[turbofan] Optimize loads of global constants in JSTypedLowering.

test/mjsunit/global-nan.js

Index: test/mjsunit/global-nan.js
diff --git a/test/mjsunit/global-nan.js b/test/mjsunit/global-nan.js
new file mode 100644
index 0000000000000000000000000000000000000000..5a98eff1c88c3fa83e0075cd79996c39602adb19
--- /dev/null
+++ b/test/mjsunit/global-nan.js
@@ -0,0 +1,127 @@
+// 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: --allow-natives-syntax
+
+function test(expected, f) {
+  assertEquals(expected, f());
+  assertEquals(expected, f());
+  %OptimizeFunctionOnNextCall(f);
+  assertEquals(expected, f());
+  assertEquals(expected, f());
+}
+
+function f1() { return NaN; }
+test((0/0), f1);
+
+function f2() { return (0/0); }
+test((0/0), f2);
+
+function f3() { return (0/0) == (0/0); }
+test(false, f3);
+
+function f4() { return (0/0) == NaN; }
+test(false, f4);
+
+function f5() { return NaN == (0/0); }
+test(false, f5);
+
+function f6() { return "" + NaN; }
+test("NaN", f6);
+
+function f7() { return (0/0) === (0/0); }
+test(false, f7);
+
+function f8() { return (0/0) === NaN; }
+test(false, f8);
+
+function f9() { return NaN === (0/0); }
+test(false, f9);
+
+delete NaN;
+
+function g1() { return NaN; }
+test((0/0), g1);
+
+function g2() { return (0/0); }
+test((0/0), g2);
+
+function g3() { return (0/0) == (0/0); }
+test(false, g3);
+
+function g4() { return (0/0) == NaN; }
+test(false, g4);
+
+function g5() { return NaN == (0/0); }
+test(false, g5);
+
+function g6() { return "" + NaN; }
+test("NaN", g6);
+
+function g7() { return (0/0) === (0/0); }
+test(false, g7);
+
+function g8() { return (0/0) === NaN; }
+test(false, g8);
+
+function g9() { return NaN === (0/0); }
+test(false, g9);
+
+NaN = 111;
+
+function h1() { return NaN; }
+test((0/0), h1);
+
+function h2() { return (0/0); }
+test((0/0), h2);
+
+function h3() { return (0/0) == (0/0); }
+test(false, h3);
+
+function h4() { return (0/0) == NaN; }
+test(false, h4);
+
+function h5() { return NaN == (0/0); }
+test(false, h5);
+
+function h6() { return "" + NaN; }
+test("NaN", h6);
+
+function h7() { return (0/0) === (0/0); }
+test(false, h7);
+
+function h8() { return (0/0) === NaN; }
+test(false, h8);
+
+function h9() { return NaN === (0/0); }
+test(false, h9);
+
+// -------------
+
+function k1() { return this.NaN; }
+test((0/0), k1);
+
+function k2() { return (0/0); }
+test((0/0), k2);
+
+function k3() { return (0/0) == (0/0); }
+test(false, k3);
+
+function k4() { return (0/0) == this.NaN; }
+test(false, k4);
+
+function k5() { return this.NaN == (0/0); }
+test(false, k5);
+
+function k6() { return "" + this.NaN; }
+test("NaN", k6);
+
+function k7() { return (0/0) === (0/0); }
+test(false, k7);
+
+function k8() { return (0/0) === this.NaN; }
+test(false, k8);
+
+function k9() { return this.NaN === (0/0); }
+test(false, k9);