1 /* Copyright 2022 The TensorFlow Authors. All Rights Reserved.
2 
3 Licensed under the Apache License, Version 2.0 (the "License");
4 you may not use this file except in compliance with the License.
5 You may obtain a copy of the License at
6 
7     http://www.apache.org/licenses/LICENSE-2.0
8 
9 Unless required by applicable law or agreed to in writing, software
10 distributed under the License is distributed on an "AS IS" BASIS,
11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 See the License for the specific language governing permissions and
13 limitations under the License.
14 ==============================================================================*/
15 
16 // This files implements the logic for converting multidimensional
17 // `scf.parallel` loops into 1D loops.
18 
19 #include <memory>
20 #include <numeric>
21 #include <vector>
22 
23 #include "mlir-hlo/Transforms/PassDetail.h"
24 #include "mlir-hlo/Transforms/passes.h"
25 #include "mlir/Dialect/Func/IR/FuncOps.h"
26 #include "mlir/Dialect/SCF/IR/SCF.h"
27 #include "mlir/Dialect/SCF/Utils/Utils.h"
28 
29 using ::mlir::scf::ParallelOp;
30 
31 namespace mlir {
32 namespace {
33 
34 // This is the implementation of the CollapseParallelLoopsTo1D pass declared in
35 //  include/mlir-hlo/Transforms/passes.td
36 struct CollapseParallelLoopsTo1D
37     : public CollapseParallelLoopsTo1DPassBase<CollapseParallelLoopsTo1D> {
38   void runOnOperation() override;
39 };
40 
41 }  // namespace
42 }  // namespace mlir
43 
44 using namespace mlir;
45 
runOnOperation()46 void mlir::CollapseParallelLoopsTo1D::runOnOperation() {
47   getOperation()->walk([&](ParallelOp op) {
48     unsigned numLoops = op.getNumLoops();
49     if (numLoops == 1) return;
50     std::vector<unsigned> combinedLoops(numLoops);
51     std::iota(combinedLoops.begin(), combinedLoops.end(), 0u);
52     mlir::collapseParallelLoops(op, {combinedLoops});
53   });
54 }
55 
createCollapseParallelLoopsTo1DPass()56 std::unique_ptr<OperationPass<>> mlir::createCollapseParallelLoopsTo1DPass() {
57   return std::make_unique<CollapseParallelLoopsTo1D>();
58 }
59