diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/jaeger/undoAdd.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/jaeger/undoAdd.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,25 @@
+
+/* Test undoing addition in overflow paths when under heavy register pressure. */
+
+function add1(x, y, a, b, res) { var nres = res + 0; var z = (x + a) + (y + b); assertEq(z, nres); }
+function add2(x, y, a, b, res) { var nres = res + 0; var z = (x + a) + (y + b); assertEq(z, nres); }
+function add3(x, y, a, b, res) { var nres = res + 0; var z = (x + a) + (y + b); assertEq(z, nres); }
+add1(0x7ffffff0, 100, 0, 0, 2147483732);
+add2(-1000, -0x80000000, 0, 0, -2147484648);
+add3(-0x80000000, -1000, 0, 0, -2147484648);
+
+function cadd1(x, a, b, res) {
+  var nres = res + 0;
+  var nb = b + 0;
+  var z = (x + a) + 1000;
+  assertEq(z, nres + nb);
+}
+cadd1(0x7ffffff0, 0, 0, 2147484632);
+
+function cadd2(x, a, b, res) {
+  var nres = res + 0;
+  var nb = b + 0;
+  var z = (x + a) + (-0x80000000);
+  assertEq(z, nres + nb);
+}
+cadd2(-1000, 0, 0, -2147484648);