Make sure transitioned arrays efficiently call builtin Array functions

src/x64/macro-assembler-x64.cc

-// Copyright 2011 the V8 project authors. All rights reserved.
+// 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
 //       with the distribution.
@@ skipping 2723 matching lines @@
   cvtlsi2sd(xmm_scratch, kScratchRegister);
   movsd(FieldOperand(elements, index, times_8, FixedDoubleArray::kHeaderSize),
         xmm_scratch);
   bind(&done);
 }
 
 
 void MacroAssembler::CheckMap(Register obj,
                               Handle<Map> map,
                               Label* fail,
-                              SmiCheckType smi_check_type) {
+                              SmiCheckType smi_check_type,
+                              MapCheckMode mode) {
   if (smi_check_type == DO_SMI_CHECK) {
     JumpIfSmi(obj, fail);
   }
+
+  Label success;
   Cmp(FieldOperand(obj, HeapObject::kMapOffset), map);
+  if (mode == ALLOW_ELEMENT_TRANSITION_MAPS) {

[fschneider, 2012/01/04 09:20:18]

The following code is the same as in lithium-codegen, except there is a branch
at the end instead of the deoptimize. I'd strongly prefer having only one
version of this code around.

[danno, 2012/01/04 10:42:15]

Done.

+    bool ignore;
+    Map* transitioned_double_map =
+        map->LookupElementsTransitionMap(FAST_DOUBLE_ELEMENTS, &ignore);
+    ASSERT(transitioned_double_map == NULL ||
+           map->elements_kind() == FAST_SMI_ONLY_ELEMENTS);
+    Map* transitioned_fast_element_map =
+        map->LookupElementsTransitionMap(FAST_ELEMENTS, &ignore);
+    ASSERT(transitioned_fast_element_map == NULL ||
+           map->elements_kind() != FAST_ELEMENTS);
+    if (transitioned_fast_element_map != NULL) {
+      j(equal, &success, Label::kNear);
+      Cmp(FieldOperand(obj, HeapObject::kMapOffset),
+          Handle<Map>(transitioned_fast_element_map));
+    }
+
+    if (transitioned_double_map != NULL) {
+      j(equal, &success, Label::kNear);
+      Cmp(FieldOperand(obj, HeapObject::kMapOffset),
+          Handle<Map>(transitioned_double_map));
+    }
+  }
   j(not_equal, fail);
+  bind(&success);
 }
 
 
 void MacroAssembler::ClampUint8(Register reg) {
   Label done;
   testl(reg, Immediate(0xFFFFFF00));
   j(zero, &done, Label::kNear);
   setcc(negative, reg);  // 1 if negative, 0 if positive.
   decb(reg);  // 0 if negative, 255 if positive.
   bind(&done);
@@ skipping 1518 matching lines @@
 
   and_(bitmap_scratch, Immediate(~Page::kPageAlignmentMask));
   addl(Operand(bitmap_scratch, MemoryChunk::kLiveBytesOffset), length);
 
   bind(&done);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64