Support SAB atomics for offset-TypedArray

test/mjsunit/asm/atomics-exchange.js

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --harmony-sharedarraybuffer
 
-function Module(stdlib, foreign, heap) {
+function Module(stdlib, foreign, heap, offset) {
   "use asm";
-  var MEM8 = new stdlib.Int8Array(heap);
-  var MEM16 = new stdlib.Int16Array(heap);
-  var MEM32 = new stdlib.Int32Array(heap);
-  var MEMU8 = new stdlib.Uint8Array(heap);
-  var MEMU16 = new stdlib.Uint16Array(heap);
-  var MEMU32 = new stdlib.Uint32Array(heap);
+  var MEM8 = new stdlib.Int8Array(heap, offset);
+  var MEM16 = new stdlib.Int16Array(heap, offset);
+  var MEM32 = new stdlib.Int32Array(heap, offset);
+  var MEMU8 = new stdlib.Uint8Array(heap, offset);
+  var MEMU16 = new stdlib.Uint16Array(heap, offset);
+  var MEMU32 = new stdlib.Uint32Array(heap, offset);
   var exchange = stdlib.Atomics.exchange;
   var fround = stdlib.Math.fround;
 
   function exchangei8(i, x) {
     i = i | 0;
     x = x | 0;
     return exchange(MEM8, i, x)|0;
   }
 
   function exchangei16(i, x) {
@@ skipping 39 matching lines @@
 var sab = new SharedArrayBuffer(16);
 var m = Module(this, {}, sab);
 
 function clearArray() {
   var ui8 = new Uint8Array(sab);
   for (var i = 0; i < sab.byteLength; ++i) {
     ui8[i] = 0;
   }
 }
 
-function testElementType(taConstr, f) {
+function testElementType(taConstr, f, offset) {
   clearArray();
 
-  var ta = new taConstr(sab);
+  var ta = new taConstr(sab, offset);
   var name = Object.prototype.toString.call(ta);
   ta[0] = 0x7f;
   assertEquals(0x7f, f(0, 0xf), name);
   assertEquals(0xf, ta[0]);
   // out of bounds
   assertEquals(0, f(-1, 0), name);
   assertEquals(0, f(ta.length, 0), name);
 }
 
-testElementType(Int8Array, m.exchangei8);
-testElementType(Int16Array, m.exchangei16);
-testElementType(Int32Array, m.exchangei32);
-testElementType(Uint8Array, m.exchangeu8);
-testElementType(Uint16Array, m.exchangeu16);
-testElementType(Uint32Array, m.exchangeu32);
+function testElement(m, offset) {
+  testElementType(Int8Array, m.exchangei8, offset);
+  testElementType(Int16Array, m.exchangei16, offset);
+  testElementType(Int32Array, m.exchangei32, offset);
+  testElementType(Uint8Array, m.exchangeu8, offset);
+  testElementType(Uint16Array, m.exchangeu16, offset);
+  testElementType(Uint32Array, m.exchangeu32, offset);
+}
+
+var offset = 0;
+var sab = new SharedArrayBuffer(16);
+var m1 = Module(this, {}, sab, offset);
+testElement(m1, offset);
+
+offset = 32;
+sab = new SharedArrayBuffer(64);
+var m2 = Module(this, {}, sab, offset);
+testElement(m2, offset);