[llvm] [RISCV] Use vwadd.vx for splat vector with extension (PR #87249)

[Luke Lau via llvm-commits]

================
@@ -1466,3 +1466,159 @@ define <vscale x 2 x i32> @vwadd_wv_disjoint_or(<vscale x 2 x i32> %x.i32, <vsca
   %or = or disjoint <vscale x 2 x i32> %x.i32, %y.i32
   ret <vscale x 2 x i32> %or
 }
+
+define <vscale x 8 x i64> @vwadd_vx_splat_zext(<vscale x 8 x i32> %va, i32 %b) {
+; RV32-LABEL: vwadd_vx_splat_zext:
+; RV32:       # %bb.0:
+; RV32-NEXT:    addi sp, sp, -16
+; RV32-NEXT:    .cfi_def_cfa_offset 16
+; RV32-NEXT:    sw zero, 12(sp)
+; RV32-NEXT:    sw a0, 8(sp)
+; RV32-NEXT:    addi a0, sp, 8
+; RV32-NEXT:    vsetvli a1, zero, e32, m4, ta, ma
+; RV32-NEXT:    vlse64.v v16, (a0), zero
+; RV32-NEXT:    vwaddu.wv v16, v16, v8
+; RV32-NEXT:    vmv8r.v v8, v16
+; RV32-NEXT:    addi sp, sp, 16
+; RV32-NEXT:    ret
+;
+; RV64-LABEL: vwadd_vx_splat_zext:
+; RV64:       # %bb.0:
+; RV64-NEXT:    andi a0, a0, -1
+; RV64-NEXT:    vsetvli a1, zero, e32, m4, ta, ma
+; RV64-NEXT:    vwaddu.vx v16, v8, a0
+; RV64-NEXT:    vmv8r.v v8, v16
+; RV64-NEXT:    ret
+  %sb = zext i32 %b to i64
----------------
lukel97 wrote:

Nit, should this be %zb if it's zero extended?

https://github.com/llvm/llvm-project/pull/87249