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

[Tom Eccles via flang-commits]

================
@@ -3867,12 +3911,35 @@ static ReductionProcessor::GenCombinerCBTy processReductionCombiner(
                 if (expectedType == refType.getElementType())
                   exprResult = fir::LoadOp::create(builder, loc, exprResult);
               }
+              // For component-level derived-type combiners (e.g.
+              // omp_out%x = omp_out%x + omp_in%x), the assignment was
+              // not performed during expression lowering since
+              // convertExprToValue only evaluates the RHS value.
+              // The result type won't match the reduction variable type.
+              // Use the typed assignment LHS to store to the correct
+              // component, then skip the whole-variable fir.store below.
+              if (isByRef &&
+                  exprResult.getType() != fir::unwrapRefType(lhs.getType())) {
+                if (assign) {
+                  lower::StatementContext assignCtx;
+                  hlfir::Entity lhsEntity = lower::convertExprToHLFIR(
+                      loc, converter, assign->lhs, symTable, assignCtx);
+                  hlfir::AssignOp::create(builder, loc, exprResult, lhsEntity);
+                  assignCtx.finalizeAndPop();
+                } else {
+                  // Fallback: store to omp_out directly (shouldn't normally
+                  // happen for well-formed component-level combiners).
+                  fir::StoreOp::create(builder, loc, exprResult, ompOutVar);
+                }
+                return mlir::Value{};
+              }
               return exprResult;
             }},
         evalExpr.u);
     stmtCtx.finalizeAndPop();
     if (isByRef) {
-      fir::StoreOp::create(builder, loc, result, lhs);
+      if (result)
+        fir::StoreOp::create(builder, loc, result, lhs);
----------------
tblah wrote:

Maybe instead of having two different paths it would be cleaner to always do the store above?

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