Only swap undefined for the global object if necessary in the prologue

src/x64/full-codegen-x64.cc

 // Copyright 2012 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/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
@@ skipping 96 matching lines @@
 #ifdef DEBUG
   if (strlen(FLAG_stop_at) > 0 &&
       info->function()->name()->IsUtf8EqualTo(CStrVector(FLAG_stop_at))) {
     __ int3();
   }
 #endif
 
   // Sloppy mode functions and builtins need to replace the receiver with the
   // global proxy when called as functions (without an explicit receiver
   // object).
-  if (is_sloppy(info->language_mode()) && !info->is_native()) {
+  if (is_sloppy(info->language_mode()) && !info->is_native() &&
+      info->MayUseThis()) {
     Label ok;
     // +1 for return address.
     StackArgumentsAccessor args(rsp, info->scope()->num_parameters());
     __ movp(rcx, args.GetReceiverOperand());
 
     __ CompareRoot(rcx, Heap::kUndefinedValueRootIndex);
     __ j(not_equal, &ok, Label::kNear);
 
     __ movp(rcx, GlobalObjectOperand());
     __ movp(rcx, FieldOperand(rcx, GlobalObject::kGlobalProxyOffset));
@@ skipping 5260 matching lines @@
   DCHECK_EQ(isolate->builtins()->OsrAfterStackCheck()->entry(),
             Assembler::target_address_at(call_target_address,
                                          unoptimized_code));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64