1 //===- LinalgTransforms.cpp - Linalg transformations as patterns ----------===//
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 rewrite
10 // patterns.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "mlir/Dialect/Linalg/Transforms/Transforms.h"
15 #include "mlir/Dialect/Affine/Utils.h"
16 #include "mlir/Dialect/Arithmetic/IR/Arithmetic.h"
17 #include "mlir/Dialect/Linalg/Analysis/DependenceAnalysis.h"
18 #include "mlir/Dialect/Linalg/IR/Linalg.h"
19 #include "mlir/Dialect/Linalg/Transforms/HoistPadding.h"
20 #include "mlir/Dialect/Linalg/Utils/Utils.h"
21 #include "mlir/Dialect/SCF/Transforms.h"
22 #include "mlir/Dialect/Tensor/IR/Tensor.h"
23 #include "mlir/Dialect/Utils/StaticValueUtils.h"
24 #include "mlir/Dialect/Utils/StructuredOpsUtils.h"
25 #include "mlir/Dialect/Vector/VectorOps.h"
26 #include "mlir/IR/AffineExpr.h"
27 #include "mlir/IR/Matchers.h"
28 #include "mlir/Pass/Pass.h"
29 #include "mlir/Support/LLVM.h"
30 #include "mlir/Transforms/GreedyPatternRewriteDriver.h"
31 #include "llvm/ADT/ScopeExit.h"
32 #include "llvm/ADT/TypeSwitch.h"
33 #include "llvm/Support/Debug.h"
34 #include "llvm/Support/raw_ostream.h"
35 #include <type_traits>
36 #include <utility>
37 
38 #define DEBUG_TYPE "linalg-transforms"
39 
40 using namespace mlir;
41 using namespace mlir::linalg;
42 
43 #define DBGS() (llvm::dbgs() << "[" DEBUG_TYPE << "]: ")
44 
45 //===----------------------------------------------------------------------===//
46 // Transformations exposed as rewrite patterns.
47 //===----------------------------------------------------------------------===//
48 // Marker used as attribute name in generated Linalg rewriting transformations.
49 const StringLiteral mlir::linalg::LinalgTransforms::kLinalgTransformMarker =
50     "__internal_linalg_transform__";
51 
52 mlir::linalg::LinalgTransformationFilter::LinalgTransformationFilter(
53     ArrayRef<StringAttr> matchDisjunction, Optional<StringAttr> replacement)
54     : matchDisjunction(matchDisjunction.begin(), matchDisjunction.end()),
55       replacement(replacement), matchByDefault(false) {}
56 
57 mlir::linalg::LinalgTransformationFilter::LinalgTransformationFilter(
58     const FilterFunction &f, ArrayRef<StringAttr> matchDisjunction,
59     Optional<StringAttr> replacement)
60     : filters(),
61       matchDisjunction(matchDisjunction.begin(), matchDisjunction.end()),
62       replacement(replacement), matchByDefault(false) {
63   if (f)
64     filters.push_back(f);
65 }
66 
67 LogicalResult mlir::linalg::LinalgTransformationFilter::checkAndNotify(
68     PatternRewriter &rewriter, Operation *op) const {
69   if (llvm::any_of(filters,
70                    [&](const FilterFunction &f) { return failed(f(op)); }))
71     return failure();
72 
73   auto attr = op->template getAttrOfType<StringAttr>(
74       LinalgTransforms::kLinalgTransformMarker);
75 
76   if (!attr) {
77     // 1. Has no filter case and matchDisjunction is empty.
78     if (matchDisjunction.empty() || matchByDefault)
79       return success();
80 
81     // 2. Has no filter but was expecting a filter.
82     return rewriter.notifyMatchFailure(op, [&](Diagnostic &diag) {
83       diag << " does not have any filter from list: ";
84       interleaveComma(matchDisjunction, diag);
85     });
86   }
87 
88   // 4. Match explicit filter.
89   for (auto filter : matchDisjunction)
90     if (attr.getValue() == filter)
91       return success();
92 
93   // 5. Fail to match.
94   return rewriter.notifyMatchFailure(op, [&](Diagnostic &diag) {
95     diag << " does not have any filter from list: ";
96     interleaveComma(matchDisjunction, diag);
97   });
98 }
99 
100 void mlir::linalg::LinalgTransformationFilter::
101     replaceLinalgTransformationFilter(PatternRewriter &rewriter,
102                                       Operation *op) const {
103   if (replacement.hasValue())
104     op->setAttr(LinalgTransforms::kLinalgTransformMarker,
105                 replacement.getValue());
106   else
107     op->removeAttr(
108         rewriter.getStringAttr(LinalgTransforms::kLinalgTransformMarker));
109 }
110 
111 bool mlir::linalg::LinalgTransformationFilter::hasReplacementFilter(
112     Operation *op) const {
113   if (!replacement)
114     return false;
115   auto attr = op->getAttr(LinalgTransforms::kLinalgTransformMarker)
116                   .dyn_cast<StringAttr>();
117   return attr && attr == replacement.getValue();
118 }
119 
120 LinalgTilingOptions &
121 mlir::linalg::LinalgTilingOptions::setTileSizes(ArrayRef<int64_t> ts) {
122   assert(!tileSizeComputationFunction && "tile sizes already set");
123   SmallVector<int64_t, 4> tileSizes(ts.begin(), ts.end());
124   tileSizeComputationFunction = [tileSizes](OpBuilder &b, Operation *op) {
125     OpBuilder::InsertionGuard guard(b);
126     b.setInsertionPointToStart(
127         &op->getParentOfType<FuncOp>().getBody().front());
128     return llvm::to_vector<4>(map_range(tileSizes, [&](int64_t s) {
129       Value v = b.create<arith::ConstantIndexOp>(op->getLoc(), s);
130       return v;
131     }));
132   };
133   return *this;
134 }
135 
136 LinalgTilingOptions &mlir::linalg::LinalgTilingOptions::scalarizeDynamicDims() {
137   assert(!tileSizeComputationFunction && "tile sizes already set");
138   tileSizeComputationFunction = [](OpBuilder &b, Operation *op) {
139     SmallVector<Value, 4> tileSizes;
140     auto linalgOp = dyn_cast<LinalgOp>(op);
141     if (!linalgOp)
142       return tileSizes;
143     Location loc = linalgOp.getLoc();
144     auto allShapeSizes = linalgOp.createFlatListOfOperandDims(b, loc);
145     AffineMap map = linalgOp.getShapesToLoopsMap();
146     if (!map)
147       return tileSizes;
148     auto shapeSizes = applyMapToValues(b, loc, map, allShapeSizes);
149     // If the shape size is dynamic, tile by 1. Otherwise, do not tile (tile
150     // size 0).
