1 //===-- AffineDemotion.cpp -----------------------------------------------===//
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 transformation is a prototype that demote affine dialects operations
10 // after optimizations to FIR loops operations.
11 // It is used after the AffinePromotion pass.
12 // It is not part of the production pipeline and would need more work in order
13 // to be used in production.
14 // More information can be found in this presentation:
15 // https://slides.com/rajanwalia/deck
16 //
17 //===----------------------------------------------------------------------===//
18 
19 #include "PassDetail.h"
20 #include "flang/Optimizer/Dialect/FIRDialect.h"
21 #include "flang/Optimizer/Dialect/FIROps.h"
22 #include "flang/Optimizer/Dialect/FIRType.h"
23 #include "flang/Optimizer/Transforms/Passes.h"
24 #include "mlir/Dialect/Affine/IR/AffineOps.h"
25 #include "mlir/Dialect/Affine/Utils.h"
26 #include "mlir/Dialect/Func/IR/FuncOps.h"
27 #include "mlir/Dialect/MemRef/IR/MemRef.h"
28 #include "mlir/Dialect/SCF/SCF.h"
29 #include "mlir/IR/BuiltinAttributes.h"
30 #include "mlir/IR/IntegerSet.h"
31 #include "mlir/IR/Visitors.h"
32 #include "mlir/Pass/Pass.h"
33 #include "mlir/Transforms/DialectConversion.h"
34 #include "llvm/ADT/DenseMap.h"
35 #include "llvm/ADT/Optional.h"
36 #include "llvm/Support/CommandLine.h"
37 #include "llvm/Support/Debug.h"
38 
39 #define DEBUG_TYPE "flang-affine-demotion"
40 
41 using namespace fir;
42 using namespace mlir;
43 
44 namespace {
45 
46 class AffineLoadConversion : public OpConversionPattern<mlir::AffineLoadOp> {
47 public:
48   using OpConversionPattern<mlir::AffineLoadOp>::OpConversionPattern;
49 
50   LogicalResult
51   matchAndRewrite(mlir::AffineLoadOp op, OpAdaptor adaptor,
52                   ConversionPatternRewriter &rewriter) const override {
53     SmallVector<Value> indices(adaptor.indices());
54     auto maybeExpandedMap =
55         expandAffineMap(rewriter, op.getLoc(), op.getAffineMap(), indices);
56     if (!maybeExpandedMap)
57       return failure();
58 
59     auto coorOp = rewriter.create<fir::CoordinateOp>(
60         op.getLoc(), fir::ReferenceType::get(op.getResult().getType()),
61         adaptor.memref(), *maybeExpandedMap);
62 
63     rewriter.replaceOpWithNewOp<fir::LoadOp>(op, coorOp.getResult());
64     return success();
65   }
66 };
67 
68 class AffineStoreConversion : public OpConversionPattern<mlir::AffineStoreOp> {
69 public:
70   using OpConversionPattern<mlir::AffineStoreOp>::OpConversionPattern;
71 
72   LogicalResult
73   matchAndRewrite(mlir::AffineStoreOp op, OpAdaptor adaptor,
74                   ConversionPatternRewriter &rewriter) const override {
75     SmallVector<Value> indices(op.indices());
76     auto maybeExpandedMap =
77         expandAffineMap(rewriter, op.getLoc(), op.getAffineMap(), indices);
78     if (!maybeExpandedMap)
79       return failure();
80 
81     auto coorOp = rewriter.create<fir::CoordinateOp>(
82         op.getLoc(), fir::ReferenceType::get(op.getValueToStore().getType()),
83         adaptor.memref(), *maybeExpandedMap);
84     rewriter.replaceOpWithNewOp<fir::StoreOp>(op, adaptor.value(),
85                                               coorOp.getResult());
86     return success();
87   }
88 };
89 
90 class ConvertConversion : public mlir::OpRewritePattern<fir::ConvertOp> {
91 public:
92   using OpRewritePattern::OpRewritePattern;
93   mlir::LogicalResult
94   matchAndRewrite(fir::ConvertOp op,
95                   mlir::PatternRewriter &rewriter) const override {
