Frontend dumps core consistently compiling rocblas in Debian/Ubuntu on `ppc64el`

The same sources work fine on other architectures like `amd64` or `arm64`.

Please find the Debian unstable build log here: https://buildd.debian.org/status/logs.php?pkg=rocblas&ver=6.4.4-1&arch=ppc64el
Please find the Ubuntu resolute build log here: https://launchpad.net/ubuntu/+source/rocblas/6.4.4-1/+build/31463786

Here is the backtrace:
```
Stack dump:
0. Program arguments: /usr/lib/llvm-21/bin/clang -cc1 -triple powerpc64le-unknown-linux-gnu -aux-triple amdgcn-amd-amdhsa -O3 -emit-obj -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard
-value-names -main-file-name common_gemm_ex3.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu ppc64le -m
abi=ieeelongdouble -mfloat-abi hard -target-abi elfv2 -debug-info-kind=constructor -dwarf-version=5 -debugger-tuning=gdb --compress-debug-sections=zlib -fdebug-compilation-dir=/home/ubuntu/workspace/rocblas/rocbl
as-6.4.4/obj-powerpc64le-linux-gnu/clients/common -fdebug-prefix-map=/home/ubuntu/workspace/rocblas/rocblas-6.4.4=. -fdebug-prefix-map=/home/ubuntu/workspace/rocblas/rocblas-6.4.4=/usr/src/rocblas-6.4.4-1 -fcover
age-compilation-dir=/home/ubuntu/workspace/rocblas/rocblas-6.4.4/obj-powerpc64le-linux-gnu/clients/common -resource-dir /usr/lib/llvm-21/lib/clang/21 -dependency-file CMakeFiles/rocblas_clients_common.dir/blas_ex
/common_gemm_ex3.cpp.o.d -MT clients/common/CMakeFiles/rocblas_clients_common.dir/blas_ex/common_gemm_ex3.cpp.o -sys-header-deps -internal-isystem /usr/lib/llvm-21/lib/clang/21/include/cuda_wrappers -idirafter /u
sr/include -include __clang_hip_runtime_wrapper.h -D BUILD_WITH_TENSILE -D GOOGLE_TEST -D ROCBLAS_INTERNAL_API -D ROCBLAS_NO_DEPRECATED_WARNINGS -D ROCBLAS_TENSILE_LAZY_LOAD=1 -D ROCBLAS_TENSILE_SEPARATE_ARCH=1 -
D ROCM_USE_FLOAT16 -D USE_PROF_API=1 -D __HIP_PLATFORM_AMD__=1 -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/obj-powerpc64le-linux-gnu/include/rocblas -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/obj-powerpc
64le-linux-gnu/include/rocblas/internal -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/clients/common/../include -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/clients/common/../include/blas1 -I /home/ubuntu/wo
rkspace/rocblas/rocblas-6.4.4/clients/common/../include/blas2 -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/clients/common/../include/blas3 -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/clients/common/../incl
ude/blas_ex -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/clients/common/blas_ex -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/clients/common/../../library/include -I /home/ubuntu/workspace/rocblas/rocblas-6.
4.4/clients/common/../../library/src/include -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/clients/common/../../library/src -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/clients/common -I /home/ubuntu/workspa
ce/rocblas/rocblas-6.4.4/library/src -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/library/include -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/library/include/internal -I /home/ubuntu/workspace/rocblas/rocb
las-6.4.4/library/src/include -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/obj-powerpc64le-linux-gnu/include -I /home/ubuntu/workspace/rocblas/rocblas-6.4.4/library/src/blas3/Tensile -D _FORTIFY_SOURCE=3 -D __
HIP_HCC_COMPAT_MODE__=1 -D NDEBUG -D GTEST_HAS_PTHREAD=1 -internal-isystem /usr/lib/gcc/powerpc64le-linux-gnu/15/../../../../include/c++/15 -internal-isystem /usr/lib/gcc/powerpc64le-linux-gnu/15/../../../../incl
ude/powerpc64le-linux-gnu/c++/15 -internal-isystem /usr/lib/gcc/powerpc64le-linux-gnu/15/../../../../include/c++/15/backward -internal-isystem /usr/lib/gcc/powerpc64le-linux-gnu/15/../../../../include/c++/15 -int
ernal-isystem /usr/lib/gcc/powerpc64le-linux-gnu/15/../../../../include/powerpc64le-linux-gnu/c++/15 -internal-isystem /usr/lib/gcc/powerpc64le-linux-gnu/15/../../../../include/c++/15/backward -internal-isystem /
usr/lib/llvm-21/lib/clang/21/include/ppc_wrappers -internal-isystem /usr/lib/llvm-21/lib/clang/21/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/powerpc64le-linux-gnu/15/../../../../p
owerpc64le-linux-gnu/include -internal-externc-isystem /usr/include/powerpc64le-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -internal-isystem /usr/lib/llvm-21/lib/clang/21/
include/ppc_wrappers -internal-isystem /usr/lib/llvm-21/lib/clang/21/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/powerpc64le-linux-gnu/15/../../../../powerpc64le-linux-gnu/include
-internal-externc-isystem /usr/include/powerpc64le-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/home/ubuntu/workspace/rocblas/rocblas-6.4.4=. -fcoverage-
prefix-map=/home/ubuntu/workspace/rocblas/rocblas-6.4.4=. -Wformat -Werror=format-security -Wdate-time -Wno-unused-result -std=c++17 -fdeprecated-macro -ferror-limit 19 -fmessage-length=143 -stack-protector 2 -fh
ip-new-launch-api -fno-signed-char -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -fcolor-diagnostics -vectorize-loops -vectorize-slp -fcuda-include-gpubinary /tmp/common_gemm_ex3-b25c
