Make Failure inherit from MaybeObject instead of Object.

src/x64/stub-cache-x64.cc

Index: src/x64/stub-cache-x64.cc
===================================================================
--- src/x64/stub-cache-x64.cc	(revision 5696)
+++ src/x64/stub-cache-x64.cc	(working copy)
@@ -796,13 +796,16 @@
 // Generate code to check that a global property cell is empty. Create
 // the property cell at compilation time if no cell exists for the
 // property.
-static Object* GenerateCheckPropertyCell(MacroAssembler* masm,
-                                         GlobalObject* global,
-                                         String* name,
-                                         Register scratch,
-                                         Label* miss) {
-  Object* probe = global->EnsurePropertyCell(name);
-  if (probe->IsFailure()) return probe;
+MUST_USE_RESULT static MaybeObject* GenerateCheckPropertyCell(
+    MacroAssembler* masm,
+    GlobalObject* global,
+    String* name,
+    Register scratch,
+    Label* miss) {
+  Object* probe;
+  { MaybeObject* maybe_probe = global->EnsurePropertyCell(name);
+    if (!maybe_probe->ToObject(&probe)) return maybe_probe;
+  }
   JSGlobalPropertyCell* cell = JSGlobalPropertyCell::cast(probe);
   ASSERT(cell->value()->IsTheHole());
   __ Move(scratch, Handle<Object>(cell));
@@ -879,19 +882,23 @@
 }
 
 
-Object* CallStubCompiler::GenerateMissBranch() {
-  Object* obj = StubCache::ComputeCallMiss(arguments().immediate(), kind_);
-  if (obj->IsFailure()) return obj;
+MaybeObject* CallStubCompiler::GenerateMissBranch() {
+  Object* obj;
+  { MaybeObject* maybe_obj =
+        StubCache::ComputeCallMiss(arguments().immediate(), kind_);
+    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
+  }
   __ Jump(Handle<Code>(Code::cast(obj)), RelocInfo::CODE_TARGET);
   return obj;
 }
 
 
-Object* CallStubCompiler::CompileCallConstant(Object* object,
-                                              JSObject* holder,
-                                              JSFunction* function,
-                                              String* name,
-                                              StubCompiler::CheckType check) {
+MaybeObject* CallStubCompiler::CompileCallConstant(
+    Object* object,
+    JSObject* holder,
+    JSFunction* function,
+    String* name,
+    StubCompiler::CheckType check) {
   // ----------- S t a t e -------------
   // rcx                 : function name
   // rsp[0]              : return address
@@ -905,8 +912,10 @@
   SharedFunctionInfo* function_info = function->shared();
   if (function_info->HasCustomCallGenerator()) {
     const int id = function_info->custom_call_generator_id();
-    Object* result = CompileCustomCall(
+    MaybeObject* maybe_result = CompileCustomCall(
         id, object, holder,  NULL, function, name);
+    Object* result;
+    if (!maybe_result->ToObject(&result)) return maybe_result;
     // undefined means bail out to regular compiler.
     if (!result->IsUndefined()) return result;
   }
@@ -1034,18 +1043,20 @@
 
   // Handle call cache miss.
   __ bind(&miss_in_smi_check);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
+  Object* obj;
+  { MaybeObject* maybe_obj = GenerateMissBranch();
+    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
+  }
 
   // Return the generated code.
   return GetCode(function);
 }
 
 
-Object* CallStubCompiler::CompileCallField(JSObject* object,
-                                           JSObject* holder,
-                                           int index,
-                                           String* name) {
+MaybeObject* CallStubCompiler::CompileCallField(JSObject* object,
+                                                JSObject* holder,
+                                                int index,
+                                                String* name) {
   // ----------- S t a t e -------------
   // rcx                 : function name
   // rsp[0]              : return address
@@ -1089,19 +1100,21 @@
 
   // Handle call cache miss.
   __ bind(&miss);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
+  Object* obj;
+  { MaybeObject* maybe_obj = GenerateMissBranch();
+    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
+  }
 
   // Return the generated code.
   return GetCode(FIELD, name);
 }
 
 
-Object* CallStubCompiler::CompileArrayPushCall(Object* object,
-                                               JSObject* holder,
-                                               JSGlobalPropertyCell* cell,
-                                               JSFunction* function,
-                                               String* name) {
+MaybeObject* CallStubCompiler::CompileArrayPushCall(Object* object,
+                                                    JSObject* holder,
+                                                    JSGlobalPropertyCell* cell,
+                                                    JSFunction* function,
+                                                    String* name) {
   // ----------- S t a t e -------------
   //  -- rcx                 : name
   //  -- rsp[0]              : return address
@@ -1251,19 +1264,21 @@
   }
 
