Extend the regression test case for crbug.com/9746 to...

test/cctest/test-strings.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 
 // Check that we can traverse very deep stacks of ConsStrings using
 // StringInputBuffer.  Check that Get(int) works on very deep stacks
 // of ConsStrings.  These operations may not be very fast, but they
 // should be possible without getting errors due to too deep recursion.
 
 #include <stdlib.h>
 
 #include "v8.h"
@@ skipping 413 matching lines @@
 
   // Setup lengths that guarantee we'll get slices instead of simple
   // flat strings.
   static const int kFullStringLength = String::kMinNonFlatLength * 2;
   static const int kSliceStringLength = String::kMinNonFlatLength + 1;
 
   uint16_t* source = new uint16_t[kFullStringLength];
   for (int i = 0; i < kFullStringLength; i++) source[i] = '1';
   char* key = new char[kSliceStringLength];
   for (int i = 0; i < kSliceStringLength; i++) key[i] = '1';
+  Vector<const char> key_vector(key, kSliceStringLength);
 
   // Allocate an external string resource that keeps track of when it
   // is destructed.
   bool resource_destructed = false;
   TwoByteResource* resource =
       new TwoByteResource(source, kFullStringLength, &resource_destructed);
 
   {
     v8::HandleScope scope;
 
@@ skipping 31 matching lines @@
     Handle<JSObject> wrapper = GetScriptWrapper(script);
   }
 
   // When we collect all garbage, we cannot get rid of the sliced
   // symbol entry in the symbol table because it is used by the script
   // kept alive by the weak wrapper. Make sure we don't destruct the
   // external string.
   Heap::CollectAllGarbage();
   CHECK(!resource_destructed);
 
-  // Make sure the sliced symbol is still in the table.
+  {
+    v8::HandleScope scope;
+
+    // Make sure the sliced symbol is still in the table.
+    Handle<String> symbol = Factory::LookupSymbol(key_vector);
+    CHECK(StringShape(*symbol).IsSliced());
+
+    // Make sure the buffer is still a two-byte external string.
+    Handle<String> buffer(Handle<SlicedString>::cast(symbol)->buffer());
+    CHECK(StringShape(*buffer).IsExternal());
+    CHECK(buffer->IsTwoByteRepresentation());
+  }
+
+  // Forcing another garbage collection should let us get rid of the
+  // slice from the symbol table. The external string remains in the
+  // heap until the next GC.
+  Heap::CollectAllGarbage();
+  CHECK(!resource_destructed);
   v8::HandleScope scope;
-  Vector<const char> vector(key, kSliceStringLength);
-  Handle<String> symbol = Factory::LookupSymbol(vector);
-  CHECK(StringShape(*symbol).IsSliced());
+  Handle<String> key_string = Factory::NewStringFromAscii(key_vector);
+  String* out;
+  CHECK(!Heap::LookupSymbolIfExists(*key_string, &out));
 
-  // Make sure the buffer is still a two-byte external string.
-  Handle<String> buffer(Handle<SlicedString>::cast(symbol)->buffer());
-  CHECK(StringShape(*buffer).IsExternal());
-  CHECK(buffer->IsTwoByteRepresentation());
+  // Forcing yet another garbage collection must allow us to finally
+  // get rid of the external string.
+  Heap::CollectAllGarbage();
+  CHECK(resource_destructed);
 
   delete[] source;
   delete[] key;
 }