[llvm] [GlobalIsel] Combine G_UNMERGE_VALUES from opaque vectors into scalars (PR #113040)

[Matt Arsenault via llvm-commits]

================
@@ -3983,6 +3983,11 @@ define <2 x i16> @v_fshl_v2i16(<2 x i16> %lhs, <2 x i16> %rhs, <2 x i16> %amt) {
 ; GFX6-NEXT:    v_and_b32_e32 v3, 0xffff, v4
 ; GFX6-NEXT:    v_lshrrev_b32_e32 v2, v3, v2
 ; GFX6-NEXT:    v_or_b32_e32 v1, v1, v2
+; GFX6-NEXT:    v_and_b32_e32 v1, 0xffff, v1
----------------
arsenm wrote:

Pretty bad 

https://github.com/llvm/llvm-project/pull/113040