1 //===- Transforms.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/Arithmetic/IR/Arithmetic.h"
16 #include "mlir/Dialect/Linalg/Analysis/DependenceAnalysis.h"
17 #include "mlir/Dialect/Linalg/IR/Linalg.h"
18 #include "mlir/Dialect/Linalg/Transforms/HoistPadding.h"
19 #include "mlir/Dialect/Linalg/Utils/Utils.h"
20 #include "mlir/Dialect/SCF/Transforms.h"
21 #include "mlir/Dialect/Tensor/IR/Tensor.h"
22 #include "mlir/Dialect/Tensor/IR/TensorTilingInterfaceImpl.h"
23 #include "mlir/Dialect/Utils/StaticValueUtils.h"
24 #include "mlir/Dialect/Utils/StructuredOpsUtils.h"
25 #include "mlir/Dialect/Vector/IR/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 tensor::PadOp
164 /// or and return success if the operand either has been padded to a static
165 /// shape 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::SmallBitVector 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.test(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 /// Try to peel a loop `op` and return the new result.
288 // TODO: Add support for scf.parallel and affine.for loops.
289 static SmallVector<Value, 4> peelLoop(RewriterBase &rewriter, Operation *op) {
290   return llvm::TypeSwitch<Operation *, SmallVector<Value, 4>>(op)
291       .Case<scf::ForOp>([&](scf::ForOp forOp) {
292         scf::ForOp partialIteration;
293         if (succeeded(scf::peelAndCanonicalizeForLoop(rewriter, forOp,
294                                                       partialIteration)))
295           return partialIteration->getResults();
296         assert(!partialIteration && "expected that loop was not peeled");
297         return forOp->getResults();
298       })
299       .Default([&](Operation *op) { return op->getResults(); });
300 }
301 
302 /// Peel loops after tiling.
303 void mlir::linalg::peelTiledLinalgOp(RewriterBase &rewriter, TiledLinalgOp &res,
304                                      ArrayRef<int64_t> peeledLoops,
305                                      LinalgTilingLoopType loopType) {
306   for (int64_t loop : peeledLoops) {
307     assert(loop < static_cast<int64_t>(res.loops.size()) &&
308            "requested peeling of non-existing loop");
309     SmallVector<Value, 4> loopResults;
310     Operation *loopOp = res.loops[loop];
311     loopResults = peelLoop(rewriter, loopOp);
312 
313     // The result of the loop nest may change with peeling.
314     if (res.tensorResults.size() == loopOp->getNumResults() &&
315         std::equal(res.tensorResults.begin(), res.tensorResults.end(),
316                    loopOp->getResults().begin()))
317       res.tensorResults = loopResults;
318   }
319 }
320 
321 static ValueRange getTiledOpResult(TiledLinalgOp tiledOp) {
322   if (tiledOp.loops.empty())
323     return tiledOp.op.getOperation()->getResults();
324   return tiledOp.loops.front()->getResults();
325 }
326 
327 static ValueRange
328 getTiledAndFusedOpResult(TiledAndFusedLinalgOps tiledAndFusedOp) {
329   if (tiledAndFusedOp.fusedLoops.empty())
330     return tiledAndFusedOp.op.getOperation()->getResults();
331   return tiledAndFusedOp.fusedLoops.front()->getResults();
332 }
333 
334 mlir::linalg::LinalgBaseTileAndFusePattern::LinalgBaseTileAndFusePattern(
335     StringRef opName, MLIRContext *context,
336     const LinalgDependenceGraph &dependenceGraph,
337     LinalgTilingOptions tilingOptions, LinalgFusionOptions fusionOptions,
338     LinalgTransformationFilter f, LinalgTransformationFilter fusedOpMarker,
339     LinalgTransformationFilter originalOpMarker, PatternBenefit benefit)
340     : RewritePattern(opName, benefit, context, {}),
341       dependenceGraph(dependenceGraph), tilingOptions(std::move(tilingOptions)),
342       fusionOptions(std::move(fusionOptions)), filter(std::move(f)),
343       fusedOpMarker(std::move(fusedOpMarker)),
344       originalOpMarker(std::move(originalOpMarker)) {}
345 
346 LogicalResult mlir::linalg::LinalgBaseTileAndFusePattern::matchAndRewrite(
347     Operation *op, PatternRewriter &rewriter) const {
348   LinalgOp linalgOp = dyn_cast<LinalgOp>(op);
349   // TODO: remove hasIndexSemantics check once index ops are supported.
