[turbofan] Add initial support for growing stores.

src/compiler/simplified-lowering.cc

 // Copyright 2014 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/compiler/simplified-lowering.h"
 
 #include <limits>
 
 #include "src/address-map.h"
 #include "src/base/bits.h"
@@ skipping 2371 matching lines @@
         return;
       }
       case IrOpcode::kCheckMaps:
       case IrOpcode::kTransitionElementsKind: {
         VisitInputs(node);
         return SetOutput(node, MachineRepresentation::kNone);
       }
       case IrOpcode::kEnsureWritableFastElements:
         return VisitBinop(node, UseInfo::AnyTagged(),
                           MachineRepresentation::kTagged);
+      case IrOpcode::kMaybeGrowFastElements: {
+        ProcessInput(node, 0, UseInfo::AnyTagged());
+        ProcessInput(node, 1, UseInfo::AnyTagged());
+        ProcessInput(node, 2, UseInfo::TruncatingWord32());
+        ProcessInput(node, 3, UseInfo::TruncatingWord32());

[Jarin, 2016/08/08 08:03:47]

Again, the magic indices are not helping readability here. Could we have at
least a one-word comment at the end of each line above? (Such as // length
etc.).

[Benedikt Meurer, 2016/08/08 08:12:56]

Done.

+        ProcessRemainingInputs(node, 4);
+        SetOutput(node, MachineRepresentation::kTagged);
+        return;
+      }
 
       //------------------------------------------------------------------
       // Machine-level operators.
       //------------------------------------------------------------------
       case IrOpcode::kLoad: {
         // TODO(jarin) Eventually, we should get rid of all machine stores
         // from the high-level phases, then this becomes UNREACHABLE.
         LoadRepresentation rep = LoadRepresentationOf(node->op());
         ProcessInput(node, 0, UseInfo::AnyTagged());   // tagged pointer
         ProcessInput(node, 1, UseInfo::PointerInt());  // index
@@ skipping 908 matching lines @@
         isolate(), graph()->zone(), callable.descriptor(), 0, flags,
         Operator::kNoProperties);
     to_number_operator_.set(common()->Call(desc));
   }
   return to_number_operator_.get();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8