1 //===- InlineScalarOperands.cpp - Pass to inline scalar operands =============//
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 // This file implements patterns/pass to inline scalar operands into a generic
10 // operation. A scalar operand is an operand whose indexing map has a constant
11 // rhs.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "PassDetail.h"
16 #include "mlir/Dialect/Linalg/IR/LinalgOps.h"
17 #include "mlir/Dialect/Linalg/Passes.h"
18 #include "mlir/Dialect/Linalg/Transforms/Transforms.h"
19 #include "mlir/IR/AffineExpr.h"
20 #include "mlir/IR/AffineMap.h"
21 #include "mlir/Transforms/GreedyPatternRewriteDriver.h"
22 
23 using namespace mlir;
24 using namespace mlir::linalg;
25 
26 namespace {
27 struct InlineScalarOperands : public OpRewritePattern<GenericOp> {
28   using OpRewritePattern<GenericOp>::OpRewritePattern;
29   LogicalResult matchAndRewrite(GenericOp genericOp,
30                                 PatternRewriter &rewriter) const override {
31     if (!genericOp.hasTensorSemantics())
32       return failure();
33 
34     SmallVector<size_t> scalarOperands;
35     SmallVector<AffineMap> newIndexingMaps;
36     SmallVector<Value> newOperands;
37     for (OpOperand *opOperand : genericOp.getInputOperands()) {
38       AffineMap map = genericOp.getTiedIndexingMap(opOperand);
39       if (genericOp.isInputTensor(opOperand) && map.isConstant()) {
40         scalarOperands.emplace_back(opOperand->getOperandNumber());
41       } else {
42         newIndexingMaps.emplace_back(map);
43         newOperands.emplace_back(opOperand->get());
44       }
45     }
46 
47     if (scalarOperands.empty())
48       return failure();
49 
50     for (OpOperand *opOperand : genericOp.getOutputOperands())
51       newIndexingMaps.emplace_back(genericOp.getTiedIndexingMap(opOperand));
52 
53     Location loc = genericOp->getLoc();
54     SmallVector<Value> outputOperands = genericOp.getOutputOperands();
55     auto newOp = rewriter.create<GenericOp>(
56         loc, genericOp->getResultTypes(), newOperands, outputOperands,
57         newIndexingMaps,
58         llvm::to_vector<4>(
59             genericOp.iterator_types().template getAsValueRange<StringAttr>()));
60     rewriter.cloneRegionBefore(genericOp.region(), newOp.region(),
61                                newOp.region().begin());
62 
63     Block *body = newOp.getBody();
64     PatternRewriter::InsertionGuard guard(rewriter);
65     rewriter.setInsertionPointToStart(body);
66 
67     for (auto idx : llvm::reverse(scalarOperands)) {
68       OpOperand *opOperand = genericOp.getInputOperand(idx);
69       AffineMap map = genericOp.getTiedIndexingMap(opOperand);
70       SmallVector<int64_t> indices = map.getConstantResults();
71       SmallVector<Value> indicesValues;
72       for (auto idx : indices)
73         indicesValues.emplace_back(rewriter.create<ConstantIndexOp>(loc, idx));
74       Value extractedValue = rewriter.create<tensor::ExtractOp>(
75           loc, opOperand->get(), indicesValues);
76       body->getArgument(idx).replaceAllUsesWith(extractedValue);
77       body->eraseArgument(idx);
78     }
79 
80     rewriter.replaceOp(genericOp, newOp->getResults());
81     return success();
82   }
83 };
84 } // namespace
85 
86 /// Patterns that are used to inline constant operands into linalg generic
87 /// ops.
88 void mlir::linalg::populateInlineConstantOperandsPatterns(
89     RewritePatternSet &patterns) {
90   auto *context = patterns.getContext();
91   patterns.add<InlineScalarOperands>(context);
92 }
93 
94 namespace {
95 /// Pass that removes unit-extent dims within generic ops.
96 struct LinalgInlineScalarOperandsPass
97     : public LinalgInlineScalarOperandsBase<LinalgInlineScalarOperandsPass> {
98   void runOnFunction() override {
99     FuncOp funcOp = getFunction();
100     MLIRContext *context = funcOp.getContext();
101     RewritePatternSet patterns(context);
102 
103     populateInlineConstantOperandsPatterns(patterns);
104     (void)applyPatternsAndFoldGreedily(funcOp.getBody(), std::move(patterns));
105   }
106 };
107 } // namespace
108 
109 std::unique_ptr<OperationPass<FuncOp>>
110 mlir::createLinalgInlineScalarOperandsPass() {
111   return std::make_unique<LinalgInlineScalarOperandsPass>();
112 }
113