fix embedded vector copy constructor and assignment.

Thanks to Tobias Kaes, an issue with default copy constructor and assignment operator is found and fixed.

BUG=http://code.google.com/p/v8/issues/detail?id=358

Review URL: http://codereview.chromium.org/113992


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2077 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/utils.h

@@ -379,6 +379,9 @@ class Vector {
   // Factory method for creating empty vectors.
   static Vector<T> empty() { return Vector<T>(NULL, 0); }
 
+ protected:
+  void set_start(T* start) { start_ = start; }
+
  private:
   T* start_;
   int length_;
@@ -406,6 +409,22 @@ template <typename T, int kSize>
 class EmbeddedVector : public Vector<T> {
  public:
   EmbeddedVector() : Vector<T>(buffer_, kSize) { }
+
+  // When copying, make underlying Vector to reference our buffer.
+  EmbeddedVector(const EmbeddedVector& rhs)
+      : Vector<T>(rhs) {
+    memcpy(buffer_, rhs.buffer_, sizeof(T) * kSize);
+    set_start(buffer_);
+  }
+
+  EmbeddedVector& operator=(const EmbeddedVector& rhs) {
+    if (this == &rhs) return *this;
+    Vector<T>::operator=(rhs);
+    memcpy(buffer_, rhs.buffer_, sizeof(T) * kSize);
+    set_start(buffer_);
+    return *this;
+  }
+
  private:
   T buffer_[kSize];
 };

test/cctest/test-utils.cc

@@ -177,3 +177,32 @@ TEST(SNPrintF) {
     buffer.Dispose();
   }
 }
+
+
+// Issue 358: When copying EmbeddedVector, Vector::start_ must point
+// to the buffer in the copy, not in the source.
+TEST(EmbeddedVectorCopy) {
+  EmbeddedVector<int, 1> src;
+  src[0] = 100;
+  EmbeddedVector<int, 1> dst = src;
+  CHECK_NE(src.start(), dst.start());
+  CHECK_EQ(src[0], dst[0]);
+  src[0] = 200;
+  CHECK_NE(src[0], dst[0]);
+}
+
+
+// Also Issue 358, assignment case.
+TEST(EmbeddedVectorAssign) {
+  EmbeddedVector<int, 1> src;
+  src[0] = 100;
+  EmbeddedVector<int, 1> dst;
+  dst[0] = 200;
+  CHECK_NE(src.start(), dst.start());
+  CHECK_NE(src[0], dst[0]);
+  dst = src;
+  CHECK_NE(src.start(), dst.start());
+  CHECK_EQ(src[0], dst[0]);
+  src[0] = 200;
+  CHECK_NE(src[0], dst[0]);
+}