[WIP] Typ aided removal of redundant modulus.

src/compiler/js-typed-lowering.cc

 // Copyright 2014 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.
 
 #include "src/compiler/access-builder.h"
 #include "src/compiler/graph-inl.h"
 #include "src/compiler/js-builtin-reducer.h"
 #include "src/compiler/js-typed-lowering.h"
 #include "src/compiler/node-aux-data-inl.h"
 #include "src/compiler/node-properties-inl.h"
@@ skipping 249 matching lines @@
     // TODO(jarin): Propagate frame state input from non-primitive input node to
     // JSToNumber node.
     r.ConvertInputsToNumber();
     return r.ChangeToPureOperator(simplified()->NumberMultiply());
   }
   // TODO(turbofan): relax/remove the effects of this operator in other cases.
   return NoChange();
 }
 
 
+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);
   if (r.BothInputsAre(Type::Primitive())) {
     r.ConvertInputsToNumber();
     return r.ChangeToPureOperator(numberOp);
   }
 #if 0
   // TODO(turbofan): General ToNumber disabled for now because:
   //   a) The inserted ToNumber operation screws up observability of valueOf.
@@ skipping 459 matching lines @@
       return ReduceI32Shift(node, false, machine()->Word32Shr());
     case IrOpcode::kJSAdd:
       return ReduceJSAdd(node);
     case IrOpcode::kJSSubtract:
       return ReduceNumberBinop(node, simplified()->NumberSubtract());
     case IrOpcode::kJSMultiply:
       return ReduceJSMultiply(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;
       if (result.Changed()) {
         // JSUnaryNot(x:boolean) => BooleanNot(x)
         value =
             graph()->NewNode(simplified()->BooleanNot(), result.replacement());
         NodeProperties::ReplaceWithValue(node, value);
         return Changed(value);
       } else {
@@ skipping 22 matching lines @@
       return JSBuiltinReducer(jsgraph()).Reduce(node);
     default:
       break;
   }
   return NoChange();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8