Revert "Add basic crankshaft support for slow-mode for-in to avoid disabling optimizations"

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 3e87d69f24ccfb04e42a846b45106de2fac5d405..736f895a01f4e1c4b7a88b64c5132b3de55efa5e 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -5051,6 +5051,10 @@ void HOptimizedGraphBuilder::VisitForInStatement(ForInStatement* stmt) {
     return Bailout(kForInStatementOptimizationIsDisabled);
   }
 
+  if (stmt->for_in_type() != ForInStatement::FAST_FOR_IN) {
+    return Bailout(kForInStatementIsNotFastCase);
+  }
+
   if (!stmt->each()->IsVariableProxy() ||
       !stmt->each()->AsVariableProxy()->var()->IsStackLocal()) {
     return Bailout(kForInStatementWithNonLocalEachVariable);
@@ -5061,42 +5065,13 @@ void HOptimizedGraphBuilder::VisitForInStatement(ForInStatement* stmt) {
   CHECK_ALIVE(VisitForValue(stmt->enumerable()));
   HValue* enumerable = Top();  // Leave enumerable at the top.
 
-  HInstruction* map;
-  HInstruction* array;
-  HInstruction* enum_length;
-  bool fast = stmt->for_in_type() == ForInStatement::FAST_FOR_IN;
-  if (fast) {
-    map = Add<HForInPrepareMap>(enumerable);
-    Add<HSimulate>(stmt->PrepareId());
-
-    array = Add<HForInCacheArray>(enumerable, map,
-                                  DescriptorArray::kEnumCacheBridgeCacheIndex);
-    enum_length = Add<HMapEnumLength>(map);
-
-    HInstruction* index_cache = Add<HForInCacheArray>(
-        enumerable, map, DescriptorArray::kEnumCacheBridgeIndicesCacheIndex);
-    HForInCacheArray::cast(array)
-        ->set_index_cache(HForInCacheArray::cast(index_cache));
-  } else {
-    Add<HSimulate>(stmt->PrepareId());
-    {
-      NoObservableSideEffectsScope no_effects(this);
-      BuildJSObjectCheck(enumerable, 0);
-    }
-    Add<HSimulate>(stmt->ToObjectId());
+  HInstruction* map = Add<HForInPrepareMap>(enumerable);
+  Add<HSimulate>(stmt->PrepareId());
 
-    map = graph()->GetConstant1();
-    Runtime::FunctionId function_id = Runtime::kGetPropertyNamesFast;
-    Add<HPushArguments>(enumerable);
-    array = Add<HCallRuntime>(isolate()->factory()->empty_string(),
-                              Runtime::FunctionForId(function_id), 1);
-    Push(array);
-    Add<HSimulate>(stmt->EnumId());
-    Drop(1);
-    Handle<Map> array_map = isolate()->factory()->fixed_array_map();
-    HValue* check = Add<HCheckMaps>(array, array_map);
-    enum_length = AddLoadFixedArrayLength(array, check);
-  }
+  HInstruction* array = Add<HForInCacheArray>(
+      enumerable, map, DescriptorArray::kEnumCacheBridgeCacheIndex);
+
+  HInstruction* enum_length = Add<HMapEnumLength>(map);
 
   HInstruction* start_index = Add<HConstant>(0);
 
@@ -5105,12 +5080,13 @@ void HOptimizedGraphBuilder::VisitForInStatement(ForInStatement* stmt) {
   Push(enum_length);
   Push(start_index);
 
+  HInstruction* index_cache = Add<HForInCacheArray>(
+      enumerable, map, DescriptorArray::kEnumCacheBridgeIndicesCacheIndex);
+  HForInCacheArray::cast(array)
+      ->set_index_cache(HForInCacheArray::cast(index_cache));
+
   HBasicBlock* loop_entry = BuildLoopEntry(stmt);
 
-  // Reload the values to ensure we have up-to-date values inside of the loop.
-  // This is relevant especially for OSR where the values don't come from the
-  // computation above, but from the OSR entry block.
-  enumerable = environment()->ExpressionStackAt(4);
   HValue* index = environment()->ExpressionStackAt(0);
   HValue* limit = environment()->ExpressionStackAt(1);
 
@@ -5134,21 +5110,15 @@ void HOptimizedGraphBuilder::VisitForInStatement(ForInStatement* stmt) {
 
   HValue* key =
       Add<HLoadKeyed>(environment()->ExpressionStackAt(2),  // Enum cache.
-                      index, index, FAST_ELEMENTS);
+                      environment()->ExpressionStackAt(0),  // Iteration index.
+                      environment()->ExpressionStackAt(0), FAST_ELEMENTS);
 
-  if (fast) {
-    // Check if the expected map still matches that of the enumerable.
-    // If not just deoptimize.
-    Add<HCheckMapValue>(enumerable, environment()->ExpressionStackAt(3));
-    Bind(each_var, key);
-  } else {
-    HValue* function = AddLoadJSBuiltin(Builtins::FILTER_KEY);
-    Add<HPushArguments>(enumerable, key);
-    key = Add<HInvokeFunction>(function, 2);
-    Bind(each_var, key);
-    Add<HSimulate>(stmt->AssignmentId());
-    Add<HCheckHeapObject>(key);
-  }
+  // Check if the expected map still matches that of the enumerable.
+  // If not just deoptimize.
+  Add<HCheckMapValue>(environment()->ExpressionStackAt(4),
+                      environment()->ExpressionStackAt(3));
+
+  Bind(each_var, key);
 
   BreakAndContinueInfo break_info(stmt, scope(), 5);
   {