Allow monomorphic loads when static type is known.

This allows Crankshaft to generate monomorphic loads when the receiver
type is statically known even though the load site has polymorphic type
feedback. This applies to inlined constructor calls and literals.

R=jkummerow@chromium.org
TEST=mjsunit/compiler/property-static

Review URL: https://codereview.chromium.org/12051058

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13500 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.cc

@@ -571,6 +571,11 @@ void HValue::PrintNameTo(StringStream* stream) {
 }
 
 
+bool HValue::HasMonomorphicJSObjectType() {
+  return !GetMonomorphicJSObjectMap().is_null();
+}
+
+
 bool HValue::UpdateInferredType() {
   HType type = CalculateInferredType();
   bool result = (!type.Equals(type_));

src/hydrogen-instructions.h

@@ -770,6 +770,14 @@ class HValue: public ZoneObject {
 
   const char* Mnemonic() const;
 
+  // Type information helpers.
+  bool HasMonomorphicJSObjectType();
+
+  // TODO(mstarzinger): For now instructions can override this function to
+  // specify statically known types, once HType can convey more information
+  // it should be based on the HType.
+  virtual Handle<Map> GetMonomorphicJSObjectMap() { return Handle<Map>(); }
+
   // Updated the inferred type of this instruction and returns true if
   // it has changed.
   bool UpdateInferredType();
@@ -5019,6 +5027,10 @@ class HAllocateObject: public HTemplateInstruction<1> {
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
+  virtual Handle<Map> GetMonomorphicJSObjectMap() {
+    ASSERT(constructor()->has_initial_map());
+    return Handle<Map>(constructor()->initial_map());
+  }
   virtual HType CalculateInferredType();
 
   DECLARE_CONCRETE_INSTRUCTION(AllocateObject)
@@ -5086,6 +5098,9 @@ class HFastLiteral: public HMaterializedLiteral<1> {
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
+  virtual Handle<Map> GetMonomorphicJSObjectMap() {
+    return Handle<Map>(boilerplate()->map());
+  }
   virtual HType CalculateInferredType();
 
   DECLARE_CONCRETE_INSTRUCTION(FastLiteral)

src/hydrogen.cc

@@ -6796,12 +6796,16 @@ void HOptimizedGraphBuilder::VisitProperty(Property* expr) {
   } else if (expr->key()->IsPropertyName()) {
     Handle<String> name = expr->key()->AsLiteral()->AsPropertyName();
     SmallMapList* types = expr->GetReceiverTypes();
+    HValue* object = Top();
 
-    bool monomorphic = expr->IsMonomorphic();
     Handle<Map> map;
+    bool monomorphic = false;
     if (expr->IsMonomorphic()) {
       map = types->first();
-      if (map->is_dictionary_map()) monomorphic = false;
+      monomorphic = !map->is_dictionary_map();
+    } else if (object->HasMonomorphicJSObjectType()) {
+      map = object->GetMonomorphicJSObjectMap();
+      monomorphic = !map->is_dictionary_map();
     }
     if (monomorphic) {
       Handle<JSFunction> getter;

test/mjsunit/compiler/property-static.js

+// Copyright 2013 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Flags: --allow-natives-syntax
+
+// Test usage of static type information for loads that would otherwise
+// turn into polymorphic or generic loads.
+
+// Prepare a highly polymorphic load to be used by all tests.
+Object.prototype.load = function() { return this.property; };
+Object.prototype.load.call({ A:0, property:10 });
+Object.prototype.load.call({ A:0, B:0, property:11 });
+Object.prototype.load.call({ A:0, B:0, C:0, property:12 });
+Object.prototype.load.call({ A:0, B:0, C:0, D:0, property:13 });
+Object.prototype.load.call({ A:0, B:0, C:0, D:0, E:0, property:14 });
+Object.prototype.load.call({ A:0, B:0, C:0, D:0, E:0, F:0, property:15 });
+
+// Test for object literals.
+(function() {
+  function f(x) {
+    var object = { property:x };
+    return object.load();
+  }
+
+  assertSame(1, f(1));
+  assertSame(2, f(2));
+  %OptimizeFunctionOnNextCall(f);
+  assertSame(3, f(3));
+})();
+
+// Test for inlined constructors.
+(function() {
+  function c(x) {
+    this.property = x;
+  }
+  function f(x) {
+    var object = new c(x);
+    return object.load();
+  }
+
+  assertSame(1, f(1));
+  assertSame(2, f(2));
+  %OptimizeFunctionOnNextCall(f);
+  assertSame(3, f(3));
+})();