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

[via flang-commits]

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@@ -2391,6 +2391,122 @@ genSingleOp(lower::AbstractConverter &converter, lower::SymMap &symTable,
       queue, item, clauseOps);
 }
 
+static mlir::FlatSymbolRefAttr getOrGenImplicitDefaultDeclareMapper(
+    lower::AbstractConverter &converter, mlir::Location loc,
+    fir::RecordType recordType, llvm::StringRef mapperNameStr) {
+  if (converter.getModuleOp().lookupSymbol(mapperNameStr))
+    return mlir::FlatSymbolRefAttr::get(&converter.getMLIRContext(),
+                                        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());
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agozillon wrote:

I wonder if this would break if the input record type to a function was optional and we opted to not provide the argument, ran into a similar issue a while ago. Not the biggest deal for this PR, but good idea to test it at some point! 

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