devicelib: provide __builtin_amdgcn_atomic_inc32 and dec32 on SPIR-V - #1392
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__builtin_amdgcn_atomic_inc32 and __builtin_amdgcn_atomic_dec32 are undeclared on the SPIR-V target, so the test fails to compile today. It checks the modular semantics step by step for a single thread and the wrapped total for a contended counter.
Clang declares these builtins only for the amdgcn target, so HIP code written against ROCm that uses them does not compile for SPIR-V. desul, which Kokkos bundles, uses them for atomic_fetch_inc_mod and atomic_fetch_dec_mod, which takes out every Kokkos translation unit that includes desul/atomics/Fetch_Op_HIP.hpp. Their semantics match atomicInc and atomicDec, already implemented by __chip_atomic_inc2_u and __chip_atomic_dec2_u, so forward to those. Fixes #1390
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Fixes #1390
Clang declares these builtins only for the amdgcn target, so HIP code written against ROCm that uses them does not compile for SPIR-V. desul, bundled by Kokkos, uses them for atomic_fetch_inc_mod and atomic_fetch_dec_mod.
Their semantics match atomicInc and atomicDec, already implemented by __chip_atomic_inc2_u and __chip_atomic_dec2_u, so the shims forward to those.
New test tests/devicelib/TestAtomicIncDecMod.cpp, verified on Intel Arc B570 (OpenCL): fails to compile before the header change, PASSED after.