151     for (Value shapeSize : shapeSizes)
152       tileSizes.push_back(getConstantIntValue(shapeSize).hasValue()
153                               ? b.create<arith::ConstantIndexOp>(loc, 0)
154                               : b.create<arith::ConstantIndexOp>(loc, 1));
155     return tileSizes;
156   };
157   return *this;
158 }
159 
160 /// Helper function that tries to pad `opOperand`. Exit early for scalar
161 /// operands, if `paddingFunc` returns failure, or if `opOperand` is not defined
162 /// by an ExtractSliceOp. Otherwise, try to pad the operand even if it already
163 /// has a static shape. Set `result` to the result of the created PadTensorOp or
164 /// and return success if the operand either has been padded to a static shape
165 /// or already had a static shape and failure otherwise.
166 static LogicalResult padOperandToSmallestStaticBoundingBox(
167     OpBuilder &b, linalg::LinalgOp opToPad, OpOperand *opOperand,
168     const PaddingValueComputationFunction &paddingFunc,
169     const PaddingNoFoldComputationFunction &nofoldFunc, Value &result) {
170   // Get the shape of the operand and check if it has a dynamic shape. Only
171   // return failure if the operand is not a scalar and has a dynamic shape.
172   ArrayRef<int64_t> shape = opToPad.getShape(opOperand);
173   bool hasDynamicShape = llvm::is_contained(shape, ShapedType::kDynamicSize);
174 
175   // Cannot pad scalar operands.
176   if (shape.empty())
177     return success();
178 
179   // Cannot pad if the padding value is unknown.
180   FailureOr<Value> paddingValue = paddingFunc(b, *opOperand);
181   if (failed(paddingValue))
182     return failure(hasDynamicShape);
183 
184   // Cannot construct a static bounding box if the operand is not defined by an
185   // ExtractSliceOp.
186   auto sliceOp = opOperand->get().getDefiningOp<tensor::ExtractSliceOp>();
187   if (!sliceOp)
188     return failure(hasDynamicShape);
189 
190   // Compute the dropped dimensions if `sliceOp` is ranke-reducing.
191   llvm::SmallDenseSet<unsigned> droppedDims = sliceOp.getDroppedDims();
192 
193   // Upper bound the `sliceOp` sizes to obtain a static bounding box.
194   SmallVector<int64_t> staticSizes;
195   staticSizes.reserve(shape.size());
196   auto shapedOp = cast<OffsetSizeAndStrideOpInterface>(sliceOp.getOperation());
197   for (const auto &en : enumerate(shapedOp.getMixedSizes())) {
198     // Skip dropped dimensions.
199     if (droppedDims.contains(en.index()))
200       continue;
201     // If the size is an attribute add it directly to `staticSizes`.
202     if (en.value().is<Attribute>()) {
203       staticSizes.push_back(
204           en.value().get<Attribute>().dyn_cast<IntegerAttr>().getInt());
205       continue;
206     }
207     // Otherwise, try to compute a constant upper bound for the size value.
208     FailureOr<int64_t> upperBound =
209         getConstantUpperBoundForIndex(en.value().get<Value>());
210     if (failed(upperBound)) {
211       LLVM_DEBUG(DBGS() << "No constant bounding box can be found for padding");
212       return failure();
213     }
214     staticSizes.push_back(upperBound.getValue());
215   }
216   assert(staticSizes.size() == shape.size() &&
217          "expect the dynamic and static ranks to match");
218 
219   // Pad the operand to the bounding box defined by `staticSizes`.
220   auto staticTensorType = RankedTensorType::get(
221       staticSizes, getElementTypeOrSelf(opOperand->get()));
222   bool nofold = nofoldFunc ? nofoldFunc(*opOperand) : false;
223   result =
224       makeComposedPadHighOp(b, opToPad->getLoc(), staticTensorType,
225                             opOperand->get(), paddingValue.getValue(), nofold);
226   return success();
227 }
228 
229 FailureOr<SmallVector<Value>>
230 linalg::rewriteAsPaddedOp(OpBuilder &b, LinalgOp opToPad,
231                           const PaddingValueComputationFunction &paddingFunc,
232                           const PaddingNoFoldComputationFunction &nofoldFunc,
233                           LinalgOp &paddedOp) {
234   Location loc = opToPad->getLoc();
235 
236   // TODO: there are cases where we may still want to pad to larger sizes.
237   assert(opToPad.hasTensorSemantics() &&
238          "expected operation to have tensor semantics");
239 
240   OpBuilder::InsertionGuard g(b);
241   // Set IP after op because we also take the dims of the original output.
242   b.setInsertionPointAfter(opToPad);
243   // Make a copy of the shaped operands and update it.
244   SmallVector<Value> newOperands;
245   newOperands.reserve(opToPad.getNumInputsAndOutputs());
246   for (OpOperand *opOperand : opToPad.getInputAndOutputOperands()) {
247     Value paddedOperand;
248     // If padding was requested but the shape cannot be bounded statically then
249     // the pattern fails to apply.
250     if (failed(padOperandToSmallestStaticBoundingBox(
251             b, opToPad, opOperand, paddingFunc, nofoldFunc, paddedOperand)))
252       return failure();
253     newOperands.push_back(paddedOperand ? paddedOperand : opOperand->get());
254   }
255 
256   SmallVector<SmallVector<Value>> reifiedResultShapes;
257   if (failed(cast<ReifyRankedShapedTypeOpInterface>(opToPad.getOperation())
258                  .reifyResultShapes(b, reifiedResultShapes)))
259     return failure();
260   assert(reifiedResultShapes.size() == opToPad->getNumResults() &&
261          "expected same number of results");
262 
263   // Clone `opToPad` to operate on the statically padded shapes.
264   auto resultTensorTypes =
265       ValueRange(newOperands).take_back(opToPad.getNumOutputs()).getTypes();
266   paddedOp = opToPad.clone(b, loc, resultTensorTypes, newOperands);
267 
268   // Recover the slice out of the new static results. This keeps the original
269   // linalg op around because it uses the dims of the original results.
270   SmallVector<Value> paddedSubviewResults;
271   paddedSubviewResults.reserve(opToPad->getNumResults());
272   for (const auto &en : llvm::enumerate(paddedOp->getResults())) {
273     Value paddedResult = en.value();
274     int64_t resultNumber = en.index();
275     int64_t rank = paddedResult.getType().cast<RankedTensorType>().getRank();
276     SmallVector<OpFoldResult> offsets(rank, b.getIndexAttr(0));
277     SmallVector<OpFoldResult> sizes;
278     for (Value v : reifiedResultShapes[resultNumber])
279       sizes.push_back(getAsOpFoldResult(v));
280     SmallVector<OpFoldResult> strides(rank, b.getIndexAttr(1));
281     paddedSubviewResults.push_back(b.create<tensor::ExtractSliceOp>(
282         loc, paddedResult, offsets, sizes, strides));
283   }
284   return paddedSubviewResults;
285 }
286 
287 /// Linalg base tiling pattern.
