[llvm] [AMDGPU]: Add support to unpack V_PK_MOV_B32 (PR #163464)

[Matt Arsenault via llvm-commits]

================
@@ -687,9 +681,6 @@ body:             |
     ; GFX90A-NEXT: $vgpr5 = V_MOV_B32_e32 killed $sgpr15, implicit $exec, implicit $exec
     ; GFX90A-NEXT: $vgpr4 = V_MOV_B32_dpp $vgpr4, $vgpr4, 228, 15, 15, -1, implicit $exec
     ; GFX90A-NEXT: $vgpr5 = V_CVT_PK_BF8_F32_e64 0, killed $vgpr4, 0, $vgpr4, $vgpr5, 0, implicit $mode, implicit $exec
-    ; GFX90A-NEXT: $vgpr6_vgpr7 = V_MOV_B64_e32 $sgpr48_sgpr49, implicit $exec, implicit $sgpr48_sgpr49_sgpr50_sgpr51, implicit $exec
----------------
arsenm wrote:

Deleting unrelated instructions is a suspicious test change 

https://github.com/llvm/llvm-project/pull/163464