350   if (!linalgOp || linalgOp.hasIndexSemantics())
351     return failure();
352   if (failed(filter.checkAndNotify(rewriter, linalgOp)))
353     return failure();
354 
355   DenseSet<Operation *> producers;
356   producers.insert(linalgOp);
357   for (auto dependence : dependenceGraph.getDependentOperationsInto(linalgOp)) {
358     Optional<unsigned> operandNumber = dependence.getIndexingOpViewOperandNum();
359     // When looking at dependences into, indexingOp is always OpOperand. We
360     // could assert, but continue if this is not the case.
361     if (!operandNumber)
362       continue;
363     if (!fusionOptions.indicesToFuse.count(operandNumber.getValue()))
364       continue;
365     if (isa<LinalgOp>(dependence.getDependentOp()))
366       producers.insert(dependence.getDependentOp());
367   }
368 
369   SmallVector<LinalgOp, 1> fusionOps;
370   for (auto it = op->getBlock()->begin(), ie = Block::iterator(op); it != ie;
371        ++it) {
372     auto producerLinalgOp = dyn_cast<LinalgOp>(&(*it));
373     if (producerLinalgOp && producers.count(producerLinalgOp))
374       fusionOps.push_back(producerLinalgOp);
375   }
376   fusionOps.push_back(linalgOp);
377 
378   SmallVector<Value, 4> tileSizes =
379       tilingOptions.tileSizeComputationFunction(rewriter, op);
380   LinalgTilingOptions instanceTilingOptions = tilingOptions;
381   instanceTilingOptions.setTileSizes(tileSizes);
382   Optional<TiledAndFusedLinalgOps> tiledAndFusedOps = tileAndFuseLinalgOps(
383       rewriter, fusionOps, dependenceGraph, instanceTilingOptions);
384   if (!tiledAndFusedOps)
385     return failure();
386 
387   // Tile the unfused loops;
388   SmallVector<Value, 4> unfusedLoopTileSizes;
389   Value zero = rewriter.create<arith::ConstantIndexOp>(op->getLoc(), 0);
390   for (const auto &tileSize : enumerate(tileSizes)) {
391     if (tiledAndFusedOps->fusedLoopDims.count(tileSize.index()))
392       unfusedLoopTileSizes.push_back(zero);
393     else
394       unfusedLoopTileSizes.push_back(tileSize.value());
395   }
396   // Tile the loop only if there is a non-zero tile size.
397   if (unfusedLoopTileSizes.size() > linalgOp.getNumLoops())
398     unfusedLoopTileSizes.resize(linalgOp.getNumLoops());
399   if (llvm::any_of(unfusedLoopTileSizes, [](Value val) {
400         if (auto cst = val.getDefiningOp<arith::ConstantIndexOp>())
401           return cst.value() != 0;
402         return true;
403       })) {
404     LinalgTilingOptions unfusedTilingOptions = tilingOptions;
405     unfusedTilingOptions.setTileSizes(unfusedLoopTileSizes);
406     FailureOr<TiledLinalgOp> unfusedTiledOp =
407         tileLinalgOp(rewriter, tiledAndFusedOps->op, unfusedTilingOptions);
408     if (failed(unfusedTiledOp))
409       return failure();
410     rewriter.replaceOp(tiledAndFusedOps->op,
411                        getTiledOpResult(unfusedTiledOp.getValue()));
412     tiledAndFusedOps->op = unfusedTiledOp->op;
413   }
414   op->replaceAllUsesWith(getTiledAndFusedOpResult(tiledAndFusedOps.getValue()));
415 
416   filter.replaceLinalgTransformationFilter(rewriter,
417                                            tiledAndFusedOps->op.getOperation());
418   for (auto fusedOp : tiledAndFusedOps->fusedProducers) {
419     fusedOpMarker.replaceLinalgTransformationFilter(rewriter,
420                                                     fusedOp.getOperation());
421   }
422   for (auto origProducerOp : ArrayRef<LinalgOp>(fusionOps).drop_back()) {
423     originalOpMarker.replaceLinalgTransformationFilter(
424         rewriter, origProducerOp.getOperation());
425   }
426   rewriter.updateRootInPlace(op, [&]() {
427     originalOpMarker.replaceLinalgTransformationFilter(rewriter, op);
428   });
429   return success();
430 }
431 
432 /// Linalg tiling pattern.
