diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -2729,6 +2729,31 @@
   return splatSplitI64WithVL(DL, VT, Passthru, Scalar, VL, DAG);
 }
 
+// If a vector_shuffle source is from a same and contiguous (and started with 0
+// index) vector, return the vector. Otherwise, return SDValue().
+static SDValue isOneSourceVECTOR_SHUFFLE(SDValue N0, SDValue N1,
+                                         ArrayRef<int> Mask) {
+  if (N1.isUndef())
+    return N0;
+
+  // Both input must be extracts.
+  if (N0.getOpcode() != ISD::EXTRACT_SUBVECTOR ||
+      N1.getOpcode() != ISD::EXTRACT_SUBVECTOR)
+    return SDValue();
+
+  // Extracting from the same source.
+  SDValue Src = N0.getOperand(0);
+  if (Src != N1.getOperand(0))
+    return SDValue();
+
+  // Make sure N0 and N1 are continuous.
+  if (N0.getConstantOperandVal(1) != 0 ||
+      N1.getConstantOperandVal(1) != Mask.size())
+    return SDValue();
+
+  return Src;
+}
+
 // Mask can only be this form.
 // X X X X ... -1 -1 -1 ..., while X is not -1.
 // X X X X ... must be in ascending order.
@@ -2740,22 +2765,8 @@
 // In addition, N0 and N1 must from a same vector (or N1 is undef).
 static bool isVnsrlShuffle(SDValue N0, SDValue N1, ArrayRef<int> Mask, EVT VT,
                            const RISCVSubtarget &Subtarget) {
-  if (!N1.isUndef()) {
-    // Both input must be extracts.
-    if (N0.getOpcode() != ISD::EXTRACT_SUBVECTOR ||
-        N1.getOpcode() != ISD::EXTRACT_SUBVECTOR)
-      return false;
-
-    // Extracting from the same source.
-    SDValue Src = N0.getOperand(0);
-    if (Src != N1.getOperand(0))
-      return false;
-
-    // Make sure N0 and N1 are continuous.
-    if (N0.getConstantOperandVal(1) != 0 ||
-        N1.getConstantOperandVal(1) != Mask.size())
-      return false;
-  }
+  if (!isOneSourceVECTOR_SHUFFLE(N0, N1, Mask))
+    return false;
   if (Mask.size() < 2)
     return false;
   // Find first -1 and check whether the mask behind is -1.
@@ -2962,22 +2973,9 @@
                                                ArrayRef<int> Mask,
                                                const RISCVSubtarget &Subtarget,
                                                SelectionDAG &DAG) {
-  // Both input must be extracts.
-  if (V1.getOpcode() != ISD::EXTRACT_SUBVECTOR ||
-      V2.getOpcode() != ISD::EXTRACT_SUBVECTOR)
+  SDValue Src = isOneSourceVECTOR_SHUFFLE(V1, V2, Mask);
+  if (!Src)
     return SDValue();
-
-  // Extracting from the same source.
-  SDValue Src = V1.getOperand(0);
-  if (Src != V2.getOperand(0))
-    return SDValue();
-
-  // V1 must be started with 0.
-  // V1 and V2 are continuous.
-  if (V1.getConstantOperandVal(1) != 0 ||
-      VT.getVectorNumElements() != V2.getConstantOperandVal(1))
-    return SDValue();
-
   // First index must be known and non-zero. It will be used as the slidedown
   // amount.
   if (Mask[0] <= 0)