[RFC][OpenMP] Translation of allocate clause to LLVM IR in taskgroup directive

[kaviya2510]

@kiranchandramohan

Does ___kmp_allocate(size_t size) allocate in the memory specified by the allocator clause? Or does it not honour the allocate clause at all?

Hi @kiranchandramohan ,Thanks for the comments.
No, ___kmp_allocate(size_t size) doesn’t allocate the memory specified by the allocator clause. It is actually allocating memory for private variables using malloc() with required size and default alignment.

In taskgroup directive

• Function __kmp_allocate(size_t size)(size is obtained from the struct kmp_taskred_input_t populated for taskgroup) is called at runtime by __kmpc_taskred_init(int gtid, int num, void *data), which initializes task reduction. In this case all allocations are managed internally by the OpenMP runtime, which does not use the allocator/align information specified by the allocate clause in taskgroup.

@kiranchandramohan

Do you mean to say that the implementation is not complete in Clang? Or do you mean to say that the implementation is complete but most of the handling for allocating memory is handled internally by the OpenMP runtime?

Based on current observations it seems like clang does not fully support allocate clause(allocator or align) for taskgroup as it does for other directives like parallel and allocate.
It’s unclear if this is due to incomplete support or an intentional design choice that we need to check with clang community.
I have created an RFC for the Clang community. Please take a look at it for more details.