Eliminated manual allocation folding in BuildCloneShallowArray.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index ba1de7aa2258a308927c90f937d5d1e6beccd841..2fab7adf9235ae99204af7d4d5f5465de31e8999 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -1679,14 +1679,6 @@ HValue* HGraphBuilder::BuildCloneShallowArray(HValue* boilerplate,
   if (mode == TRACK_ALLOCATION_SITE) {
     size += AllocationMemento::kSize;
   }
-  int elems_offset = size;
-  InstanceType instance_type = IsFastDoubleElementsKind(kind) ?
-      FIXED_DOUBLE_ARRAY_TYPE : FIXED_ARRAY_TYPE;
-  if (length > 0) {
-    size += IsFastDoubleElementsKind(kind)
-        ? FixedDoubleArray::SizeFor(length)
-        : FixedArray::SizeFor(length);
-  }
 
   // Allocate both the JS array and the elements array in one big

[Michael Starzinger, 2013/08/16 20:02:11]

nit: Comment is outdated.

[Hannes Payer (out of office), 2013/08/28 13:10:59]

Done.

   // allocation. This avoids multiple limit checks.
@@ -1694,7 +1686,7 @@ HValue* HGraphBuilder::BuildCloneShallowArray(HValue* boilerplate,
   HInstruction* object = Add<HAllocate>(size_in_bytes,
                                         HType::JSObject(),
                                         NOT_TENURED,
-                                        instance_type);
+                                        JS_OBJECT_TYPE);

[Michael Starzinger, 2013/08/16 20:02:11]

Nice, that would have been a disaster once we would have pretenured these.

 
   // Copy the JS array part.
   for (int i = 0; i < JSArray::kSize; i += kPointerSize) {
@@ -1714,7 +1706,16 @@ HValue* HGraphBuilder::BuildCloneShallowArray(HValue* boilerplate,
     // Get hold of the elements array of the boilerplate and setup the

[Michael Starzinger, 2013/08/16 20:02:11]

nit: Comment is outdated.

[Hannes Payer (out of office), 2013/08/28 13:10:59]

Done.

     // elements pointer in the resulting object.
     HValue* boilerplate_elements = AddLoadElements(boilerplate, NULL);
-    HValue* object_elements = Add<HInnerAllocatedObject>(object, elems_offset);
+    HValue* object_elements;
+    if (IsFastDoubleElementsKind(kind)) {
+      HValue* elems_size = Add<HConstant>(FixedDoubleArray::SizeFor(length));
+      object_elements = Add<HAllocate>(elems_size, HType::JSArray(),
+          NOT_TENURED, FIXED_DOUBLE_ARRAY_TYPE);
+    } else {
+      HValue* elems_size = Add<HConstant>(FixedArray::SizeFor(length));
+      object_elements = Add<HAllocate>(elems_size, HType::JSArray(),
+          NOT_TENURED, FIXED_ARRAY_TYPE);
+    }
     Add<HStoreNamedField>(object, HObjectAccess::ForElementsPointer(),
                           object_elements);