288 mlir::linalg::LinalgBaseTilingPattern::LinalgBaseTilingPattern(
289     StringRef opName, MLIRContext *context, LinalgTilingOptions options,
290     LinalgTransformationFilter filter, PatternBenefit benefit)
291     : RewritePattern(opName, benefit, context), filter(std::move(filter)),
292       options(std::move(options)) {}
293 
294 mlir::linalg::LinalgBaseTilingPattern::LinalgBaseTilingPattern(
295     MLIRContext *context, LinalgTilingOptions options,
296     LinalgTransformationFilter filter, PatternBenefit benefit)
297     : RewritePattern(MatchAnyOpTypeTag(), benefit, context),
298       filter(std::move(filter)), options(std::move(options)) {}
299 
300 /// Try to peel a loop `op` and return the new result.
301 // TODO: Add support for scf.parallel and affine.for loops.
302 static SmallVector<Value, 4> peelLoop(RewriterBase &rewriter, Operation *op) {
303   return llvm::TypeSwitch<Operation *, SmallVector<Value, 4>>(op)
304       .Case<scf::ForOp>([&](scf::ForOp forOp) {
305         scf::ForOp partialIteration;
306         if (succeeded(scf::peelAndCanonicalizeForLoop(rewriter, forOp,
307                                                       partialIteration)))
308           return partialIteration->getResults();
309         assert(!partialIteration && "expected that loop was not peeled");
310         return forOp->getResults();
311       })
312       .Default([&](Operation *op) { return op->getResults(); });
313 }
314 
315 /// Try to peel a TiledLoopOp and return the new result.
316 static SmallVector<Value, 4> peelLoop(RewriterBase &rewriter,
317                                       TiledLoopOp tiledLoop, int64_t idx) {
318   assert(idx < static_cast<int64_t>(tiledLoop.iterator_types().size()) &&
319          "requested peeling of non-existing loop");
320   TiledLoopOp result;
321   if (succeeded(peelAndCanonicalizeTiledLoop(rewriter, tiledLoop, idx, result)))
322     return result->getResults();
323   assert(!result && "expected that loop was not peeled");
324   return tiledLoop->getResults();
325 }
326 
327 /// Peel loops after tiling.
328 static void peelLoops(RewriterBase &rewriter, TiledLinalgOp &res,
329                       const LinalgTilingOptions &options) {
330   for (int64_t loop : options.peeledLoops) {
331     assert(loop < static_cast<int64_t>(res.loops.size()) &&
332            "requested peeling of non-existing loop");
333     SmallVector<Value, 4> loopResults;
334     Operation *loopOp = res.loops[loop];
335     if (options.loopType == LinalgTilingLoopType::TiledLoops) {
336       assert(llvm::all_of(
337                  res.loops,
338                  [&](Operation *op) { return op == res.loops.front(); }) &&
339              "expected that all loop ops are the same TiledLoopOp");
340       auto tiledLoopOp = dyn_cast<TiledLoopOp>(loopOp);
341       assert(tiledLoopOp && "expected TiledLoopOp");
342       loopResults = peelLoop(rewriter, tiledLoopOp, loop);
343     } else {
344       loopResults = peelLoop(rewriter, loopOp);
345     }
346 
347     // The result of the loop nest may change with peeling.
348     if (res.tensorResults.size() == loopOp->getNumResults() &&
349         std::equal(res.tensorResults.begin(), res.tensorResults.end(),
350                    loopOp->getResults().begin()))
351       res.tensorResults = loopResults;
352   }
353 }
354 
355 LogicalResult mlir::linalg::LinalgBaseTilingPattern::matchAndRewriteBase(
356     Operation *op, PatternRewriter &rewriter, TiledLinalgOp &result) const {
357   LinalgOp linalgOp = dyn_cast<LinalgOp>(op);
358   if (!linalgOp)
359     return failure();
360   if (failed(filter.checkAndNotify(rewriter, linalgOp)))
361     return failure();
362 
363   Optional<TiledLinalgOp> res = tileLinalgOp(rewriter, linalgOp, options);
364 
365   if (!res)
366     return failure();
367   // Clear filter to stop recursive pattern application.
368   filter.replaceLinalgTransformationFilter(rewriter, res->op);
369 
370   // Peel loops.
371   peelLoops(rewriter, *res, options);
372 
373   result = *res;
374   return success();
375 }
376 
377 static ValueRange getTiledOpResult(TiledLinalgOp tiledOp) {
378   if (tiledOp.loops.empty())
379     return tiledOp.op.getOperation()->getResults();
380   return tiledOp.loops.front()->getResults();
381 }
382 
383 static ValueRange
384 getTiledAndFusedOpResult(TiledAndFusedLinalgOps tiledAndFusedOp) {
385   if (tiledAndFusedOp.fusedLoops.empty())
386     return tiledAndFusedOp.op.getOperation()->getResults();
387   return tiledAndFusedOp.fusedLoops.front()->getResults();
388 }
389 
390 mlir::linalg::LinalgBaseTileAndFusePattern::LinalgBaseTileAndFusePattern(
391     StringRef opName, MLIRContext *context,
392     const LinalgDependenceGraph &dependenceGraph,
393     LinalgTilingOptions tilingOptions, LinalgFusionOptions fusionOptions,
394     LinalgTransformationFilter filter, LinalgTransformationFilter fusedOpMarker,
395     LinalgTransformationFilter originalOpMarker, PatternBenefit benefit)
396     : RewritePattern(opName, benefit, context, {}),
397       dependenceGraph(dependenceGraph), tilingOptions(std::move(tilingOptions)),
398       fusionOptions(std::move(fusionOptions)), filter(std::move(filter)),
399       fusedOpMarker(std::move(fusedOpMarker)),
400       originalOpMarker(std::move(originalOpMarker)) {}
401 
402 LogicalResult mlir::linalg::LinalgBaseTileAndFusePattern::matchAndRewrite(
403     Operation *op, PatternRewriter &rewriter) const {
404   LinalgOp linalgOp = dyn_cast<LinalgOp>(op);
405   // TODO: remove hasIndexSemantics check once index ops are supported.
406   if (!linalgOp || linalgOp.hasIndexSemantics())
407     return failure();
408   if (failed(filter.checkAndNotify(rewriter, linalgOp)))
409     return failure();
410 
411   DenseSet<Operation *> producers;
412   producers.insert(linalgOp);
413   for (auto dependence : dependenceGraph.getDependentOperationsInto(linalgOp)) {
414     Optional<unsigned> operandNumber = dependence.getIndexingOpViewOperandNum();
415     // When looking at dependences into, indexingOp is always OpOperand. We
416     // could assert, but continue if this is not the case.
