[flang-commits] [flang] [llvm] [mlir] [openmp] [Flang][OpenMP] Lower scan directive and inscan reduction modifier (PR #206747)

[CHANDRA GHALE via flang-commits]

chandraghale wrote:

> This builds on top of #167031 to complete scan reduction lowering for OpenMP workshare loops. On top of that PR, it resets each reduction variable to its identity at the start of every input-loop iteration; otherwise the scan buffer holds a running sum and emitScanReduction prefix-sums it twice, producing incorrect results. SIMD, composite/nested loops, collapse, tiling, the linear clause and the exclusive clause are not enabled for scan reductions in this PR.

Assisted-by: Claude Opus 4.8 

https://github.com/llvm/llvm-project/pull/206747