[clang] [llvm] [CoroSplit] Erase trivially dead allocas after spilling (PR #189295)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-nvptx64-nvidia-win` running on `as-builder-8` while building `clang,llvm` at step 7 "test-build-unified-tree-check-llvm".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/155/builds/18513

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

```
Step 7 (test-build-unified-tree-check-llvm) failure: test (failure)
******************** TEST 'LLVM :: Transforms/Coroutines/coro-debug-coro-frame.ll' FAILED ********************
Exit Code: 2

Command Output (stdout):
--
# RUN: at line 1
c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe < C:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\llvm-project\llvm\test\Transforms\Coroutines\coro-debug-coro-frame.ll -passes='module(coro-early),cgscc(coro-split,coro-split)' -S | c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\filecheck.exe C:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\llvm-project\llvm\test\Transforms\Coroutines\coro-debug-coro-frame.ll
# executed command: 'c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe' '-passes=module(coro-early),cgscc(coro-split,coro-split)' -S
# .---command stderr------------
# | Assertion failed: hasUseList(), file C:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\llvm-project\llvm\include\llvm/IR/Value.h, line 358
# | PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and instructions to reproduce the bug.
# | Stack dump:
# | 0.	Program arguments: c:\\buildbot\\as-builder-8\\llvm-nvptx64-nvidia-win\\build\\bin\\opt.exe -passes=module(coro-early),cgscc(coro-split,coro-split) -S
# | 1.	Running pass "cgscc(coro-split,coro-split)" on module "<stdin>"
# | 2.	While splitting coroutine @f
# | Exception Code: 0x80000003
# |  #0 0x00007ff6531c9ef5 (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0x1559ef5)
# |  #1 0x00007fff1cf1d88d (C:\Windows\System32\ucrtbase.dll+0x6d88d)
# |  #2 0x00007fff1cf1e761 (C:\Windows\System32\ucrtbase.dll+0x6e761)
# |  #3 0x00007fff1cf200c1 (C:\Windows\System32\ucrtbase.dll+0x700c1)
# |  #4 0x00007fff1cf203f1 (C:\Windows\System32\ucrtbase.dll+0x703f1)
# |  #5 0x00007ff652db00c3 (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0x11400c3)
# |  #6 0x00007ff653b3b50d (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0x1ecb50d)
# |  #7 0x00007ff653b35368 (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0x1ec5368)
# |  #8 0x00007ff653b1f2f5 (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0x1eaf2f5)
# |  #9 0x00007ff653b2518b (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0x1eb518b)
# | #10 0x00007ff653393cf6 (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0x1723cf6)
# | #11 0x00007ff6523be87d (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0x74e87d)
# | #12 0x00007ff653393d56 (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0x1723d56)
# | #13 0x00007ff6523c0ff9 (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0x750ff9)
# | #14 0x00007ff651daa792 (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0x13a792)
# | #15 0x00007ff652bc7103 (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0xf57103)
# | #16 0x00007ff651d2a594 (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0xba594)
# | #17 0x00007ff651d2063f (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0xb063f)
# | #18 0x00007ff651d16827 (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0xa6827)
# | #19 0x00007ff651d2ec28 (c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\opt.exe+0xbec28)
# | #20 0x00007fff1f407ac4 (C:\Windows\System32\KERNEL32.DLL+0x17ac4)
# | #21 0x00007fff1feaa8c1 (C:\Windows\SYSTEM32\ntdll.dll+0x5a8c1)
# `-----------------------------
# error: command failed with exit status: 0x80000003
# executed command: 'c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\filecheck.exe' 'C:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\llvm-project\llvm\test\Transforms\Coroutines\coro-debug-coro-frame.ll'
# .---command stderr------------
# | FileCheck error: '<stdin>' is empty.
# | FileCheck command line:  c:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\bin\filecheck.exe C:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\llvm-project\llvm\test\Transforms\Coroutines\coro-debug-coro-frame.ll
# `-----------------------------
# error: command failed with exit status: 2

--

********************


```

</details>

https://github.com/llvm/llvm-project/pull/189295