1 //===- BufferizationToMemRef.cpp - Bufferization to MemRef conversion -----===//
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 to convert Bufferization dialect to MemRef
10 // dialect.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "mlir/Conversion/BufferizationToMemRef/BufferizationToMemRef.h"
15 #include "../PassDetail.h"
16 #include "mlir/Dialect/Arithmetic/IR/Arithmetic.h"
17 #include "mlir/Dialect/Bufferization/IR/Bufferization.h"
18 #include "mlir/Dialect/MemRef/IR/MemRef.h"
19 #include "mlir/IR/BuiltinTypes.h"
20 #include "mlir/Support/LogicalResult.h"
21 #include "mlir/Transforms/DialectConversion.h"
22 
23 using namespace mlir;
24 
25 namespace {
26 /// The CloneOpConversion transforms all bufferization clone operations into
27 /// memref alloc and memref copy operations. In the dynamic-shape case, it also
28 /// emits additional dim and constant operations to determine the shape. This
29 /// conversion does not resolve memory leaks if it is used alone.
30 struct CloneOpConversion : public OpConversionPattern<bufferization::CloneOp> {
31   using OpConversionPattern<bufferization::CloneOp>::OpConversionPattern;
32 
33   LogicalResult
34   matchAndRewrite(bufferization::CloneOp op, OpAdaptor adaptor,
35                   ConversionPatternRewriter &rewriter) const override {
36     // Check for unranked memref types which are currently not supported.
37     Type type = op.getType();
38     if (type.isa<UnrankedMemRefType>()) {
39       return rewriter.notifyMatchFailure(
40           op, "UnrankedMemRefType is not supported.");
41     }
42     MemRefType memrefType = type.cast<MemRefType>();
43     MemRefLayoutAttrInterface layout;
44     auto allocType =
45         MemRefType::get(memrefType.getShape(), memrefType.getElementType(),
46                         layout, memrefType.getMemorySpace());
47     // Since this implementation always allocates, certain result types of the
48     // clone op cannot be lowered.
49     if (!memref::CastOp::areCastCompatible({allocType}, {memrefType}))
50       return failure();
51 
52     // Transform a clone operation into alloc + copy operation and pay
53     // attention to the shape dimensions.
54     Location loc = op->getLoc();
55     SmallVector<Value, 4> dynamicOperands;
56     for (int i = 0; i < memrefType.getRank(); ++i) {
57       if (!memrefType.isDynamicDim(i))
58         continue;
59       Value size = rewriter.createOrFold<arith::ConstantIndexOp>(loc, i);
60       Value dim =
61           rewriter.createOrFold<memref::DimOp>(loc, op.getInput(), size);
62       dynamicOperands.push_back(dim);
63     }
64 
65     // Allocate a memref with identity layout.
66     Value alloc = rewriter.create<memref::AllocOp>(op->getLoc(), allocType,
67                                                    dynamicOperands);
68     // Cast the allocation to the specified type if needed.
69     if (memrefType != allocType)
70       alloc = rewriter.create<memref::CastOp>(op->getLoc(), memrefType, alloc);
71     rewriter.replaceOp(op, alloc);
72     rewriter.create<memref::CopyOp>(loc, op.getInput(), alloc);
73     return success();
74   }
75 };
76 } // namespace
77 
78 void mlir::populateBufferizationToMemRefConversionPatterns(
79     RewritePatternSet &patterns) {
80   patterns.add<CloneOpConversion>(patterns.getContext());
81 }
82 
83 namespace {
84 struct BufferizationToMemRefPass
85     : public ConvertBufferizationToMemRefBase<BufferizationToMemRefPass> {
86   BufferizationToMemRefPass() = default;
87 
88   void runOnOperation() override {
89     RewritePatternSet patterns(&getContext());
90     populateBufferizationToMemRefConversionPatterns(patterns);
91 
92     ConversionTarget target(getContext());
93     target.addLegalDialect<memref::MemRefDialect>();
94     target.addLegalOp<arith::ConstantOp>();
95     target.addIllegalDialect<bufferization::BufferizationDialect>();
96 
97     if (failed(applyPartialConversion(getOperation(), target,
98                                       std::move(patterns))))
99       signalPassFailure();
100   }
101 };
102 } // namespace
103 
104 std::unique_ptr<Pass> mlir::createBufferizationToMemRefPass() {
105   return std::make_unique<BufferizationToMemRefPass>();
106 }
107