diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoVSDPatterns.td b/llvm/lib/Target/RISCV/RISCVInstrInfoVSDPatterns.td
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoVSDPatterns.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoVSDPatterns.td
@@ -733,6 +733,27 @@
 defm : VPatWidenBinarySDNode_VV_VX_WV_WX<sub, zext_oneuse, "PseudoVWSUBU">;
 defm : VPatWidenBinarySDNode_VV_VX_WV_WX<sub, anyext_oneuse, "PseudoVWSUBU">;
 
+// shl (ext v, splat 1) is a special case of widening add.
+foreach vtiToWti = AllWidenableIntVectors in {
+  defvar vti = vtiToWti.Vti;
+  defvar wti = vtiToWti.Wti;
+  let Predicates = !listconcat(GetVTypePredicates<vti>.Predicates,
+                               GetVTypePredicates<wti>.Predicates) in {
+    def : Pat<(shl (wti.Vector (sext_oneuse (vti.Vector vti.RegClass:$rs1))),
+                   (wti.Vector (riscv_vmv_v_x_vl (wti.Vector undef), 1, (XLenVT srcvalue)))),
+              (!cast<Instruction>("PseudoVWADD_VV_"#vti.LMul.MX)
+                  vti.RegClass:$rs1, vti.RegClass:$rs1, vti.AVL, vti.Log2SEW)>;
+    def : Pat<(shl (wti.Vector (zext_oneuse (vti.Vector vti.RegClass:$rs1))),
+                   (wti.Vector (riscv_vmv_v_x_vl (wti.Vector undef), 1, (XLenVT srcvalue)))),
+              (!cast<Instruction>("PseudoVWADDU_VV_"#vti.LMul.MX)
+                  vti.RegClass:$rs1, vti.RegClass:$rs1, vti.AVL, vti.Log2SEW)>;
+    def : Pat<(shl (wti.Vector (anyext_oneuse (vti.Vector vti.RegClass:$rs1))),
+                   (wti.Vector (riscv_vmv_v_x_vl (wti.Vector undef), 1, (XLenVT srcvalue)))),
+              (!cast<Instruction>("PseudoVWADDU_VV_"#vti.LMul.MX)
+                  vti.RegClass:$rs1, vti.RegClass:$rs1, vti.AVL, vti.Log2SEW)>;
+  }
+}
+
 // 11.3. Vector Integer Extension
 defm : VPatExtendSDNode_V<[zext, anyext], "PseudoVZEXT", "VF2",
                           AllFractionableVF2IntVectors>;
diff --git a/llvm/test/CodeGen/RISCV/rvv/mgather-sdnode.ll b/llvm/test/CodeGen/RISCV/rvv/mgather-sdnode.ll
--- a/llvm/test/CodeGen/RISCV/rvv/mgather-sdnode.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/mgather-sdnode.ll
@@ -549,10 +549,8 @@
 define <vscale x 8 x i16> @mgather_baseidx_nxv8i16(ptr %base, <vscale x 8 x i16> %idxs, <vscale x 8 x i1> %m, <vscale x 8 x i16> %passthru) {
 ; RV32-LABEL: mgather_baseidx_nxv8i16:
 ; RV32:       # %bb.0:
-; RV32-NEXT:    vsetvli a1, zero, e32, m4, ta, ma
-; RV32-NEXT:    vsext.vf2 v12, v8
-; RV32-NEXT:    vadd.vv v12, v12, v12
-; RV32-NEXT:    vsetvli zero, zero, e16, m2, ta, mu
+; RV32-NEXT:    vsetvli a1, zero, e16, m2, ta, mu
+; RV32-NEXT:    vwadd.vv v12, v8, v8
 ; RV32-NEXT:    vluxei32.v v10, (a0), v12, v0.t
 ; RV32-NEXT:    vmv.v.v v8, v10
 ; RV32-NEXT:    ret
@@ -1510,10 +1508,8 @@
 define <vscale x 8 x half> @mgather_baseidx_nxv8f16(ptr %base, <vscale x 8 x i16> %idxs, <vscale x 8 x i1> %m, <vscale x 8 x half> %passthru) {
 ; RV32-LABEL: mgather_baseidx_nxv8f16:
 ; RV32:       # %bb.0:
-; RV32-NEXT:    vsetvli a1, zero, e32, m4, ta, ma
-; RV32-NEXT:    vsext.vf2 v12, v8
-; RV32-NEXT:    vadd.vv v12, v12, v12
-; RV32-NEXT:    vsetvli zero, zero, e16, m2, ta, mu
+; RV32-NEXT:    vsetvli a1, zero, e16, m2, ta, mu
+; RV32-NEXT:    vwadd.vv v12, v8, v8
 ; RV32-NEXT:    vluxei32.v v10, (a0), v12, v0.t
 ; RV32-NEXT:    vmv.v.v v8, v10
 ; RV32-NEXT:    ret
diff --git a/llvm/test/CodeGen/RISCV/rvv/mscatter-sdnode.ll b/llvm/test/CodeGen/RISCV/rvv/mscatter-sdnode.ll
--- a/llvm/test/CodeGen/RISCV/rvv/mscatter-sdnode.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/mscatter-sdnode.ll
@@ -406,10 +406,8 @@
 define void @mscatter_baseidx_nxv8i16(<vscale x 8 x i16> %val, ptr %base, <vscale x 8 x i16> %idxs, <vscale x 8 x i1> %m) {
 ; RV32-LABEL: mscatter_baseidx_nxv8i16:
 ; RV32:       # %bb.0:
-; RV32-NEXT:    vsetvli a1, zero, e32, m4, ta, ma
-; RV32-NEXT:    vsext.vf2 v12, v10
-; RV32-NEXT:    vadd.vv v12, v12, v12
-; RV32-NEXT:    vsetvli zero, zero, e16, m2, ta, ma
+; RV32-NEXT:    vsetvli a1, zero, e16, m2, ta, ma
+; RV32-NEXT:    vwadd.vv v12, v10, v10
 ; RV32-NEXT:    vsoxei32.v v8, (a0), v12, v0.t
 ; RV32-NEXT:    ret
 ;
@@ -1192,10 +1190,8 @@
 define void @mscatter_baseidx_nxv8f16(<vscale x 8 x half> %val, ptr %base, <vscale x 8 x i16> %idxs, <vscale x 8 x i1> %m) {
 ; RV32-LABEL: mscatter_baseidx_nxv8f16:
 ; RV32:       # %bb.0:
-; RV32-NEXT:    vsetvli a1, zero, e32, m4, ta, ma
-; RV32-NEXT:    vsext.vf2 v12, v10
-; RV32-NEXT:    vadd.vv v12, v12, v12
-; RV32-NEXT:    vsetvli zero, zero, e16, m2, ta, ma
+; RV32-NEXT:    vsetvli a1, zero, e16, m2, ta, ma
+; RV32-NEXT:    vwadd.vv v12, v10, v10
 ; RV32-NEXT:    vsoxei32.v v8, (a0), v12, v0.t
 ; RV32-NEXT:    ret
 ;
diff --git a/llvm/test/CodeGen/RISCV/rvv/vpgather-sdnode.ll b/llvm/test/CodeGen/RISCV/rvv/vpgather-sdnode.ll
--- a/llvm/test/CodeGen/RISCV/rvv/vpgather-sdnode.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/vpgather-sdnode.ll
@@ -601,9 +601,8 @@
