[MC] Add createFPImm/isFPImm/setFPImm to smooth migration from FPImm to DFPImm after D96091

Author: MaskRay

llvm/include/llvm/MC/MCInst.h

@@ -100,11 +100,19 @@ class MCOperand {
     assert(isDFPImm() && "This is not an FP immediate");
     return FPImmVal;
   }
+  double getFPImm() const {
+    assert(isDFPImm() && "This is not an FP immediate");
+    return bit_cast<double>(FPImmVal);
+  }
 
   void setDFPImm(uint64_t Val) {
     assert(isDFPImm() && "This is not an FP immediate");
     FPImmVal = Val;
   }
+  void setFPImm(double Val) {
+    assert(isDFPImm() && "This is not an FP immediate");
+    FPImmVal = bit_cast<uint64_t>(Val);
+  }
 
   const MCExpr *getExpr() const {
     assert(isExpr() && "This is not an expression");
@@ -153,6 +161,12 @@ class MCOperand {
     Op.FPImmVal = Val;
     return Op;
   }
+  static MCOperand createFPImm(double Val) {
+    MCOperand Op;
+    Op.Kind = kDFPImmediate;
+    Op.FPImmVal = bit_cast<uint64_t>(Val);
+    return Op;
+  }
 
   static MCOperand createExpr(const MCExpr *Val) {
     MCOperand Op;