[Flang][OpenMP] WIP: Add a Device Interface

[kiranchandramohan]

Summary

Co-authored-by: Dominik Adamski <[e-mail]>

[domada]

Hi Kiran,
thanks for the patch.
It looks good to me and I will update my review: https://reviews.llvm.org/D146612 . I will use interface instead of module attributes.

flang/lib/Frontend/FrontendActions.cpp

lower::LoweringBridge lb = Fortran::lower::LoweringBridge::create(
       kindMap, ci.getInvocation().getLoweringOpts(),
       ci.getInvocation().getFrontendOpts().envDefaults);
 
   // Fetch module from lb, so we can set
   mlirModule = std::make_unique<mlir::ModuleOp>(lb.getModule());
 
   if (ci.getInvocation().getFrontendOpts().features.IsEnabled(
           Fortran::common::LanguageFeature::OpenMP)) {
+    mlir::ModuleOp::attachInterface<mlir::omp::DeviceModuleInterface>(
+        *mlirModule->getContext());
     mlir::omp::OpenMPDialect::setIsDevice(
         *mlirModule, ci.getInvocation().getLangOpts().OpenMPIsDevice);
   }
 
   if (!setUpTargetMachine())
     return false;
   const llvm::DataLayout &dl = tm->createDataLayout();
   setMLIRDataLayout(*mlirModule, dl);

flang/tools/bbc/bbc.cpp

static mlir::LogicalResult convertFortranSourceToMLIR(
   loweringOptions.setPolymorphicTypeImpl(enablePolymorphic);
   loweringOptions.setLowerToHighLevelFIR(useHLFIR);
   auto burnside = Fortran::lower::LoweringBridge::create(
       ctx, semanticsContext, defKinds, semanticsContext.intrinsics(),
       semanticsContext.targetCharacteristics(), parsing.allCooked(), "",
       kindMap, loweringOptions, {});
   burnside.lower(parseTree, semanticsContext);
   mlir::ModuleOp mlirModule = burnside.getModule();
+  mlir::ModuleOp::attachInterface<mlir::omp::DeviceModuleInterface>(
+      *mlirModule.getContext());
   if (enableOpenMP)
     mlir::omp::OpenMPDialect::setIsDevice(mlirModule, enableOpenMPDevice);
   std::error_code ec;
   std::string outputName = outputFilename;
   if (!outputName.size())
     outputName = llvm::sys::path::stem(inputFilename).str().append(".mlir");
   llvm::raw_fd_ostream out(outputName, ec);
   if (ec)

mlir/include/mlir/Dialect/OpenMP/OpenMPOpsInterfaces.td

let methods = [
     InterfaceMethod<
       "Get reduction vars", "::mlir::SmallVector<::mlir::Value>",
       "getAllReductionVars", (ins), [{}], [{
         return $_op.getReductionVars();
       }]>,
   ];
 }
 
+def DeviceModuleInterface : OpInterface<"DeviceModuleInterface"> {
+  let description = [{
+    Operations that represent a device module should have this interface.
+  }];
+
+  let cppNamespace = "::mlir::omp";
+
+  let methods = [
+    InterfaceMethod<
+      "Get target CPU", "std::string",
+      "getTargetCPU", (ins), [{}], [{
+          if (::mlir::Attribute targetCpu = $_op->getAttr("omp.target_cpu"))
+            if (targetCpu.isa<::mlir::StringAttr>())
+              return targetCpu.dyn_cast<::mlir::StringAttr>().getValue().str();
+          return llvm::Twine{""}.str();
+      }]>,
+    InterfaceMethod<
+      "Set target CPU", "std::string",
+      "setTargetCPU", (ins "llvm::StringRef":$cpu), [{}], [{
+        $_op->setAttr(mlir::StringAttr::get($_op->getContext(),
+                                        llvm::Twine{"omp.target_cpu"}),
+                  mlir::StringAttr::get($_op->getContext(), cpu));
+      }]>,
+  ];
+}
+
 #endif // OpenMP_OPS_INTERFACES