[llvm] [AMDGPU] Replace dynamic VGPR feature with attribute (PR #133444)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-aarch64-sve-vls-2stage` running on `linaro-g3-03` while building `llvm` at step 12 "ninja check 2".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/4/builds/7534

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

```
Step 12 (ninja check 2) failure: stage 2 checked (failure)
******************** TEST 'LLVM :: CodeGen/AMDGPU/pal-metadata-3.0-callable-dvgpr.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
/home/tcwg-buildbot/worker/clang-aarch64-sve-vls-2stage/stage2/bin/llc -mtriple=amdgcn--amdpal -mcpu=gfx1200 -verify-machineinstrs < /home/tcwg-buildbot/worker/clang-aarch64-sve-vls-2stage/llvm/llvm/test/CodeGen/AMDGPU/pal-metadata-3.0-callable-dvgpr.ll | /home/tcwg-buildbot/worker/clang-aarch64-sve-vls-2stage/stage2/bin/FileCheck /home/tcwg-buildbot/worker/clang-aarch64-sve-vls-2stage/llvm/llvm/test/CodeGen/AMDGPU/pal-metadata-3.0-callable-dvgpr.ll # RUN: at line 1
+ /home/tcwg-buildbot/worker/clang-aarch64-sve-vls-2stage/stage2/bin/llc -mtriple=amdgcn--amdpal -mcpu=gfx1200 -verify-machineinstrs
+ /home/tcwg-buildbot/worker/clang-aarch64-sve-vls-2stage/stage2/bin/FileCheck /home/tcwg-buildbot/worker/clang-aarch64-sve-vls-2stage/llvm/llvm/test/CodeGen/AMDGPU/pal-metadata-3.0-callable-dvgpr.ll
/home/tcwg-buildbot/worker/clang-aarch64-sve-vls-2stage/llvm/llvm/test/CodeGen/AMDGPU/pal-metadata-3.0-callable-dvgpr.ll:83:15: error: CHECK-NEXT: expected string not found in input
; CHECK-NEXT: .sgpr_count: 0x1
              ^
<stdin>:933:14: note: scanning from here
 .lds_size: 0
             ^
<stdin>:934:2: note: possible intended match here
 .sgpr_count: 0x21
 ^

Input file: <stdin>
Check file: /home/tcwg-buildbot/worker/clang-aarch64-sve-vls-2stage/llvm/llvm/test/CodeGen/AMDGPU/pal-metadata-3.0-callable-dvgpr.ll

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

Input was:
<<<<<<
           .
           .
           .
         928:  .sgpr_count: 0x22 
         929:  .stack_frame_size_in_bytes: 0x10 
         930:  .vgpr_count: 0x3 
         931:  multiple_stack: 
         932:  .backend_stack_size: 0x24 
         933:  .lds_size: 0 
next:83'0                  X error: no match found
         934:  .sgpr_count: 0x21 
next:83'0     ~~~~~~~~~~~~~~~~~~~
next:83'1      ?                  possible intended match
         935:  .stack_frame_size_in_bytes: 0x24 
next:83'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
         936:  .vgpr_count: 0x3 
next:83'0     ~~~~~~~~~~~~~~~~~~
         937:  no_stack: 
next:83'0     ~~~~~~~~~~~
         938:  .backend_stack_size: 0 
next:83'0     ~~~~~~~~~~~~~~~~~~~~~~~~
         939:  .lds_size: 0 
next:83'0     ~~~~~~~~~~~~~~
           .
           .
...

```

</details>

https://github.com/llvm/llvm-project/pull/133444