[compiler-rt] [llvm] [SPARC] Allow overaligned `alloca`s (PR #107223)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-ppc64le-rhel` running on `ppc64le-clang-rhel-test` while building `compiler-rt,llvm` at step 5 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/145/builds/2912

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

```
Step 5 (build-unified-tree) failure: build (failure)
...
9.584 [267/13/236] Linking CXX shared library lib/libclangAnalysisFlowSensitive.so.20.0git
9.593 [266/13/237] Creating library symlink lib/libclangAnalysisFlowSensitive.so
9.626 [265/13/238] Building CXX object lib/Target/Sparc/CMakeFiles/LLVMSparcCodeGen.dir/SparcSubtarget.cpp.o
9.654 [265/12/239] Linking CXX shared library lib/libclangAnalysisFlowSensitiveModels.so.20.0git
9.663 [264/12/240] Creating library symlink lib/libclangAnalysisFlowSensitiveModels.so
9.732 [264/11/241] Building CXX object tools/lld/Common/CMakeFiles/lldCommon.dir/Version.cpp.o
9.764 [263/11/242] Building CXX object lib/Target/Sparc/CMakeFiles/LLVMSparcCodeGen.dir/DelaySlotFiller.cpp.o
9.786 [263/10/243] Linking CXX shared library lib/liblldCommon.so.20.0git
9.792 [262/10/244] Creating library symlink lib/liblldCommon.so
9.917 [262/9/245] Building CXX object lib/Target/Sparc/CMakeFiles/LLVMSparcCodeGen.dir/SparcFrameLowering.cpp.o
FAILED: lib/Target/Sparc/CMakeFiles/LLVMSparcCodeGen.dir/SparcFrameLowering.cpp.o 
ccache /home/docker/llvm-external-buildbots/clang.17.0.6/bin/clang++ --gcc-toolchain=/gcc-toolchain/usr -DGTEST_HAS_RTTI=0 -DLLVM_EXPORTS -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/build/lib/Target/Sparc -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/lib/Target/Sparc -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/build/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG -std=c++17 -fPIC  -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -MD -MT lib/Target/Sparc/CMakeFiles/LLVMSparcCodeGen.dir/SparcFrameLowering.cpp.o -MF lib/Target/Sparc/CMakeFiles/LLVMSparcCodeGen.dir/SparcFrameLowering.cpp.o.d -o lib/Target/Sparc/CMakeFiles/LLVMSparcCodeGen.dir/SparcFrameLowering.cpp.o -c /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/lib/Target/Sparc/SparcFrameLowering.cpp
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/lib/Target/Sparc/SparcFrameLowering.cpp:226:29: error: unused variable 'RegInfo' [-Werror,-Wunused-variable]
  226 |   const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
      |                             ^~~~~~~
1 error generated.
9.932 [262/8/246] Linking CXX shared library lib/libclangSema.so.20.0git
10.016 [262/7/247] Building CXX object lib/Target/Sparc/CMakeFiles/LLVMSparcCodeGen.dir/SparcInstrInfo.cpp.o
10.491 [262/6/248] Building CXX object lib/Target/Sparc/CMakeFiles/LLVMSparcCodeGen.dir/LeonPasses.cpp.o
10.638 [262/5/249] Building CXX object lib/Target/Sparc/CMakeFiles/LLVMSparcCodeGen.dir/SparcAsmPrinter.cpp.o
10.798 [262/4/250] Building CXX object lib/Target/Sparc/CMakeFiles/LLVMSparcCodeGen.dir/SparcISelDAGToDAG.cpp.o
13.143 [262/3/251] Building CXX object lib/Target/Sparc/CMakeFiles/LLVMSparcCodeGen.dir/SparcISelLowering.cpp.o
23.180 [262/2/252] Building CXX object lib/CodeGen/AsmPrinter/CMakeFiles/LLVMAsmPrinter.dir/AsmPrinter.cpp.o
24.778 [262/1/253] Building CXX object lib/LTO/CMakeFiles/LLVMLTO.dir/LTO.cpp.o
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/107223