417     if (!operandNumber)
418       continue;
419     if (!fusionOptions.indicesToFuse.count(operandNumber.getValue()))
420       continue;
421     if (isa<LinalgOp>(dependence.getDependentOp()))
422       producers.insert(dependence.getDependentOp());
423   }
424 
425   SmallVector<LinalgOp, 1> fusionOps;
426   for (auto it = op->getBlock()->begin(), ie = Block::iterator(op); it != ie;
427        ++it) {
428     auto producerLinalgOp = dyn_cast<LinalgOp>(&(*it));
429     if (producerLinalgOp && producers.count(producerLinalgOp))
430       fusionOps.push_back(producerLinalgOp);
431   }
432   fusionOps.push_back(linalgOp);
433 
434   SmallVector<Value, 4> tileSizes =
435       tilingOptions.tileSizeComputationFunction(rewriter, op);
436   LinalgTilingOptions instanceTilingOptions = tilingOptions;
437   instanceTilingOptions.setTileSizes(tileSizes);
438   Optional<TiledAndFusedLinalgOps> tiledAndFusedOps = tileAndFuseLinalgOps(
439       rewriter, fusionOps, dependenceGraph, instanceTilingOptions);
440   if (!tiledAndFusedOps)
441     return failure();
442 
443   // Tile the unfused loops;
444   SmallVector<Value, 4> unfusedLoopTileSizes;
445   Value zero = rewriter.create<arith::ConstantIndexOp>(op->getLoc(), 0);
446   for (const auto &tileSize : enumerate(tileSizes)) {
447     if (tiledAndFusedOps->fusedLoopDims.count(tileSize.index()))
448       unfusedLoopTileSizes.push_back(zero);
449     else
450       unfusedLoopTileSizes.push_back(tileSize.value());
451   }
452   // Tile the loop only if there is a non-zero tile size.
453   if (unfusedLoopTileSizes.size() > linalgOp.getNumLoops())
454     unfusedLoopTileSizes.resize(linalgOp.getNumLoops());
455   if (llvm::any_of(unfusedLoopTileSizes, [](Value val) {
456         if (auto cst = val.getDefiningOp<arith::ConstantIndexOp>())
457           return cst.value() != 0;
458         return true;
459       })) {
460     LinalgTilingOptions unfusedTilingOptions = tilingOptions;
461     unfusedTilingOptions.setTileSizes(unfusedLoopTileSizes);
462     Optional<TiledLinalgOp> unfusedTiledOp =
463         tileLinalgOp(rewriter, tiledAndFusedOps->op, unfusedTilingOptions);
464     if (!unfusedTiledOp)
465       return failure();
466     rewriter.replaceOp(tiledAndFusedOps->op,
467                        getTiledOpResult(unfusedTiledOp.getValue()));
468     tiledAndFusedOps->op = unfusedTiledOp->op;
469   }
470   op->replaceAllUsesWith(getTiledAndFusedOpResult(tiledAndFusedOps.getValue()));
471 
472   filter.replaceLinalgTransformationFilter(rewriter,
473                                            tiledAndFusedOps->op.getOperation());
474   for (auto fusedOp : tiledAndFusedOps->fusedProducers) {
475     fusedOpMarker.replaceLinalgTransformationFilter(rewriter,
476                                                     fusedOp.getOperation());
477   }
478   for (auto origProducerOp : ArrayRef<LinalgOp>(fusionOps).drop_back()) {
479     originalOpMarker.replaceLinalgTransformationFilter(
480         rewriter, origProducerOp.getOperation());
481   }
482   rewriter.updateRootInPlace(op, [&]() {
483     originalOpMarker.replaceLinalgTransformationFilter(rewriter, op);
484   });
485   return success();
486 }
487 
488 /// Linalg padding pattern.
489 mlir::linalg::LinalgPaddingPattern::LinalgPaddingPattern(
490     MLIRContext *context, LinalgPaddingOptions options,
491     LinalgTransformationFilter filter, PatternBenefit benefit)
492     : RewritePattern(MatchAnyOpTypeTag(), benefit, context),
493       filter(std::move(filter)), options(std::move(options)) {}
494 
495 mlir::linalg::LinalgPaddingPattern::LinalgPaddingPattern(
496     StringRef opName, MLIRContext *context, LinalgPaddingOptions options,
497     LinalgTransformationFilter filter, PatternBenefit benefit)
498     : RewritePattern(opName, benefit, context, {}), filter(std::move(filter)),
499       options(std::move(options)) {}
500 
501 LogicalResult mlir::linalg::LinalgPaddingPattern::matchAndRewrite(
502     Operation *op, PatternRewriter &rewriter) const {
503   LinalgOp linalgOp = dyn_cast<LinalgOp>(op);
504   if (!linalgOp)
505     return failure();
506   if (!linalgOp.hasTensorSemantics())
507     return failure();
508   if (failed(filter.checkAndNotify(rewriter, op)))
509     return failure();
510 
511   // Pad the operation.
512   LinalgOp paddedOp;
513   FailureOr<SmallVector<Value>> newResults = rewriteAsPaddedOp(
514       rewriter, linalgOp, options.paddingValueComputationFunction,
515       options.paddingNoFoldComputationFunction, paddedOp);
516   if (failed(newResults))
517     return failure();
518 
519   // Compute the desired hoisting depths.
520   SmallVector<int64_t> depths;
521   if (options.paddingHoistComputationFunction) {
522     for (OpOperand *opOperand : linalgOp.getInputAndOutputOperands())
523       depths.push_back(options.paddingHoistComputationFunction(*opOperand));
524   }
525 
526   // Hoist the padding.
527   for (const auto &en : enumerate(depths)) {
528     OpOperand &opOperand = paddedOp->getOpOperand(en.index());
529     auto padTensorOp = opOperand.get().getDefiningOp<PadTensorOp>();
530     if (!padTensorOp || en.value() == 0)
531       continue;
532     PadTensorOp hoistedOp;
533     FailureOr<Value> newResult =
534         hoistPaddingOnTensors(padTensorOp, en.value(), hoistedOp);
535     if (failed(newResult))
536       continue;
537     rewriter.replaceOp(padTensorOp, newResult.getValue());
538   }
539 
540   // Replace the original operation to pad.
541   rewriter.replaceOp(op, newResults.getValue());
542   filter.replaceLinalgTransformationFilter(rewriter, paddedOp);
543   return success();
544 }
545 
546 /// Linalg tile and fuse tensor ops pattern.
547 mlir::linalg::LinalgTileAndFuseTensorOpsPattern::
548     LinalgTileAndFuseTensorOpsPattern(MLIRContext *context,
549                                       LinalgTilingAndFusionOptions options,
550                                       LinalgTransformationFilter filter,
551                                       PatternBenefit benefit)
552     : RewritePattern(MatchAnyOpTypeTag(), benefit, context),
553       filter(std::move(filter)), options(std::move(options)) {}
554 
555 mlir::linalg::LinalgTileAndFuseTensorOpsPattern::
556     LinalgTileAndFuseTensorOpsPattern(StringRef opName, MLIRContext *context,
557                                       LinalgTilingAndFusionOptions options,
558                                       LinalgTransformationFilter filter,
559                                       PatternBenefit benefit)
560     : RewritePattern(opName, benefit, context), filter(std::move(filter)),
561       options(std::move(options)) {}
562 
563 LogicalResult mlir::linalg::LinalgTileAndFuseTensorOpsPattern::matchAndRewrite(
564     Operation *op, PatternRewriter &rewriter) const {
565   LinalgOp rootOp = dyn_cast<LinalgOp>(op);
566   if (!rootOp)
567     return failure();
568   if (failed(filter.checkAndNotify(rewriter, op)))
569     return failure();
570 
571   // Check `tileSizes` contains a tile size for every `rootOp` loop dimension.