 define <vscale x 8 x i16> @vpgather_baseidx_nxv8i16(ptr %base, <vscale x 8 x i16> %idxs, <vscale x 8 x i1> %m, i32 zeroext %evl) {
 ; RV32-LABEL: vpgather_baseidx_nxv8i16:
 ; RV32:       # %bb.0:
-; RV32-NEXT:    vsetvli a2, zero, e32, m4, ta, ma
-; RV32-NEXT:    vsext.vf2 v12, v8
-; RV32-NEXT:    vadd.vv v12, v12, v12
+; RV32-NEXT:    vsetvli a2, zero, e16, m2, ta, ma
+; RV32-NEXT:    vwadd.vv v12, v8, v8
 ; RV32-NEXT:    vsetvli zero, a1, e16, m2, ta, ma
 ; RV32-NEXT:    vluxei32.v v8, (a0), v12, v0.t
 ; RV32-NEXT:    ret
@@ -1423,9 +1422,8 @@
 define <vscale x 8 x half> @vpgather_baseidx_nxv8f16(ptr %base, <vscale x 8 x i16> %idxs, <vscale x 8 x i1> %m, i32 zeroext %evl) {
 ; RV32-LABEL: vpgather_baseidx_nxv8f16:
 ; RV32:       # %bb.0:
-; RV32-NEXT:    vsetvli a2, zero, e32, m4, ta, ma
-; RV32-NEXT:    vsext.vf2 v12, v8
-; RV32-NEXT:    vadd.vv v12, v12, v12
+; RV32-NEXT:    vsetvli a2, zero, e16, m2, ta, ma
+; RV32-NEXT:    vwadd.vv v12, v8, v8
 ; RV32-NEXT:    vsetvli zero, a1, e16, m2, ta, ma
 ; RV32-NEXT:    vluxei32.v v8, (a0), v12, v0.t
 ; RV32-NEXT:    ret
diff --git a/llvm/test/CodeGen/RISCV/rvv/vpscatter-sdnode.ll b/llvm/test/CodeGen/RISCV/rvv/vpscatter-sdnode.ll
--- a/llvm/test/CodeGen/RISCV/rvv/vpscatter-sdnode.ll
+++ b/llvm/test/CodeGen/RISCV/rvv/vpscatter-sdnode.ll
@@ -400,9 +400,8 @@
 define void @vpscatter_baseidx_nxv8i16(<vscale x 8 x i16> %val, ptr %base, <vscale x 8 x i16> %idxs, <vscale x 8 x i1> %m, i32 zeroext %evl) {
 ; RV32-LABEL: vpscatter_baseidx_nxv8i16:
 ; RV32:       # %bb.0:
-; RV32-NEXT:    vsetvli a2, zero, e32, m4, ta, ma
-; RV32-NEXT:    vsext.vf2 v12, v10
-; RV32-NEXT:    vadd.vv v12, v12, v12
+; RV32-NEXT:    vsetvli a2, zero, e16, m2, ta, ma
+; RV32-NEXT:    vwadd.vv v12, v10, v10
 ; RV32-NEXT:    vsetvli zero, a1, e16, m2, ta, ma
 ; RV32-NEXT:    vsoxei32.v v8, (a0), v12, v0.t
 ; RV32-NEXT:    ret
@@ -1181,9 +1180,8 @@
 define void @vpscatter_baseidx_nxv8f16(<vscale x 8 x half> %val, ptr %base, <vscale x 8 x i16> %idxs, <vscale x 8 x i1> %m, i32 zeroext %evl) {
 ; RV32-LABEL: vpscatter_baseidx_nxv8f16:
 ; RV32:       # %bb.0:
-; RV32-NEXT:    vsetvli a2, zero, e32, m4, ta, ma
-; RV32-NEXT:    vsext.vf2 v12, v10
-; RV32-NEXT:    vadd.vv v12, v12, v12
+; RV32-NEXT:    vsetvli a2, zero, e16, m2, ta, ma
+; RV32-NEXT:    vwadd.vv v12, v10, v10
 ; RV32-NEXT:    vsetvli zero, a1, e16, m2, ta, ma
 ; RV32-NEXT:    vsoxei32.v v8, (a0), v12, v0.t
 ; RV32-NEXT:    ret