[x64] check sahf correctly

src/compiler/x64/code-generator-x64.cc

 // Copyright 2013 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/code-generator.h"
 
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties-inl.h"
@@ skipping 484 matching lines @@
       __ movsd(Operand(rsp, 0), i.InputDoubleRegister(0));
       __ fld_d(Operand(rsp, 0));
       // Loop while fprem isn't done.
       Label mod_loop;
       __ bind(&mod_loop);
       // This instructions traps on all kinds inputs, but we are assuming the
       // floating point control word is set to ignore them all.
       __ fprem();
       // The following 2 instruction implicitly use rax.
       __ fnstsw_ax();
-      if (CpuFeatures::IsSupported(SAHF) && masm()->IsEnabled(SAHF)) {
+      if (CpuFeatures::IsSupported(SAHF)) {
+        CpuFeatureScope sahf_scope(masm(), SAHF);
         __ sahf();
       } else {
         __ shrl(rax, Immediate(8));
         __ andl(rax, Immediate(0xFF));
         __ pushq(rax);
         __ popfq();
       }
       __ j(parity_even, &mod_loop);
       // Move output to stack and clean up.
       __ fstp(1);
@@ skipping 689 matching lines @@
     }
   }
   MarkLazyDeoptSite();
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace compiler
 }  // namespace v8