[llvm] [AMDGPU] Fix S_ADD_I32 frame index folding emitting COPY with immediate (PR #212440)

[Matt Arsenault via llvm-commits]

================
@@ -1990,3 +1990,50 @@ body:             |
     SI_RETURN implicit $vcc_lo, implicit $vcc_hi, implicit $sgpr0, implicit $sgpr1, implicit $sgpr2, implicit $sgpr3, implicit $sgpr4, implicit $sgpr5, implicit $sgpr6, implicit $sgpr7, implicit $sgpr8, implicit $sgpr9, implicit $sgpr10, implicit $sgpr11, implicit $sgpr12, implicit $sgpr13, implicit $sgpr14, implicit $sgpr15, implicit $sgpr16, implicit $sgpr17, implicit $sgpr18, implicit $sgpr19, implicit $sgpr20, implicit $sgpr21, implicit $sgpr22, implicit $sgpr23, implicit $sgpr24, implicit $sgpr25, implicit $sgpr26, implicit $sgpr27, implicit $sgpr28, implicit $sgpr29, implicit $sgpr30, implicit $sgpr31, implicit $sgpr32, implicit $sgpr33, implicit $sgpr34, implicit $sgpr35, implicit $sgpr36, implicit $sgpr37, implicit $sgpr38, implicit $sgpr39, implicit $sgpr40, implicit $sgpr41, implicit $sgpr42, implicit $sgpr43, implicit $sgpr44, implicit $sgpr45, implicit $sgpr46, implicit $sgpr47, implicit $sgpr48, implicit $sgpr49, implicit $sgpr50, implicit $sgpr51, implicit $sgpr52, implicit $sgpr53, implicit $sgpr54, implicit $sgpr55, implicit $sgpr56, implicit $sgpr57, implicit $sgpr58, implicit $sgpr59, implicit $sgpr60, implicit $sgpr61, implicit $sgpr62, implicit $sgpr63, implicit $sgpr64, implicit $sgpr65, implicit $sgpr66, implicit $sgpr67, implicit $sgpr68, implicit $sgpr69, implicit $sgpr70, implicit $sgpr71, implicit $sgpr72, implicit $sgpr73, implicit $sgpr74, implicit $sgpr75, implicit $sgpr76, implicit $sgpr77, implicit $sgpr78, implicit $sgpr79, implicit $sgpr80, implicit $sgpr81, implicit $sgpr82, implicit $sgpr83, implicit $sgpr84, implicit $sgpr85, implicit $sgpr86, implicit $sgpr87, implicit $sgpr88, implicit $sgpr89, implicit $sgpr90, implicit $sgpr91, implicit $sgpr92, implicit $sgpr93, implicit $sgpr94, implicit $sgpr95
 
 ...
+---
+name: s_add_i32__kernel__fi_offset0__inline_imm_dead_scc_subreg
+tracksRegLiveness: true
+stack:
+  - { id: 0, type: default, offset: 0, size: 8, alignment: 4 }
+machineFunctionInfo:
+  scratchRSrcReg:  '$sgpr0_sgpr1_sgpr2_sgpr3'
+  frameOffsetReg:  '$sgpr33'
+  stackPtrOffsetReg: '$sgpr32'
+  isEntryFunction: true
+body:             |
+  bb.0:
+    ; MUBUFW64-LABEL: name: s_add_i32__kernel__fi_offset0__inline_imm_dead_scc_subreg
+    ; MUBUFW64: liveins: $sgpr0_sgpr1_sgpr2_sgpr3
+    ; MUBUFW64-NEXT: {{  $}}
+    ; MUBUFW64-NEXT: frame-setup CFI_INSTRUCTION escape 0x0f, 0x04, 0x30, 0x36, 0xe9, 0x02
+    ; MUBUFW64-NEXT: frame-setup CFI_INSTRUCTION undefined $pc_reg
+    ; MUBUFW64-NEXT: $sgpr0 = S_ADD_U32 $sgpr0, $noreg, implicit-def $scc, implicit-def $sgpr0_sgpr1_sgpr2_sgpr3
+    ; MUBUFW64-NEXT: $sgpr1 = S_ADDC_U32 $sgpr1, 0, implicit-def dead $scc, implicit $scc, implicit-def $sgpr0_sgpr1_sgpr2_sgpr3
+    ; MUBUFW64-NEXT: renamable $sgpr4 = S_MOV_B32 4, implicit-def $sgpr5
+    ; MUBUFW64-NEXT: S_ENDPGM 0
+    ;
+    ; MUBUFW32-LABEL: name: s_add_i32__kernel__fi_offset0__inline_imm_dead_scc_subreg
+    ; MUBUFW32: liveins: $sgpr0_sgpr1_sgpr2_sgpr3
+    ; MUBUFW32-NEXT: {{  $}}
+    ; MUBUFW32-NEXT: frame-setup CFI_INSTRUCTION escape 0x0f, 0x04, 0x30, 0x36, 0xe9, 0x02
+    ; MUBUFW32-NEXT: frame-setup CFI_INSTRUCTION undefined $pc_reg
+    ; MUBUFW32-NEXT: $sgpr0 = S_ADD_U32 $sgpr0, $noreg, implicit-def $scc, implicit-def $sgpr0_sgpr1_sgpr2_sgpr3
----------------
arsenm wrote:

There's still a broken $noreg. I'm not sure if this patch is responsible or not 

https://github.com/llvm/llvm-project/pull/212440