Implement tracking and optimizations of packed arrays

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index 3d380a26440fbbaa308da7baaeefd5096efff738..6308fa323532fca430c022948bc31bbbfedb8f5c 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -2658,10 +2658,12 @@ void MacroAssembler::CmpInstanceType(Register map, InstanceType type) {
 void MacroAssembler::CheckFastElements(Register map,
                                        Label* fail,
                                        Label::Distance distance) {
-  STATIC_ASSERT(FAST_SMI_ONLY_ELEMENTS == 0);
-  STATIC_ASSERT(FAST_ELEMENTS == 1);
+  STATIC_ASSERT(FAST_SMI_ELEMENTS == 0);
+  STATIC_ASSERT(FAST_HOLEY_SMI_ELEMENTS == 1);
+  STATIC_ASSERT(FAST_ELEMENTS == 2);
+  STATIC_ASSERT(FAST_HOLEY_ELEMENTS == 3);
   cmpb(FieldOperand(map, Map::kBitField2Offset),
-       Immediate(Map::kMaximumBitField2FastElementValue));
+       Immediate(Map::kMaximumBitField2FastHoleyElementValue));
   j(above, fail, distance);
 }
 
@@ -2669,23 +2671,26 @@ void MacroAssembler::CheckFastElements(Register map,
 void MacroAssembler::CheckFastObjectElements(Register map,
                                              Label* fail,
                                              Label::Distance distance) {
-  STATIC_ASSERT(FAST_SMI_ONLY_ELEMENTS == 0);
-  STATIC_ASSERT(FAST_ELEMENTS == 1);
+  STATIC_ASSERT(FAST_SMI_ELEMENTS == 0);
+  STATIC_ASSERT(FAST_HOLEY_SMI_ELEMENTS == 1);
+  STATIC_ASSERT(FAST_ELEMENTS == 2);
+  STATIC_ASSERT(FAST_HOLEY_ELEMENTS == 3);
   cmpb(FieldOperand(map, Map::kBitField2Offset),
-       Immediate(Map::kMaximumBitField2FastSmiOnlyElementValue));
+       Immediate(Map::kMaximumBitField2FastHoleySmiElementValue));
   j(below_equal, fail, distance);
   cmpb(FieldOperand(map, Map::kBitField2Offset),
-       Immediate(Map::kMaximumBitField2FastElementValue));
+       Immediate(Map::kMaximumBitField2FastHoleyElementValue));
   j(above, fail, distance);
 }
 
 
-void MacroAssembler::CheckFastSmiOnlyElements(Register map,
-                                              Label* fail,
-                                              Label::Distance distance) {
-  STATIC_ASSERT(FAST_SMI_ONLY_ELEMENTS == 0);
+void MacroAssembler::CheckFastSmiElements(Register map,
+                                          Label* fail,
+                                          Label::Distance distance) {
+  STATIC_ASSERT(FAST_SMI_ELEMENTS == 0);
+  STATIC_ASSERT(FAST_HOLEY_SMI_ELEMENTS == 1);
   cmpb(FieldOperand(map, Map::kBitField2Offset),
-       Immediate(Map::kMaximumBitField2FastSmiOnlyElementValue));
+       Immediate(Map::kMaximumBitField2FastHoleySmiElementValue));
   j(above, fail, distance);
 }
 
@@ -2749,24 +2754,18 @@ void MacroAssembler::CompareMap(Register obj,
                                 CompareMapMode mode) {
   Cmp(FieldOperand(obj, HeapObject::kMapOffset), map);
   if (mode == ALLOW_ELEMENT_TRANSITION_MAPS) {
-    Map* transitioned_fast_element_map(
-        map->LookupElementsTransitionMap(FAST_ELEMENTS, NULL));
-    ASSERT(transitioned_fast_element_map == NULL ||
-           map->elements_kind() != FAST_ELEMENTS);
-    if (transitioned_fast_element_map != NULL) {
-      j(equal, early_success, Label::kNear);
-      Cmp(FieldOperand(obj, HeapObject::kMapOffset),
-          Handle<Map>(transitioned_fast_element_map));
-    }
-
-    Map* transitioned_double_map(
-        map->LookupElementsTransitionMap(FAST_DOUBLE_ELEMENTS, NULL));
-    ASSERT(transitioned_double_map == NULL ||
-           map->elements_kind() == FAST_SMI_ONLY_ELEMENTS);
-    if (transitioned_double_map != NULL) {
-      j(equal, early_success, Label::kNear);
-      Cmp(FieldOperand(obj, HeapObject::kMapOffset),
-          Handle<Map>(transitioned_double_map));
+    ElementsKind kind = map->elements_kind();
+    if (IsFastElementsKind(kind)) {
+      bool packed = IsFastPackedElementsKind(kind);
+      Map* current_map = *map;
+      while (CanTransitionToMoreGeneralFastElementsKind(kind, packed)) {
+        kind = GetNextMoreGeneralFastElementsKind(kind, packed);
+        current_map = current_map->LookupElementsTransitionMap(kind, NULL);
+        if (!current_map) break;
+        j(equal, early_success, Label::kNear);
+        Cmp(FieldOperand(obj, HeapObject::kMapOffset),
+            Handle<Map>(current_map));
+      }
     }
   }
 }
@@ -4057,27 +4056,38 @@ void MacroAssembler::LoadTransitionedArrayMapConditional(
   movq(scratch, FieldOperand(scratch, GlobalObject::kGlobalContextOffset));
 
   // Check that the function's map is the same as the expected cached map.
-  int expected_index =
-      Context::GetContextMapIndexFromElementsKind(expected_kind);
-  cmpq(map_in_out, Operand(scratch, Context::SlotOffset(expected_index)));
+  movq(scratch, Operand(scratch,
+                        Context::SlotOffset(Context::JS_ARRAY_MAPS_INDEX)));
+
+  size_t offset = expected_kind * kPointerSize +
+      FixedArrayBase::kHeaderSize;
+  cmpq(map_in_out, FieldOperand(scratch, offset));
   j(not_equal, no_map_match);
 
   // Use the transitioned cached map.
-  int trans_index =
-      Context::GetContextMapIndexFromElementsKind(transitioned_kind);
-  movq(map_in_out, Operand(scratch, Context::SlotOffset(trans_index)));
+  offset = transitioned_kind * kPointerSize +
+      FixedArrayBase::kHeaderSize;
+  movq(map_in_out, FieldOperand(scratch, offset));
 }
 
 
 void MacroAssembler::LoadInitialArrayMap(
-    Register function_in, Register scratch, Register map_out) {
+    Register function_in, Register scratch,
+    Register map_out, bool can_have_holes) {
   ASSERT(!function_in.is(map_out));
   Label done;
   movq(map_out, FieldOperand(function_in,
                              JSFunction::kPrototypeOrInitialMapOffset));
   if (!FLAG_smi_only_arrays) {
-    LoadTransitionedArrayMapConditional(FAST_SMI_ONLY_ELEMENTS,
-                                        FAST_ELEMENTS,
+    ElementsKind kind = can_have_holes ? FAST_HOLEY_ELEMENTS : FAST_ELEMENTS;
+    LoadTransitionedArrayMapConditional(FAST_SMI_ELEMENTS,
+                                        kind,
+                                        map_out,
+                                        scratch,
+                                        &done);
+  } else if (can_have_holes) {
+    LoadTransitionedArrayMapConditional(FAST_SMI_ELEMENTS,
+                                        FAST_HOLEY_SMI_ELEMENTS,
                                         map_out,
                                         scratch,
                                         &done);