Reland of [stubs] Port KeyedLoadIC_Generic stub to TurboFan

src/builtins/builtins-sharedarraybuffer.cc

 // Copyright 2016 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/builtins/builtins.h"
 #include "src/builtins/builtins-utils.h"
 
 #include "src/code-factory.h"
 
 namespace v8 {
@@ skipping 123 matching lines @@
   a->Bind(&done);
   return var_result.value();
 }
 
 void ValidateAtomicIndex(CodeStubAssembler* a, compiler::Node* index_word,
                          compiler::Node* array_length_word,
                          compiler::Node* context) {
   using namespace compiler;
   // Check if the index is in bounds. If not, throw RangeError.
   CodeStubAssembler::Label if_inbounds(a), if_notinbounds(a);
+  // TODO(jkummerow): Use unsigned comparison instead of "i<0 || i>length".
   a->Branch(
       a->WordOr(a->Int32LessThan(index_word, a->Int32Constant(0)),
                 a->Int32GreaterThanOrEqual(index_word, array_length_word)),
       &if_notinbounds, &if_inbounds);
   a->Bind(&if_notinbounds);
   a->Return(
       a->CallRuntime(Runtime::kThrowInvalidAtomicAccessIndexError, context));
   a->Bind(&if_inbounds);
 }
 
@@ skipping 103 matching lines @@
                  a->WordShl(index_word, 2), value_word32);
   a->Return(value_integer);
 
   // This shouldn't happen, we've already validated the type.
   a->Bind(&other);
   a->Return(a->Int32Constant(0));
 }
 
 }  // namespace internal
 }  // namespace v8