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	Q: Does OpenMP offloading support work in pre-packaged LLVM releases?			Q: Does OpenMP offloading support work in pre-packaged LLVM releases?
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^			^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
	For now, the answer is most likely no. Please see :ref:`build_offload_capable_compiler`.			For now, the answer is most likely no. Please see :ref:`build_offload_capable_compiler`.

	Q: Does OpenMP offloading support work in packages distributed as part of my OS?			Q: Does OpenMP offloading support work in packages distributed as part of my OS?
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^			^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
	For now, the answer is most likely no. Please see :ref:`build_offload_capable_compiler`.			For now, the answer is most likely no. Please see :ref:`build_offload_capable_compiler`.


				.. _math_and_complex_in_target_regions:

				Q: Does Clang support `<math.h>` and `<complex.h>` operations in OpenMP target on GPUs?
				^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

				Yes, LLVM/Clang allows math functions and complex arithmetic inside of OpenMP target regions
				that are compiled for GPUs.

				Clang provides a set of wrapper headers that are found first when `math.h`,
				ye-luoUnsubmitted Not Done Reply Inline Actions I remember math.h can be difficult for C++. better to say math.h and complex.h for C and cmath and complex for C++. ye-luo: I remember math.h can be difficult for C++. better to say math.h and complex.h for C and cmath…
				jdoerfertAuthorUnsubmitted Done Reply Inline Actions Will do, though I'm curious what the problem is. jdoerfert: Will do, though I'm curious what the problem is.
				`cmath`, `complex.h`, or similar headers are included by the application. These
				wrappers will eventually include the system version of the corresponding header
				file after setting up a target device specific environment. The fact that the
				system header is included is important because they differ based on the
				architecture and operating system and may contain preprocessor, variable, and
				function definitions that need to be available in the target region regardless
				of the targeted device architecture. However, various functions may require
				specialized device versions, e.g., `sin`, and others are only available on
				certain devices, e.g., `__umul64hi`. To provide "native" support for math and
				complex on the respective architecture, Clang will wrap the "native" math
				functions, e.g., as provided by the device vendor, in an OpenMP begin/end
				declare variant. These functions will then be picked up instead of the host
				versions while host only variables and function definitions are still
				available. Complex arithmetic and functions are support through a similar
				mechanism. It is worth noting that this support requires `extensions to the
				OpenMP begin/end declare variant context selector
				<https://clang.llvm.org/docs/AttributeReference.html#pragma-omp-declare-variant>`__
				that are exposed through LLVM/Clang.

This is an archive of the discontinued LLVM Phabricator instance.

[OpenMP][Docs] Add FAQ entry about math and complex on GPUsClosedPublic

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[OpenMP][Docs] Add FAQ entry about math and complex on GPUs
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