Make the ResolvePossiblyDirectEval faster by avoiding the...

src/x64/codegen-x64.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2653 matching lines @@
     }
 
     // Prepare the stack for the call to ResolvePossiblyDirectEval.
     frame_->PushElementAt(arg_count + 1);
     if (arg_count > 0) {
       frame_->PushElementAt(arg_count);
     } else {
       frame_->Push(Factory::undefined_value());
     }
 
+    // Push the receiver.
+    frame_->PushParameterAt(-1);
+
     // Resolve the call.
     Result result =
-        frame_->CallRuntime(Runtime::kResolvePossiblyDirectEval, 2);
+        frame_->CallRuntime(Runtime::kResolvePossiblyDirectEval, 3);
 
-    // Touch up the stack with the right values for the function and the
-    // receiver.  Use a scratch register to avoid destroying the result.
-    Result scratch = allocator_->Allocate();
-    ASSERT(scratch.is_valid());
-    __ movq(scratch.reg(),
-            FieldOperand(result.reg(), FixedArray::OffsetOfElementAt(0)));
-    frame_->SetElementAt(arg_count + 1, &scratch);
-
-    // We can reuse the result register now.
-    frame_->Spill(result.reg());
-    __ movq(result.reg(),
-            FieldOperand(result.reg(), FixedArray::OffsetOfElementAt(1)));
-    frame_->SetElementAt(arg_count, &result);
+    // The runtime call returns a pair of values in rax (function) and
+    // rdx (receiver). Touch up the stack with the right values.
+    Result receiver = allocator_->Allocate(rdx);
+    frame_->SetElementAt(arg_count + 1, &result);
+    frame_->SetElementAt(arg_count, &receiver);
+    receiver.Unuse();
 
     // Call the function.
     CodeForSourcePosition(node->position());
     InLoopFlag in_loop = loop_nesting() > 0 ? IN_LOOP : NOT_IN_LOOP;
     CallFunctionStub call_function(arg_count, in_loop);
     result = frame_->CallStub(&call_function, arg_count + 1);
 
     // Restore the context and overwrite the function on the stack with
     // the result.
     frame_->RestoreContextRegister();
@@ skipping 5343 matching lines @@
   masm.GetCode(&desc);
   // Call the function from C++.
   return FUNCTION_CAST<ModuloFunction>(buffer);
 }
 
 #endif
 
 #undef __
 
 } }  // namespace v8::internal