[llvm] [AMDGPU][MIR] Serialize NumPhysicalVGPRSpillLanes (PR #115291)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-ppc64le-linux-test-suite` running on `ppc64le-clang-test-suite` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/95/builds/5934

<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 :: tools/llvm-reduce/mir/preserve-machine-function-info-amdgpu.mir' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 2: llvm-reduce -abort-on-invalid-reduction -simplify-mir -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 --test /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/bin/FileCheck --test-arg --check-prefix=CHECK-INTERESTINGNESS --test-arg /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/test/tools/llvm-reduce/mir/preserve-machine-function-info-amdgpu.mir --test-arg --input-file /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/test/tools/llvm-reduce/mir/preserve-machine-function-info-amdgpu.mir -o /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/test/tools/llvm-reduce/mir/Output/preserve-machine-function-info-amdgpu.mir.tmp 2> /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/test/tools/llvm-reduce/mir/Output/preserve-machine-function-info-amdgpu.mir.tmp.log
+ llvm-reduce -abort-on-invalid-reduction -simplify-mir -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 --test /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/bin/FileCheck --test-arg --check-prefix=CHECK-INTERESTINGNESS --test-arg /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/test/tools/llvm-reduce/mir/preserve-machine-function-info-amdgpu.mir --test-arg --input-file /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/test/tools/llvm-reduce/mir/preserve-machine-function-info-amdgpu.mir -o /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/test/tools/llvm-reduce/mir/Output/preserve-machine-function-info-amdgpu.mir.tmp
RUN: at line 3: /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/bin/FileCheck --check-prefix=RESULT /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/test/tools/llvm-reduce/mir/preserve-machine-function-info-amdgpu.mir < /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/test/tools/llvm-reduce/mir/Output/preserve-machine-function-info-amdgpu.mir.tmp
+ /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/bin/FileCheck --check-prefix=RESULT /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/test/tools/llvm-reduce/mir/preserve-machine-function-info-amdgpu.mir
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/test/tools/llvm-reduce/mir/preserve-machine-function-info-amdgpu.mir:55:16: error: RESULT-NEXT: is not on the line after the previous match
# RESULT-NEXT: wwmReservedRegs:
               ^
<stdin>:64:2: note: 'next' match was here
 wwmReservedRegs:
 ^
<stdin>:62:14: note: previous match ended here
 occupancy: 8
             ^
<stdin>:63:1: note: non-matching line after previous match is here
 numPhysicalVGPRSpillLanes: 0
^

Input file: <stdin>
Check file: /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/test/tools/llvm-reduce/mir/preserve-machine-function-info-amdgpu.mir

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

Input was:
<<<<<<
         .
         .
         .
        59:  fp64-fp16-input-denormals: false 
        60:  fp64-fp16-output-denormals: false 
        61:  highBitsOf32BitAddress: 4276993775 
        62:  occupancy: 8 
        63:  numPhysicalVGPRSpillLanes: 0 
        64:  wwmReservedRegs: 
next:55      !~~~~~~~~~~~~~~~  error: match on wrong line
        65:  - '$vgpr2' 
        66:  - '$vgpr3' 
        67:  vgprForAGPRCopy: '$vgpr33' 
        68: body: | 
        69:  bb.0: 
         .
         .
         .
>>>>>>

--
...

```

</details>

https://github.com/llvm/llvm-project/pull/115291