Implemented the RoundInt64ToFloat32 TurboFan operator for x64, arm64, and mips64.

src/compiler/mips64/code-generator-mips64.cc

 // Copyright 2014 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/osr.h"
 #include "src/mips/macro-assembler-mips.h"
@@ skipping 839 matching lines @@
       break;
     case kMips64CvtDS:
       __ cvt_d_s(i.OutputDoubleRegister(), i.InputSingleRegister(0));
       break;
     case kMips64CvtDW: {
       FPURegister scratch = kScratchDoubleReg;
       __ mtc1(i.InputRegister(0), scratch);
       __ cvt_d_w(i.OutputDoubleRegister(), scratch);
       break;
     }
+    case kMips64CvtSL: {
+      FPURegister scratch = kScratchDoubleReg;
+      __ dmtc1(i.InputRegister(0), scratch);
+      __ cvt_s_l(i.OutputDoubleRegister(), scratch);
+      break;
+    }
     case kMips64CvtDL: {
       FPURegister scratch = kScratchDoubleReg;
       __ dmtc1(i.InputRegister(0), scratch);
       __ cvt_d_l(i.OutputDoubleRegister(), scratch);
       break;
     }
     case kMips64CvtDUw: {
       FPURegister scratch = kScratchDoubleReg;
       __ Cvt_d_uw(i.OutputDoubleRegister(), i.InputRegister(0), scratch);
       break;
@@ skipping 737 matching lines @@
       padding_size -= v8::internal::Assembler::kInstrSize;
     }
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8