   __ bind(&miss);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
+  Object* obj;
+  { MaybeObject* maybe_obj = GenerateMissBranch();
+    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
+  }
 
   // Return the generated code.
   return GetCode(function);
 }
 
 
-Object* CallStubCompiler::CompileArrayPopCall(Object* object,
-                                              JSObject* holder,
-                                              JSGlobalPropertyCell* cell,
-                                              JSFunction* function,
-                                              String* name) {
+MaybeObject* CallStubCompiler::CompileArrayPopCall(Object* object,
+                                                   JSObject* holder,
+                                                   JSGlobalPropertyCell* cell,
+                                                   JSFunction* function,
+                                                   String* name) {
   // ----------- S t a t e -------------
   //  -- rcx                 : name
   //  -- rsp[0]              : return address
@@ -1333,19 +1348,22 @@
                                1);
 
   __ bind(&miss);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
+  Object* obj;
+  { MaybeObject* maybe_obj = GenerateMissBranch();
+    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
+  }
 
   // Return the generated code.
   return GetCode(function);
 }
 
 
-Object* CallStubCompiler::CompileStringCharAtCall(Object* object,
-                                                  JSObject* holder,
-                                                  JSGlobalPropertyCell* cell,
-                                                  JSFunction* function,
-                                                  String* name) {
+MaybeObject* CallStubCompiler::CompileStringCharAtCall(
+    Object* object,
+    JSObject* holder,
+    JSGlobalPropertyCell* cell,
+    JSFunction* function,
+    String* name) {
   // ----------- S t a t e -------------
   //  -- rcx                 : function name
   //  -- rsp[0]              : return address
@@ -1405,15 +1423,17 @@
   __ ret((argc + 1) * kPointerSize);
 
   __ bind(&miss);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
+  Object* obj;
+  { MaybeObject* maybe_obj = GenerateMissBranch();
+    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
+  }
 
   // Return the generated code.
   return GetCode(function);
 }
 
 
-Object* CallStubCompiler::CompileStringCharCodeAtCall(
+MaybeObject* CallStubCompiler::CompileStringCharCodeAtCall(
     Object* object,
     JSObject* holder,
     JSGlobalPropertyCell* cell,
@@ -1475,15 +1495,17 @@
   __ ret((argc + 1) * kPointerSize);
 
   __ bind(&miss);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
+  Object* obj;
+  { MaybeObject* maybe_obj = GenerateMissBranch();
+    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
+  }
 
   // Return the generated code.
   return GetCode(function);
 }
 
 
-Object* CallStubCompiler::CompileStringFromCharCodeCall(
+MaybeObject* CallStubCompiler::CompileStringFromCharCodeCall(
     Object* object,
     JSObject* holder,
     JSGlobalPropertyCell* cell,
@@ -1544,29 +1566,31 @@
 
   __ bind(&miss);
   // rcx: function name.
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
+  Object* obj;
+  { MaybeObject* maybe_obj = GenerateMissBranch();
+    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
+  }
 
   // Return the generated code.
   return (cell == NULL) ? GetCode(function) : GetCode(NORMAL, name);
 }
 
 
-Object* CallStubCompiler::CompileMathFloorCall(Object* object,
-                                               JSObject* holder,
-                                               JSGlobalPropertyCell* cell,
-                                               JSFunction* function,
-                                               String* name) {
+MaybeObject* CallStubCompiler::CompileMathFloorCall(Object* object,
+                                                    JSObject* holder,
+                                                    JSGlobalPropertyCell* cell,
+                                                    JSFunction* function,
+                                                    String* name) {
   // TODO(872): implement this.
   return Heap::undefined_value();
 }
 
 
-Object* CallStubCompiler::CompileMathAbsCall(Object* object,
-                                             JSObject* holder,
-                                             JSGlobalPropertyCell* cell,
-                                             JSFunction* function,
-                                             String* name) {
+MaybeObject* CallStubCompiler::CompileMathAbsCall(Object* object,
+                                                  JSObject* holder,
+                                                  JSGlobalPropertyCell* cell,
+                                                  JSFunction* function,
+                                                  String* name) {
   // ----------- S t a t e -------------
   //  -- rcx                 : function name
   //  -- rsp[0]              : return address
@@ -1657,17 +1681,19 @@
 
   __ bind(&miss);
   // rcx: function name.
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
+  Object* obj;
+  { MaybeObject* maybe_obj = GenerateMissBranch();
+    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
+  }
 