1c.hipfb -cuid=c90d31e2da28f391 -fcuda-allow-variadic-functions -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o CMakeFiles/rocblas_clients_common.dir/blas_ex/common_gemm_ex3.cpp.o -x hip /home/ubuntu/workspace/rocblas
/rocblas-6.4.4/clients/common/blas_ex/common_gemm_ex3.cpp
1. parser at end of file
2. Code generation
3. Running pass 'Function Pass Manager' on module '/home/ubuntu/workspace/rocblas/rocblas-6.4.4/clients/common/blas_ex/common_gemm_ex3.cpp'.
4. Running pass 'PowerPC DAG->DAG Pattern Instruction Selection' on function '@_Z19rocblas_init_matrixIDF16_Lb0EEvR11host_matrixIT_ERK9Arguments23rocblas_check_nan_init_26rocblas_check_matrix_type_bb'
#0 0x0000646c77b19178 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4079178)
#1 0x0000646c77b19a04 (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4079a04)
#2 0x0000646c77b15f14 llvm::sys::RunSignalHandlers() (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4075f14)
#3 0x0000646c77b1a724 (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x407a724)
#4 0x0000646c80cb04e4 (linux-vdso64.so.1+0x4e4)
#5 0x0000646c78609540 llvm::SelectionDAG::isConstantIntBuildVectorOrConstantInt(llvm::SDValue, bool) const (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4b69540)
#6 0x0000646c78609304 llvm::SelectionDAG::canonicalizeCommutativeBinop(unsigned int, llvm::SDValue&, llvm::SDValue&) const (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4b69304)
#7 0x0000646c78607b24 llvm::SelectionDAG::getNode(unsigned int, llvm::SDLoc const&, llvm::EVT, llvm::SDValue, llvm::SDValue, llvm::SDNodeFlags) (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4b67b24)
#8 0x0000646c784d7960 (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4a37960)
#9 0x0000646c784d644c (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4a3644c)
#10 0x0000646c7850f414 (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4a6f414)
#11 0x0000646c785140d0 llvm::SelectionDAG::LegalizeTypes() (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4a740d0)
#12 0x0000646c786400a0 llvm::SelectionDAGISel::CodeGenAndEmitDAG() (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4ba00a0)
#13 0x0000646c7863ff2c llvm::SelectionDAGISel::SelectBasicBlock(llvm::ilist_iterator_w_bits, false, true>, llvm::ili
st_iterator_w_bits, false, true>, bool&) (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4b9ff2c)
#14 0x0000646c7863f970 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4b9f970)
#15 0x0000646c7863da00 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4b9da00)
#16 0x0000646c7b307448 (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x7867448)
#17 0x0000646c7863bdb4 llvm::SelectionDAGISelLegacy::runOnMachineFunction(llvm::MachineFunction&) (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x4b9bdb4)
#18 0x0000646c78062ec8 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x45c2ec8)
#19 0x0000646c77cfd908 llvm::FPPassManager::runOnFunction(llvm::Function&) (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x425d908)
#20 0x0000646c77d0512c llvm::FPPassManager::runOnModule(llvm::Module&) (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x426512c)
#21 0x0000646c77cfe330 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x425e330)
#22 0x0000646c77d0567c llvm::legacy::PassManager::run(llvm::Module&) (/usr/lib/powerpc64le-linux-gnu/libLLVM.so.21.1+0x426567c)
#23 0x0000646c7f358f34 clang::emitBackendOutput(clang::CompilerInstance&, clang::CodeGenOptions&, llvm::StringRef, llvm::Module*, clang::BackendAction, llvm::IntrusiveRefCntPtr, std::unique
_ptr>, clang::BackendConsumer*) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x2938f34)
#24 0x0000646c7f6d5c34 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x2cb5c34)
#25 0x0000646c7dd36490 clang::ParseAST(clang::Sema&, bool, bool) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1316490)
#26 0x0000646c800212bc clang::ASTFrontendAction::ExecuteAction() (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x36012bc)
#27 0x0000646c7f6da6fc clang::CodeGenAction::ExecuteAction() (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x2cba6fc)
#28 0x0000646c80020a80 clang::FrontendAction::Execute() (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x3600a80)
#29 0x0000646c7ff8a088 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x356a088)
#30 0x0000646c800c8f04 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x36a8f04)
#31 0x0000095b61a62d10 cc1_main(llvm::ArrayRef, char const*, void*) (/usr/lib/llvm-21/bin/clang+0x22d10)
#32 0x0000095b61a5ef10 (/usr/lib/llvm-21/bin/clang+0x1ef10)
#33 0x0000095b61a5e058 clang_main(int, char**, llvm::ToolContext const&) (/usr/lib/llvm-21/bin/clang+0x1e058)
#34 0x0000095b61a700cc main (/usr/lib/llvm-21/bin/clang+0x300cc)
#35 0x0000646c73356ec4 (/usr/lib/powerpc64le-linux-gnu/libc.so.6+0x26ec4)
#36 0x0000646c7335711c __libc_start_main (/usr/lib/powerpc64le-linux-gnu/libc.so.6+0x2711c)
clang++-21: error: unable to execute command: Segmentation fault (core dumped)
clang++-21: error: clang frontend command failed due to signal (use -v to see invocation)
Ubuntu clang version 21.1.2 (2ubuntu6)
Target: powerpc64le-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/lib/llvm-21/bin
clang++-21: note: diagnostic msg: Error generating preprocessed source(s).
```

