Re-enable Parser::symbol_cache_ (after a long time!)

The Parser never used the symbol stream produced by the PreParser for anything
useful, due to a bug introduced 3.5 years ago by
https://codereview.chromium.org/3356010/diff/7001/src/parser.cc.

The bug is that calling Initialize on symbol_cache_ doesn't change its
length. So the length remains 0, and the "if" in Parser::LookupSymbol is always
true, and Parser::LookupCachedSymbol is never called and symbol_cache_ never
filled.

This bug also masked a bug that the symbol stream produced by PreParser doesn't
match what Parser wants to consume. The repro case is the following:

var myo = {if: 4}; print(myo.if);

PreParser doesn't log a symbol for the first "if", but in the corresponding
place, Parser consumes one symbol from the symbol stream. Since the consumed
symbols were never really used, this mismatch went unnoticed.

This CL also fixes that bug.

BUG=
R=ulan@chromium.org

Review URL: https://codereview.chromium.org/172753002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19505 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/parser.cc

@@ -207,12 +207,12 @@ void RegExpBuilder::AddQuantifierToAtom(
 
 
 Handle<String> Parser::LookupSymbol(int symbol_id) {
-  // Length of symbol cache is the number of identified symbols.
-  // If we are larger than that, or negative, it's not a cached symbol.
-  // This might also happen if there is no preparser symbol data, even
-  // if there is some preparser data.
-  if (static_cast<unsigned>(symbol_id)
-      >= static_cast<unsigned>(symbol_cache_.length())) {
+  // If there is no preparser symbol data, a negative number will be passed. In
+  // that case, we'll just read the literal from Scanner. This also guards
+  // against corrupt preparse data where the symbol id is larger than the symbol
+  // count.
+  if (symbol_id < 0 ||
+      (pre_parse_data_ && symbol_id >= pre_parse_data_->symbol_count())) {
     if (scanner()->is_literal_ascii()) {
       return isolate()->factory()->InternalizeOneByteString(
           Vector<const uint8_t>::cast(scanner()->literal_ascii_string()));

src/preparser.cc

@@ -1184,6 +1184,7 @@ PreParser::Expression PreParser::ParseObjectLiteral(bool* ok) {
         if (Token::IsKeyword(next)) {
           Consume(next);
           checker.CheckProperty(next, kValueProperty, CHECK_OK);
+          LogSymbol();
         } else {
           // Unexpected token.
           *ok = false;

test/cctest/cctest.h

@@ -315,6 +315,18 @@ static inline v8::Local<v8::Value> CompileRun(const char* source) {
 }
 
 
+static inline v8::Local<v8::Value> PreCompileCompileRun(const char* source) {
+  v8::Local<v8::String> script_source =
+      v8::String::NewFromUtf8(v8::Isolate::GetCurrent(), source);
+  v8::ScriptData* preparse = v8::ScriptData::PreCompile(script_source);
+  v8::Local<v8::Script> script =
+      v8::Script::Compile(script_source, NULL, preparse);
+  v8::Local<v8::Value> result = script->Run();
+  delete preparse;
+  return result;
+}
+
+
 // Helper function that compiles and runs the source with given origin.
 static inline v8::Local<v8::Value> CompileRunWithOrigin(const char* source,
                                                         const char* origin_url,

test/cctest/test-parsing.cc

@@ -324,6 +324,43 @@ TEST(StandAlonePreParserNoNatives) {
 }
 
 
+TEST(PreparsingObjectLiterals) {
+  // Regression test for a bug where the symbol stream produced by PreParser
+  // didn't match what Parser wanted to consume.
+  v8::Isolate* isolate = CcTest::isolate();
+  v8::HandleScope handles(isolate);
+  v8::Local<v8::Context> context = v8::Context::New(isolate);
+  v8::Context::Scope context_scope(context);
+  int marker;
+  CcTest::i_isolate()->stack_guard()->SetStackLimit(
+      reinterpret_cast<uintptr_t>(&marker) - 128 * 1024);
+
+  {
+    const char* source = "var myo = {if: \"foo\"}; myo.if;";
+    v8::Local<v8::Value> result = PreCompileCompileRun(source);
+    CHECK(result->IsString());
+    v8::String::Utf8Value utf8(result);
+    CHECK_EQ("foo", *utf8);
+  }
+
+  {
+    const char* source = "var myo = {\"bar\": \"foo\"}; myo[\"bar\"];";
+    v8::Local<v8::Value> result = PreCompileCompileRun(source);
+    CHECK(result->IsString());
+    v8::String::Utf8Value utf8(result);
+    CHECK_EQ("foo", *utf8);
+  }
+
+  {
+    const char* source = "var myo = {1: \"foo\"}; myo[1];";
+    v8::Local<v8::Value> result = PreCompileCompileRun(source);
+    CHECK(result->IsString());
+    v8::String::Utf8Value utf8(result);
+    CHECK_EQ("foo", *utf8);
+  }
+}
+
+
 TEST(RegressChromium62639) {
   v8::V8::Initialize();
   i::Isolate* isolate = CcTest::i_isolate();