[WIP] Typ aided removal of redundant modulus.

src/compiler/js-typed-lowering.cc

Index: src/compiler/js-typed-lowering.cc
diff --git a/src/compiler/js-typed-lowering.cc b/src/compiler/js-typed-lowering.cc
index 4765bc2e5fc618a6ddbed3983f8c4c9a678beb90..680bb8b0a4426aa8ee9b38b7938905b13e1b38fa 100644
--- a/src/compiler/js-typed-lowering.cc
+++ b/src/compiler/js-typed-lowering.cc
@@ -267,6 +267,22 @@ Reduction JSTypedLowering::ReduceJSMultiply(Node* node) {
 }
 
 
+Reduction JSTypedLowering::ReduceJSModulus(Node* node) {
+  JSBinopReduction r(this, node);
+  if (r.left_type()->Is(NodeProperties::GetBounds(node).upper)) {
+    Node* const value = r.left();
+    NodeProperties::ReplaceWithValue(node, value);
+    return Changed(value);
+  }
+  if (r.BothInputsAre(Type::Primitive())) {
+    r.ConvertInputsToNumber();
+    return r.ChangeToPureOperator(simplified()->NumberModulus());
+  }
+  // TODO(turbofan): relax/remove the effects of this operator in other cases.
+  return NoChange();
+}
+
+
 Reduction JSTypedLowering::ReduceNumberBinop(Node* node,
                                              const Operator* numberOp) {
   JSBinopReduction r(this, node);
@@ -746,7 +762,7 @@ Reduction JSTypedLowering::Reduce(Node* node) {
     case IrOpcode::kJSDivide:
       return ReduceNumberBinop(node, simplified()->NumberDivide());
     case IrOpcode::kJSModulus:
-      return ReduceNumberBinop(node, simplified()->NumberModulus());
+      return ReduceJSModulus(node);
     case IrOpcode::kJSUnaryNot: {
       Reduction result = ReduceJSToBooleanInput(node->InputAt(0));
       Node* value;