[RISCV] Refactor helper in isDesirableToCommuteWithShift. NFC (#119526)

Instead of duplicating the loop twice, add arguments to the lambda.
I plan on reusing this in #119527

Author: lukel97

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -18237,41 +18237,21 @@ bool RISCVTargetLowering::isDesirableToCommuteWithShift(
   // LD/ST will optimize constant Offset extraction, so when AddNode is used by
   // LD/ST, it can still complete the folding optimization operation performed
   // above.
-  auto isUsedByLdSt = [&]() {
-    bool CanOptAlways = false;
-    if (N0->getOpcode() == ISD::ADD && !N0->hasOneUse()) {
-      for (SDNode *Use : N0->uses()) {
-        // This use is the one we're on right now. Skip it
-        if (Use == N || Use->getOpcode() == ISD::SELECT)
-          continue;
-        if (!isa<StoreSDNode>(Use) && !isa<LoadSDNode>(Use)) {
-          CanOptAlways = false;
-          break;
-        }
-        CanOptAlways = true;
-      }
-    }
-
-    if (N0->getOpcode() == ISD::SIGN_EXTEND &&
-        !N0->getOperand(0)->hasOneUse()) {
-      for (SDNode *Use : N0->getOperand(0)->uses()) {
-        // This use is the one we're on right now. Skip it
-        if (Use == N0.getNode() || Use->getOpcode() == ISD::SELECT)
-          continue;
-        if (!isa<StoreSDNode>(Use) && !isa<LoadSDNode>(Use)) {
-          CanOptAlways = false;
-          break;
-        }
-        CanOptAlways = true;
-      }
+  auto isUsedByLdSt = [](const SDNode *X, const SDNode *User) {
+    for (SDNode *Use : X->uses()) {
+      // This use is the one we're on right now. Skip it
+      if (Use == User || Use->getOpcode() == ISD::SELECT)
+        continue;
+      if (!isa<StoreSDNode>(Use) && !isa<LoadSDNode>(Use))
+        return false;
     }
-    return CanOptAlways;
+    return true;
   };
 
   if (Ty.isScalarInteger() &&
       (N0.getOpcode() == ISD::ADD || N0.getOpcode() == ISD::OR)) {
     if (N0.getOpcode() == ISD::ADD && !N0->hasOneUse())
-      return isUsedByLdSt();
+      return isUsedByLdSt(N0.getNode(), N);
 
     auto *C1 = dyn_cast<ConstantSDNode>(N0->getOperand(1));
     auto *C2 = dyn_cast<ConstantSDNode>(N->getOperand(1));
@@ -18314,7 +18294,7 @@ bool RISCVTargetLowering::isDesirableToCommuteWithShift(
   if (N0->getOpcode() == ISD::SIGN_EXTEND &&
       N0->getOperand(0)->getOpcode() == ISD::ADD &&
       !N0->getOperand(0)->hasOneUse())
-    return isUsedByLdSt();
+    return isUsedByLdSt(N0->getOperand(0).getNode(), N0.getNode());
 
   return true;
 }