572   if (options.tileSizes.size() < rootOp.getNumLoops())
573     return rewriter.notifyMatchFailure(op, "expect #tile sizes >= #loops");
574 
575   // Check `tileInterchange` contains no entries or as many as `tileSizes`.
576   if (!options.tileInterchange.empty() &&
577       options.tileInterchange.size() != options.tileSizes.size())
578     return rewriter.notifyMatchFailure(
579         op, "expect the number of tile sizes and interchange dims to match");
580 
581   // Copy the `tileSizes` and `tileInterchange` prefixes needed for `rootOp`.
582   SmallVector<int64_t> rootTileSizes(options.tileSizes.begin(),
583                                      options.tileSizes.begin() +
584                                          rootOp.getNumLoops());
585   SmallVector<int64_t> rootInterchange =
586       options.tileInterchange.empty()
587           ? llvm::to_vector<6>(llvm::seq<int64_t>(0, rootOp.getNumLoops()))
588           : SmallVector<int64_t>(options.tileInterchange.begin(),
589                                  options.tileInterchange.begin() +
590                                      rootOp.getNumLoops());
591 
592   // Check `rootInterchange` is a permutation of the `rootOp` loop dimensions.
593   // It has to be a permutation since the tiling cannot tile the same loop
594   // dimension multiple times.
595   if (!isPermutation(rootInterchange))
596     return rewriter.notifyMatchFailure(
597         op, "expect the tile interchange permutes the root loops");
598 
599   // Tile `rootOp` and fuse its producers.
600   FailureOr<TileLoopNest> tileLoopNest = tileConsumerAndFuseProducers(
601       rewriter, rootOp, rootTileSizes, rootInterchange);
602   if (failed(tileLoopNest))
603     return rewriter.notifyMatchFailure(
604         op, "tileConsumerAndFuseProducers failed unexpectedly");
605 
606   // Replace all uses of the tiled loop operation.
607   rootOp->replaceAllUsesWith(tileLoopNest->getRootOpReplacementResults());
608 
609   // Apply the filter if specified.
610   for (LinalgOp linalgOp : tileLoopNest->getAllTiledAndFusedOps())
611     filter.replaceLinalgTransformationFilter(rewriter, linalgOp);
612   return failure();
613 }
614 
615 /// Linalg generic interchange pattern.
616 mlir::linalg::GenericOpInterchangePattern::GenericOpInterchangePattern(
617     MLIRContext *context, ArrayRef<unsigned> interchangeVector,
618     LinalgTransformationFilter filter, PatternBenefit benefit)
619     : OpRewritePattern(context, benefit), filter(std::move(filter)),
620       interchangeVector(interchangeVector.begin(), interchangeVector.end()) {}
621 
622 LogicalResult mlir::linalg::GenericOpInterchangePattern::matchAndRewrite(
623     GenericOp genericOp, PatternRewriter &rewriter) const {
624   if (failed(filter.checkAndNotify(rewriter, genericOp)))
625     return failure();
626 
627   FailureOr<GenericOp> transformedOp =
628       interchangeGenericOp(rewriter, genericOp, interchangeVector);
629   if (failed(transformedOp))
630     return failure();
631 
632   // New filter if specified.
633   filter.replaceLinalgTransformationFilter(rewriter, genericOp);
634   return success();
635 }
636 
637 /// Linalg generalization pattern.
638 mlir::linalg::LinalgGeneralizationPattern::LinalgGeneralizationPattern(
639     MLIRContext *context, LinalgTransformationFilter filter,
640     PatternBenefit benefit)
641     : RewritePattern(MatchAnyOpTypeTag(), benefit, context),
642       filter(std::move(filter)) {}
643 
644 mlir::linalg::LinalgGeneralizationPattern::LinalgGeneralizationPattern(
645     StringRef opName, MLIRContext *context, LinalgTransformationFilter filter,
646     PatternBenefit benefit)
647     : RewritePattern(opName, benefit, context, {}), filter(std::move(filter)) {}
648 
649 LogicalResult mlir::linalg::LinalgGeneralizationPattern::matchAndRewrite(
650     Operation *op, PatternRewriter &rewriter) const {
651   // TODO: Interface pattern.
652   LinalgOp linalgOp = dyn_cast<LinalgOp>(op);
653   if (!linalgOp)
654     return failure();
655   if (failed(filter.checkAndNotify(rewriter, op)))
656     return failure();
657   FailureOr<GenericOp> genericOp = generalizeNamedOp(rewriter, linalgOp);
658   if (failed(genericOp))
659     return failure();
660   filter.replaceLinalgTransformationFilter(rewriter, *genericOp);
661   return success();
662 }
663 
664 mlir::linalg::LinalgBasePromotionPattern::LinalgBasePromotionPattern(
665     MLIRContext *context, LinalgTransformationFilter filter,
666     LinalgPromotionOptions options, PatternBenefit benefit)
667     : RewritePattern(MatchAnyOpTypeTag(), benefit, context),
668       filter(std::move(filter)), options(std::move(options)) {}
669 
670 mlir::linalg::LinalgBasePromotionPattern::LinalgBasePromotionPattern(
671     StringRef opName, MLIRContext *context, LinalgPromotionOptions options,
672     LinalgTransformationFilter filter, PatternBenefit benefit)
673     : RewritePattern(opName, benefit, context, {}), filter(std::move(filter)),
674       options(std::move(options)) {}
675 
676 LogicalResult mlir::linalg::LinalgBasePromotionPattern::matchAndRewrite(
677     Operation *op, PatternRewriter &rewriter) const {
678   if (failed(filter.checkAndNotify(rewriter, op)))
679     return failure();
680   if (failed(promoteSubviewsPrecondition(op, options)))
681     return failure();
682 
683   // TODO: We cannot use root update here. This pattern is creating other ops,
684   // so if the promotion fails, those need to be cleaned up, which doesnt seem
685   // to be happening here. So to fail properly, we should be cloning the op and
686   // deleting the previous op. This needs more investigation.
