[generators] Fix loading of FormalParameterCount on 64bit archs.

src/mips64/builtins-mips64.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.
 
 #if V8_TARGET_ARCH_MIPS64
 
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 745 matching lines @@
   __ ld(a3, FieldMemOperand(a4, JSFunction::kSharedFunctionInfoOffset));
   __ ld(a3, FieldMemOperand(a3, SharedFunctionInfo::kFunctionDataOffset));
   __ GetObjectType(a3, a3, a3);
   __ Branch(&old_generator, ne, a3, Operand(BYTECODE_ARRAY_TYPE));
 
   // New-style (ignition/turbofan) generator object.
   {
     __ ld(a0, FieldMemOperand(a4, JSFunction::kSharedFunctionInfoOffset));
     __ lw(a0,
          FieldMemOperand(a0, SharedFunctionInfo::kFormalParameterCountOffset));
-    __ SmiUntag(a0);
     // We abuse new.target both to indicate that this is a resume call and to
     // pass in the generator object.  In ordinary calls, new.target is always
     // undefined because generator functions are non-constructable.
     __ Move(a3, a1);
     __ Move(a1, a4);
     __ ld(a2, FieldMemOperand(a1, JSFunction::kCodeEntryOffset));
     __ Jump(a2);
   }
 
   // Old-style (full-codegen) generator object
@@ skipping 2073 matching lines @@
   }
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS64