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 "../PassDetail.h"
15 #include "mlir/Conversion/BufferizationToMemRef/BufferizationToMemRef.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 = rewriter.createOrFold<memref::DimOp>(loc, op.input(), size);
61       dynamicOperands.push_back(dim);
62     }
63 
64     // Allocate a memref with identity layout.
65     Value alloc = rewriter.create<memref::AllocOp>(op->getLoc(), allocType,
66                                                    dynamicOperands);
67     // Cast the allocation to the specified type if needed.
68     if (memrefType != allocType)
69       alloc = rewriter.create<memref::CastOp>(op->getLoc(), memrefType, alloc);
70     rewriter.replaceOp(op, alloc);
71     rewriter.create<memref::CopyOp>(loc, op.input(), alloc);
72     return success();
73   }
74 };
75 } // namespace
76 
77 void mlir::populateBufferizationToMemRefConversionPatterns(
78     RewritePatternSet &patterns) {
79   patterns.add<CloneOpConversion>(patterns.getContext());
80 }
81 
82 namespace {
83 struct BufferizationToMemRefPass
84     : public ConvertBufferizationToMemRefBase<BufferizationToMemRefPass> {
85   BufferizationToMemRefPass() = default;
86 
87   void runOnOperation() override {
88     RewritePatternSet patterns(&getContext());
89     populateBufferizationToMemRefConversionPatterns(patterns);
90 
91     ConversionTarget target(getContext());
92     target.addLegalDialect<memref::MemRefDialect>();
93     target.addLegalOp<arith::ConstantOp>();
94     target.addIllegalDialect<bufferization::BufferizationDialect>();
95 
96     if (failed(applyPartialConversion(getOperation(), target,
97                                       std::move(patterns))))
98       signalPassFailure();
99   }
100 };
101 } // namespace
102 
103 std::unique_ptr<Pass> mlir::createBufferizationToMemRefPass() {
104   return std::make_unique<BufferizationToMemRefPass>();
105 }
106