VM: Reland Inline instance object hash code into object header on 64bit.

runtime/vm/intrinsifier.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 // Class for intrinsifying functions.
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/cpu.h"
 #include "vm/flags.h"
 #include "vm/flow_graph.h"
@@ skipping 210 matching lines @@
   const Function& function = parsed_function.function();
   if (!CanIntrinsify(function)) {
     return false;
   }
 
   ASSERT(!compiler->flow_graph().IsCompiledForOsr());
   if (GraphIntrinsify(parsed_function, compiler)) {
     return compiler->intrinsic_slow_path_label()->IsUnused();
   }
 
+#if !defined(HASH_IN_OBJECT_HEADER)

[Vyacheslav Egorov (Google), 2017/06/30 16:47:26]

I think it is just okay to have an empty intrinsic on these platforms. Does
having empty intrinsic break anything?

[erikcorry, 2017/06/30 20:00:09]

I assumed it would break things.  The implementation on 32 bit is a native,
whereas on 64 bit it's intrinsified.

I guess you can't fall through from an intrinsified version to a native version.

+  // These two are more complicated on 32 bit platforms, where the
+  // identity hash is not stored in the header of the object.  We
+  // therefore don't intrinsify them, falling back on the native C++
+  // implementations.
+  if (function.recognized_kind() == MethodRecognizer::kObject_getHash ||
+      function.recognized_kind() == MethodRecognizer::kObject_setHash) {
+    return false;
+  }
+#endif
+
 #define EMIT_CASE(class_name, function_name, enum_name, type, fp)              \
   case MethodRecognizer::k##enum_name:                                         \
     compiler->assembler()->Comment("Intrinsic");                               \
     enum_name(compiler->assembler());                                          \
     break;
 
   switch (function.recognized_kind()) {
     ALL_INTRINSICS_NO_INTEGER_LIB_LIST(EMIT_CASE);
     default:
       break;
@@ skipping 934 matching lines @@
 }
 
 
 void Intrinsifier::RegExp_ExecuteMatchSticky(Assembler* assembler) {
   IntrinsifyRegExpExecuteMatch(assembler, /*sticky=*/true);
 }
 #endif  // !defined(TARGET_ARCH_DBC)
 
 
 }  // namespace dart