1 //===- ShapeToShapeLowering.cpp - Prepare for lowering to Standard --------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "PassDetail.h"
10 #include "mlir/Dialect/Arithmetic/IR/Arithmetic.h"
11 #include "mlir/Dialect/Shape/IR/Shape.h"
12 #include "mlir/Dialect/Shape/Transforms/Passes.h"
13 #include "mlir/Dialect/StandardOps/IR/Ops.h"
14 #include "mlir/IR/Builders.h"
15 #include "mlir/IR/PatternMatch.h"
16 #include "mlir/Pass/Pass.h"
17 #include "mlir/Transforms/DialectConversion.h"
18 
19 using namespace mlir;
20 using namespace mlir::shape;
21 
22 namespace {
23 /// Converts `shape.num_elements` to `shape.reduce`.
24 struct NumElementsOpConverter : public OpRewritePattern<NumElementsOp> {
25 public:
26   using OpRewritePattern::OpRewritePattern;
27 
28   LogicalResult matchAndRewrite(NumElementsOp op,
29                                 PatternRewriter &rewriter) const final;
30 };
31 } // namespace
32 
33 LogicalResult
34 NumElementsOpConverter::matchAndRewrite(NumElementsOp op,
35                                         PatternRewriter &rewriter) const {
36   auto loc = op.getLoc();
37   Type valueType = op.getResult().getType();
38   Value init = op->getDialect()
39                    ->materializeConstant(rewriter, rewriter.getIndexAttr(1),
40                                          valueType, loc)
41                    ->getResult(0);
42   ReduceOp reduce = rewriter.create<ReduceOp>(loc, op.getShape(), init);
43 
44   // Generate reduce operator.
45   Block *body = reduce.getBody();
46   OpBuilder b = OpBuilder::atBlockEnd(body);
47   Value product = b.create<MulOp>(loc, valueType, body->getArgument(1),
48                                   body->getArgument(2));
49   b.create<shape::YieldOp>(loc, product);
50 
51   rewriter.replaceOp(op, reduce.getResult());
52   return success();
53 }
54 
55 namespace {
56 struct ShapeToShapeLowering
57     : public ShapeToShapeLoweringBase<ShapeToShapeLowering> {
58   void runOnOperation() override;
59 };
60 } // namespace
61 
62 void ShapeToShapeLowering::runOnOperation() {
63   MLIRContext &ctx = getContext();
64 
65   RewritePatternSet patterns(&ctx);
66   populateShapeRewritePatterns(patterns);
67 
68   ConversionTarget target(getContext());
69   target.addLegalDialect<arith::ArithmeticDialect, ShapeDialect,
70                          StandardOpsDialect>();
71   target.addIllegalOp<NumElementsOp>();
72   if (failed(mlir::applyPartialConversion(getOperation(), target,
73                                           std::move(patterns))))
74     signalPassFailure();
75 }
76 
77 void mlir::populateShapeRewritePatterns(RewritePatternSet &patterns) {
78   patterns.add<NumElementsOpConverter>(patterns.getContext());
79 }
80 
81 std::unique_ptr<Pass> mlir::createShapeToShapeLowering() {
82   return std::make_unique<ShapeToShapeLowering>();
83 }
84