Get rid of HStringLength.

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 3032 matching lines @@
           ? left()->range()->Copy(zone)
           : new(zone) Range();
       result->Shl(c->Integer32Value());
       return result;
     }
   }
   return HValue::InferRange(zone);
 }
 
 
+Range* HLoadNamedField::InferRange(Zone* zone) {
+  if (access().IsStringLength()) {
+    return new(zone) Range(0, String::kMaxLength);
+  }
+  return HValue::InferRange(zone);
+}
+
+
 Range* HLoadKeyed::InferRange(Zone* zone) {
   switch (elements_kind()) {
     case EXTERNAL_PIXEL_ELEMENTS:
       return new(zone) Range(0, 255);
     case EXTERNAL_BYTE_ELEMENTS:
       return new(zone) Range(-128, 127);
     case EXTERNAL_UNSIGNED_BYTE_ELEMENTS:
       return new(zone) Range(0, 255);
     case EXTERNAL_SHORT_ELEMENTS:
       return new(zone) Range(-32768, 32767);
@@ skipping 861 matching lines @@
         return HConstant::New(zone, context,
             LookupSingleCharacterStringFromCode(isolate, code));
       }
       return HConstant::New(zone, context, isolate->factory()->empty_string());
     }
   }
   return new(zone) HStringCharFromCode(context, char_code);
 }
 
 
-HInstruction* HStringLength::New(Zone* zone, HValue* context, HValue* string) {
-  if (FLAG_fold_constants && string->IsConstant()) {
-    HConstant* c_string = HConstant::cast(string);
-    if (c_string->HasStringValue()) {
-      return HConstant::New(zone, context, 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;
     if (!value->IsConstant()) break;
     HConstant* constant = HConstant::cast(value);
     if (!constant->HasNumberValue()) break;
     double d = constant->DoubleValue();
     if (std::isnan(d)) {  // NaN poisons everything.
       return H_CONSTANT_DOUBLE(OS::nan_value());
@@ skipping 457 matching lines @@
     // try to GVN loads, but don't hoist above map changes
     instr->SetFlag(HValue::kUseGVN);
     instr->SetGVNFlag(kDependsOnMaps);
   }
 
   switch (portion()) {
     case kArrayLengths:
       instr->SetGVNFlag(is_store
           ? kChangesArrayLengths : kDependsOnArrayLengths);
       break;
+    case kStringLengths:
+      instr->SetGVNFlag(is_store
+          ? kChangesStringLengths : kDependsOnStringLengths);
+      break;
     case kInobject:
       instr->SetGVNFlag(is_store
           ? kChangesInobjectFields : kDependsOnInobjectFields);
       break;
     case kDouble:
       instr->SetGVNFlag(is_store
           ? kChangesDoubleFields : kDependsOnDoubleFields);
       break;
     case kBackingStore:
       instr->SetGVNFlag(is_store
@@ skipping 13 matching lines @@
       break;
   }
 }
 
 
 void HObjectAccess::PrintTo(StringStream* stream) {
   stream->Add(".");
 
   switch (portion()) {
     case kArrayLengths:
+    case kStringLengths:
       stream->Add("%length");
       break;
     case kElementsPointer:
       stream->Add("%elements");
       break;
     case kMaps:
       stream->Add("%map");
       break;
     case kDouble:  // fall through
     case kInobject:
       if (!name_.is_null()) stream->Add(*String::cast(*name_)->ToCString());
       stream->Add("[in-object]");
       break;
     case kBackingStore:
       if (!name_.is_null()) stream->Add(*String::cast(*name_)->ToCString());
       stream->Add("[backing-store]");
       break;
     case kExternalMemory:
       stream->Add("[external-memory]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal