[flang-commits] [flang] [Flang][OpenMP] Move char box bounds generation for Maps to DirectiveCommons.h (PR #165918)

[via flang-commits]

https://github.com/agozillon updated https://github.com/llvm/llvm-project/pull/165918

>From ebc7adbb675fa25e6e02a68b4d192e4881ba2862 Mon Sep 17 00:00:00 2001
From: agozillon <Andrew.Gozillon at amd.com>
Date: Fri, 31 Oct 2025 15:24:35 -0500
Subject: [PATCH] [Flang][OpenMP] Move char box bounds generation for Maps to
 DirectiveCommons.h

Currently we generate these bounds in the MapInfoFinalization.cpp pass as it seems
there's a missing case for character strings/arrays (length parameter) in the
DirectiveCommons bounds generation functionality OpenMP uses for it's map
operations.

This PR tries to add this case to the DirectiveCommons function and remove the
need for the bounds generation in the MapInfoFinalization pass, so that we are
generating the bounds in the same place most other bounds are generated.
---
 flang/include/flang/Lower/DirectivesCommon.h  | 12 +++++--
 .../Optimizer/OpenMP/MapInfoFinalization.cpp  | 32 -------------------
 .../OpenMP/dynamic-len-char-bounds-gen.f90    | 19 +++++++++++
 3 files changed, 29 insertions(+), 34 deletions(-)
 create mode 100644 flang/test/Lower/OpenMP/dynamic-len-char-bounds-gen.f90

diff --git a/flang/include/flang/Lower/DirectivesCommon.h b/flang/include/flang/Lower/DirectivesCommon.h
index 2d6906738773a..b564ee1f64423 100644
--- a/flang/include/flang/Lower/DirectivesCommon.h
+++ b/flang/include/flang/Lower/DirectivesCommon.h
@@ -512,11 +512,19 @@ fir::factory::AddrAndBoundsInfo gatherDataOperandAddrAndBounds(
       }
       bool dataExvIsAssumedSize =
           Fortran::semantics::IsAssumedSizeArray(symRef->get().GetUltimate());
-      if (genDefaultBounds &&
-          mlir::isa<fir::SequenceType>(fir::unwrapRefType(info.addr.getType())))
+      if (genDefaultBounds && mlir::isa<fir::SequenceType>(
+                                  fir::unwrapRefType(info.addr.getType()))) {
         bounds = fir::factory::genBaseBoundsOps<BoundsOp, BoundsType>(
             builder, operandLocation, dataExv, dataExvIsAssumedSize,
             strideIncludeLowerExtent);
+      }
+      if (genDefaultBounds && fir::characterWithDynamicLen(
+                                  fir::unwrapRefType(info.addr.getType())) ||
+          mlir::isa<fir::BoxCharType>(
+              fir::unwrapRefType(info.addr.getType()))) {
+        bounds = {fir::factory::genBoundsOpFromBoxChar<BoundsOp, BoundsType>(
+            builder, operandLocation, dataExv, info)};
+      }
       asFortran << symRef->get().name().ToString();
     } else { // Unsupported
       llvm::report_fatal_error("Unsupported type of OpenACC operand");
diff --git a/flang/lib/Optimizer/OpenMP/MapInfoFinalization.cpp b/flang/lib/Optimizer/OpenMP/MapInfoFinalization.cpp
index d60da8971efd9..8382a481ee875 100644
--- a/flang/lib/Optimizer/OpenMP/MapInfoFinalization.cpp
+++ b/flang/lib/Optimizer/OpenMP/MapInfoFinalization.cpp
@@ -943,38 +943,6 @@ class MapInfoFinalizationPass
       localBoxAllocas.clear();
       deferrableDesc.clear();
 
-      // First, walk `omp.map.info` ops to see if any of them have varPtrs
-      // with an underlying type of fir.char<k, ?>, i.e a character
-      // with dynamic length. If so, check if they need bounds added.
-      func->walk([&](mlir::omp::MapInfoOp op) {
-        if (!op.getBounds().empty())
-          return;
-
-        mlir::Value varPtr = op.getVarPtr();
-        mlir::Type underlyingVarType = fir::unwrapRefType(varPtr.getType());
-
-        if (!fir::characterWithDynamicLen(underlyingVarType))
-          return;
-
-        fir::factory::AddrAndBoundsInfo info =
-            fir::factory::getDataOperandBaseAddr(
-                builder, varPtr, /*isOptional=*/false, varPtr.getLoc());
-
-        fir::ExtendedValue extendedValue =
-            hlfir::translateToExtendedValue(varPtr.getLoc(), builder,
-                                            hlfir::Entity{info.addr},
-                                            /*continguousHint=*/true)
-                .first;
-        builder.setInsertionPoint(op);
-        llvm::SmallVector<mlir::Value> boundsOps =
-            fir::factory::genImplicitBoundsOps<mlir::omp::MapBoundsOp,
-                                               mlir::omp::MapBoundsType>(
-                builder, info, extendedValue,
-                /*dataExvIsAssumedSize=*/false, varPtr.getLoc());
-
-        op.getBoundsMutable().append(boundsOps);
-      });
-
       // Next, walk `omp.map.info` ops to see if any record members should be
       // implicitly mapped.
       func->walk([&](mlir::omp::MapInfoOp op) {
diff --git a/flang/test/Lower/OpenMP/dynamic-len-char-bounds-gen.f90 b/flang/test/Lower/OpenMP/dynamic-len-char-bounds-gen.f90
new file mode 100644
index 0000000000000..88839221cc6d2
--- /dev/null
+++ b/flang/test/Lower/OpenMP/dynamic-len-char-bounds-gen.f90
@@ -0,0 +1,19 @@
+! RUN: %flang_fc1 -emit-hlfir -fopenmp -o - %s 2>&1 | FileCheck %s
+
+subroutine TestCharLenBounds(clen)
+
+  character(len=*) :: clen
+
+  !$omp target map(clen)
+  !$omp end target
+end subroutine TestCharLenBounds
+
+!CHECK: %[[DUMMY:.*]] = fir.dummy_scope : !fir.dscope
+!CHECK: %[[UNBOX:.*]]:2 = fir.unboxchar %{{.*}} : (!fir.boxchar<1>) -> (!fir.ref<!fir.char<1,?>>, index)
+!CHECK: %[[DECLARE:.*]]:2 = hlfir.declare %[[UNBOX]]#0 typeparams %2#1 dummy_scope %[[DUMMY]] {uniq_name = "_QFtestcharlenboundsEclen"} : (!fir.ref<!fir.char<1,?>>, index, !fir.dscope) -> (!fir.boxchar<1>, !fir.ref<!fir.char<1,?>>)
+!CHECK: %[[LB_START_IDX:.*]] = arith.constant 0 : index
+!CHECK: %[[STRIDE:.*]] = arith.constant 1 : index
+!CHECK: %[[EXTENT:.*]]:2 = fir.unboxchar %[[DECLARE]]#0 : (!fir.boxchar<1>) -> (!fir.ref<!fir.char<1,?>>, index)
+!CHECK: %[[UB:.*]] = arith.subi %[[EXTENT]]#1, %[[STRIDE]] : index
+!CHECK: %[[BOUNDS:.*]] = omp.map.bounds lower_bound(%[[LB_START_IDX]] : index) upper_bound(%[[UB]] : index) extent(%[[EXTENT]]#1 : index) stride(%[[STRIDE]] : index) start_idx(%[[LB_START_IDX]] : index) {stride_in_bytes = true}
+!CHECK: %{{.*}} = omp.map.info {{.*}} bounds(%[[BOUNDS]]) {{.*}}