Implement tracking and optimizations of packed arrays

src/ia32/macro-assembler-ia32.cc

Index: src/ia32/macro-assembler-ia32.cc
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index c31b0c24bef9e63fc15793c278349549ca4510dd..3075eb0c4dd7bbd26d528263ac4277b79aaa35fd 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -382,10 +382,12 @@ 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),
-       Map::kMaximumBitField2FastElementValue);
+       Map::kMaximumBitField2FastHoleyElementValue);
   j(above, fail, distance);
 }
 
@@ -393,13 +395,15 @@ 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),
-       Map::kMaximumBitField2FastSmiOnlyElementValue);
+       Map::kMaximumBitField2FastHoleySmiOnlyElementValue);
   j(below_equal, fail, distance);
   cmpb(FieldOperand(map, Map::kBitField2Offset),
-       Map::kMaximumBitField2FastElementValue);
+       Map::kMaximumBitField2FastHoleyElementValue);
   j(above, fail, distance);
 }
 
@@ -407,9 +411,10 @@ void MacroAssembler::CheckFastObjectElements(Register map,
 void MacroAssembler::CheckFastSmiOnlyElements(Register map,
                                               Label* fail,
                                               Label::Distance distance) {
-  STATIC_ASSERT(FAST_SMI_ONLY_ELEMENTS == 0);
+  STATIC_ASSERT(FAST_SMI_ELEMENTS == 0);
+  STATIC_ASSERT(FAST_HOLEY_SMI_ELEMENTS == 1);
   cmpb(FieldOperand(map, Map::kBitField2Offset),
-       Map::kMaximumBitField2FastSmiOnlyElementValue);
+       Map::kMaximumBitField2FastHoleySmiOnlyElementValue);
   j(above, fail, distance);
 }
 
@@ -493,24 +498,19 @@ 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 =

[Jakob Kummerow, 2012/05/13 21:55:27]

nit: fits on one line?

[danno, 2012/05/22 11:05:21]

Done.

+            current_map->LookupElementsTransitionMap(kind, NULL);
+        if (!current_map) break;
+        j(equal, early_success, Label::kNear);
+        cmp(FieldOperand(obj, HeapObject::kMapOffset),
+            Handle<Map>(current_map));
+      }
     }
   }
 }
@@ -2161,27 +2161,40 @@ void MacroAssembler::LoadTransitionedArrayMapConditional(
   mov(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);
-  cmp(map_in_out, Operand(scratch, Context::SlotOffset(expected_index)));
+  mov(scratch, Operand(scratch,
+                       Context::SlotOffset(Context::JS_ARRAY_MAPS_INDEX)));
+
+  size_t offset = expected_kind * kPointerSize +
+      FixedArrayBase::kHeaderSize;
+  cmp(map_in_out, FieldOperand(scratch, offset));
   j(not_equal, no_map_match);
 
   // Use the transitioned cached map.
-  int trans_index =
-      Context::GetContextMapIndexFromElementsKind(transitioned_kind);
-  mov(map_in_out, Operand(scratch, Context::SlotOffset(trans_index)));
+  offset = transitioned_kind * kPointerSize +
+      FixedArrayBase::kHeaderSize;
+  mov(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;
   mov(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 :

[Jakob Kummerow, 2012/05/13 21:55:27]

nit: I'd put the : under the ?

[danno, 2012/05/22 11:05:21]

Done.

+        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);