Add mjsunit tests for optimization of float min/max.

test/mjsunit/compiler/optimize_max.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.
+
+var DOUBLE_ZERO = 1.0 - 1.0;

[Michael Starzinger, 2015/06/23 16:56:25]

As discussed offline: This doesn't yield a boxed double. The only way I could
figure out to get a boxed double was %AllocateHeapNumber(), maybe there is a
nicer way that I am not aware of.

+var SMI_ZERO = 0;
+var MINUS_ZERO = -0.0;
+
+function max1(a, b) {
+  a = +a;
+  b = +b;
+  return +(a < b ? b : a);
+}
+
+function max2(a, b) {
+  a = +a;
+  b = +b;
+  return a < b ? b : a;
+}
+
+for (f of [max1, max2]) {
+  for (var i = 0; i < 5; i++) {
+    assertEquals(4, f(3, 4));
+    assertEquals(4, f(4, 3));
+    assertEquals(4.3, f(3.3, 4.3));
+    assertEquals(4.4, f(4.4, 3.4));
+
+    assertEquals(Infinity, 1 / f(SMI_ZERO, MINUS_ZERO));
+    assertEquals(Infinity, 1 / f(DOUBLE_ZERO, MINUS_ZERO));
+    assertEquals(-Infinity, 1 / f(MINUS_ZERO, SMI_ZERO));
+    assertEquals(-Infinity, 1 / f(MINUS_ZERO, DOUBLE_ZERO));
+
+    assertEquals(NaN, f(NaN, NaN));
+    assertEquals(3, f(3, NaN));
+    assertEquals(NaN, f(NaN, 3));
+  }
+}
+
+function max3(a, b) {
+  a = +a;
+  b = +b;
+  return +(a > b ? a : b);
+}
+
+function max4(a, b) {
+  a = +a;
+  b = +b;
+  return a > b ? a : b;
+}
+
+for (f of [max3, max4]) {
+  for (var i = 0; i < 5; i++) {
+    assertEquals(4, f(3, 4));
+    assertEquals(4, f(4, 3));
+    assertEquals(4.3, f(3.3, 4.3));
+    assertEquals(4.4, f(4.4, 3.4));
+
+    assertEquals(-Infinity, 1 / f(SMI_ZERO, MINUS_ZERO));
+    assertEquals(-Infinity, 1 / f(DOUBLE_ZERO, MINUS_ZERO));
+    assertEquals(Infinity, 1 / f(MINUS_ZERO, SMI_ZERO));
+    assertEquals(Infinity, 1 / f(MINUS_ZERO, DOUBLE_ZERO));
+
+    assertEquals(NaN, f(NaN, NaN));
+    assertEquals(NaN, f(3, NaN));
+    assertEquals(3, f(NaN, 3));
+  }
+}