Hydrogen array constructor cleanup and improvements

src/ia32/code-stubs-ia32.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 4682 matching lines @@
   // A monomorphic cache hit or an already megamorphic state: invoke the
   // function without changing the state.
   __ cmp(ecx, edi);
   __ j(equal, &done);
   __ cmp(ecx, Immediate(TypeFeedbackCells::MegamorphicSentinel(isolate)));
   __ j(equal, &done);
 
   // Special handling of the Array() function, which caches not only the
   // monomorphic Array function but the initial ElementsKind with special
   // sentinels
-  Handle<Object> terminal_kind_sentinel =
-      TypeFeedbackCells::MonomorphicArraySentinel(isolate,
-                                                  LAST_FAST_ELEMENTS_KIND);
   __ JumpIfNotSmi(ecx, &miss);
-  __ cmp(ecx, Immediate(terminal_kind_sentinel));
-  __ j(above, &miss);
   // Load the global or builtins object from the current context
   __ LoadGlobalContext(ecx);
   // Make sure the function is the Array() function
   __ cmp(edi, Operand(ecx,
                       Context::SlotOffset(Context::ARRAY_FUNCTION_INDEX)));
   __ j(not_equal, &megamorphic);
   __ jmp(&done);
 
   __ bind(&miss);
 
@@ skipping 3067 matching lines @@
   __ mov(ecx, Operand(esp, kPointerSize));
   __ test(ecx, ecx);
   __ j(zero, &normal_sequence);
 
   // We are going to create a holey array, but our kind is non-holey.
   // Fix kind and retry
   __ inc(edx);
   __ cmp(ebx, Immediate(undefined_sentinel));
   __ j(equal, &normal_sequence);
 
+  // The type cell may have gone megamorphic, don't overwrite if so
+  __ mov(ecx, FieldOperand(ebx, kPointerSize));
+  __ JumpIfNotSmi(ecx, &normal_sequence);
+
   // Save the resulting elements kind in type info
   __ SmiTag(edx);
   __ mov(FieldOperand(ebx, kPointerSize), edx);
   __ SmiUntag(edx);
 
   __ bind(&normal_sequence);
   int last_index = GetSequenceIndexFromFastElementsKind(
       TERMINAL_FAST_ELEMENTS_KIND);
   for (int i = 0; i <= last_index; ++i) {
     Label next;
     ElementsKind kind = GetFastElementsKindFromSequenceIndex(i);
     __ cmp(edx, kind);
     __ j(not_equal, &next);
     ArraySingleArgumentConstructorStub stub(kind);
     __ TailCallStub(&stub);
     __ bind(&next);
   }
 
   // If we reached this point there is a problem.
   __ Abort("Unexpected ElementsKind in array constructor");
 }
 
 
 template<class T>
 static void ArrayConstructorStubAheadOfTimeHelper(Isolate* isolate) {
   int to_index = GetSequenceIndexFromFastElementsKind(
       TERMINAL_FAST_ELEMENTS_KIND);
   for (int i = 0; i <= to_index; ++i) {
     ElementsKind kind = GetFastElementsKindFromSequenceIndex(i);
-    T stub(kind, false);
+    T stub(kind, true, false);
     stub.GetCode(isolate)->set_is_pregenerated(true);
     if (AllocationSiteInfo::GetMode(kind) != DONT_TRACK_ALLOCATION_SITE) {
-      T stub1(kind, true);
+      T stub1(kind, true, true);
       stub1.GetCode(isolate)->set_is_pregenerated(true);
     }
   }
 }
 
 
 void ArrayConstructorStubBase::GenerateStubsAheadOfTime(Isolate* isolate) {
   ArrayConstructorStubAheadOfTimeHelper<ArrayNoArgumentConstructorStub>(
       isolate);
   ArrayConstructorStubAheadOfTimeHelper<ArraySingleArgumentConstructorStub>(
@@ skipping 175 matching lines @@
   __ bind(&fast_elements_case);
   GenerateCase(masm, FAST_ELEMENTS);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32