[llvm] [AMDGPU] Remove leftover implicit operands from SI_SPILL/SI_RESTORE. (PR #168546)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-expensive-checks-ubuntu` running on `as-builder-4` while building `llvm` at step 7 "test-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/187/builds/13765

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 7 (test-check-all) failure: Test just built components: check-all completed (failure)
******************** TEST 'LLVM :: CodeGen/AMDGPU/collapse-endcf.ll' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 2
/home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/bin/llc -mtriple=amdgcn -mcpu=tahiti -amdgpu-remove-redundant-endcf -amdgpu-codegenprepare-break-large-phis=0 < /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/llvm-project/llvm/test/CodeGen/AMDGPU/collapse-endcf.ll | /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/bin/FileCheck -enable-var-scope -check-prefix=GCN /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/llvm-project/llvm/test/CodeGen/AMDGPU/collapse-endcf.ll
# executed command: /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/bin/llc -mtriple=amdgcn -mcpu=tahiti -amdgpu-remove-redundant-endcf -amdgpu-codegenprepare-break-large-phis=0
# executed command: /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/bin/FileCheck -enable-var-scope -check-prefix=GCN /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/llvm-project/llvm/test/CodeGen/AMDGPU/collapse-endcf.ll
# RUN: at line 5
/home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/bin/llc -mtriple=amdgcn -mcpu=tahiti -O0 -amdgpu-remove-redundant-endcf -amdgpu-codegenprepare-break-large-phis=0 < /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/llvm-project/llvm/test/CodeGen/AMDGPU/collapse-endcf.ll | /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/bin/FileCheck -enable-var-scope -check-prefix=GCN-O0 /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/llvm-project/llvm/test/CodeGen/AMDGPU/collapse-endcf.ll
# executed command: /home/buildbot/worker/as-builder-4/ramdisk/expensive-checks/build/bin/llc -mtriple=amdgcn -mcpu=tahiti -O0 -amdgpu-remove-redundant-endcf -amdgpu-codegenprepare-break-large-phis=0
# .---command stderr------------
# | 
# | # After Post-RA pseudo instruction expansion pass
# | # Machine code for function scc_liveness: NoPHIs, TracksLiveness, NoVRegs, TiedOpsRewritten
# | Frame Objects:
# |   fi#0: dead
# |   fi#1: dead
# |   fi#2: dead
# |   fi#3: dead
# |   fi#4: dead
# |   fi#5: dead
# |   fi#6: dead
# |   fi#7: dead
# |   fi#8: dead
# |   fi#9: dead
# |   fi#10: size=4, align=4, at location [SP]
# |   fi#11: size=4, align=4, at location [SP+4]
# |   fi#12: size=16, align=4, at location [SP+8]
# |   fi#13: size=16, align=4, at location [SP+24]
# |   fi#14: size=16, align=4, at location [SP+40]
# |   fi#15: size=16, align=4, at location [SP+56]
# |   fi#16: size=4, align=4, at location [SP+72]
# |   fi#17: size=4, align=4, at location [SP+76]
# | save/restore points:
# | save points are empty
# | restore points are empty
# | Function Live Ins: $vgpr0
# | 
# | bb.0.bb:
# |   successors: %bb.1(0x80000000); %bb.1(100.00%)
# |   liveins: $vgpr0
# |   $sgpr4_sgpr5 = S_XOR_SAVEEXEC_B64 -1, implicit-def $exec, implicit-def dead $scc, implicit $exec
# |   BUFFER_STORE_DWORD_OFFSET killed $vgpr7, $sgpr0_sgpr1_sgpr2_sgpr3, $sgpr32, 72, 0, 0, implicit $exec :: (store (s32) into %stack.16, addrspace 5)
# |   $exec = S_MOV_B64 killed $sgpr4_sgpr5
# |   BUFFER_STORE_DWORD_OFFSET killed $vgpr0, $sgpr0_sgpr1_sgpr2_sgpr3, $sgpr32, 4, 0, 0, implicit $exec :: (store (s32) into %stack.11, addrspace 5)
# |   renamable $sgpr4_sgpr5 = S_MOV_B64 0
# |   $sgpr6_sgpr7 = S_MOV_B64 $sgpr4_sgpr5
# |   $vgpr7 = IMPLICIT_DEF
...

```

</details>

https://github.com/llvm/llvm-project/pull/168546