[llvm] [RISCV] Lower VP_SELECT constant false to use vmerge.vxm/vmerge.vim (PR #144461)

[Philip Reames via llvm-commits]

================
@@ -470,6 +470,28 @@ define <vscale x 2 x i64> @select_nxv2i64(<vscale x 2 x i1> %a, <vscale x 2 x i6
   ret <vscale x 2 x i64> %v
 }
 
+define <vscale x 2 x i64> @select_nxv2i64_constant_true(<vscale x 2 x i1> %a, <vscale x 2 x i64> %b, i32 zeroext %evl) {
----------------
preames wrote:

Can you precommit these tests so that we can see the test delta?

https://github.com/llvm/llvm-project/pull/144461