[flang-commits] [flang] [OpenMP][Flang] Emit default declare mappers implicitly for derived types (PR #140562)

[Sergio Afonso via flang-commits]

================
@@ -2348,6 +2348,122 @@ genSingleOp(lower::AbstractConverter &converter, lower::SymMap &symTable,
       queue, item, clauseOps);
 }
 
+static mlir::FlatSymbolRefAttr
+genImplicitDefaultDeclareMapper(lower::AbstractConverter &converter,
+                                mlir::Location loc, fir::RecordType recordType,
+                                llvm::StringRef mapperNameStr) {
+  fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
+
+  // Save current insertion point before moving to the module scope to create
+  // the DeclareMapperOp
+  mlir::OpBuilder::InsertionGuard guard(firOpBuilder);
+
+  firOpBuilder.setInsertionPointToStart(converter.getModuleOp().getBody());
+  auto declMapperOp = firOpBuilder.create<mlir::omp::DeclareMapperOp>(
+      loc, mapperNameStr, recordType);
+  auto &region = declMapperOp.getRegion();
+  firOpBuilder.createBlock(&region);
+  auto mapperArg = region.addArgument(firOpBuilder.getRefType(recordType), loc);
+
+  auto declareOp =
+      firOpBuilder.create<hlfir::DeclareOp>(loc, mapperArg, /*uniq_name=*/"");
+
+  const auto genBoundsOps = [&](mlir::Value mapVal,
+                                llvm::SmallVectorImpl<mlir::Value> &bounds) {
+    fir::ExtendedValue extVal =
+        hlfir::translateToExtendedValue(mapVal.getLoc(), firOpBuilder,
+                                        hlfir::Entity{mapVal},
+                                        /*contiguousHint=*/true)
+            .first;
+    fir::factory::AddrAndBoundsInfo info = fir::factory::getDataOperandBaseAddr(
+        firOpBuilder, mapVal, /*isOptional=*/false, mapVal.getLoc());
+    bounds = fir::factory::genImplicitBoundsOps<mlir::omp::MapBoundsOp,
+                                                mlir::omp::MapBoundsType>(
+        firOpBuilder, info, extVal,
+        /*dataExvIsAssumedSize=*/false, mapVal.getLoc());
+  };
+
+  // Return a reference to the contents of a derived type with one field.
+  // Also return the field type.
+  const auto getFieldRef =
+      [&](mlir::Value rec,
+          unsigned index) -> std::tuple<mlir::Value, mlir::Type> {
+    auto recType = mlir::dyn_cast<fir::RecordType>(
----------------
skatrak wrote:

It's assumed that `recType != nullptr` below, so either `assert` this is the case by using `cast` or we need to handle that situation.
```suggestion
    auto recType = mlir::cast<fir::RecordType>(
```

https://github.com/llvm/llvm-project/pull/140562