Please find a tarball [1] containing a subset of the sources (generated by `strace`ing the failing process), that leads to a fast and consistent reproducer using the following procedure.
Please make sure to run that in an isolated environment. 1) you can never trust a tarball from the Internet and 2) this will make a mess of the machine, writing to many system-owned paths.
```
# Start a VM/container (any VM/container would likely do)
lxc launch ubuntu-daily:resolute resolute
lxc file push sources.tar.zst resolute/
lxc exec resolute bash
# Extract the sources at the root of the machine
cd /
tar xvPf sources.tar.zst
# Install the build dependencies
sed -i 's# deb$# deb deb-src#' /etc/apt/sources.list.d/ubuntu.sources
apt update
apt build-dep rocblas
# Finally make the build
cd /home/ubuntu/workspace/rocblas/rocblas-6.4.4/obj-powerpc64le-linux-gnu/clients/common
mkdir -p CMakeFiles/rocblas_clients_common.dir/blas_ex
./run.sh
```
[1]: https://people.canonical.com/~skia/sources.tar.zst

Reproduce the crash in an isolated environment using the provided sources.tar.zst and clang++-21 command. Start with clients/common/blas_ex/common_gemm_ex3.cpp and the rocblas_init_matrix function, then inspect the PowerPC SelectionDAG path named in the backtrace. Done means compilation no longer segfaults on ppc64el while preserving successful builds on other architectures.

Written by the indexing model from the issue text.