   // Return the generated code.
   return (cell == NULL) ? GetCode(function) : GetCode(NORMAL, name);
 }
 
 
-Object* CallStubCompiler::CompileCallInterceptor(JSObject* object,
-                                                 JSObject* holder,
-                                                 String* name) {
+MaybeObject* CallStubCompiler::CompileCallInterceptor(JSObject* object,
+                                                      JSObject* holder,
+                                                      String* name) {
   // ----------- S t a t e -------------
   // rcx                 : function name
   // rsp[0]              : return address
@@ -1723,19 +1749,21 @@
 
   // Handle load cache miss.
   __ bind(&miss);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
+  Object* obj;
+  { MaybeObject* maybe_obj = GenerateMissBranch();
+    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
+  }
 
   // Return the generated code.
   return GetCode(INTERCEPTOR, name);
 }
 
 
-Object* CallStubCompiler::CompileCallGlobal(JSObject* object,
-                                            GlobalObject* holder,
-                                            JSGlobalPropertyCell* cell,
-                                            JSFunction* function,
-                                            String* name) {
+MaybeObject* CallStubCompiler::CompileCallGlobal(JSObject* object,
+                                                 GlobalObject* holder,
+                                                 JSGlobalPropertyCell* cell,
+                                                 JSFunction* function,
+                                                 String* name) {
   // ----------- S t a t e -------------
   // rcx                 : function name
   // rsp[0]              : return address
@@ -1749,8 +1777,10 @@
   SharedFunctionInfo* function_info = function->shared();
   if (function_info->HasCustomCallGenerator()) {
     const int id = function_info->custom_call_generator_id();
-    Object* result = CompileCustomCall(
+    MaybeObject* maybe_result = CompileCustomCall(
         id, object, holder, cell, function, name);
+    Object* result;
+    if (!maybe_result->ToObject(&result)) return maybe_result;
     // undefined means bail out to regular compiler.
     if (!result->IsUndefined()) return result;
   }
@@ -1786,18 +1816,20 @@
   // Handle call cache miss.
   __ bind(&miss);
   __ IncrementCounter(&Counters::call_global_inline_miss, 1);
-  Object* obj = GenerateMissBranch();
-  if (obj->IsFailure()) return obj;
+  Object* obj;
+  { MaybeObject* maybe_obj = GenerateMissBranch();
+    if (!maybe_obj->ToObject(&obj)) return maybe_obj;
+  }
 
   // Return the generated code.
   return GetCode(NORMAL, name);
 }
 
 
-Object* LoadStubCompiler::CompileLoadCallback(String* name,
-                                              JSObject* object,
-                                              JSObject* holder,
-                                              AccessorInfo* callback) {
+MaybeObject* LoadStubCompiler::CompileLoadCallback(String* name,
+                                                   JSObject* object,
+                                                   JSObject* holder,
+                                                   AccessorInfo* callback) {
   // ----------- S t a t e -------------
   //  -- rax    : receiver
   //  -- rcx    : name
@@ -1821,10 +1853,10 @@
 }
 
 
-Object* LoadStubCompiler::CompileLoadConstant(JSObject* object,
-                                              JSObject* holder,
-                                              Object* value,
-                                              String* name) {
+MaybeObject* LoadStubCompiler::CompileLoadConstant(JSObject* object,
+                                                   JSObject* holder,
+                                                   Object* value,
+                                                   String* name) {
   // ----------- S t a t e -------------
   //  -- rax    : receiver
   //  -- rcx    : name
@@ -1841,9 +1873,9 @@
 }
 
 
-Object* LoadStubCompiler::CompileLoadNonexistent(String* name,
-                                                 JSObject* object,
-                                                 JSObject* last) {
+MaybeObject* LoadStubCompiler::CompileLoadNonexistent(String* name,
+                                                      JSObject* object,
+                                                      JSObject* last) {
   // ----------- S t a t e -------------
   //  -- rax    : receiver
   //  -- rcx    : name
@@ -1862,11 +1894,11 @@
   // If the last object in the prototype chain is a global object,
   // check that the global property cell is empty.
   if (last->IsGlobalObject()) {
-    Object* cell = GenerateCheckPropertyCell(masm(),
-                                             GlobalObject::cast(last),
-                                             name,
-                                             rdx,
-                                             &miss);
+    MaybeObject* cell = GenerateCheckPropertyCell(masm(),
+                                                  GlobalObject::cast(last),
+                                                  name,
+                                                  rdx,
+                                                  &miss);
     if (cell->IsFailure()) {
       miss.Unuse();
       return cell;
@@ -1886,10 +1918,10 @@
 }
 
