Don't explicitly pass requested representations to constants; implement ConstantS

src/hydrogen-instructions.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1124 matching lines @@
   }
   if (skip_check()) {
     stream->Add(" [DISABLED]");
   }
 }
 
 
 void HBoundsCheck::InferRepresentation(HInferRepresentation* h_infer) {
   ASSERT(CheckFlag(kFlexibleRepresentation));
   Representation r;
+  HValue* actual_index = index()->ActualValue();
   HValue* actual_length = length()->ActualValue();
-  HValue* actual_index = index()->ActualValue();
-  if (key_mode_ == DONT_ALLOW_SMI_KEY ||
-      !actual_length->representation().IsSmiOrTagged()) {
+  Representation index_rep = actual_index->representation();
+  if (!actual_length->representation().IsSmiOrTagged()) {
     r = Representation::Integer32();
-  } else if (actual_index->representation().IsSmiOrTagged() ||
-             (actual_index->IsConstant() &&
-              HConstant::cast(actual_index)->HasSmiValue())) {
-    // If the index is smi, or a constant that holds a Smi, allow the length to
-    // be smi, since it is usually already smi from loading it out of the length
-    // field of a JSArray. This allows for direct comparison without untagging.
+  } else if ((index_rep.IsTagged() && actual_index->type().IsSmi()) ||
+      index_rep.IsSmi()) {
+    // If the index is smi, allow the length to be smi, since it is usually
+    // already smi from loading it out of the length field of a JSArray.  This
+    // allows for direct comparison without untagging.
     r = Representation::Smi();
   } else {
     r = Representation::Integer32();
   }
   UpdateRepresentation(r, h_infer, "boundscheck");
 }
 
 
 bool HBoundsCheckBaseIndexInformation::IsRelationTrueInternal(
     NumericRelation relation,
@@ skipping 2077 matching lines @@
     }
   }
   return new(zone) HStringCharFromCode(context, char_code);
 }
 
 
 HInstruction* HStringLength::New(Zone* zone, HValue* string) {
   if (FLAG_fold_constants && string->IsConstant()) {
     HConstant* c_string = HConstant::cast(string);
     if (c_string->HasStringValue()) {
-      return H_CONSTANT_INT32(c_string->StringValue()->length());
+      return new(zone) HConstant(c_string->StringValue()->length());
     }
   }
   return new(zone) HStringLength(string);
 }
 
 
 HInstruction* HUnaryMathOperation::New(
     Zone* zone, HValue* context, HValue* value, BuiltinFunctionId op) {
   do {
     if (!FLAG_fold_constants) break;
@@ skipping 533 matching lines @@
     case kBackingStore:
       if (!name_.is_null()) stream->Add(*String::cast(*name_)->ToCString());
       stream->Add("[backing-store]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal