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

src/arm/code-stubs-arm.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 326 matching lines @@
   // Need to collect. Call into runtime system.
   __ bind(&gc);
   __ TailCallRuntime(Runtime::kPushBlockContext, 2, 1);
 }
 
 
 static void GenerateFastCloneShallowArrayCommon(
     MacroAssembler* masm,
     int length,
     FastCloneShallowArrayStub::Mode mode,
+    AllocationSiteInfoMode allocation_site_info_mode,

[danno, 2013/01/07 08:03:48]

Do we really need a new enum type for this (yet?). It seems that you can discern
whether an AllocationSiteInfo is necessary directly from mode, and since we
don't yet have allocation routines that would only need AllocationSiteInfoMode
without some other context, maybe it makes sense to postpone adding the enum
until that time?

[mvstanton, 2013/01/07 09:28:41]

As we discussed, I'll keep it because this helper method is a bit quirky,
asserting that the mode flag is just a specific subset of the possible values.
That has the effect of splitting off the allocation site info decision into
another flag. I'd also like to keep the decision about doing or not doing
certain pretransitions (such as the problematic DOUBLE->FAST) upstream...it is
handled at a higher level.

     Label* fail) {
   // Registers on entry:
   //
   // r3: boilerplate literal array.
   ASSERT(mode != FastCloneShallowArrayStub::CLONE_ANY_ELEMENTS);
 
   // All sizes here are multiples of kPointerSize.
   int elements_size = 0;
   if (length > 0) {
     elements_size = mode == FastCloneShallowArrayStub::CLONE_DOUBLE_ELEMENTS
         ? FixedDoubleArray::SizeFor(length)
         : FixedArray::SizeFor(length);
   }
-  int size = JSArray::kSize + elements_size;
+  int size = JSArray::kSize;
+  int allocation_info_start = size;
+  if (allocation_site_info_mode == TRACK_ALLOCATION_SITE_INFO) {
+    size += AllocationSiteInfo::kSize;
+  }
+  size += elements_size;
 
   // Allocate both the JS array and the elements array in one big
   // allocation. This avoids multiple limit checks.
   AllocationFlags flags = TAG_OBJECT;
   if (mode == FastCloneShallowArrayStub::CLONE_DOUBLE_ELEMENTS) {
     flags = static_cast<AllocationFlags>(DOUBLE_ALIGNMENT | flags);
   }
   __ AllocateInNewSpace(size, r0, r1, r2, fail, flags);
 
+  if (allocation_site_info_mode == TRACK_ALLOCATION_SITE_INFO) {
+    __ mov(r2, Operand(Handle<Map>(masm->isolate()->heap()->
+                                   allocation_site_info_map())));
+    __ str(r2, FieldMemOperand(r0, allocation_info_start));
+    __ str(r3, FieldMemOperand(r0, allocation_info_start + kPointerSize));
+  }
+
   // Copy the JS array part.
   for (int i = 0; i < JSArray::kSize; i += kPointerSize) {
     if ((i != JSArray::kElementsOffset) || (length == 0)) {
       __ ldr(r1, FieldMemOperand(r3, i));
       __ str(r1, FieldMemOperand(r0, i));
     }
   }
 
   if (length > 0) {
     // Get hold of the elements array of the boilerplate and setup the
     // elements pointer in the resulting object.
     __ ldr(r3, FieldMemOperand(r3, JSArray::kElementsOffset));
-    __ add(r2, r0, Operand(JSArray::kSize));
+    if (allocation_site_info_mode == TRACK_ALLOCATION_SITE_INFO) {
+      __ add(r2, r0, Operand(JSArray::kSize + AllocationSiteInfo::kSize));
+    } else {
+      __ add(r2, r0, Operand(JSArray::kSize));
+    }
     __ str(r2, FieldMemOperand(r0, JSArray::kElementsOffset));
 
     // Copy the elements array.
     ASSERT((elements_size % kPointerSize) == 0);
     __ CopyFields(r2, r3, r1.bit(), elements_size / kPointerSize);
   }
 }
 
 void FastCloneShallowArrayStub::Generate(MacroAssembler* masm) {
   // Stack layout on entry:
   //
   // [sp]: constant elements.
   // [sp + kPointerSize]: literal index.
   // [sp + (2 * kPointerSize)]: literals array.
 
   // Load boilerplate object into r3 and check if we need to create a
   // boilerplate.
   Label slow_case;
   __ ldr(r3, MemOperand(sp, 2 * kPointerSize));
   __ ldr(r0, MemOperand(sp, 1 * kPointerSize));
   __ add(r3, r3, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
   __ ldr(r3, MemOperand(r3, r0, LSL, kPointerSizeLog2 - kSmiTagSize));
   __ CompareRoot(r3, Heap::kUndefinedValueRootIndex);
   __ b(eq, &slow_case);
 
   FastCloneShallowArrayStub::Mode mode = mode_;
+  AllocationSiteInfoMode allocation_site_info_mode =
+      DONT_TRACK_ALLOCATION_SITE_INFO;
+  if (mode == CLONE_ANY_ELEMENTS_WITH_ALLOCATION_SITE_INFO) {
+    mode = CLONE_ANY_ELEMENTS;
+    allocation_site_info_mode = TRACK_ALLOCATION_SITE_INFO;
+  }
+
   if (mode == CLONE_ANY_ELEMENTS) {
     Label double_elements, check_fast_elements;
     __ ldr(r0, FieldMemOperand(r3, JSArray::kElementsOffset));
     __ ldr(r0, FieldMemOperand(r0, HeapObject::kMapOffset));
     __ CompareRoot(r0, Heap::kFixedCOWArrayMapRootIndex);
     __ b(ne, &check_fast_elements);
     GenerateFastCloneShallowArrayCommon(masm, 0,
-                                        COPY_ON_WRITE_ELEMENTS, &slow_case);
+                                        COPY_ON_WRITE_ELEMENTS,
+                                        allocation_site_info_mode,
+                                        &slow_case);
     // Return and remove the on-stack parameters.
     __ add(sp, sp, Operand(3 * kPointerSize));
     __ Ret();
 
     __ bind(&check_fast_elements);
     __ CompareRoot(r0, Heap::kFixedArrayMapRootIndex);
     __ b(ne, &double_elements);
     GenerateFastCloneShallowArrayCommon(masm, length_,
-                                        CLONE_ELEMENTS, &slow_case);
+                                        CLONE_ELEMENTS,
+                                        allocation_site_info_mode,
+                                        &slow_case);
     // Return and remove the on-stack parameters.
     __ add(sp, sp, Operand(3 * kPointerSize));
     __ Ret();
 
     __ bind(&double_elements);
     mode = CLONE_DOUBLE_ELEMENTS;
     // Fall through to generate the code to handle double elements.
   }
 
   if (FLAG_debug_code) {
@@ skipping 11 matching lines @@
       expected_map_index = Heap::kFixedCOWArrayMapRootIndex;
     }
     __ push(r3);
     __ ldr(r3, FieldMemOperand(r3, JSArray::kElementsOffset));
     __ ldr(r3, FieldMemOperand(r3, HeapObject::kMapOffset));
     __ CompareRoot(r3, expected_map_index);
     __ Assert(eq, message);
     __ pop(r3);
   }
 
-  GenerateFastCloneShallowArrayCommon(masm, length_, mode, &slow_case);
+  GenerateFastCloneShallowArrayCommon(masm, length_, mode,
+                                      allocation_site_info_mode, &slow_case);
 
   // Return and remove the on-stack parameters.
   __ add(sp, sp, Operand(3 * kPointerSize));
   __ Ret();
 
   __ bind(&slow_case);
   __ TailCallRuntime(Runtime::kCreateArrayLiteralShallow, 3, 1);
 }
 
 
@@ skipping 7242 matching lines @@
 
   __ Pop(lr, r5, r1);
   __ Ret();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM