[llvm-branch-commits] [flang] [flang] Introduce custom loop nest generation for loops in workshare construct (PR #101445)

[Ivan R. Ivanov via llvm-branch-commits]

ivanradanov wrote:

> Maybe support for this operation could be just based on changes to how the MLIR representation is built in the first place, what do you think?

This is partly what this implementation aims to do. In fact, after the pass that lowers the omp.workshare operation we are left with IR very close to the one you showed in your example.

The approach taken here is similar to the omp.workdistribute implementation, in that the purpose of the omp.workshare and omp.workshare.loop_wrapper ops are to preserve the high-level optimizations available when using HLFIR, after we are done with the LowerWorkshare pass, both omp.workdistribute and omp.workdistribute.loop_wrapper disappear.

The sole purpose of the omp.workdistribute.loop_wrapper op is to be able to more explicitly mark loops that need to "parallelized" by the workshare construct and preserve that information through the pipeline. Its lifetime is from the frontend (Fortran->{HLFIR,FIR}) up to the the LowerWorkshare pass which runs after we are done with HLFIR optimizations (after HLFIR->FIR lowering), same for omp.workshare.


https://github.com/llvm/llvm-project/pull/101445