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/Arithmetic/IR/Arithmetic.h"
17 #include "mlir/Dialect/Linalg/IR/Linalg.h"
18 #include "mlir/Dialect/Linalg/Passes.h"
19 #include "mlir/Dialect/Linalg/Transforms/Transforms.h"
20 #include "mlir/IR/AffineExpr.h"
21 #include "mlir/IR/AffineMap.h"
22 #include "mlir/Transforms/GreedyPatternRewriteDriver.h"
23 
24 using namespace mlir;
25 using namespace mlir::linalg;
26 
27 namespace {
28 struct InlineScalarOperands : public OpRewritePattern<GenericOp> {
29   using OpRewritePattern<GenericOp>::OpRewritePattern;
30   LogicalResult matchAndRewrite(GenericOp genericOp,
31                                 PatternRewriter &rewriter) const override {
32     if (!genericOp.hasTensorSemantics())
33       return failure();
34 
35     SmallVector<size_t> scalarOperands;
36     SmallVector<AffineMap> newIndexingMaps;
37     SmallVector<Value> newOperands;
38     for (OpOperand *opOperand : genericOp.getInputOperands()) {
39       AffineMap map = genericOp.getTiedIndexingMap(opOperand);
40       if (genericOp.isInputTensor(opOperand) && map.isConstant()) {
41         scalarOperands.emplace_back(opOperand->getOperandNumber());
42       } else {
43         newIndexingMaps.emplace_back(map);
44         newOperands.emplace_back(opOperand->get());
45       }
46     }
47 
48     if (scalarOperands.empty())
49       return failure();
50 
51     for (OpOperand *opOperand : genericOp.getOutputOperands())
52       newIndexingMaps.emplace_back(genericOp.getTiedIndexingMap(opOperand));
53 
54     Location loc = genericOp->getLoc();
55     SmallVector<Value> outputOperands = genericOp.getOutputOperands();
56     auto newOp = rewriter.create<GenericOp>(
57         loc, genericOp->getResultTypes(), newOperands, outputOperands,
58         newIndexingMaps,
59         llvm::to_vector<4>(
60             genericOp.iterator_types().template getAsValueRange<StringAttr>()));
61     rewriter.cloneRegionBefore(genericOp.region(), newOp.region(),
62                                newOp.region().begin());
63 
64     Block *body = newOp.getBody();
65     PatternRewriter::InsertionGuard guard(rewriter);
66     rewriter.setInsertionPointToStart(body);
67 
68     for (auto idx : llvm::reverse(scalarOperands)) {
69       OpOperand *opOperand = genericOp.getInputOperand(idx);
70       AffineMap map = genericOp.getTiedIndexingMap(opOperand);
71       SmallVector<int64_t> indices = map.getConstantResults();
72       SmallVector<Value> indicesValues;
73       for (auto idx : indices)
74         indicesValues.emplace_back(
75             rewriter.create<arith::ConstantIndexOp>(loc, idx));
76       Value extractedValue = rewriter.create<tensor::ExtractOp>(
77           loc, opOperand->get(), indicesValues);
78       body->getArgument(idx).replaceAllUsesWith(extractedValue);
79       body->eraseArgument(idx);
80     }
81 
82     rewriter.replaceOp(genericOp, newOp->getResults());
83     return success();
84   }
85 };
86 } // namespace
87 
88 /// Patterns that are used to inline constant operands into linalg generic
89 /// ops.
90 void mlir::linalg::populateInlineConstantOperandsPatterns(
91     RewritePatternSet &patterns) {
92   auto *context = patterns.getContext();
93   patterns.add<InlineScalarOperands>(context);
94 }
95 
96 namespace {
97 /// Pass that removes unit-extent dims within generic ops.
98 struct LinalgInlineScalarOperandsPass
99     : public LinalgInlineScalarOperandsBase<LinalgInlineScalarOperandsPass> {
100   void runOnOperation() override {
101     func::FuncOp funcOp = getOperation();
102     MLIRContext *context = funcOp.getContext();
103     RewritePatternSet patterns(context);
104 
105     populateInlineConstantOperandsPatterns(patterns);
106     (void)applyPatternsAndFoldGreedily(funcOp.getBody(), std::move(patterns));
107   }
108 };
109 } // namespace
110 
111 std::unique_ptr<OperationPass<func::FuncOp>>
112 mlir::createLinalgInlineScalarOperandsPass() {
113   return std::make_unique<LinalgInlineScalarOperandsPass>();
114 }
115