 
-Object* LoadStubCompiler::CompileLoadField(JSObject* object,
-                                           JSObject* holder,
-                                           int index,
-                                           String* name) {
+MaybeObject* LoadStubCompiler::CompileLoadField(JSObject* object,
+                                                JSObject* holder,
+                                                int index,
+                                                String* name) {
   // ----------- S t a t e -------------
   //  -- rax    : receiver
   //  -- rcx    : name
@@ -1906,9 +1938,9 @@
 }
 
 
-Object* LoadStubCompiler::CompileLoadInterceptor(JSObject* receiver,
-                                                 JSObject* holder,
-                                                 String* name) {
+MaybeObject* LoadStubCompiler::CompileLoadInterceptor(JSObject* receiver,
+                                                      JSObject* holder,
+                                                      String* name) {
   // ----------- S t a t e -------------
   //  -- rax    : receiver
   //  -- rcx    : name
@@ -1940,11 +1972,11 @@
 }
 
 
-Object* LoadStubCompiler::CompileLoadGlobal(JSObject* object,
-                                            GlobalObject* holder,
-                                            JSGlobalPropertyCell* cell,
-                                            String* name,
-                                            bool is_dont_delete) {
+MaybeObject* LoadStubCompiler::CompileLoadGlobal(JSObject* object,
+                                                 GlobalObject* holder,
+                                                 JSGlobalPropertyCell* cell,
+                                                 String* name,
+                                                 bool is_dont_delete) {
   // ----------- S t a t e -------------
   //  -- rax    : receiver
   //  -- rcx    : name
@@ -1988,10 +2020,11 @@
 }
 
 
-Object* KeyedLoadStubCompiler::CompileLoadCallback(String* name,
-                                                   JSObject* receiver,
-                                                   JSObject* holder,
-                                                   AccessorInfo* callback) {
+MaybeObject* KeyedLoadStubCompiler::CompileLoadCallback(
+    String* name,
+    JSObject* receiver,
+    JSObject* holder,
+    AccessorInfo* callback) {
   // ----------- S t a t e -------------
   //  -- rax     : key
   //  -- rdx     : receiver
@@ -2022,7 +2055,7 @@
 }
 
 
-Object* KeyedLoadStubCompiler::CompileLoadArrayLength(String* name) {
+MaybeObject* KeyedLoadStubCompiler::CompileLoadArrayLength(String* name) {
   // ----------- S t a t e -------------
   //  -- rax    : key
   //  -- rdx    : receiver
@@ -2046,10 +2079,10 @@
 }
 
 
-Object* KeyedLoadStubCompiler::CompileLoadConstant(String* name,
-                                                   JSObject* receiver,
-                                                   JSObject* holder,
-                                                   Object* value) {
+MaybeObject* KeyedLoadStubCompiler::CompileLoadConstant(String* name,
+                                                        JSObject* receiver,
+                                                        JSObject* holder,
+                                                        Object* value) {
   // ----------- S t a t e -------------
   //  -- rax    : key
   //  -- rdx    : receiver
@@ -2074,7 +2107,7 @@
 }
 
 
-Object* KeyedLoadStubCompiler::CompileLoadFunctionPrototype(String* name) {
+MaybeObject* KeyedLoadStubCompiler::CompileLoadFunctionPrototype(String* name) {
   // ----------- S t a t e -------------
   //  -- rax    : key
   //  -- rdx    : receiver
@@ -2098,9 +2131,9 @@
 }
 
 
-Object* KeyedLoadStubCompiler::CompileLoadInterceptor(JSObject* receiver,
-                                                      JSObject* holder,
-                                                      String* name) {
+MaybeObject* KeyedLoadStubCompiler::CompileLoadInterceptor(JSObject* receiver,
+                                                           JSObject* holder,
+                                                           String* name) {
   // ----------- S t a t e -------------
   //  -- rax    : key
   //  -- rdx    : receiver
@@ -2135,7 +2168,7 @@
 }
 
 
-Object* KeyedLoadStubCompiler::CompileLoadStringLength(String* name) {
+MaybeObject* KeyedLoadStubCompiler::CompileLoadStringLength(String* name) {
   // ----------- S t a t e -------------
   //  -- rax    : key
   //  -- rdx    : receiver
@@ -2159,9 +2192,9 @@
 }
 
