Implement core support for FixedDoubleArrays.

test/mjsunit/unbox-double-arrays.js

+// Copyright 2011 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:
+//
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+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Test dictionary -> double elements -> dictionary elements round trip
+
+var foo = new Array(500000);
+
+function func(a) {
+  for (var i= 0; i < 100000; ++i ) {
+    a[i] = i+0.5;
+  }
+}
+
+func(foo);
+
+for (var i= 0; i < 100000; i += 500 ) {
+  assertEquals(i+0.5, foo[i]);
+}
+
+delete foo[5];
+// Don't use assertEquals for comparison to undefined due to
+assertTrue(undefined === foo[5]);
+assertTrue(undefined === foo[500000-1]);
+assertTrue(undefined === foo[-1]);
+assertEquals(500000, foo.length);
+
+// Cause the array to grow beyond it's JSArray length. This will double the
+// size of the capacity and force the array into "slow" dictionary case.
+foo[500001] = 50;
+assertEquals(50, foo[500001]);
+assertEquals(500002, foo.length);
+assertTrue(undefined === foo[5])
+assertTrue(undefined === foo[500000-1])
+assertTrue(undefined === foo[-1])
+assertEquals(500002, foo.length);
+
+// Test dictionary -> double elements -> fast elements.
+
+var foo2 = new Array(500000);
+func(foo2);
+delete foo2[5];
+
+// Convert back to fast elements and make sure the contents of the array are
+// unchanged.
+foo2[25] = new Object();
+for (var i= 0; i < 100000; i += 500 ) {
+  if (i != 25 && i != 5) {
+    assertEquals(i+0.5, foo2[i]);
+  }
+}
+assertTrue(undefined === foo2[5])
+assertTrue(undefined === foo2[500000-1])
+assertTrue(undefined === foo2[-1])
+assertEquals(500000, foo2.length);