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 27e460cda4a3d2b2b797eeab5b896f9470d96a38..183f84740dc932a1038a364fc6b8ccb8a5729b1b 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -103,6 +103,10 @@ void LCodeGen::FinishCode(Handle<Code> code) {
   if (!info()->IsStub()) {
     Deoptimizer::EnsureRelocSpaceForLazyDeoptimization(code);
   }
+  for (int i = 0 ; i < prototype_maps_.length(); i++) {
+    prototype_maps_.at(i)->AddDependentCode(
+        DependentCode::kPrototypeCheckGroup, code);
+  }
 }
 
 
@@ -919,7 +923,7 @@ void LCodeGen::RegisterDependentCodeForEmbeddedMaps(Handle<Code> code) {
   NoWeakEmbeddedMapsVerificationScope disable_verification_of_embedded_maps;
 #endif
   for (int i = 0; i < maps.length(); i++) {
-    maps.at(i)->AddDependentCode(code);
+    maps.at(i)->AddDependentCode(DependentCode::kWeaklyEmbeddedGroup, code);
   }
 }
 
@@ -5325,9 +5329,20 @@ 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);
+  // TODO(ulan): Move this check to hydrogen and split HCheckPrototypeMaps
+  // into two instruction: one that checks the prototypes and another that
+  // loads the holder (HConstant). Find a way to do it without breaking
+  // parallel recompilation.
+  if (instr->hydrogen()->CanOmitPrototypeChecks()) {
+    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);
+    }
   }
 }