MIPS64: Fix test Cvt_s_uw_Trunc_uw_s.

test/cctest/test-macro-assembler-mips64.cc

 // Copyright 2013 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 586 matching lines @@
       CALL_GENERATED_CODE(isolate, f, x, 0, 0, 0, 0));
 }
 
 TEST(Cvt_s_uw_Trunc_uw_s) {
   CcTest::InitializeVM();
   FOR_UINT32_INPUTS(i) {
     uint32_t input = *i;
     CHECK_EQ(static_cast<float>(input),
              run_Cvt<uint64_t>(input, [](MacroAssembler* masm) {
                __ Cvt_s_uw(f0, a0);
+               __ mthc1(zero_reg, f2);
                __ Trunc_uw_s(f2, f0, f1);
              }));
   }
 }
 
 TEST(Cvt_s_ul_Trunc_ul_s) {
   CcTest::InitializeVM();
   FOR_UINT64_INPUTS(i) {
     uint64_t input = *i;
     CHECK_EQ(static_cast<float>(input),
@@ skipping 52 matching lines @@
                __ mtc1(a0, f4);
                __ cvt_d_w(f0, f4);
                __ Trunc_w_d(f2, f0);
                __ mfc1(v1, f2);
                __ dmtc1(v1, f2);
              }));
   }
 }
 
 #undef __