Ensure double arrays are filled with holes when extended from variations of empty arrays.

test/mjsunit/array-natives-elements.js

 // Copyright 2012 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
@@ skipping 31 matching lines @@
 } else {
   print("Tests do NOT include smi-only arrays.");
 }
 
 // IC and Crankshaft support for smi-only elements in dynamic array literals.
 function get(foo) { return foo; }  // Used to generate dynamic values.
 
 function array_natives_test() {
 
   // Ensure small array literals start in specific element kind mode.
-  assertTrue(%HasFastObjectElements([]));
+  assertTrue(%HasFastSmiElements([]));
   assertTrue(%HasFastSmiElements([1]));
   assertTrue(%HasFastSmiElements([1,2]));
   assertTrue(%HasFastDoubleElements([1.1]));
   assertTrue(%HasFastDoubleElements([1.1,2]));
 
   // Push
   var a0 = [1, 2, 3];
   assertTrue(%HasFastSmiElements(a0));
   a0.push(4);
   assertTrue(%HasFastSmiElements(a0));
   a0.push(1.3);
   assertTrue(%HasFastDoubleElements(a0));
   a0.push(1.5);
   assertTrue(%HasFastDoubleElements(a0));
   a0.push({});
   assertTrue(%HasFastObjectElements(a0));
   a0.push({});
   assertTrue(%HasFastObjectElements(a0));
   assertEquals([1,2,3,4,1.3,1.5,{},{}], a0);
 
   // Concat
   var a1;
   a1 = [1,2,3].concat([]);
-  assertTrue(%HasFastObjectElements(a1));
+  assertTrue(%HasFastSmiElements(a1));
   assertEquals([1,2,3], a1);
   a1 = [1,2,3].concat([4,5,6]);
   assertTrue(%HasFastSmiElements(a1));
   assertEquals([1,2,3,4,5,6], a1);
   a1 = [1,2,3].concat([4,5,6], [7,8,9]);
   assertTrue(%HasFastSmiElements(a1));
   assertEquals([1,2,3,4,5,6,7,8,9], a1);
   a1 = [1.1,2,3].concat([]);
-  assertTrue(%HasFastObjectElements(a1));
+  assertTrue(%HasFastDoubleElements(a1));
   assertEquals([1.1,2,3], a1);
   a1 = [1,2,3].concat([1.1, 2]);
   assertTrue(%HasFastDoubleElements(a1));
   assertEquals([1,2,3,1.1,2], a1);
   a1 = [1.1,2,3].concat([1, 2]);
   assertTrue(%HasFastDoubleElements(a1));
   assertEquals([1.1,2,3,1,2], a1);
   a1 = [1.1,2,3].concat([1.2, 2]);
   assertTrue(%HasFastDoubleElements(a1));
   assertEquals([1.1,2,3,1.2,2], a1);
@@ skipping 70 matching lines @@
   a3 = [1.1,2,3];
   a3r = a3.splice(0, 1);
   assertTrue(%HasFastDoubleElements(a3r));
   assertTrue(%HasFastDoubleElements(a3));
   assertEquals([1.1], a3r);
   assertEquals([2, 3], a3);
   a3 = [1.1,2,3];
   a3r = a3.splice(0, 0, 2);
   // Commented out since handled in js, which takes the best fit.
   // assertTrue(%HasFastDoubleElements(a3r));
-  assertTrue(%HasFastObjectElements(a3r));
+  assertTrue(%HasFastSmiElements(a3r));
   assertTrue(%HasFastDoubleElements(a3));
   assertEquals([], a3r);
   assertEquals([2, 1.1, 2, 3], a3);
   a3 = [1.1,2,3];
   a3r = a3.splice(0, 1, 2);
   assertTrue(%HasFastDoubleElements(a3r));
   assertTrue(%HasFastDoubleElements(a3));
   assertEquals([1.1], a3r);
   assertEquals([2, 2, 3], a3);
   a3 = [1.1,2,3];
   a3r = a3.splice(0, 0, 2.1);
   // Commented out since handled in js, which takes the best fit.
   // assertTrue(%HasFastDoubleElements(a3r));
-  assertTrue(%HasFastObjectElements(a3r));
+  assertTrue(%HasFastSmiElements(a3r));
   assertTrue(%HasFastDoubleElements(a3));
   assertEquals([], a3r);
   assertEquals([2.1, 1.1, 2, 3], a3);
   a3 = [1.1,2,3];
   a3r = a3.splice(0, 1, 2.2);
   assertTrue(%HasFastDoubleElements(a3r));
   assertTrue(%HasFastDoubleElements(a3));
   assertEquals([1.1], a3r);
   assertEquals([2.2, 2, 3], a3);
   a3 = [1,2,3];
   a3r = a3.splice(0, 0, 2.1);
   // Commented out since handled in js, which takes the best fit.
   // assertTrue(%HasFastDoubleElements(a3r));
-  assertTrue(%HasFastObjectElements(a3r));
+  assertTrue(%HasFastSmiElements(a3r));
   assertTrue(%HasFastDoubleElements(a3));
   assertEquals([], a3r);
   assertEquals([2.1, 1, 2, 3], a3);
   a3 = [1,2,3];
   a3r = a3.splice(0, 1, 2.2);
   assertTrue(%HasFastDoubleElements(a3r));
   assertTrue(%HasFastDoubleElements(a3));
   assertEquals([1], a3r);
   assertEquals([2.2, 2, 3], a3);
 
@@ skipping 83 matching lines @@
   assertEquals([1.1,{},2,3], a4);
 }
 
 if (support_smi_only_arrays) {
   for (var i = 0; i < 3; i++) {
     array_natives_test();
   }
   %OptimizeFunctionOnNextCall(array_natives_test);
   array_natives_test();
 }