[turbofan] Fix recognition of Uint32Div in simplified lowering.

TEST=mjsunit/asm
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/701813003

Cr-Commit-Position: refs/heads/master@{#25103}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25103 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/compiler/simplified-lowering.cc

@@ -632,7 +632,7 @@ class RepresentationSelector {
           if (lower()) DeferReplacement(node, lowering->Int32Div(node));
           break;
         }
-        if (CanLowerToUint32Binop(node, use)) {
+        if (BothInputsAre(node, Type::Unsigned32()) && !CanObserveNaN(use)) {
           // => unsigned Uint32Div
           VisitUint32Binop(node);
           if (lower()) DeferReplacement(node, lowering->Uint32Div(node));

test/mjsunit/asm/uint32div.js

@@ -22,8 +22,24 @@ function Uint32Div(divisor) {
 var divisors = [0, 1, 3, 4, 10, 42, 64, 100, 1024, 2147483647, 4294967295];
 for (var i in divisors) {
   var divisor = divisors[i];
-  var mod = Uint32Div(divisor);
+  var div = Uint32Div(divisor);
   for (var dividend = 0; dividend < 4294967296; dividend += 3999773) {
-    assertEquals((dividend / divisor) >>> 0, mod(dividend));
+    assertEquals((dividend / divisor) >>> 0, div(dividend));
+  }
+}
+
+var div = (function(stdlib, foreign, heap) {
+  "use asm";
+  function div(dividend, divisor) {
+    return (dividend >>> 0) / (divisor >>> 0) | 0;
+  }
+  return {div: div};
+})(stdlib, foreign, heap).div;
+
+for (var i in divisors) {
+  var divisor =  divisors[i];
+  for (var dividend = 0; dividend < 4294967296; dividend += 3999773) {
+    assertEquals((dividend >>> 0) / (divisor >>> 0) | 0,
+                 div(dividend, divisor));
   }
 }