[RISCV][GISel] Slightly simplify the regbank selection for G_LOAD/STORE. NFC (#101431)

Merge the isVector early out with the previous check for isVector.

Author: topperc

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

@@ -311,15 +311,16 @@ RISCVRegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
   case TargetOpcode::G_LOAD: {
     LLT Ty = MRI.getType(MI.getOperand(0).getReg());
     TypeSize Size = Ty.getSizeInBits();
-    if (Ty.isVector())
-      OpdsMapping[0] = getVRBValueMapping(Size.getKnownMinValue());
-    else
-      OpdsMapping[0] = GPRValueMapping;
 
     OpdsMapping[1] = GPRValueMapping;
 
-    if (Ty.isVector())
+    if (Ty.isVector()) {
+      OpdsMapping[0] = getVRBValueMapping(Size.getKnownMinValue());
       break;
+    }
+
+    OpdsMapping[0] = GPRValueMapping;
+
     // Use FPR64 for s64 loads on rv32.
     if (GPRSize == 32 && Size.getFixedValue() == 64) {
       assert(MF.getSubtarget<RISCVSubtarget>().hasStdExtD());
@@ -342,15 +343,15 @@ RISCVRegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
   case TargetOpcode::G_STORE: {
     LLT Ty = MRI.getType(MI.getOperand(0).getReg());
     TypeSize Size = Ty.getSizeInBits();
-    if (Ty.isVector())
-      OpdsMapping[0] = getVRBValueMapping(Size.getKnownMinValue());
-    else
-      OpdsMapping[0] = GPRValueMapping;
 
     OpdsMapping[1] = GPRValueMapping;
 
-    if (Ty.isVector())
+    if (Ty.isVector()) {
+      OpdsMapping[0] = getVRBValueMapping(Size.getKnownMinValue());
       break;
+    }
+
+    OpdsMapping[0] = GPRValueMapping;
 
     // Use FPR64 for s64 stores on rv32.
     if (GPRSize == 32 && Size.getFixedValue() == 64) {