[RISCV][GISel] Don't check for FP uses of of IMPLICIT_DEF if the type…

… is vector. NFC

If the type is vector, we can immediately know to use vector mapping.
Previously we searched for FP uses, but then replaced it if the type
was vector.

llvm/lib/Target/RISCV/GISel/RISCVRegisterBankInfo.cpp

@@ -341,18 +341,17 @@ RISCVRegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
   case TargetOpcode::G_IMPLICIT_DEF: {
     Register Dst = MI.getOperand(0).getReg();
     LLT DstTy = MRI.getType(Dst);
-    uint64_t DstMinSize = DstTy.getSizeInBits().getKnownMinValue();
+    unsigned DstMinSize = DstTy.getSizeInBits().getKnownMinValue();
     auto Mapping = GPRValueMapping;
     // FIXME: May need to do a better job determining when to use FPRB.
     // For example, the look through COPY case:
     // %0:_(s32) = G_IMPLICIT_DEF
     // %1:_(s32) = COPY %0
     // $f10_d = COPY %1(s32)
-    if (anyUseOnlyUseFP(Dst, MRI, TRI))
-      Mapping = getFPValueMapping(DstMinSize);
-
     if (DstTy.isVector())
       Mapping = getVRBValueMapping(DstMinSize);
+    else if (anyUseOnlyUseFP(Dst, MRI, TRI))
+      Mapping = getFPValueMapping(DstMinSize);
 
     return getInstructionMapping(DefaultMappingID, /*Cost=*/1, Mapping,
                                  NumOperands);