[flang][openacc] Lower reduction for compute constructs

[razvanlupusoru]

Summary

Parallel and serial constructs support reduction clause. Extend
recent D151564 loop reduction clause support to also include these
compute constructs.

[vzakhari]

LGTM. Thank you!

[clementval]

LGTM

[razvanlupusoru]

Adding tests
Rebasing on top of https://reviews.llvm.org/D152389

[razvanlupusoru]

Added serial, serial loop, kernels loop, and loop reduction tests.

[razvanlupusoru]

Fixed kernels reduction test.

flang/lib/Lower/OpenACC.cpp

 //===-- OpenACC.cpp -- OpenACC directive lowering -------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
createComputeOp(Fortran::lower::AbstractConverter &converter,
   mlir::Value selfCond;
   mlir::Value waitDevnum;
   llvm::SmallVector<mlir::Value> waitOperands, attachEntryOperands,
       copyEntryOperands, copyoutEntryOperands, createEntryOperands,
       dataClauseOperands;
 
   llvm::SmallVector<mlir::Value> reductionOperands, privateOperands,
       firstprivateOperands;
-  llvm::SmallVector<mlir::Attribute> privatizations;
+  llvm::SmallVector<mlir::Attribute> privatizations, reductionRecipes;
 
   // Async, wait and self clause have optional values but can be present with
   // no value as well. When there is no value, the op has an attribute to
   // represent the clause.
   bool addAsyncAttr = false;
   bool addWaitAttr = false;
   bool addSelfAttr = false;
 
if (const auto *asyncClause =
                        &clause.u)) {
       genPrivatizations(privateClause->v, converter, semanticsContext, stmtCtx,
                         privateOperands, privatizations);
     } else if (const auto *firstprivateClause =
                    std::get_if<Fortran::parser::AccClause::Firstprivate>(
                        &clause.u)) {
       genObjectList(firstprivateClause->v, converter, semanticsContext, stmtCtx,
                     firstprivateOperands);
-    } else if (std::get_if<Fortran::parser::AccClause::Reduction>(&clause.u)) {
-      TODO(clauseLocation, "compute construct reduction clause lowering");
+    } else if (const auto *reductionClause =
+                   std::get_if<Fortran::parser::AccClause::Reduction>(
+                       &clause.u)) {
+      genReductions(reductionClause->v, converter, semanticsContext, stmtCtx,
+                    reductionOperands, reductionRecipes);
     }
   }
 
   // Prepare the operand segment size attribute and the operands value range.
   llvm::SmallVector<mlir::Value, 8> operands;
   llvm::SmallVector<int32_t, 8> operandSegments;
   addOperand(operands, operandSegments, async);
   addOperands(operands, operandSegments, waitOperands);
if (addWaitAttr)
     computeOp.setWaitAttrAttr(builder.getUnitAttr());
   if (addSelfAttr)
     computeOp.setSelfAttrAttr(builder.getUnitAttr());
 
   if constexpr (!std::is_same_v<Op, mlir::acc::KernelsOp>) {
     if (!privatizations.empty())
       computeOp.setPrivatizationsAttr(
           mlir::ArrayAttr::get(builder.getContext(), privatizations));
+    if (!reductionRecipes.empty())
+      computeOp.setReductionRecipesAttr(
+          mlir::ArrayAttr::get(builder.getContext(), reductionRecipes));
   }
 
   auto insPt = builder.saveInsertionPoint();
   builder.setInsertionPointAfter(computeOp);
 
   // Create the exit operations after the region.
   genDataExitOperations<mlir::acc::CopyinOp, mlir::acc::CopyoutOp>(
       builder, copyEntryOperands, /*structured=*/true, /*implicit=*/false);

mlir/lib/Dialect/OpenACC/IR/OpenACC.cpp

 //===- OpenACC.cpp - OpenACC MLIR Operations ------------------------------===//
 //
 // Part of the MLIR Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 // =============================================================================
 

 
 LogicalResult acc::ParallelOp::verify() {
   if (failed(checkSymOperandList<mlir::acc::PrivateRecipeOp>(
           *this, getPrivatizations(), getGangPrivateOperands(), "private",
           "privatizations")))
     return failure();
   if (failed(checkSymOperandList<mlir::acc::ReductionRecipeOp>(
           *this, getReductionRecipes(), getReductionOperands(), "reduction",
-          "reductions")))
+          "reductions", false)))
     return failure();
   return checkDataOperands<acc::ParallelOp>(*this, getDataClauseOperands());
 }
 
 //===----------------------------------------------------------------------===//
 // SerialOp
 //===----------------------------------------------------------------------===//
 

 
 LogicalResult acc::SerialOp::verify() {
   if (failed(checkSymOperandList<mlir::acc::PrivateRecipeOp>(
           *this, getPrivatizations(), getGangPrivateOperands(), "private",
           "privatizations")))
     return failure();
   if (failed(checkSymOperandList<mlir::acc::ReductionRecipeOp>(
           *this, getReductionRecipes(), getReductionOperands(), "reduction",
-          "reductions")))
+          "reductions", false)))
     return failure();
   return checkDataOperands<acc::SerialOp>(*this, getDataClauseOperands());
 }
 
 //===----------------------------------------------------------------------===//
 // KernelsOp
 //===----------------------------------------------------------------------===//