[Mlir-commits] [flang] [mlir] [Flang][OpenMP] Support iterator modifier in map and motion clauses (PR #197757)

[llvmlistbot at llvm.org]

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@@ -6996,7 +6997,35 @@ genOpenMPDeclareMapperImpl(lower::AbstractConverter &converter,
   List<Clause> clauses = makeClauses(construct.v.Clauses(), semaCtx);
   ClauseProcessor cp(converter, semaCtx, clauses);
   cp.processMap(loc, stmtCtx, clauseOps);
+  // Emit cleanups inside the mapper region, before its terminator.
+  stmtCtx.finalizeAndReset();
   mlir::omp::DeclareMapperInfoOp::create(firOpBuilder, loc, clauseOps);
+
+  // Values of the enclosing procedure are not available in the mapper region.
+  mlir::WalkResult usesOutsideValue = region.walk([&](mlir::Operation *op) {
+    for (mlir::Value operand : op->getOperands())
+      if (!region.isAncestor(operand.getParentRegion()))
+        return mlir::WalkResult::interrupt();
+    return mlir::WalkResult::advance();
+  });
+  if (usesOutsideValue.wasInterrupted())
+    TODO(loc, "declare mapper using a value from outside the mapper region");
+
+  // The mapper region must remain a single block once control flow is lowered.
+  // With an iterator modifier, intrinsic simplification may also add loops.
+  bool hasIterator = llvm::any_of(clauses, [](const Clause &clause) {
+    const auto *map = std::get_if<clause::Map>(&clause.u);
+    return map && std::get<std::optional<clause::Iterator>>(map->t).has_value();
+  });
+  for (mlir::Operation &op : region.front()) {
+    bool mayAddLoops =
+        hasIterator && mlir::isa<hlfir::hlfirDialect>(op.getDialect()) &&
----------------
MattPD wrote:

This check also rejects parenthesized scalar expressions, although they lower to `hlfir.no_reassoc` and do not add control flow:

```fortran
subroutine paren_range
  type :: t
    integer :: a(4), n
  end type
  !$omp declare mapper(m: t :: v) &
  !$omp& map(iterator(i=1:(v%n)), to: v%a(i))
end subroutine
```

Save this as `repro.f90` and run `flang -c -fopenmp -fopenmp-version=52 repro.f90`. At 7391dbf, Flang reports `not yet implemented: declare mapper with control flow`. The previous revision e3eaf33 compiles it, and 7391dbf compiles it without the parentheses.

Could the check accept `hlfir.no_reassoc` and keep rejecting operations that can become loops, such as `maxval`?

https://github.com/llvm/llvm-project/pull/197757