[libclc] Add generic implementation of some atomic functions in OpenCL spec section 6.15.12.7#146814
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…L spec section 6.15.12.7 Add corresponding clc functions, which are implemented with clang __scoped_atomic builtins. OpenCL functions are implemented as a wrapper over clc functions. Also change legacy atomic_inc and atomic_dec to re-use the newly added clc_atomic_inc/dec implementations. llvm-diff only no change to atomic_inc and atomic_dec in bitcode. Notes: * Generic OpenCL built-ins functions uses __ATOMIC_SEQ_CST and __MEMORY_SCOPE_SYSTEM for memory order and memory scope parameters. Ideally we should check if __opencl_c_atomic_order_seq_cst, __opencl_c_atomic_scope_all_devices and __opencl_c_atomic_scope_device feature macros should be checked. However, none of them are defined for nvptx64 and amdgcn arch yet. We can add the check when the backends are fixed. * OpenCL atomic_*_explicit, atomic_flag* built-ins are not implemented yet. * OpenCL built-ins of atomic_intptr_t, atomic_uintptr_t, atomic_size_t and atomic_ptrdiff_t types are not implemented yet. * llvm-diff only shows new built-ins are added to nvptx64--nvidiacl.bc and amdgcn--amdhsa.bc. The number of newly added built-ins in amdgcn--amdhsa.bc is higher than in nvptx64--nvidiacl.bc because 64-bit atomics are enabled for amdgcn--amdhsa.
frasercrmck
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Jul 10, 2025
…_opencl_c_atomic_scope_device
…c_atomic_scope_device macro is required for the new built-ins
frasercrmck
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Jul 14, 2025
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Can we do anything about the warnings I'm seeing while building this? They're noisy.
In file included from /llvm-project/libclc/clc/lib/generic/atomic/clc_atomic_fetch_min.cl:18:
In file included from /llvm-project/libclc/clc/include/clc/math/gentype.inc:239:
/llvm-project/libclc/clc/lib/generic/atomic/atomic_def.inc:59:1: warning: large atomic operation may incur significant performance penalty; the access size (2 bytes) exceeds the max lock-free size (0 bytes) [-Watomic-alignment]
59 | __CLC_DEFINE_ATOMIC()
| ^
/llvm-project/libclc/clc/lib/generic/atomic/atomic_def.inc:51:9: note: expanded from macro '__CLC_DEFINE_ATOMIC'
51 | __IMPL_FUNCTION((ADDRSPACE __CLC_PTR_CASTTYPE *)Ptr, Value, \
| ^
/llvm-project/libclc/clc/lib/generic/atomic/clc_atomic_fetch_min.cl:12:25: note: expanded from macro '__IMPL_FUNCTION'
12 | #define __IMPL_FUNCTION __scoped_atomic_fetch_min
| ^
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…for spir64 Set MaxAtomicInlineWidth the same way as SPIR-V targets in 3cfd0c0. This PR fixes build warning in scoped atomic built-in in llvm#146814: `warning: large atomic operation may incur significant performance penalty`
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thanks @frasercrmck |
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…for spir64 (#148997) Set MaxAtomicInlineWidth the same way as SPIR-V targets in 3cfd0c0. This PR fixes build warning in scoped atomic built-in in #146814: `warning: large atomic operation may incur significant performance penalty; ; the access size (2 bytes) exceeds the max lock-free size (0 bytes) [-Watomic-alignment]`
…ning 'large atomic operation may incur significant performance penalty' Also rename clc/lib/generic/atomic/atomic_def.inc to clc_atomic_def.inc
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@frasercrmck please review new two changes in c88bf9b:
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This was referenced Jul 23, 2025
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Add corresponding clc functions, which are implemented with clang __scoped_atomic builtins. OpenCL functions are implemented as a wrapper over clc functions.
Also change legacy atomic_inc and atomic_dec to re-use the newly added clc_atomic_inc/dec implementations. llvm-diff only no change to atomic_inc and atomic_dec in bitcode.
Notes: