Avoid one repeated property lookup when computing load ICs.

src/field-index.cc

Index: src/field-index.cc
diff --git a/src/field-index.cc b/src/field-index.cc
index 5392afc9f2cf592746d046382db347848f047b20..9670031536cf75433bb51d3ae330d4dea76233db 100644
--- a/src/field-index.cc
+++ b/src/field-index.cc
@@ -5,6 +5,7 @@
 #include "src/v8.h"
 
 #include "src/field-index.h"
+#include "src/lookup.h"
 #include "src/objects.h"
 #include "src/objects-inl.h"
 
@@ -20,4 +21,10 @@ FieldIndex FieldIndex::ForLookupResult(const LookupResult* lookup_result) {
 }
 
 
+FieldIndex FieldIndex::ForLookupIterator(const LookupIterator* lookup) {

[Toon Verwaest, 2014/07/30 16:54:52]

Let the LookupIterator calculate the FieldIndex instead, perhaps by calling a
lower-level interface on FieldIndex.

[Jakob Kummerow, 2014/07/31 13:55:50]

Done.

+  Handle<Map> map = lookup->holder_map();
+  int index =
+      map->instance_descriptors()->GetFieldIndex(lookup->descriptor_number());
+  return ForPropertyIndex(*map, index, lookup->representation().IsDouble());
+}
 } }  // namespace v8::internal