[llvm] [AMDGPU] Add MachineVerifier check to detect illegal copies from vector register to SGPR (PR #105494)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-expensive-checks-debian` running on `gribozavr4` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/16/builds/5632

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

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: CodeGen/AMDGPU/illegal-sgpr-to-vgpr-copy.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 1: not /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -mtriple=amdgcn < /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/illegal-sgpr-to-vgpr-copy.ll 2>&1 | /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck -check-prefix=ERR /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/illegal-sgpr-to-vgpr-copy.ll
+ not /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/llc -mtriple=amdgcn
+ /b/1/llvm-clang-x86_64-expensive-checks-debian/build/bin/FileCheck -check-prefix=ERR /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/illegal-sgpr-to-vgpr-copy.ll
/b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/illegal-sgpr-to-vgpr-copy.ll:4:8: error: ERR: expected string not found in input
; ERR: error: <unknown>:0:0: in function illegal_vgpr_to_sgpr_copy_i32 void (): illegal VGPR to SGPR copy
       ^
<stdin>:1:1: note: scanning from here

^

Input file: <stdin>
Check file: /b/1/llvm-clang-x86_64-expensive-checks-debian/llvm-project/llvm/test/CodeGen/AMDGPU/illegal-sgpr-to-vgpr-copy.ll

-dump-input=help explains the following input dump.

Input was:
<<<<<<
         1:  
check:4     X error: no match found
         2: # After Eliminate PHI nodes for register allocation 
check:4     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
         3: # Machine code for function illegal_vgpr_to_sgpr_copy_i32: NoPHIs, TracksLiveness 
check:4     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
         4:  
check:4     ~
         5: bb.0 (%ir-block.0): 
check:4     ~~~~~~~~~~~~~~~~~~~~
         6:  INLINEASM &"; def $0" [sideeffect] [attdialect], $0:[regdef], implicit-def $vgpr1 
check:4     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
         .
         .
         .
>>>>>>

--

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


```

</details>

https://github.com/llvm/llvm-project/pull/105494