1 //===- CodegenStrategy.cpp - Linalg programmable codegen strategy ---------===//
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 logic and helpers to expose Linalg transforms as
10 // composable rewrite patterns through a programmable CodegenStrategy object.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "mlir/Dialect/Linalg/Transforms/CodegenStrategy.h"
15 
16 #include "mlir/Dialect/Linalg/Transforms/Hoisting.h"
17 #include "mlir/Dialect/Vector/VectorOps.h"
18 #include "mlir/Dialect/Vector/VectorTransforms.h"
19 #include "mlir/Pass/PassManager.h"
20 #include "mlir/Transforms/GreedyPatternRewriteDriver.h"
21 #include "mlir/Transforms/LoopUtils.h"
22 #include "mlir/Transforms/Passes.h"
23 
24 using namespace mlir;
25 using namespace mlir::linalg;
26 
27 #define DEBUG_TYPE "linalg-codegen-strategy"
28 
29 void mlir::linalg::CodegenStrategy::transform(FuncOp func) const {
30   MLIRContext *context = func.getContext();
31   // Emplace patterns one at a time while also maintaining a simple chained
32   // state transition.
33   unsigned stepCount = 0;
34   SmallVector<FrozenRewritePatternList, 4> stage1Patterns;
35   auto zeroState = Identifier::get(std::to_string(stepCount), context);
36   auto currentState = zeroState;
37   for (const std::unique_ptr<Transformation> &t : transformationSequence) {
38     auto nextState = Identifier::get(std::to_string(++stepCount), context);
39     auto marker = (currentState == zeroState)
40                       ? linalg::LinalgMarker({}, nextState)
41                       : linalg::LinalgMarker(currentState, nextState);
42     stage1Patterns.emplace_back(t->buildRewritePatterns(context, marker));
43     currentState = nextState;
44   }
45 
46   OwningRewritePatternList stage2Patterns =
47       linalg::getLinalgTilingCanonicalizationPatterns(context);
48   stage2Patterns.insert<AffineMinSCFCanonicalizationPattern>(context);
49 
50   auto stage3Transforms = [](Operation *op) {
51     // Some of these may be too aggressive as a stage 3 that is applied on each
52     // stage 1 application and may have to be split out to post staged patterns
53     // application (in which case they could just be passes, TBD).
54     PassManager pm(op->getContext());
55     pm.addPass(createLoopInvariantCodeMotionPass());
56     if (failed(pm.run(op->getParentOfType<ModuleOp>())))
57       llvm_unreachable("Unexpected failure in cleanup pass pipeline.");
58     promoteSingleIterationLoops(cast<FuncOp>(op));
59     hoistViewAllocOps(cast<FuncOp>(op));
60     hoistRedundantVectorTransfers(cast<FuncOp>(op));
61     return success();
62   };
63   linalg::applyStagedPatterns(func, stage1Patterns, std::move(stage2Patterns),
64                               stage3Transforms);
65 
66   //===--------------------------------------------------------------------===//
67   // Post staged patterns transforms
68   //===--------------------------------------------------------------------===//
69 
70   ModuleOp module = func->getParentOfType<ModuleOp>();
71 
72   // Programmatic splitting of slow/fast path vector transfers.
73   OwningRewritePatternList patterns;
74   patterns.insert<vector::VectorTransferFullPartialRewriter>(
75       context, vectorTransformsOptions);
76   applyPatternsAndFoldGreedily(module, std::move(patterns));
77 
78   // Programmatic controlled lowering of vector.contract only.
79   OwningRewritePatternList vectorContractLoweringPatterns;
80   vectorContractLoweringPatterns
81       .insert<ContractionOpToOuterProductOpLowering,
82               ContractionOpToMatmulOpLowering, ContractionOpLowering>(
83           vectorTransformsOptions, context);
84   applyPatternsAndFoldGreedily(module,
85                                std::move(vectorContractLoweringPatterns));
86 
87   // Programmatic controlled lowering of vector.transfer only.
88   OwningRewritePatternList vectorToLoopsPatterns;
89   populateVectorToSCFConversionPatterns(vectorToLoopsPatterns, context,
90                                         vectorToSCFOptions);
91   applyPatternsAndFoldGreedily(module, std::move(vectorToLoopsPatterns));
92 
93   // Ensure we drop the marker in the end.
94   module.walk([](LinalgOp op) {
95     op.removeAttr(LinalgTransforms::kLinalgTransformMarker);
96   });
97 }
98