[turbofan] Only do value numbering when types are compatible.

test/mjsunit/compiler/regress-633497.js

Index: test/mjsunit/compiler/regress-633497.js
diff --git a/test/mjsunit/compiler/regress-628403.js b/test/mjsunit/compiler/regress-633497.js
similarity index 50%
copy from test/mjsunit/compiler/regress-628403.js
copy to test/mjsunit/compiler/regress-633497.js
index 4096ac32aee4692487618fc53f6b7bcf703a9098..8bf358af00a5dbfc03ab8f3a11f2170b174d3d4b 100644
--- a/test/mjsunit/compiler/regress-628403.js
+++ b/test/mjsunit/compiler/regress-633497.js
@@ -4,24 +4,26 @@
 
 // Flags: --allow-natives-syntax
 
-var dothrow = false;
-
-function g() {
-  if (dothrow) throw 1;
-}
-
 function f(a) {
-  try {
-    g();
-  } catch(e) {
-    if (typeof e !== 'number' && e !== 1) throw e;
-    return a[0];
+  var x;
+  a = a|0;
+  var dummy;
+  if (a === 1) {
+    x = 277.5;
+  } else if (a === 2) {
+    x = 0;
+  } else {
+    dummy = 527.5;

[ahaas, 2016/08/18 06:57:07]

Could we add a comment which describes the purpose of these dummy values?

+    dummy = 958.5;
+    dummy = 1143.5;
+    dummy = 1368.5;
+    dummy = 1558.5;
+    x = 277.5;
   }
+  return +x;
 }
 
-%NeverOptimizeFunction(g);
 f();
 f();
 %OptimizeFunctionOnNextCall(f);
-dothrow = true;
-assertEquals(42, f([42]));
+assertEquals(277.5, f());