96     if (op.getRes().getType().isa<mlir::MemRefType>()) {
97       // due to index calculation moving to affine maps we still need to
98       // add converts for sequence types this has a side effect of losing
99       // some information about arrays with known dimensions by creating:
100       // fir.convert %arg0 : (!fir.ref<!fir.array<5xi32>>) ->
101       // !fir.ref<!fir.array<?xi32>>
102       if (auto refTy = op.getValue().getType().dyn_cast<fir::ReferenceType>())
103         if (auto arrTy = refTy.getEleTy().dyn_cast<fir::SequenceType>()) {
104           fir::SequenceType::Shape flatShape = {
105               fir::SequenceType::getUnknownExtent()};
106           auto flatArrTy = fir::SequenceType::get(flatShape, arrTy.getEleTy());
107           auto flatTy = fir::ReferenceType::get(flatArrTy);
108           rewriter.replaceOpWithNewOp<fir::ConvertOp>(op, flatTy,
109                                                       op.getValue());
110           return success();
111         }
112       rewriter.startRootUpdate(op->getParentOp());
113       op.getResult().replaceAllUsesWith(op.getValue());
114       rewriter.finalizeRootUpdate(op->getParentOp());
115       rewriter.eraseOp(op);
116     }
117     return success();
118   }
119 };
120 
121 mlir::Type convertMemRef(mlir::MemRefType type) {
122   return fir::SequenceType::get(
123       SmallVector<int64_t>(type.getShape().begin(), type.getShape().end()),
124       type.getElementType());
125 }
126 
127 class StdAllocConversion : public mlir::OpRewritePattern<memref::AllocOp> {
128 public:
129   using OpRewritePattern::OpRewritePattern;
130   mlir::LogicalResult
131   matchAndRewrite(memref::AllocOp op,
132                   mlir::PatternRewriter &rewriter) const override {
133     rewriter.replaceOpWithNewOp<fir::AllocaOp>(op, convertMemRef(op.getType()),
134                                                op.memref());
135     return success();
136   }
137 };
138 
139 class AffineDialectDemotion
140     : public AffineDialectDemotionBase<AffineDialectDemotion> {
141 public:
142   void runOnOperation() override {
143     auto *context = &getContext();
144     auto function = getOperation();
145     LLVM_DEBUG(llvm::dbgs() << "AffineDemotion: running on function:\n";
146                function.print(llvm::dbgs()););
147 
148     mlir::RewritePatternSet patterns(context);
149     patterns.insert<ConvertConversion>(context);
150     patterns.insert<AffineLoadConversion>(context);
151     patterns.insert<AffineStoreConversion>(context);
152     patterns.insert<StdAllocConversion>(context);
153     mlir::ConversionTarget target(*context);
154     target.addIllegalOp<memref::AllocOp>();
155     target.addDynamicallyLegalOp<fir::ConvertOp>([](fir::ConvertOp op) {
156       if (op.getRes().getType().isa<mlir::MemRefType>())
157         return false;
158       return true;
159     });
160     target.addLegalDialect<FIROpsDialect, mlir::scf::SCFDialect,
161                            mlir::arith::ArithmeticDialect,
162                            mlir::func::FuncDialect>();
163 
164     if (mlir::failed(mlir::applyPartialConversion(function, target,
165                                                   std::move(patterns)))) {
166       mlir::emitError(mlir::UnknownLoc::get(context),
167                       "error in converting affine dialect\n");
168       signalPassFailure();
169     }
170   }
171 };
172 
173 } // namespace
174 
175 std::unique_ptr<mlir::Pass> fir::createAffineDemotionPass() {
176   return std::make_unique<AffineDialectDemotion>();
177 }
178