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

src/x64/assembler-x64.h

Index: src/x64/assembler-x64.h
diff --git a/src/x64/assembler-x64.h b/src/x64/assembler-x64.h
index 3f958b886448bf5955e1f789f6ff15c1754f520a..2182dbb3ff6b1452792bd58052e9a6f61cc2c382 100644
--- a/src/x64/assembler-x64.h
+++ b/src/x64/assembler-x64.h
@@ -1082,6 +1082,10 @@ class Assembler : public AssemblerBase {
 
   void cvtlsi2sd(XMMRegister dst, const Operand& src);
   void cvtlsi2sd(XMMRegister dst, Register src);
+
+  void cvtqsi2ss(XMMRegister dst, const Operand& src);
+  void cvtqsi2ss(XMMRegister dst, Register src);
+
   void cvtqsi2sd(XMMRegister dst, const Operand& src);
   void cvtqsi2sd(XMMRegister dst, Register src);
 
@@ -1363,6 +1367,13 @@ class Assembler : public AssemblerBase {
   void vcvtlsi2sd(XMMRegister dst, XMMRegister src1, const Operand& src2) {
     vsd(0x2a, dst, src1, src2, kF2, k0F, kW0);
   }
+  void vcvtqsi2ss(XMMRegister dst, XMMRegister src1, Register src2) {
+    XMMRegister isrc2 = {src2.code()};
+    vsd(0x2a, dst, src1, isrc2, kF3, k0F, kW1);
+  }
+  void vcvtqsi2ss(XMMRegister dst, XMMRegister src1, const Operand& src2) {
+    vsd(0x2a, dst, src1, src2, kF3, k0F, kW1);
+  }
   void vcvtqsi2sd(XMMRegister dst, XMMRegister src1, Register src2) {
     XMMRegister isrc2 = {src2.code()};
     vsd(0x2a, dst, src1, isrc2, kF2, k0F, kW1);