[llvm] AMDGPU: Restrict src0 to VGPRs only for certain cvt scale opcodes. (PR #127464)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `openmp-offload-amdgpu-runtime` running on `omp-vega20-0` while building `llvm` at step 7 "Add check check-offload".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/30/builds/16183

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

```
Step 7 (Add check check-offload) failure: test (failure)
...
PASS: libomptarget :: x86_64-unknown-linux-gnu-LTO :: offloading/bug53727.cpp (1002 of 1011)
PASS: libomptarget :: x86_64-unknown-linux-gnu-LTO :: offloading/bug50022.cpp (1003 of 1011)
PASS: libomptarget :: x86_64-unknown-linux-gnu-LTO :: offloading/wtime.c (1004 of 1011)
PASS: libomptarget :: x86_64-unknown-linux-gnu-LTO :: offloading/test_libc.cpp (1005 of 1011)
PASS: libomptarget :: x86_64-unknown-linux-gnu :: offloading/bug49021.cpp (1006 of 1011)
PASS: libomptarget :: x86_64-unknown-linux-gnu :: offloading/std_complex_arithmetic.cpp (1007 of 1011)
PASS: libomptarget :: x86_64-unknown-linux-gnu-LTO :: offloading/complex_reduction.cpp (1008 of 1011)
PASS: libomptarget :: x86_64-unknown-linux-gnu-LTO :: offloading/bug49021.cpp (1009 of 1011)
PASS: libomptarget :: x86_64-unknown-linux-gnu-LTO :: offloading/std_complex_arithmetic.cpp (1010 of 1011)
TIMEOUT: libomptarget :: amdgcn-amd-amdhsa :: offloading/ctor_dtor.cpp (1011 of 1011)
******************** TEST 'libomptarget :: amdgcn-amd-amdhsa :: offloading/ctor_dtor.cpp' FAILED ********************
Exit Code: -9
Timeout: Reached timeout of 100 seconds

Command Output (stdout):
--
# RUN: at line 1
/home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/./bin/clang++ -fopenmp    -I /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.src/offload/test -I /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/openmp/runtime/src -L /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload -L /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/./lib -L /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/openmp/runtime/src  -nogpulib -Wl,-rpath,/home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload -Wl,-rpath,/home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/openmp/runtime/src -Wl,-rpath,/home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/./lib  -fopenmp-targets=amdgcn-amd-amdhsa /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.src/offload/test/offloading/ctor_dtor.cpp -o /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload/test/amdgcn-amd-amdhsa/offloading/Output/ctor_dtor.cpp.tmp /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/./lib/libomptarget.devicertl.a && /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload/test/amdgcn-amd-amdhsa/offloading/Output/ctor_dtor.cpp.tmp | /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/./bin/FileCheck /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.src/offload/test/offloading/ctor_dtor.cpp
# executed command: /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/./bin/clang++ -fopenmp -I /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.src/offload/test -I /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/openmp/runtime/src -L /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload -L /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/./lib -L /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/openmp/runtime/src -nogpulib -Wl,-rpath,/home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload -Wl,-rpath,/home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/openmp/runtime/src -Wl,-rpath,/home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/./lib -fopenmp-targets=amdgcn-amd-amdhsa /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.src/offload/test/offloading/ctor_dtor.cpp -o /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload/test/amdgcn-amd-amdhsa/offloading/Output/ctor_dtor.cpp.tmp /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/./lib/libomptarget.devicertl.a
# note: command had no output on stdout or stderr
# executed command: /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/runtimes/runtimes-bins/offload/test/amdgcn-amd-amdhsa/offloading/Output/ctor_dtor.cpp.tmp
# note: command had no output on stdout or stderr
# error: command failed with exit status: -9
# error: command reached timeout: True
# executed command: /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.build/./bin/FileCheck /home/ompworker/bbot/openmp-offload-amdgpu-runtime/llvm.src/offload/test/offloading/ctor_dtor.cpp
# note: command had no output on stdout or stderr
# error: command failed with exit status: -9
# error: command reached timeout: True

--

********************
Slowest Tests:
--------------------------------------------------------------------------
100.05s: libomptarget :: amdgcn-amd-amdhsa :: offloading/ctor_dtor.cpp
15.46s: libomptarget :: amdgcn-amd-amdhsa :: offloading/bug49021.cpp
12.70s: libomptarget :: amdgcn-amd-amdhsa :: offloading/parallel_target_teams_reduction_max.cpp
12.43s: libomptarget :: amdgcn-amd-amdhsa :: offloading/parallel_target_teams_reduction_min.cpp
10.98s: libomptarget :: amdgcn-amd-amdhsa :: offloading/complex_reduction.cpp
9.31s: libomptarget :: amdgcn-amd-amdhsa :: jit/empty_kernel_lvl2.c
9.23s: libomptarget :: x86_64-unknown-linux-gnu :: offloading/bug49021.cpp
7.58s: libomptarget :: x86_64-unknown-linux-gnu :: offloading/std_complex_arithmetic.cpp
7.48s: libomptarget :: amdgcn-amd-amdhsa :: offloading/barrier_fence.c
7.34s: libomptarget :: amdgcn-amd-amdhsa :: offloading/ompx_saxpy_mixed.c
7.25s: libomptarget :: x86_64-unknown-linux-gnu :: offloading/complex_reduction.cpp
6.61s: libomptarget :: x86_64-unknown-linux-gnu-LTO :: offloading/bug49021.cpp
5.67s: libomptarget :: amdgcn-amd-amdhsa :: offloading/parallel_target_teams_reduction.cpp
5.16s: libomptarget :: x86_64-unknown-linux-gnu-LTO :: offloading/std_complex_arithmetic.cpp
5.11s: libomptarget :: amdgcn-amd-amdhsa :: offloading/default_thread_limit.c

```

</details>

https://github.com/llvm/llvm-project/pull/127464