[flang-commits] [flang] [flang][OpenMP] Move reductions from `loop` to `teams` when `loop` is mapped to `distribute` (PR #132920)

[Michael Klemm via flang-commits]

================
@@ -358,3 +358,40 @@ subroutine multi_block_teams
   end select
   !$omp end target teams
 end subroutine
+
+
+! Verifies that reductions are hoisted to the parent `teams` directive and removed
+! from the `loop` dreictive when `loop` is mapped to `distribute`.
+
+! CHECK-LABEL: func.func @_QPteams_loop_cannot_be_parallel_for_with_reductions
+subroutine teams_loop_cannot_be_parallel_for_with_reductions
+  implicit none
+  integer :: x, y, i, p
+
+  ! CHECK: %[[ADD_RED:.*]]:2 = hlfir.declare %{{.*}} {uniq_name = "_QF{{.*}}Ex"}
+  ! CHECK: %[[MUL_RED:.*]]:2 = hlfir.declare %{{.*}} {uniq_name = "_QF{{.*}}Ey"}
+  ! CHECK: omp.teams reduction(
+  ! CHECK-SAME:  @add_reduction_i32 %[[ADD_RED]]#0 -> %[[ADD_RED_ARG:[^[:space:]]*]], 
+  ! CHECK-SAME:  @multiply_reduction_i32 %[[MUL_RED]]#0 -> %[[MUL_RED_ARG:.*]] : {{.*}}) {
+
+  ! CHECK:       omp.distribute private(@{{.*}} %{{.*}} -> %{{.*}}, @{{.*}} %{{.*}} -> %{{.*}} : {{.*}}) {
+  ! CHECK:         %[[ADD_RED_DECL:.*]]:2 = hlfir.declare %[[ADD_RED_ARG]] {uniq_name = "_QF{{.*}}Ex"}
+  ! CHECK:         %[[MUL_RED_DECL:.*]]:2 = hlfir.declare %[[MUL_RED_ARG]] {uniq_name = "_QF{{.*}}Ey"}
+
+  ! CHECK:         %[[ADD_RES:.*]] = arith.addi %{{.*}}, %{{.*}} : i32
+  ! CHECK:         hlfir.assign %[[ADD_RES]] to %[[ADD_RED_DECL]]#0 : i32, !fir.ref<i32>
+
+  ! CHECK:         %[[MUL_RES:.*]] = arith.muli %{{.*}}, %{{.*}} : i32
+  ! CHECK:         hlfir.assign %[[MUL_RES]] to %[[MUL_RED_DECL]]#0 : i32, !fir.ref<i32>
+  ! CHECK:         omp.yield
+  ! CHECK:       }
+  ! CHECK:       omp.terminator
+  ! CHECK: }
+  !$omp teams loop reduction(+: x) reduction(*: y) private(p)
+  DO i = 1, 5
+    call foo()
+    x = x + i
+    y = y * i
+    p = 42
+  END DO
----------------
mjklemm wrote:

```suggestion
  end do
```

https://github.com/llvm/llvm-project/pull/132920