[RISCV] Generalize 'tryFoldSelectIntOp` to other operations.

Currently, only `SUB`, `ADD`, `OR` and `XOR` are covered. This patch
adds `AND`, `SHL`, `SRA`, `SRL`.

Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D155344

Author: mgudim

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -12406,9 +12406,13 @@ static SDValue tryFoldSelectIntoOp(SDNode *N, SelectionDAG &DAG,
                                    SDValue TrueVal, SDValue FalseVal,
                                    bool Swapped) {
   bool Commutative = true;
-  switch (TrueVal.getOpcode()) {
+  unsigned Opc = TrueVal.getOpcode();
+  switch (Opc) {
   default:
     return SDValue();
+  case ISD::SHL:
+  case ISD::SRA:
+  case ISD::SRL:
   case ISD::SUB:
     Commutative = false;
     break;
@@ -12431,12 +12435,18 @@ static SDValue tryFoldSelectIntoOp(SDNode *N, SelectionDAG &DAG,
 
   EVT VT = N->getValueType(0);
   SDLoc DL(N);
-  SDValue Zero = DAG.getConstant(0, DL, VT);
   SDValue OtherOp = TrueVal.getOperand(1 - OpToFold);
+  EVT OtherOpVT = OtherOp->getValueType(0);
+  SDValue IdentityOperand =
+      DAG.getNeutralElement(Opc, DL, OtherOpVT, N->getFlags());
+  if (!Commutative)
+    IdentityOperand = DAG.getConstant(0, DL, OtherOpVT);
+  assert(IdentityOperand && "No identity operand!");
 
   if (Swapped)
-    std::swap(OtherOp, Zero);
-  SDValue NewSel = DAG.getSelect(DL, VT, N->getOperand(0), OtherOp, Zero);
+    std::swap(OtherOp, IdentityOperand);
+  SDValue NewSel =
+      DAG.getSelect(DL, OtherOpVT, N->getOperand(0), OtherOp, IdentityOperand);
   return DAG.getNode(TrueVal.getOpcode(), DL, VT, FalseVal, NewSel);
 }