687   rewriter.startRootUpdate(op);
688   Optional<LinalgOp> promotedOp = promoteSubViews(rewriter, op, options);
689   if (!promotedOp) {
690     rewriter.cancelRootUpdate(op);
691     return op->emitError("subview promotion failed");
692   }
693   rewriter.finalizeRootUpdate(op);
694   filter.replaceLinalgTransformationFilter(rewriter, op);
695   return success();
696 }
697 
698 mlir::linalg::LinalgBaseVectorizationPattern::LinalgBaseVectorizationPattern(
699     MLIRContext *context, LinalgTransformationFilter filter,
700     PatternBenefit benefit)
701     : RewritePattern(MatchAnyOpTypeTag(), benefit, context),
702       filter(std::move(filter)) {}
703 
704 mlir::linalg::LinalgBaseVectorizationPattern::LinalgBaseVectorizationPattern(
705     StringRef opName, MLIRContext *context, LinalgTransformationFilter filter,
706     PatternBenefit benefit)
707     : RewritePattern(opName, benefit, context, {}), filter(std::move(filter)) {}
708 
709 LogicalResult mlir::linalg::LinalgBaseVectorizationPattern::matchAndRewrite(
710     Operation *op, PatternRewriter &rewriter) const {
711   // TODO: Interface-based rewrite.
712   LinalgOp linalgOp = dyn_cast<LinalgOp>(op);
713   if (!linalgOp)
714     return failure();
715   if (failed(filter.checkAndNotify(rewriter, op)))
716     return failure();
717   return vectorize(rewriter, linalgOp);
718 }
719 
720 LogicalResult mlir::linalg::applyStagedPatterns(
721     Operation *op, ArrayRef<FrozenRewritePatternSet> stage1Patterns,
722     const FrozenRewritePatternSet &stage2Patterns,
723     function_ref<LogicalResult(Operation *)> stage3Lambda) {
724   unsigned iteration = 0;
725   (void)iteration;
726   for (const auto &patterns : stage1Patterns) {
727     LLVM_DEBUG(DBGS() << "Before 1st stage, iter: " << ++iteration << "\n"
728                       << *op);
729     if (failed(applyPatternsAndFoldGreedily(op, patterns))) {
730       LLVM_DEBUG(DBGS() << "Underlying first stage rewrite did not converge");
731       return failure();
732     }
733     LLVM_DEBUG(DBGS() << "After 1st stage, iter: " << ++iteration << "\n"
734                       << *op);
735     if (failed(applyPatternsAndFoldGreedily(op, stage2Patterns))) {
736       LLVM_DEBUG(DBGS() << "Underlying 2nd stage rewrite did not converge");
737       return failure();
738     }
739     LLVM_DEBUG(DBGS() << "After 2nd stage, iter : " << iteration << "\n"
740                       << *op);
741     if (stage3Lambda) {
742       if (failed(stage3Lambda(op)))
743         return failure();
744       LLVM_DEBUG(DBGS() << "After 3rd stage, iter : " << iteration << "\n"
745                         << *op);
746     }
747   }
748   return success();
749 }
750 
751 static SmallVector<StringRef> getNParallelLoopsAttrs(unsigned nParallelLoops) {
752   return SmallVector<StringRef>(nParallelLoops, getParallelIteratorTypeName());
753 }
754 
755 /// Rewrite a PadTensorOp into a sequence of InitTensorOp, FillOp (to
756 /// initialize with pad_val) and GenericOp (to copy contents).
757 LogicalResult PadTensorOpTransformationPattern::matchAndRewrite(
758     linalg::PadTensorOp padOp, PatternRewriter &rewriter) const {
759 
760   auto inputShapedType = padOp.source().getType().cast<ShapedType>();
761   auto resultShapedType = padOp.result().getType().cast<ShapedType>();
762 
763   // Bail on non-static shapes.
764   if (!inputShapedType.hasStaticShape())
765     return failure();
766   if (!resultShapedType.hasStaticShape())
767     return failure();
768 
769   // Only support padding with a constant for now, i.e. either:
770   //   1. A BBarg from a different block.
771   //   2. A value defined outside of the current block.
772   Block &block = padOp.region().front();
773   auto yieldOp = cast<YieldOp>(block.getTerminator());
774   assert(yieldOp.getNumOperands() == 1 && "expected single operand yield");
775   Value padValue = yieldOp.values().front();
776   Operation *definingOp = padValue.getDefiningOp();
777   if (definingOp && definingOp->getBlock() == &block)
778     return failure();
779   if (!definingOp && padValue.cast<BlockArgument>().getOwner() == &block)
780     return failure();
781 
782   // Create tensor with the padded shape
783   Location loc = padOp.getLoc();
784   SmallVector<Value> indices(resultShapedType.getRank(),
785                              rewriter.create<arith::ConstantIndexOp>(loc, 0));
786   Value initTensor = rewriter.create<InitTensorOp>(
787       loc, resultShapedType.getShape(), resultShapedType.getElementType());
788 
789   // Initialize tensor with the pad value
790   Value tmpTensor =
791       rewriter.create<linalg::FillOp>(loc, padValue, initTensor).result();
792 
793   // Copy original contents into new tensor
794   // Uses linalg.generic, but could be done with tensor.insert_slice
795   SmallVector<AffineExpr, 4> outputExprs;
796   for (unsigned i = 0; i < resultShapedType.getRank(); ++i) {
797     outputExprs.push_back(getAffineDimExpr(i, rewriter.getContext()) +
798                           padOp.static_low()[i].cast<IntegerAttr>().getInt());
799   }
800 
801   SmallVector<AffineMap, 2> transferMaps = {
802       rewriter.getMultiDimIdentityMap(inputShapedType.getRank()),
803       AffineMap::get(resultShapedType.getRank(),
804                      /*symbolCount=*/0, outputExprs, rewriter.getContext())};
805 
806   rewriter.replaceOpWithNewOp<linalg::GenericOp>(
807       padOp, resultShapedType, padOp.source(), tmpTensor, transferMaps,
808       getNParallelLoopsAttrs(resultShapedType.getRank()),
809       [&](OpBuilder &nestedBuilder, Location nestedLoc, ValueRange args) {
810         nestedBuilder.create<linalg::YieldOp>(nestedLoc, args[0]);
811       });
812 
813   return success();
814 }
815 
816 /// Filling `dest` using FillOp constant padding value if possible.
817 /// Otherwise, generate a tensor::GenerateOp.
818 Value GeneralizePadTensorOpPattern::createFillOrGenerateOp(
819     PatternRewriter &rewriter, PadTensorOp padOp, Value dest,
820     const SmallVector<Value> &dynSizes) const {
821   auto padValue = padOp.getConstantPaddingValue();
822   if (padValue)
823     return rewriter.create<FillOp>(padOp.getLoc(), padValue, dest).result();
824 
825   // Fill could not be optimized: Lower to tensor::GenerateOp with region.
826   auto generateOp = rewriter.create<tensor::GenerateOp>(
827       padOp.getLoc(), padOp.getResultType(), dynSizes);
828   // Copy region to new op.
829   BlockAndValueMapping bvm;
830   padOp.region().cloneInto(&generateOp.getRegion(), bvm);
831   // Rewrite linalg::YieldOp to tensor::YieldOp.
832   OpBuilder::InsertionGuard guard(rewriter);
833   auto yieldOp =
834       dyn_cast<linalg::YieldOp>(generateOp.getRegion().front().getTerminator());
835   assert(yieldOp && "malformed PadTensorOp: expected YieldOp terminator");
836   assert(yieldOp.values().size() == 1);
837   rewriter.setInsertionPoint(yieldOp);
838   rewriter.replaceOpWithNewOp<tensor::YieldOp>(yieldOp, yieldOp.values()[0]);
839   return generateOp;
840 }
841 
842 LogicalResult
843 GeneralizePadTensorOpPattern::matchAndRewrite(PadTensorOp padOp,
844                                               PatternRewriter &rewriter) const {
845   // Given an OpFoldResult, return an index-typed value.
846   auto getIdxValue = [&](OpFoldResult ofr) {
847     if (auto val = ofr.dyn_cast<Value>())
848       return val;
849     return rewriter
850         .create<arith::ConstantIndexOp>(
851             padOp.getLoc(), ofr.get<Attribute>().cast<IntegerAttr>().getInt())
852         .getResult();
853   };
854 
855   auto resultType = padOp.getResultType();
856   // Compute size of InitTensorOp. Any combination of static/dynamic is
857   // supported.
858   SmallVector<Value> dynSizes;
859   SmallVector<int64_t> staticSizes;
860   for (unsigned dim = 0; dim < resultType.getRank(); ++dim) {
861     if (resultType.isDynamicDim(dim)) {
862       auto srcSize = rewriter.createOrFold<tensor::DimOp>(padOp.getLoc(),
863                                                           padOp.source(), dim);
864       // Add low and high padding value.
865       auto plusLow = rewriter.createOrFold<arith::AddIOp>(
866           padOp.getLoc(), srcSize, getIdxValue(padOp.getMixedLowPad()[dim]));
867       auto plusHigh = rewriter.createOrFold<arith::AddIOp>(
868           padOp.getLoc(), plusLow, getIdxValue(padOp.getMixedHighPad()[dim]));
869       dynSizes.push_back(plusHigh);
870     }
871     staticSizes.push_back(resultType.getDimSize(dim));
872   }
873 
874   // Init tensor and fill it with padding.
875   Value init = rewriter.create<InitTensorOp>(
876       padOp.getLoc(), dynSizes, staticSizes, resultType.getElementType());
877   Value fill = createFillOrGenerateOp(rewriter, padOp, init, dynSizes);
878 
879   // Try optimize the copy of source.
880   if (optimizeCopyFn && optimizeCopyFn(rewriter, padOp, fill).succeeded())
881     return success();
882 
883   // PadTensorOps cannot be optimized. Generate a InsertSliceOp instead
884   // for copying the PadOp source.
885   auto sourceType = padOp.getSourceType();
886   // Compute size of source of PadTensorOp.
887   SmallVector<OpFoldResult> srcSizes;
888   for (unsigned dim = 0; dim < sourceType.getRank(); ++dim) {
889     if (sourceType.isDynamicDim(dim)) {
890       srcSizes.push_back(rewriter.createOrFold<tensor::DimOp>(
891           padOp.getLoc(), padOp.source(), dim));
892     } else {
893       srcSizes.push_back(rewriter.getIndexAttr(sourceType.getDimSize(dim)));
894     }
895   }
896   // Strides of InsertSliceOp are all 1.
897   SmallVector<OpFoldResult> strides(sourceType.getRank(),
898                                     rewriter.getIndexAttr(1));
899   rewriter.replaceOpWithNewOp<tensor::InsertSliceOp>(
900       padOp, padOp.source(), fill, padOp.getMixedLowPad(), srcSizes, strides);
901 
902   return success();
903 }
904 
905 LogicalResult ExtractSliceOfPadTensorSwapPattern::matchAndRewrite(
906     tensor::ExtractSliceOp sliceOp, PatternRewriter &rewriter) const {
907   auto padOp = sliceOp.source().getDefiningOp<PadTensorOp>();
908   if (!padOp)
909     return failure();
910   // Only unit stride supported.
911   if (!sliceOp.hasUnitStride())
912     return failure();
913 
914   Operation *tiledPadOp =
915       padOp
916           .getTiledImplementation(
917               rewriter, /*dest=*/ValueRange{}, sliceOp.getMixedOffsets(),
918               sliceOp.getMixedSizes(), /*tileDestOperands=*/false)
919           .front();
920   // All shapes are static and the data source is actually used. Rewrite into
921   // pad_tensor(subtensor(x)).
922   rewriter.replaceOp(sliceOp, tiledPadOp->getResults());
923   return success();
924 }
925 
926 namespace {
927 // The following are patterns for downscaling convolution ops with size-1
928 // window dimensions.
929 //
930 // Note that we'd eventually want to write such transformations in a generic
931 // way, e.g., converting to linalg.generic, removing the size-1 dimensions,
932 // and then turning back to named ops. But for now it's fine to have a few
933 // patterns matching special ops to get started.
934 
935 /// Rewrites 2-D convolution ops with size-1 window dimensions into 1-D
936 /// convolution ops.
937 struct DownscaleSizeOneWindowed2DConvolution final
938     : public OpRewritePattern<Conv2DNhwcHwcfOp> {
939   DownscaleSizeOneWindowed2DConvolution(
940       MLIRContext *context,
941       LinalgTransformationFilter filter = LinalgTransformationFilter(),
942       PatternBenefit benefit = 1)
943       : OpRewritePattern<Conv2DNhwcHwcfOp>(context, benefit),
944         filter(std::move(filter)) {}
945 
946   LogicalResult matchAndRewrite(linalg::Conv2DNhwcHwcfOp convOp,
947                                 PatternRewriter &rewriter) const override {
948     if (failed(filter.checkAndNotify(rewriter, convOp)))
949       return failure();
950     if (convOp.hasBufferSemantics())
951       return failure(); // To be implemented
952 
953     Value input = convOp.inputs().front();
954     Value kernel = convOp.inputs().back();
955     Value output = convOp.outputs().front();
956 
957     auto inputType = input.getType().dyn_cast<RankedTensorType>();
958     auto kernelType = kernel.getType().dyn_cast<RankedTensorType>();
959     auto outputType = output.getType().dyn_cast<RankedTensorType>();
960 
961     auto kernelShape = kernelType.getShape();
962     auto outputShape = outputType.getShape();
963 
964     // Only handle the case where at least one of the window dimensions is
965     // of size 1. Other cases can rely on tiling to reduce to such cases.
966     int64_t khSize = kernelShape[0], kwSize = kernelShape[1];
967     int64_t ohSize = outputShape[1], owSize = outputShape[2];
968     bool removeH = (khSize == 1 && ohSize == 1);
969     bool removeW = (kwSize == 1 && owSize == 1);
970     if (!removeH && !removeW)
971       return failure();
972 
973     // Get new shapes and types for all operands by removing the size-1
974     // dimension.
975     using RTTBuilder = RankedTensorType::Builder;
976     RankedTensorType newInputType =
977         RTTBuilder(inputType).dropDim((removeH ? 1 : 2));
978     RankedTensorType newKernelType =
979         RTTBuilder(kernelType).dropDim((removeH ? 0 : 1));
980     RankedTensorType newOutputType =
981         RTTBuilder(outputType).dropDim(removeH ? 1 : 2);
982 
983     // Rank-reduce operands.
