[flang-commits] [flang] [flang][OpenMP] Support user-defined declare reduction with derived types (PR #184897)

[Tom Eccles via flang-commits]

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@@ -636,6 +618,18 @@ void PopulateInitAndCleanupRegionsHelper::initAndCleanupBoxchar(
 void PopulateInitAndCleanupRegionsHelper::initAndCleanupUnboxedDerivedType(
     bool needsInitialization) {
   builder.setInsertionPointToStart(initBlock);
+  // For reductions with a user-provided init value, store it into the
+  // private variable. Insert after the init value's defining op to
+  // maintain SSA dominance (the init value was generated by the
+  // callback before populateByRefInitAndCleanupRegions was called).
+  if (scalarInitValue && isReduction(kind)) {
+    mlir::OpBuilder::InsertionGuard guard(builder);
+    if (auto *defOp = scalarInitValue.getDefiningOp())
+      builder.setInsertionPointAfter(defOp);
+    else
+      builder.setInsertionPointToEnd(initBlock);
+    fir::StoreOp::create(builder, loc, scalarInitValue, allocatedPrivVarArg);
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tblah wrote:

Okay so this is a broader design issue. Ideally these would be valid `hlfir::Entity` (aka `AnyFortranEntity`). My reading is that the derived types would need to be boxed (see `isFortranVariableType`). I find it better not to fight against the design of HLFIR

I think this can be left for a later patch, perhaps when adding support for user-defined reduction of non-trivial types. But it is up to you.

https://github.com/llvm/llvm-project/pull/184897