Generalize map dependent codes array to allow multiple dependency groups.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 46539311de9625d9c7ffccc54bd476ab5510a47b..a72585d696948c827a1659fb0d0c201003b9ac11 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -9501,37 +9501,55 @@ void Map::ZapPrototypeTransitions() {
 }
 
 
-Handle<DependentCodes> DependentCodes::Append(Handle<DependentCodes> codes,
+Handle<DependentCodes> DependentCodes::Insert(Handle<DependentCodes> codes,
+                                              DependencyGroup group,
                                               Handle<Code> value) {
-  int append_index = codes->number_of_codes();
-  if (append_index > 0 && codes->code_at(append_index - 1) == *value) {
+  GroupStartIndexes starts;
+  codes->ComputeGroupStartIndexes(starts);
+  int start = starts[group];
+  int end = starts[group + 1];
+  int number_of_codes = starts[kGroupCount];
+  if (start < end && codes->code_at(end - 1) == *value) {
     // Do not append the code if it is already in the array.
     // It is sufficient to just check only the last element because
     // we process embedded maps of an optimized code in one batch.
     return codes;
   }
-  if (codes->length() < kCodesIndex + append_index + 1) {
+  if (codes->length() < kCodesStartIndex + number_of_codes + 1) {
     Factory* factory = codes->GetIsolate()->factory();
-    int capacity = kCodesIndex + append_index + 1;
+    int capacity = kCodesStartIndex + number_of_codes + 1;
     if (capacity > 5) capacity = capacity * 5 / 4;
     Handle<DependentCodes> new_codes = Handle<DependentCodes>::cast(
         factory->CopySizeFixedArray(codes, capacity));
     // The number of codes can change after GC.
-    append_index = codes->number_of_codes();
-    for (int i = 0; i < append_index; i++) {
+    codes->ComputeGroupStartIndexes(starts);
+    start = starts[group];
+    end = starts[group + 1];
+    number_of_codes = starts[kGroupCount];
+    for (int i = 0; i < number_of_codes; i++) {
       codes->clear_code_at(i);
     }
+    // If the old fixed array was empty, we need to reset counters of the
+    // new array.
+    if (number_of_codes == 0) {
+      for (int g = 0; g < kGroupCount; g++) {
+        new_codes->set_number_of_codes(static_cast<DependencyGroup>(g), 0);
+      }
+    }
     codes = new_codes;
   }
-  codes->set_code_at(append_index, *value);
-  codes->set_number_of_codes(append_index + 1);
+  codes->ExtendGroup(group);
+  codes->set_code_at(end, *value);
+  codes->set_number_of_codes(group, end + 1 - start);
   return codes;
 }
 
 
-bool DependentCodes::Contains(Code* code) {
-  int limit = number_of_codes();
-  for (int i = 0; i < limit; i++) {
+bool DependentCodes::Contains(DependencyGroup group, Code* code) {
+  GroupStartIndexes starts;
+  ComputeGroupStartIndexes(starts);
+  int number_of_codes = starts[kGroupCount];
+  for (int i = 0; i < number_of_codes; i++) {
     if (code_at(i) == code) return true;
   }
   return false;