Remove prototype checks for leaf maps in optimized code.

src/ia32/lithium-codegen-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 5314 matching lines @@
 
 void LCodeGen::DoCheckPrototypeMaps(LCheckPrototypeMaps* instr) {
   ASSERT(instr->temp()->Equals(instr->result()));
   Register reg = ToRegister(instr->temp());
 
   ZoneList<Handle<JSObject> >* prototypes = instr->prototypes();
   ZoneList<Handle<Map> >* maps = instr->maps();
 
   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);
+    }
   }
 }
 
 
 void LCodeGen::DoAllocateObject(LAllocateObject* instr) {
   class DeferredAllocateObject: public LDeferredCode {
    public:
     DeferredAllocateObject(LCodeGen* codegen, LAllocateObject* instr)
         : LDeferredCode(codegen), instr_(instr) { }
     virtual void Generate() { codegen()->DoDeferredAllocateObject(instr_); }
@@ skipping 830 matching lines @@
                               FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32