[RISCV][TTI] Add cost of typebased cast VPIntrinsics with functionalOPC.

This patch make the instrudction cost of typebased cast VP intrinsics that will be same as
their non-VP counterpart.

Author: ElvisWang123

llvm/lib/Target/RISCV/RISCVTargetTransformInfo.cpp

@@ -1015,6 +1015,24 @@ RISCVTTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
       return getArithmeticInstrCost(*FOp, ICA.getReturnType(), CostKind);
     break;
   }
+  // vp int cast ops.
+  case Intrinsic::vp_trunc:
+  case Intrinsic::vp_zext:
+  case Intrinsic::vp_sext:
+  // vp float cast ops.
+  case Intrinsic::vp_fptoui:
+  case Intrinsic::vp_fptosi:
+  case Intrinsic::vp_uitofp:
+  case Intrinsic::vp_sitofp:
+  case Intrinsic::vp_fptrunc:
+  case Intrinsic::vp_fpext: {
+    std::optional<unsigned> FOp =
+        VPIntrinsic::getFunctionalOpcodeForVP(ICA.getID());
+    if (FOp && !ICA.getArgTypes().empty())
+      return getCastInstrCost(*FOp, ICA.getReturnType(), ICA.getArgTypes()[0],
+                              TTI::CastContextHint::None, CostKind);
+    break;
+  }
   }
 
   if (ST->hasVInstructions() && RetTy->isVectorTy()) {