Remove prototype checks for leaf maps in optimized code.

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index dfced7c221335f060f7c333e02c0ec38bb7516d8..94bba205320002dff531c9356bd87a3d96e87310 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -5332,9 +5332,21 @@ void LCodeGen::DoCheckPrototypeMaps(LCheckPrototypeMaps* instr) {
 
   ASSERT(prototypes->length() == maps->length());
 
-  for (int i = 0; i < prototypes->length(); i++) {
-    __ LoadHeapObject(reg, prototypes->at(i));
-    DoCheckMapCommon(reg, maps->at(i), ALLOW_ELEMENT_TRANSITION_MAPS, instr);
+  bool can_ommit_checks = true;
+  for (int i = 0; i < maps->length() && can_ommit_checks; i++) {
+    if (maps->at(i)->HasTransitionArray()) can_ommit_checks = false;
+    if (maps->at(i)->is_dictionary_map()) can_ommit_checks = false;

[Toon Verwaest, 2013/02/11 12:23:45]

This could should really go somewhere else; probably in the map. Add a utility
method Map::CanOmitPrototypeChecks or so.

[ulan, 2013/02/12 13:42:07]

Done. After discussion with Jakob, I moved the loop above into a method of the
hydrogen instruction to make it platform independent.

+  }
+  if (can_ommit_checks) {
+      for (int i = 0; i < maps->length(); i++) {
+      prototype_maps_.Add(maps->at(i), info()->zone());
+    }
+    __ LoadHeapObject(reg, prototypes->at(prototypes->length() - 1));
+  } else {
+    for (int i = 0; i < prototypes->length(); i++) {
+      __ LoadHeapObject(reg, prototypes->at(i));
+      DoCheckMapCommon(reg, maps->at(i), ALLOW_ELEMENT_TRANSITION_MAPS, instr);
+    }
   }
 }