Improve handling of property loads on the proto chain.

Previously Crankshaft emitted a generic load for these, now we emit a load of a
named field, guarded by a proto chain check.

LCheckPrototypeMaps now returns the holder, which is for free, because it
already had to check its map as the last step, anyway. This is in sync with what
StubCompiler::CheckPrototype does.

Review URL: https://codereview.chromium.org/11338030

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12847 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/lithium-arm.cc

@@ -1680,10 +1680,10 @@ LInstruction* LChunkBuilder::DoCheckInstanceType(HCheckInstanceType* instr) {
 
 
 LInstruction* LChunkBuilder::DoCheckPrototypeMaps(HCheckPrototypeMaps* instr) {
-  LOperand* temp1 = TempRegister();
+  LUnallocated* temp1 = TempRegister();
   LOperand* temp2 = TempRegister();
-  LInstruction* result = new(zone()) LCheckPrototypeMaps(temp1, temp2);
-  return AssignEnvironment(result);
+  LCheckPrototypeMaps* result = new(zone()) LCheckPrototypeMaps(temp1, temp2);
+  return AssignEnvironment(Define(result, temp1));
 }
 
 

src/arm/lithium-arm.h

@@ -2052,7 +2052,7 @@ class LCheckMaps: public LTemplateInstruction<0, 1, 0> {
 };
 
 
-class LCheckPrototypeMaps: public LTemplateInstruction<0, 0, 2> {
+class LCheckPrototypeMaps: public LTemplateInstruction<1, 0, 2> {
  public:
   LCheckPrototypeMaps(LOperand* temp, LOperand* temp2)  {
     temps_[0] = temp;

src/arm/lithium-codegen-arm.cc

@@ -4931,6 +4931,7 @@ void LCodeGen::DoClampTToUint8(LClampTToUint8* instr) {
 
 
 void LCodeGen::DoCheckPrototypeMaps(LCheckPrototypeMaps* instr) {
+  ASSERT(instr->temp()->Equals(instr->result()));
   Register temp1 = ToRegister(instr->temp());
   Register temp2 = ToRegister(instr->temp2());
 

src/hydrogen-instructions.cc

@@ -2539,12 +2539,6 @@ void HCheckFunction::Verify() {
   ASSERT(HasNoUses());
 }
 
-
-void HCheckPrototypeMaps::Verify() {
-  HInstruction::Verify();
-  ASSERT(HasNoUses());
-}
-
 #endif
 
 } }  // namespace v8::internal

src/hydrogen-instructions.h

@@ -2376,10 +2376,6 @@ class HCheckPrototypeMaps: public HTemplateInstruction<0> {
     SetGVNFlag(kDependsOnMaps);
   }
 
-#ifdef DEBUG
-  virtual void Verify();
-#endif
-
   Handle<JSObject> prototype() const { return prototype_; }
   Handle<JSObject> holder() const { return holder_; }
 

src/hydrogen.cc

@@ -6012,6 +6012,19 @@ HInstruction* HGraphBuilder::BuildLoadNamedMonomorphic(HValue* object,
     return new(zone()) HConstant(function, Representation::Tagged());
   }
 
+  // Handle a load from a known field somewhere in the protoype chain.
+  LookupInPrototypes(map, name, &lookup);
+  if (lookup.IsField()) {
+    Handle<JSObject> prototype(JSObject::cast(map->prototype()));
+    Handle<JSObject> holder(lookup.holder());
+    Handle<Map> holder_map(holder->map());
+    AddInstruction(new(zone()) HCheckNonSmi(object));
+    AddInstruction(HCheckMaps::NewWithTransitions(object, map, zone()));
+    HInstruction* holder_value =
+        AddInstruction(new(zone()) HCheckPrototypeMaps(prototype, holder));
+    return BuildLoadNamedField(holder_value, holder_map, &lookup, false);
+  }
+
   // No luck, do a generic load.
   return BuildLoadNamedGeneric(object, name, expr);
 }

src/ia32/lithium-codegen-ia32.cc

@@ -4775,6 +4775,7 @@ void LCodeGen::DoClampTToUint8(LClampTToUint8* instr) {
 
 
 void LCodeGen::DoCheckPrototypeMaps(LCheckPrototypeMaps* instr) {
+  ASSERT(instr->temp()->Equals(instr->result()));
   Register reg = ToRegister(instr->temp());
 
   Handle<JSObject> holder = instr->holder();

src/ia32/lithium-ia32.cc

@@ -1734,9 +1734,9 @@ LInstruction* LChunkBuilder::DoCheckInstanceType(HCheckInstanceType* instr) {
 
