AMDGPU: Make a frame index test more realistic

We do not expect to see live carry out outputs on these adds,
so add a dead flag. Split the test for the degenerate case. This
makes it more apparent a regression in a future commit does not matter.

llvm/test/CodeGen/AMDGPU/eliminate-frame-index-v-add-co-u32-wave32.mir

@@ -16,10 +16,33 @@ machineFunctionInfo:
 body:             |
   bb.0:
     ; MUBUFW32-LABEL: name: v_add_co_u32_e64__inline_imm__fi_offset0
-    ; MUBUFW32: renamable $vgpr0, $vcc_lo = V_ADD_CO_U32_e64 12, $sgpr32, 0, implicit $exec
+    ; MUBUFW32: renamable $vgpr0, dead $vcc_lo = V_ADD_CO_U32_e64 12, $sgpr32, 0, implicit $exec
     ; MUBUFW32-NEXT: SI_RETURN implicit $vgpr0, implicit $sgpr0
     ;
     ; FLATSCRW32-LABEL: name: v_add_co_u32_e64__inline_imm__fi_offset0
+    ; FLATSCRW32: renamable $vgpr0, dead $vcc_lo = V_ADD_CO_U32_e64 12, $sgpr32, 0, implicit $exec
+    ; FLATSCRW32-NEXT: SI_RETURN implicit $vgpr0, implicit $sgpr0
+    renamable $vgpr0, dead $vcc_lo = V_ADD_CO_U32_e64 12, %stack.0, 0, implicit $exec
+    SI_RETURN implicit $vgpr0, implicit $sgpr0
+
+...
+
+---
+name: v_add_co_u32_e64__inline_imm__fi_offset0__live_vcc
+tracksRegLiveness: true
+stack:
+  - { id: 0, size: 4, alignment: 16 }
+machineFunctionInfo:
+  scratchRSrcReg:  '$sgpr0_sgpr1_sgpr2_sgpr3'
+  frameOffsetReg:  '$sgpr33'
+  stackPtrOffsetReg: '$sgpr32'
+body:             |
+  bb.0:
+    ; MUBUFW32-LABEL: name: v_add_co_u32_e64__inline_imm__fi_offset0__live_vcc
+    ; MUBUFW32: renamable $vgpr0, $vcc_lo = V_ADD_CO_U32_e64 12, $sgpr32, 0, implicit $exec
+    ; MUBUFW32-NEXT: SI_RETURN implicit $vgpr0, implicit $sgpr0
+    ;
+    ; FLATSCRW32-LABEL: name: v_add_co_u32_e64__inline_imm__fi_offset0__live_vcc
     ; FLATSCRW32: renamable $vgpr0, $vcc_lo = V_ADD_CO_U32_e64 12, $sgpr32, 0, implicit $exec
     ; FLATSCRW32-NEXT: SI_RETURN implicit $vgpr0, implicit $sgpr0
     renamable $vgpr0, $vcc_lo = V_ADD_CO_U32_e64 12, %stack.0, 0, implicit $exec