Adapt Danno's Track Allocation Info idea to fast literals. When allocating a literal array,

src/ia32/codegen-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 370 matching lines @@
   return FUNCTION_CAST<OS::MemCopyFunction>(buffer);
 }
 
 #undef __
 
 // -------------------------------------------------------------------------
 // Code generators
 
 #define __ ACCESS_MASM(masm)
 
+
 void ElementsTransitionGenerator::GenerateMapChangeElementsTransition(
     MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- eax    : value
   //  -- ebx    : target map
   //  -- ecx    : key
   //  -- edx    : receiver
   //  -- esp[0] : return address
   // -----------------------------------
   // Set transitioned map.
@@ skipping 12 matching lines @@
     MacroAssembler* masm, Label* fail) {
   // ----------- S t a t e -------------
   //  -- eax    : value
   //  -- ebx    : target map
   //  -- ecx    : key
   //  -- edx    : receiver
   //  -- esp[0] : return address
   // -----------------------------------
   Label loop, entry, convert_hole, gc_required, only_change_map;
 
+  if (FLAG_use_allocation_site_info) {
+    masm->PerformAllocationSiteInfoCheck(fail);
+  }
+
   // Check for empty arrays, which only require a map transition and no changes
   // to the backing store.
   __ mov(edi, FieldOperand(edx, JSObject::kElementsOffset));
   __ cmp(edi, Immediate(masm->isolate()->factory()->empty_fixed_array()));
   __ j(equal, &only_change_map);
 
   __ push(eax);
   __ push(ebx);
 
   __ mov(edi, FieldOperand(edi, FixedArray::kLengthOffset));
@@ skipping 115 matching lines @@
     MacroAssembler* masm, Label* fail) {
   // ----------- S t a t e -------------
   //  -- eax    : value
   //  -- ebx    : target map
   //  -- ecx    : key
   //  -- edx    : receiver
   //  -- esp[0] : return address
   // -----------------------------------
   Label loop, entry, convert_hole, gc_required, only_change_map, success;
 
+  // TODO(mvstanton): let's not pre-transition for the double->object case.
+  // if (FLAG_use_allocation_site_info) {
+  //   masm->PerformAllocationSiteInfoCheck(fail);
+  // }

[danno, 2013/01/04 08:50:55]

Just remove this altogether rather than leave it uncommented.

[mvstanton, 2013/01/04 12:07:52]

Done.

+
   // Check for empty arrays, which only require a map transition and no changes
   // to the backing store.
   __ mov(edi, FieldOperand(edx, JSObject::kElementsOffset));
   __ cmp(edi, Immediate(masm->isolate()->factory()->empty_fixed_array()));
   __ j(equal, &only_change_map);
 
   __ push(eax);
   __ push(edx);
   __ push(ebx);
 
@@ skipping 371 matching lines @@
     Code* stub = GetCodeAgeStub(age, parity);
     CodePatcher patcher(sequence, young_length);
     patcher.masm()->call(stub->instruction_start(), RelocInfo::NONE);
   }
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32