 
 LInstruction* LChunkBuilder::DoCheckPrototypeMaps(HCheckPrototypeMaps* instr) {
-  LOperand* temp = TempRegister();
+  LUnallocated* temp = TempRegister();
   LCheckPrototypeMaps* result = new(zone()) LCheckPrototypeMaps(temp);
-  return AssignEnvironment(result);
+  return AssignEnvironment(Define(result, temp));
 }
 
 

src/ia32/lithium-ia32.h

@@ -2148,7 +2148,7 @@ class LCheckMaps: public LTemplateInstruction<0, 1, 0> {
 };
 
 
-class LCheckPrototypeMaps: public LTemplateInstruction<0, 0, 1> {
+class LCheckPrototypeMaps: public LTemplateInstruction<1, 0, 1> {
  public:
   explicit LCheckPrototypeMaps(LOperand* temp)  {
     temps_[0] = temp;

src/mips/lithium-codegen-mips.cc

@@ -4637,6 +4637,7 @@ void LCodeGen::DoClampTToUint8(LClampTToUint8* instr) {
 
 
 void LCodeGen::DoCheckPrototypeMaps(LCheckPrototypeMaps* instr) {
+  ASSERT(instr->temp()->Equals(instr->result()));
   Register temp1 = ToRegister(instr->temp());
   Register temp2 = ToRegister(instr->temp2());
 

src/mips/lithium-mips.cc

@@ -1626,10 +1626,10 @@ LInstruction* LChunkBuilder::DoCheckInstanceType(HCheckInstanceType* instr) {
 
 
 LInstruction* LChunkBuilder::DoCheckPrototypeMaps(HCheckPrototypeMaps* instr) {
-  LOperand* temp1 = TempRegister();
+  LUnallocated* temp1 = TempRegister();
   LOperand* temp2 = TempRegister();
-  LInstruction* result = new(zone()) LCheckPrototypeMaps(temp1, temp2);
-  return AssignEnvironment(result);
+  LCheckPrototypeMaps* result = new(zone()) LCheckPrototypeMaps(temp1, temp2);
+  return AssignEnvironment(Define(result, temp1));
 }
 
 

src/mips/lithium-mips.h

@@ -2115,7 +2115,7 @@ class LCheckMaps: public LTemplateInstruction<0, 1, 0> {
 };
 
 
-class LCheckPrototypeMaps: public LTemplateInstruction<0, 0, 2> {
+class LCheckPrototypeMaps: public LTemplateInstruction<1, 0, 2> {
  public:
   LCheckPrototypeMaps(LOperand* temp, LOperand* temp2)  {
     temps_[0] = temp;

src/x64/lithium-codegen-x64.cc

@@ -4561,6 +4561,7 @@ void LCodeGen::DoClampTToUint8(LClampTToUint8* instr) {
 
 
 void LCodeGen::DoCheckPrototypeMaps(LCheckPrototypeMaps* instr) {
+  ASSERT(instr->temp()->Equals(instr->result()));
   Register reg = ToRegister(instr->temp());
 
   Handle<JSObject> holder = instr->holder();

src/x64/lithium-x64.cc

@@ -1658,9 +1658,9 @@ LInstruction* LChunkBuilder::DoCheckInstanceType(HCheckInstanceType* instr) {
 
 
 LInstruction* LChunkBuilder::DoCheckPrototypeMaps(HCheckPrototypeMaps* instr) {
-  LOperand* temp = TempRegister();
+  LUnallocated* temp = TempRegister();
   LCheckPrototypeMaps* result = new(zone()) LCheckPrototypeMaps(temp);
-  return AssignEnvironment(result);
+  return AssignEnvironment(Define(result, temp));
 }
 
 

src/x64/lithium-x64.h

@@ -2028,7 +2028,7 @@ class LCheckMaps: public LTemplateInstruction<0, 1, 0> {
 };
 
 
-class LCheckPrototypeMaps: public LTemplateInstruction<0, 0, 1> {
+class LCheckPrototypeMaps: public LTemplateInstruction<1, 0, 1> {
  public:
   explicit LCheckPrototypeMaps(LOperand* temp)  {
     temps_[0] = temp;

test/mjsunit/compiler/proto-chain-load.js

+// 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
+//       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 HLoadNamedField on the proto chain.
+
+var obj4 = Object.create(null, { f4: {value: 4} });
+var obj3 = Object.create(obj4, { f3: {value: 3} });
+var obj2 = Object.create(obj3, { f2: {value: 2} });
+var obj1 = Object.create(obj2, { f1: {value: 1} });
+var obj0 = Object.create(obj1, { f0: {value: 0} });
+
+function get4(obj) { return obj.f4; }
+
+assertEquals(4, get4(obj0));
+assertEquals(4, get4(obj0));
+%OptimizeFunctionOnNextCall(get4);
+assertEquals(4, get4(obj0));
+assertEquals(4, get4(obj0));