Faster moving FixedArray elements around.

test/mjsunit/array-elements-from-array-prototype-chain.js

+// Copyright 2010 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
+//       with the distribution.
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+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+////////////////////////////////////////////////////////////////////////
+// Tests below verify that elements set on Array.prototype's proto propagate
+// for various Array.prototype functions (like unshift, shift, etc.)
+// If add any new tests here, consider adding them to all other files:
+//   array-elements-from-array-prototype.js
+//   array-elements-from-array-prototype-chain.js
+//   array-elements-from-object-prototype.js
+// those ideally should be identical modulo host of elements and
+// the way elements introduced.
+//
+// Note: they are put into a separate file as we need maximally clean
+// VM setup---some optimizations might be already turned off in
+// 'dirty' VM.
+////////////////////////////////////////////////////////////////////////
+
+var at3 = '@3'
+var at7 = '@7'
+
+Array.prototype.__proto__ = {3: at3};
+Array.prototype.__proto__.__proto__ = {7: at7};
+
+var a = new Array(13)
+
+assertEquals(at3, a[3])
+assertFalse(a.hasOwnProperty(3))
+
+assertEquals(at7, a[7])
+assertFalse(a.hasOwnProperty(7))
+
+assertEquals(undefined, a.shift(), 'hole should be returned as undefined')
+// Side-effects: Array.prototype[3] percolates into a[2] and Array.prototype[7[
+// into a[6], still visible at the corresponding indices.
+
+assertEquals(at3, a[2])
+assertTrue(a.hasOwnProperty(2))
+assertEquals(at3, a[3])
+assertFalse(a.hasOwnProperty(3))
+
+assertEquals(at7, a[6])
+assertTrue(a.hasOwnProperty(6))
+assertEquals(at7, a[7])
+assertFalse(a.hasOwnProperty(7))
+
+a.unshift('foo', 'bar')
+// Side-effects: Array.prototype[3] now percolates into a[5] and Array.prototype[7]
+// into a[9].
+
+assertEquals(at3, a[3])
+assertFalse(a.hasOwnProperty(3))
+assertEquals(at3, a[4])
+assertTrue(a.hasOwnProperty(4))
+assertEquals(at3, a[5])
+assertTrue(a.hasOwnProperty(5))
+
+assertEquals(undefined, a[6])
+assertFalse(a.hasOwnProperty(6))
+
+assertEquals(at7, a[7])
+assertFalse(a.hasOwnProperty(7))
+assertEquals(at7, a[8])
+assertTrue(a.hasOwnProperty(8))
+assertEquals(at7, a[9])
+assertTrue(a.hasOwnProperty(9))
+
+var sliced = a.slice(3, 10)
+// Slice must keep intact a and reify holes at indices 0--2 and 4--6.
+
+assertEquals(at3, a[3])
+assertFalse(a.hasOwnProperty(3))
+assertEquals(at3, a[4])
+assertTrue(a.hasOwnProperty(4))
+assertEquals(at3, a[5])
+assertTrue(a.hasOwnProperty(5))
+
+assertEquals(undefined, a[6])
+assertFalse(a.hasOwnProperty(6))
+
+assertEquals(at7, a[7])
+assertFalse(a.hasOwnProperty(7))
+assertEquals(at7, a[8])
+assertTrue(a.hasOwnProperty(8))
+assertEquals(at7, a[9])
+assertTrue(a.hasOwnProperty(9))
+
+assertEquals(at3, sliced[0])
+assertTrue(sliced.hasOwnProperty(0))
+assertEquals(at3, sliced[1])
+assertTrue(sliced.hasOwnProperty(1))
+assertEquals(at3, sliced[2])
+assertTrue(sliced.hasOwnProperty(2))
+
+// Note: sliced[3] comes directly from Array.prototype[3]
+assertEquals(at3, sliced[3]);
+assertFalse(sliced.hasOwnProperty(3))
+
+assertEquals(at7, sliced[4])
+assertTrue(sliced.hasOwnProperty(4))
+assertEquals(at7, sliced[5])
+assertTrue(sliced.hasOwnProperty(5))
+assertEquals(at7, sliced[6])
+assertTrue(sliced.hasOwnProperty(6))
+
+
+// Splice is too complicated the operation, start afresh.
+
+// Shrking array.
+var a0 = [0, 1, , , 4, 5, , , , 9]
+var result = a0.splice(4, 1)
+// Side-effects: everything before 4 is kept intact:
+
+assertEquals(0, a0[0])
+assertTrue(a0.hasOwnProperty(0))
+assertEquals(1, a0[1])
+assertTrue(a0.hasOwnProperty(1))
+assertEquals(undefined, a0[2])
+assertFalse(a0.hasOwnProperty(2))
+assertEquals(at3, a0[3])
+assertFalse(a0.hasOwnProperty(3))
+
+// 4 and above shifted left by one reifying at7 into a0[6] and keeping
+// a hole at a0[7]
+
+assertEquals(5, a0[4])
+assertTrue(a0.hasOwnProperty(4))
+assertEquals(undefined, a0[5])
+assertFalse(a0.hasOwnProperty(5))
+assertEquals(at7, a0[6])
+assertTrue(a0.hasOwnProperty(6))
+assertEquals(at7, a0[7])
+assertFalse(a0.hasOwnProperty(7))
+assertEquals(9, a0[8])
+assertTrue(a0.hasOwnProperty(8))
+
+// Growing array.
+var a1 = [0, 1, , , 4, 5, , , , 9]
+var result = a1.splice(4, 0, undefined)
+// Side-effects: everything before 4 is kept intact:
+
+assertEquals(0, a1[0])
+assertTrue(a1.hasOwnProperty(0))
+assertEquals(1, a1[1])
+assertTrue(a1.hasOwnProperty(1))
+assertEquals(undefined, a1[2])
+assertFalse(a1.hasOwnProperty(2))
+assertEquals(at3, a1[3])
+assertFalse(a1.hasOwnProperty(3))
+
+// Now owned undefined resides at 4 and rest is shifted right by one
+// reifying at7 into a0[8] and keeping a hole at a0[7].
+
+assertEquals(undefined, a1[4])
+assertTrue(a1.hasOwnProperty(4))
+assertEquals(4, a1[5])
+assertTrue(a1.hasOwnProperty(5))
+assertEquals(5, a1[6])
+assertTrue(a1.hasOwnProperty(6))
+assertEquals(at7, a1[7])
+assertFalse(a1.hasOwnProperty(7))
+assertEquals(at7, a1[8])
+assertTrue(a1.hasOwnProperty(8))
+assertEquals(undefined, a1[9])
+assertFalse(a1.hasOwnProperty(9))
+assertEquals(9, a1[10])
+assertTrue(a1.hasOwnProperty(10))