Refactor GetCodeCopyFromTemplate to get a single point where objects are replaced in code.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 92e4dc4c8c9c98f03a6267e2f393dda5c4312803..c5a9a7c10cd429cdd4898ab901a23f9b0ba9fb43 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -10501,20 +10501,22 @@ Map* Code::FindFirstMap() {
 }
 
 
-void Code::ReplaceNthObject(int n,
-                            Map* match_map,
-                            Object* replace_with) {
+void Code::FindAndReplace(const FindAndReplacePattern& pattern) {
   ASSERT(is_inline_cache_stub() || is_handler());
   DisallowHeapAllocation no_allocation;
   int mask = RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT);
+  STATIC_ASSERT(FindAndReplacePattern::kMaxCount < 32);
+  unsigned remaining_set = (1u << pattern.count_) - 1;
   for (RelocIterator it(this, mask); !it.done(); it.next()) {
     RelocInfo* info = it.rinfo();
     Object* object = info->target_object();
     if (object->IsHeapObject()) {
-      if (HeapObject::cast(object)->map() == match_map) {
-        if (--n == 0) {
-          info->set_target_object(replace_with);
-          return;
+      Map* map = HeapObject::cast(object)->map();
+      for (int i = 0; i < pattern.count_; i++) {
+        if (((remaining_set >> i) & 1) && map == *pattern.find_[i]) {
+          info->set_target_object(*pattern.replace_[i]);
+          remaining_set ^= 1u << i;
+          if (!remaining_set) return;
         }
       }

[Toon Verwaest, 2014/03/17 09:40:14]

Why don't we just introduce an invariant that the objects in the pattern are
required to be in the right order? That way we don't have this O(m*n) algo, but
just O(m).

Then add a second invariant that all objects in the pattern are required to be
used.

[ulan, 2014/03/17 13:43:31]

Good idea, turned that into O(m) and added comment explaining the order. I hope
the UNREACHABLE below will catch possible future misuses.

     }
@@ -10550,11 +10552,6 @@ void Code::FindAllTypes(TypeHandleList* types) {
 }
 
 
-void Code::ReplaceFirstMap(Map* replace_with) {
-  ReplaceNthObject(1, GetHeap()->meta_map(), replace_with);
-}
-
-
 Code* Code::FindFirstHandler() {
   ASSERT(is_inline_cache_stub());
   DisallowHeapAllocation no_allocation;
@@ -10600,21 +10597,6 @@ Name* Code::FindFirstName() {
 }
 
 
-void Code::ReplaceNthCell(int n, Cell* replace_with) {
-  ASSERT(is_inline_cache_stub());
-  DisallowHeapAllocation no_allocation;
-  int mask = RelocInfo::ModeMask(RelocInfo::CELL);
-  for (RelocIterator it(this, mask); !it.done(); it.next()) {
-    RelocInfo* info = it.rinfo();
-    if (--n == 0) {
-      info->set_target_cell(replace_with);
-      return;
-    }
-  }
-  UNREACHABLE();
-}
-
-
 void Code::ClearInlineCaches() {
   ClearInlineCaches(NULL);
 }