[llvm] AMDGPU: Add tests with forced selection of mfmas to VGPR form (PR #150626)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-aarch64-quick` running on `linaro-clang-aarch64-quick` while building `llvm` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/65/builds/20214

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

```
Step 5 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'Clangd Unit Tests :: ./ClangdTests/89/162' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/tcwg-buildbot/worker/clang-aarch64-quick/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests-Clangd Unit Tests-1955129-89-162.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=162 GTEST_SHARD_INDEX=89 /home/tcwg-buildbot/worker/clang-aarch64-quick/stage1/tools/clang/tools/extra/clangd/unittests/./ClangdTests
--

Note: This is test shard 90 of 162.
[==========] Running 8 tests from 8 test suites.
[----------] Global test environment set-up.
[----------] 1 test from CompletionTest
[ RUN      ] CompletionTest.Snippets
Built preamble of size 707284 for file /clangd-test/foo.cpp version null in 0.03 seconds
Code complete: sema context DotMemberAccess, query scopes [] (AnyScope=false), expected type <none>
Code complete: 2 results from Sema, 0 from Index, 0 matched, 0 from identifiers, 2 returned.
[       OK ] CompletionTest.Snippets (40 ms)
[----------] 1 test from CompletionTest (40 ms total)

[----------] 1 test from CompletionStringTest
[ RUN      ] CompletionStringTest.ObjectiveCMethodOneArgument
[       OK ] CompletionStringTest.ObjectiveCMethodOneArgument (0 ms)
[----------] 1 test from CompletionStringTest (0 ms total)

[----------] 1 test from IncludeFixerTest
[ RUN      ] IncludeFixerTest.CImplicitFunctionDecl
Built preamble of size 705972 for file /clangd-test/test.c version null in 0.02 seconds
Trying to fix unresolved name "foo" in scopes: []
Built preamble of size 705836 for file /clangd-test/test.c version null in 0.02 seconds
Trying to fix unresolved name "foo" in scopes: []
[       OK ] IncludeFixerTest.CImplicitFunctionDecl (63 ms)
[----------] 1 test from IncludeFixerTest (63 ms total)

[----------] 1 test from FuzzyMatch
[ RUN      ] FuzzyMatch.Segmentation
[       OK ] FuzzyMatch.Segmentation (0 ms)
[----------] 1 test from FuzzyMatch (0 ms total)

[----------] 1 test from ParameterHints
[ RUN      ] ParameterHints.VariadicNoReferenceHintForwardingRefStdForward
Built preamble of size 707136 for file /clangd-test/TestTU.cpp version null in 0.02 seconds
[       OK ] ParameterHints.VariadicNoReferenceHintForwardingRefStdForward (33 ms)
[----------] 1 test from ParameterHints (33 ms total)

[----------] 1 test from CrossFileRenameTests
[ RUN      ] CrossFileRenameTests.WithUpToDateIndex
ASTWorker building file /clangd-test/foo.h version null with command 
[/clangd-test]
clang -xobjective-c++ /clangd-test/foo.h
Driver produced command: cc1 -cc1 -triple aarch64-unknown-linux-gnu -fsyntax-only -disable-free -clear-ast-before-backend -main-file-name foo.h -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=non-leaf -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -enable-tlsdesc -target-cpu generic -target-feature +v8a -target-feature +fp-armv8 -target-feature +neon -target-abi aapcs -debugger-tuning=gdb -fdebug-compilation-dir=/clangd-test -fcoverage-compilation-dir=/clangd-test -resource-dir lib/clang/22 -internal-isystem lib/clang/22/include -internal-isystem /usr/local/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -ferror-limit 19 -fno-signed-char -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fobjc-runtime=gcc -fobjc-encode-cxx-class-template-spec -fobjc-exceptions -fcxx-exceptions -fexceptions -no-round-trip-args -target-feature -fmv -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -x objective-c++ /clangd-test/foo.h
Building first preamble for /clangd-test/foo.h version null
Built preamble of size 820588 for file /clangd-test/foo.h version null in 0.03 seconds
...

```

</details>

https://github.com/llvm/llvm-project/pull/150626