1 files changed, 80 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/cacheir/string-at-rope.js b/js/src/jit-test/tests/cacheir/string-at-rope.js
new file mode 100644
index 0000000000..aa41fa1440
--- /dev/null
+++ b/js/src/jit-test/tests/cacheir/string-at-rope.js
@@ -0,0 +1,80 @@
+function makeRope() {
+  var left = newRope("@ABCDEFGHIJKLMNO", "PQRSTUVWXYZ[\\]^_");
+  var right = newRope("`abcdefghijklmno", "pqrstuvwxyz{|}~");
+  var rope = newRope(left, right);
+  return {left, right, rope};
+}
+
+// Load a character from the left rope child using a constant index. The input
+// to String.prototype.at is always rope.
+function testLeftChildConstant() {
+  for (var i = 0; i < 200; ++i) {
+    var {rope} = makeRope();
+
+    var ch = rope.at(0);
+    assertEq(ch, "@");
+  }
+}
+for (var i = 0; i < 2; ++i) {
+  testLeftChildConstant();
+}
+
+// Load a character from the right rope child using a constant index. The input
+// to String.prototype.at is always rope.
+function testRightChildConstant() {
+  for (var i = 0; i < 200; ++i) {
+    var {rope} = makeRope();
+
+    var ch = rope.at(32);
+    assertEq(ch, "`");
+  }
+}
+for (var i = 0; i < 2; ++i) {
+  testRightChildConstant();
+}
+
+// Load a character from the left rope child using a variable index. The input
+// to String.prototype.at is always rope.
+function testLeftChildVariable() {
+  for (var i = 0; i < 200; ++i) {
+    var {left, rope} = makeRope();
+
+    var idx = i % left.length;
+    var ch = rope.at(idx);
+    assertEq(ch, String.fromCharCode(0x40 + idx));
+  }
+}
+for (var i = 0; i < 2; ++i) {
+  testLeftChildVariable();
+}
+
+// Load a character from the right rope child using a variable index. The input
+// to String.prototype.at is always rope.
+function testRightChildVariable() {
+  for (var i = 0; i < 200; ++i) {
+    var {left, right, rope} = makeRope();
+
+    var idx = i % right.length;
+    var ch = rope.at(left.length + idx);
+    assertEq(ch, String.fromCharCode(0x60 + idx));
+  }
+}
+for (var i = 0; i < 2; ++i) {
+  testRightChildVariable();
+}
+
+// Load all characters from both child ropes. This covers the case when the
+// call to String.prototype.at linearizes the rope. 
+function testBothChildren() {
+  for (var i = 0; i < 200; ++i) {
+    var {rope} = makeRope();
+
+    for (var j = 0; j < rope.length; ++j) {
+      var ch = rope.at(j);
+      assertEq(ch, String.fromCharCode(0x40 + j));
+    }
+  }
+}
+for (var i = 0; i < 2; ++i) {
+  testBothChildren();
+}