Handle mappers

Author: kparzysz

mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp

@@ -3300,9 +3300,20 @@ static void collectMapDataFromMapOperands(
       // rematerialized, so the address of the decriptor for a given object
       // may change from one place to another.
       mapData.Types.push_back(mapType);
+      // Technically it's possible for a non-descriptor mapping to have
+      // both has-device-addr and ALWAYS, so lookup the mapper in case it
+      // exists.
+      if (mapOp.getMapperId()) {
+        mapData.Mappers.push_back(
+            SymbolTable::lookupNearestSymbolFrom<omp::DeclareMapperOp>(
+                mapOp, mapOp.getMapperIdAttr()));
+      } else {
+        mapData.Mappers.push_back(nullptr);
+      }
     } else {
       mapData.Types.push_back(
           llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_LITERAL);
+      mapData.Mappers.push_back(nullptr);
     }
     mapData.Names.push_back(LLVM::createMappingInformation(
         mapOp.getLoc(), *moduleTranslation.getOpenMPBuilder()));