Turn keyed loads with string-based (non-convertible to array-index) key into named loads

src/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/hydrogen.h"
 
 #include <algorithm>
 
 #include "src/v8.h"
 
@@ skipping 6412 matching lines @@
                                         Property* prop,
                                         BailoutId ast_id,
                                         BailoutId return_id,
                                         bool is_uninitialized) {
   if (!prop->key()->IsPropertyName()) {
     // Keyed store.
     HValue* value = environment()->ExpressionStackAt(0);
     HValue* key = environment()->ExpressionStackAt(1);
     HValue* object = environment()->ExpressionStackAt(2);
     bool has_side_effects = false;
-    HandleKeyedElementAccess(object, key, value, expr,
-                             STORE, &has_side_effects);
+    HandleKeyedElementAccess(object, key, value, expr, return_id, STORE,
+                             &has_side_effects);
     Drop(3);
     Push(value);
     Add<HSimulate>(return_id, REMOVABLE_SIMULATE);
     return ast_context()->ReturnValue(Pop());
   }
 
   // Named store.
   HValue* value = Pop();
   HValue* object = Pop();
 
@@ skipping 671 matching lines @@
   DCHECK(join->predecessors()->length() > 0);
   // Deopt if none of the cases matched.
   NoObservableSideEffectsScope scope(this);
   FinishExitWithHardDeoptimization("Unknown map in polymorphic element access");
   set_current_block(join);
   return access_type == STORE ? NULL : Pop();
 }
 
 
 HValue* HOptimizedGraphBuilder::HandleKeyedElementAccess(
-    HValue* obj,
-    HValue* key,
-    HValue* val,
-    Expression* expr,
-    PropertyAccessType access_type,
+    HValue* obj, HValue* key, HValue* val, Expression* expr,
+    BailoutId return_id, PropertyAccessType access_type,
     bool* has_side_effects) {
+  if (key->ActualValue()->IsConstant()) {
+    Handle<Object> constant =
+        HConstant::cast(key->ActualValue())->handle(isolate());
+    uint32_t array_index;
+    if (constant->IsString() &&
+        !Handle<String>::cast(constant)->AsArrayIndex(&array_index)) {
+      HInstruction* instr =
+          BuildNamedAccess(access_type, expr->id(), expr->id(), expr, obj,

[Igor Sheludko, 2014/09/18 11:25:37]

As you noticed you didn't use return_id here.

+                           Handle<String>::cast(constant), val, false);

[Igor Sheludko, 2014/09/18 11:25:37]

If instr really can't be null here then consider adding DCHECK.

+      if (instr->IsLinked()) {
+        *has_side_effects = false;
+      } else {
+        AddInstruction(instr);
+        *has_side_effects = instr->HasObservableSideEffects();
+      }
+      return instr;
+    }
+  }
+
   DCHECK(!expr->IsPropertyName());
   HInstruction* instr = NULL;
 
   SmallMapList* types;
   bool monomorphic = ComputeReceiverTypes(expr, obj, &types, zone());
 
   bool force_generic = false;
   if (access_type == STORE &&
       (monomorphic || (types != NULL && !types->is_empty()))) {
     // Stores can't be mono/polymorphic if their prototype chain has dictionary
@@ skipping 190 matching lines @@
                              object, name, NULL, expr->IsUninitialized());
     if (instr == NULL) return;
     if (instr->IsLinked()) return ast_context()->ReturnValue(instr);
 
   } else {
     HValue* key = Pop();
     HValue* obj = Pop();
 
     bool has_side_effects = false;
     HValue* load = HandleKeyedElementAccess(
-        obj, key, NULL, expr, LOAD, &has_side_effects);
+        obj, key, NULL, expr, expr->LoadId(), LOAD, &has_side_effects);
     if (has_side_effects) {
       if (ast_context()->IsEffect()) {
         Add<HSimulate>(ast_id, REMOVABLE_SIMULATE);
       } else {
         Push(load);
         Add<HSimulate>(ast_id, REMOVABLE_SIMULATE);
         Drop(1);
       }
     }
     return ast_context()->ReturnValue(load);
@@ skipping 5134 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal