literal->GetFlatContent();
+  if (content.IsAscii()) {
+    return GetOneByteString(content.ToOneByteVector());
+  }
+  ASSERT(content.IsTwoByte());
+  return GetTwoByteString(content.ToUC16Vector());
+}
+
+
+void AstValueFactory::Internalize(Isolate* isolate) {
+  if (isolate_) {
+    // Everything is already internalized.
+    return;
+  }
+  // Strings need to be internalized before values, because values refer to
+  // strings.
+  for (HashMap::Entry* p = string_table_.Start(); p != NULL;
+       p = string_table_.Next(p)) {
+    AstString* string = reinterpret_cast<AstString*>(p->key);
+    string->Internalize(isolate);
+  }
+  for (int i = 0; i < values_.length(); ++i) {
+    values_[i]->Internalize(isolate);
+  }
+  isolate_ = isolate;
+}
+
+
+const AstValue* AstValueFactory::NewString(const AstString* string) {
+  AstValue* value = new (zone_) AstValue(string);
+  ASSERT(string != NULL);
+  if (isolate_) {
+    value->Internalize(isolate_);
+  }
+  values_.Add(value);
+  return value;
+}
+
+
+const AstValue* AstValueFactory::NewNumber(double number) {
+  AstValue* value = new (zone_) AstValue(number);
+  if (isolate_) {
+    value->Internalize(isolate_);
+  }
+  values_.Add(value);
+  return value;
+}
+
+
+const AstValue* AstValueFactory::NewSmi(int number) {
+  AstValue* value =
+      new (zone_) AstValue(AstValue::SMI, number);
+  if (isolate_) {
+    value->Internalize(isolate_);
+  }
+  values_.Add(value);
+  return value;
+}
+
+
+const AstValue* AstValueFactory::NewBoolean(bool b) {
+  AstValue* value = new (zone_) AstValue(b);
+  if (isolate_) {
+    value->Internalize(isolate_);
+  }
+  values_.Add(value);
+  return value;
+}
+
+
+const AstValue* AstValueFactory::NewStringList(
+    ZoneList<const AstString*>* strings) {
+  AstValue* value = new (zone_) AstValue(strings);
+  if (isolate_) {
+    value->Internalize(isolate_);
+  }
+  values_.Add(value);
+  return value;
+}
+
+
+const AstValue* AstValueFactory::NewNull() {
+  AstValue* value = new (zone_) AstValue(AstValue::NULL_TYPE);
+  if (isolate_) {
+    value->Internalize(isolate_);
+  }
+  values_.Add(value);
+  return value;
+}
+
+
+const AstValue* AstValueFactory::NewUndefined() {
+  AstValue* value = new (zone_) AstValue(AstValue::UNDEFINED);
+  if (isolate_) {
+    value->Internalize(isolate_);
+  }
+  values_.Add(value);
+  return value;
+}
+
+
+const AstValue* AstValueFactory::NewTheHole() {
+  AstValue* value = new (zone_) AstValue(AstValue::THE_HOLE);
+  if (isolate_) {
+    value->Internalize(isolate_);
+  }
+  values_.Add(value);
+  return value;
+}
+
+
+const AstValue* AstValueFactory::NewSymbol(const char* name) {
+  AstValue* value = new (zone_) AstValue(name);
+  if (isolate_) {
+    value->Internalize(isolate_);
+  }
+  values_.Add(value);
+  return value;
+}
+
+
+const AstString* AstValueFactory::GetString(int hash, bool is_one_byte,
+                                            Vector<const byte> literal_bytes) {
+  // literal_bytes here points to whatever the user passed, and this is OK
+  // because we use vector_compare (which checks the contents) to compare
+  // against the AstStrings which are in the string_table_. We should not return
+  // this AstString.
+  AstString key(is_one_byte, literal_bytes, hash);
+  HashMap::Entry* entry = string_table_.Lookup(&key, hash, true);
+  if (entry->value == NULL) {
+    // Copy literal contents for later comparison.
+    key.literal_bytes_ =
+        Vector<const byte>::cast(literal_chars_.AddBlock(literal_bytes));
+    // This Vector will be valid as long as the Collector is alive (meaning that
+    // the AstString will not be moved).
+    Vector<AstString> new_string = string_table_keys_.AddBlock(1, key);
+    entry->key = &new_string[0];
+    if (isolate_) {
+      new_string[0].Internalize(isolate_);
+    }
+    entry->value = reinterpret_cast<void*>(1);
+  }
+  return reinterpret_cast<AstString*>(entry->key);
+}
+
+
+} }  // namespace v8::internal