 
-Object* StoreStubCompiler::CompileStoreCallback(JSObject* object,
-                                                AccessorInfo* callback,
-                                                String* name) {
+MaybeObject* StoreStubCompiler::CompileStoreCallback(JSObject* object,
+                                                     AccessorInfo* callback,
+                                                     String* name) {
   // ----------- S t a t e -------------
   //  -- rax    : value
   //  -- rcx    : name
@@ -2209,10 +2242,10 @@
 }
 
 
-Object* StoreStubCompiler::CompileStoreField(JSObject* object,
-                                             int index,
-                                             Map* transition,
-                                             String* name) {
+MaybeObject* StoreStubCompiler::CompileStoreField(JSObject* object,
+                                                  int index,
+                                                  Map* transition,
+                                                  String* name) {
   // ----------- S t a t e -------------
   //  -- rax    : value
   //  -- rcx    : name
@@ -2239,8 +2272,8 @@
 }
 
 
-Object* StoreStubCompiler::CompileStoreInterceptor(JSObject* receiver,
-                                                   String* name) {
+MaybeObject* StoreStubCompiler::CompileStoreInterceptor(JSObject* receiver,
+                                                        String* name) {
   // ----------- S t a t e -------------
   //  -- rax    : value
   //  -- rcx    : name
@@ -2287,9 +2320,9 @@
 }
 
 
-Object* StoreStubCompiler::CompileStoreGlobal(GlobalObject* object,
-                                              JSGlobalPropertyCell* cell,
-                                              String* name) {
+MaybeObject* StoreStubCompiler::CompileStoreGlobal(GlobalObject* object,
+                                                   JSGlobalPropertyCell* cell,
+                                                   String* name) {
   // ----------- S t a t e -------------
   //  -- rax    : value
   //  -- rcx    : name
@@ -2322,10 +2355,10 @@
 }
 
 
-Object* KeyedLoadStubCompiler::CompileLoadField(String* name,
-                                                JSObject* receiver,
-                                                JSObject* holder,
-                                                int index) {
+MaybeObject* KeyedLoadStubCompiler::CompileLoadField(String* name,
+                                                     JSObject* receiver,
+                                                     JSObject* holder,
+                                                     int index) {
   // ----------- S t a t e -------------
   //  -- rax     : key
   //  -- rdx     : receiver
@@ -2350,10 +2383,10 @@
 }
 
 
-Object* KeyedStoreStubCompiler::CompileStoreField(JSObject* object,
-                                                  int index,
-                                                  Map* transition,
-                                                  String* name) {
+MaybeObject* KeyedStoreStubCompiler::CompileStoreField(JSObject* object,
+                                                       int index,
+                                                       Map* transition,
+                                                       String* name) {
   // ----------- S t a t e -------------
   //  -- rax     : value
   //  -- rcx     : key
@@ -2591,7 +2624,7 @@
   // already generated).  Do not allow the assembler to perform a
   // garbage collection but instead return the allocation failure
   // object.
-  Object* result = masm()->TryCallStub(&stub);
+  MaybeObject* result = masm()->TryCallStub(&stub);
   if (result->IsFailure()) {
     *failure = Failure::cast(result);
     return false;
@@ -2647,12 +2680,12 @@
         !current->IsJSGlobalObject() &&
         !current->IsJSGlobalProxy()) {
       if (!name->IsSymbol()) {
-        Object* lookup_result = Heap::LookupSymbol(name);
+        MaybeObject* lookup_result = Heap::LookupSymbol(name);
         if (lookup_result->IsFailure()) {
           set_failure(Failure::cast(lookup_result));
           return reg;
         } else {
-          name = String::cast(lookup_result);
+          name = String::cast(lookup_result->ToObjectUnchecked());
         }
       }
       ASSERT(current->property_dictionary()->FindEntry(name) ==
@@ -2734,11 +2767,11 @@
   current = object;
   while (current != holder) {
     if (current->IsGlobalObject()) {
-      Object* cell = GenerateCheckPropertyCell(masm(),
-                                               GlobalObject::cast(current),
-                                               name,
-                                               scratch1,
-                                               miss);
+      MaybeObject* cell = GenerateCheckPropertyCell(masm(),
+                                                    GlobalObject::cast(current),
+                                                    name,
+                                                    scratch1,
+                                                    miss);
       if (cell->IsFailure()) {
         set_failure(Failure::cast(cell));
         return reg;
@@ -2800,7 +2833,7 @@
 
 // Specialized stub for constructing objects from functions which only have only
 // simple assignments of the form this.x = ...; in their body.
-Object* ConstructStubCompiler::CompileConstructStub(
+MaybeObject* ConstructStubCompiler::CompileConstructStub(
     SharedFunctionInfo* shared) {
   // ----------- S t a t e -------------
   //  -- rax : argc