[marbre]

Cherry-picks e707019 into the 7.14 release branch.

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Motivation

JIRA ID: AIROCSHMEM-439

1. llc is not shipped by all ROCm/LLVM distributions (absent on LLVM 23+), causing the device_bitcode_tester build to be silently skipped at configure time on affected machines.
2. The HSACO amdhsa.target metadata should include GPU feature suffixes (e.g. gfx950:sramecc+:xnack-) to match what the runtime GPU reports. Previously there was no way to supply these suffixes without a build-time rocminfo call against the local GPU, which fails on GPU-less build hosts and on multi-arch builds where not all target GPUs are physically present. Now, we are letting the user pass those features through GPU_TARGET var to cmake scripts.

Technical Details

1. Replace llc with clang -x ir

• Replace the llc -filetype=obj step in CMakeDeviceBitcodeTester.cmake with clang -x ir -c -target amdgcn-amd-amdhsa, which performs the same BC→object compilation using clang, which is always present.
• Arch feature flags (sramecc, xnack, etc.) previously passed as -mattr= flags to llc are now passed as -Xclang -target-feature flags to clang. The helper function arch_features_to_mattr_flags is renamed to arch_features_to_target_feature_flags and updated accordingly.
• Remove find_program(LLVM_LLC ...) and its guard. llc is no longer a build dependency.
• llc/ld.lld/opt search paths are extended to also look under ${THEROCK_TOOLCHAIN_ROOT}/lib/llvm/bin, consistent with how clang++ and llvm-link are already searched in DeviceBitcode.cmake.

2. Feature suffix support via GPU_TARGETS

• Users can now pass feature suffixes directly in the GPU_TARGETS CMake variable:

 ../scripts/build_configs/ipc_single
-DGPU_TARGETS="gfx950:sramecc+:xnack-"

• The main CMakeLists.txt normalises GPU_TARGETS into bare arch names (required by HIP compilation and rocm_check_target_ids) while preserving the original suffixed strings in a new GPU_TARGETS_FULL cache variable. DeviceBitcode.cmake reads GPU_TARGETS_FULL to populate BITCODE_GPU_ARCHS_FULL, which drives the -Xclang -target-feature flags passed to clang when building the tester HSACOs.
• The rocminfo dependency for feature suffix resolution is removed entirely. Feature suffixes now come from the user-supplied GPU_TARGETS value.
• A bug in the original CMakeLists.txt is also fixed: rocm_check_target_ids was always called with DEFAULT_GPU_TARGETS regardless of whether the user supplied GPU_TARGETS, causing the user's value to be silently ignored.

Test Result

• Functional tests pass on gfx942 and gfx950.
• Regarding AIROCSHMEM-437, the device bitcode tester is fixed with this PR, but the all-to-all issue on gfx942 should be further investigated (not related to this PR).

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JIRA ID: AIROCSHMEM-439