984     Location loc = convOp.getLoc();
985     Value newInput = tensor::createCanonicalRankReducingExtractSliceOp(
986         rewriter, loc, input, newInputType);
987     Value newKernel = tensor::createCanonicalRankReducingExtractSliceOp(
988         rewriter, loc, kernel, newKernelType);
989     Value newOutput = tensor::createCanonicalRankReducingExtractSliceOp(
990         rewriter, loc, output, newOutputType);
991 
992     // Rank-reduce strides and dilations too.
993     // TODO: dropDim 1-liner helper.
994     auto strides = llvm::to_vector<4>(convOp.strides().getValues<int64_t>());
995     strides.erase(strides.begin() + (removeH ? 0 : 1));
996     auto stridesAttr = rewriter.getI64VectorAttr(strides);
997 
998     auto dilations =
999         llvm::to_vector<4>(convOp.dilations().getValues<int64_t>());
1000     dilations.erase(dilations.begin() + (removeH ? 0 : 1));
1001     auto dilationsAttr = rewriter.getI64VectorAttr(dilations);
1002 
1003     auto conv1DOp = rewriter.create<linalg::Conv1DNwcWcfOp>(
1004         loc, newOutputType, ValueRange{newInput, newKernel},
1005         ValueRange{newOutput}, stridesAttr, dilationsAttr);
1006 
1007     // Insert back.
1008     Value inserted = tensor::createCanonicalRankReducingInsertSliceOp(
1009         rewriter, loc, conv1DOp.getResult(0), output);
1010     rewriter.replaceOp(convOp, inserted);
1011 
1012     filter.replaceLinalgTransformationFilter(rewriter, conv1DOp);
1013     return success();
1014   };
1015 
1016 private:
1017   /// LinalgTransformMarker handles special attribute manipulations.
1018   LinalgTransformationFilter filter;
1019 };
1020 
1021 /// Rewrites 2-D depthwise convolution ops with size-1 (w, kw) or (h, kh)
1022 /// dimensions into 1-D depthwise convolution ops.
1023 struct DownscaleDepthwiseConv2DNhwcHwcOp final
1024     : public OpRewritePattern<DepthwiseConv2DNhwcHwcOp> {
1025   DownscaleDepthwiseConv2DNhwcHwcOp(
1026       MLIRContext *context,
1027       LinalgTransformationFilter filter = LinalgTransformationFilter(),
1028       PatternBenefit benefit = 1)
1029       : OpRewritePattern<DepthwiseConv2DNhwcHwcOp>(context, benefit),
1030         filter(std::move(filter)) {}
1031 
1032   LogicalResult matchAndRewrite(DepthwiseConv2DNhwcHwcOp convOp,
1033                                 PatternRewriter &rewriter) const override {
1034     if (failed(filter.checkAndNotify(rewriter, convOp)))
1035       return failure();
1036     if (convOp.hasBufferSemantics())
1037       return failure(); // To be implemented
1038 
1039     Value input = convOp.inputs().front();
1040     Value kernel = convOp.inputs().back();
1041     Value output = convOp.outputs().front();
1042 
1043     auto inputType = input.getType().dyn_cast<RankedTensorType>();
1044     auto kernelType = kernel.getType().dyn_cast<RankedTensorType>();
1045     auto outputType = output.getType().dyn_cast<RankedTensorType>();
1046 
1047     auto kernelShape = kernelType.getShape();
1048     auto outputShape = outputType.getShape();
1049 
1050     // Only handle the case where at least one of the window dimensions is
1051     // of size 1. Other cases can rely on tiling to reduce to such cases.
1052     int64_t khSize = kernelShape[0], kwSize = kernelShape[1];
1053     int64_t ohSize = outputShape[1], owSize = outputShape[2];
1054     bool removeH = (khSize == 1 && ohSize == 1);
1055     bool removeW = (kwSize == 1 && owSize == 1);
1056     if (!removeH && !removeW)
1057       return failure();
1058 
1059     // Get new shapes and types for all operands by removing the size-1
1060     // dimension.
1061     using RTTBuilder = RankedTensorType::Builder;
1062     RankedTensorType newInputType =
1063         RTTBuilder(inputType).dropDim((removeH ? 1 : 2));
1064     RankedTensorType newKernelType =
1065         RTTBuilder(kernelType).dropDim((removeH ? 0 : 1));
1066     RankedTensorType newOutputType =
1067         RTTBuilder(outputType).dropDim(removeH ? 1 : 2);
1068 
1069     // Rank-reduce operands.
1070     Location loc = convOp.getLoc();
1071     Value newInput = tensor::createCanonicalRankReducingExtractSliceOp(
1072         rewriter, loc, input, newInputType);
1073     Value newKernel = tensor::createCanonicalRankReducingExtractSliceOp(
1074         rewriter, loc, kernel, newKernelType);
1075     Value newOutput = tensor::createCanonicalRankReducingExtractSliceOp(
1076         rewriter, loc, output, newOutputType);
1077 
1078     // Rank-reduce strides and dilations too.
1079     // TODO: dropDim 1-liner helper.
1080     auto strides = llvm::to_vector<4>(convOp.strides().getValues<int64_t>());
1081     strides.erase(strides.begin() + (removeH ? 0 : 1));
1082     auto stridesAttr = rewriter.getI64VectorAttr(strides);
1083 
1084     auto dilations =
1085         llvm::to_vector<4>(convOp.dilations().getValues<int64_t>());
1086     dilations.erase(dilations.begin() + (removeH ? 0 : 1));
1087     auto dilationsAttr = rewriter.getI64VectorAttr(dilations);
1088 
1089     auto conv1DOp = rewriter.create<DepthwiseConv1DNwcWcOp>(
1090         loc, newOutputType, ValueRange{newInput, newKernel},
1091         ValueRange{newOutput}, stridesAttr, dilationsAttr);
1092 
1093     // Insert back.
1094     Value inserted = tensor::createCanonicalRankReducingInsertSliceOp(
1095         rewriter, loc, conv1DOp.getResult(0), output);
1096     rewriter.replaceOp(convOp, inserted);
1097 
1098     filter.replaceLinalgTransformationFilter(rewriter, conv1DOp);
1099     return success();
1100   };
1101 
1102 private:
1103   /// LinalgTransformMarker handles special attribute manipulations.
1104   LinalgTransformationFilter filter;
1105 };
1106 
1107 } // namespace
1108 
1109 void linalg::populateDecomposeConvolutionPatterns(
1110     RewritePatternSet &patterns, const LinalgTransformationFilter &filter,
1111     PatternBenefit benefit) {
1112   patterns.add<DownscaleSizeOneWindowed2DConvolution,
1113                DownscaleDepthwiseConv2DNhwcHwcOp>(patterns.getContext(), filter,
1114                                                   benefit);
1115 }
1116