433 mlir::linalg::LinalgTilingPattern::LinalgTilingPattern(
434     MLIRContext *context, LinalgTilingOptions options,
435     LinalgTransformationFilter f, PatternBenefit benefit)
436     : OpInterfaceRewritePattern<LinalgOp>(context, benefit),
437       filter(std::move(f)), options(std::move(options)) {}
438 
439 mlir::linalg::LinalgTilingPattern::LinalgTilingPattern(
440     StringRef opName, MLIRContext *context, LinalgTilingOptions options,
441     LinalgTransformationFilter f, PatternBenefit benefit)
442     : OpInterfaceRewritePattern<LinalgOp>(context, benefit),
443       filter(f.addOpNameFilter(opName)), options(std::move(options)) {}
444 
445 FailureOr<TiledLinalgOp>
446 mlir::linalg::LinalgTilingPattern::returningMatchAndRewrite(
447     LinalgOp op, PatternRewriter &rewriter) const {
448   if (failed(filter.checkAndNotify(rewriter, op)))
449     return failure();
450 
451   FailureOr<TiledLinalgOp> res = tileLinalgOp(rewriter, op, options);
452   if (failed(res))
453     return failure();
454 
455   // Clear filter to stop recursive pattern application.
456   // This must be done here to properly propagate to peeling branches.
457   filter.replaceLinalgTransformationFilter(rewriter, res->op);
458 
459   // Peel the loops of the TiledLinalgOp.
460   peelTiledLinalgOp(rewriter, *res, options.peeledLoops, options.loopType);
461 
462   if (res->tensorResults.empty())
463     rewriter.eraseOp(op);
464   else
465     rewriter.replaceOp(op, res->tensorResults);
466 
467   return res;
468 }
469 
470 /// Linalg padding pattern.
471 mlir::linalg::LinalgPaddingPattern::LinalgPaddingPattern(
472     MLIRContext *context, LinalgPaddingOptions options,
473     LinalgTransformationFilter f, PatternBenefit benefit)
474     : OpInterfaceRewritePattern<LinalgOp>(context, benefit),
475       filter(std::move(f)), options(std::move(options)) {}
476 
477 mlir::linalg::LinalgPaddingPattern::LinalgPaddingPattern(
478     StringRef opName, MLIRContext *context, LinalgPaddingOptions options,
479     LinalgTransformationFilter f, PatternBenefit benefit)
480     : OpInterfaceRewritePattern<LinalgOp>(context, benefit),
481       filter(f.addOpNameFilter(opName)), options(std::move(options)) {}
482 
483 FailureOr<LinalgOp>
484 mlir::linalg::LinalgPaddingPattern::returningMatchAndRewrite(
485     LinalgOp linalgOp, PatternRewriter &rewriter) const {
486   if (!linalgOp.hasTensorSemantics())
487     return failure();
488   if (failed(filter.checkAndNotify(rewriter, linalgOp)))
489     return failure();
490 
491   // Pad the operation.
492   LinalgOp paddedOp;
493   FailureOr<SmallVector<Value>> newResults = rewriteAsPaddedOp(
494       rewriter, linalgOp, options.paddingValueComputationFunction,
495       options.paddingNoFoldComputationFunction, paddedOp);
496   if (failed(newResults))
497     return failure();
498 
499   // Compute the desired hoisting depths.
500   SmallVector<int64_t> depths;
501   if (options.paddingHoistComputationFunction) {
502     for (OpOperand *opOperand : linalgOp.getInputAndOutputOperands())
503       depths.push_back(options.paddingHoistComputationFunction(*opOperand));
504   }
505 
506   // Hoist the padding.
507   for (const auto &en : enumerate(depths)) {
508     OpOperand &opOperand = paddedOp->getOpOperand(en.index());
509     auto padOp = opOperand.get().getDefiningOp<tensor::PadOp>();
510     if (!padOp || en.value() == 0)
511       continue;
512     tensor::PadOp hoistedOp;
513     SmallVector<GenericOp> transposeOps;
514     SmallVector<int64_t> transposeVector =
515         options.paddingTransposeComputationFunction(opOperand);
516 
517     FailureOr<Value> newResult = hoistPaddingOnTensors(
518         padOp, en.value(), transposeVector, hoistedOp, transposeOps);
519     if (failed(newResult))
520       continue;
521     rewriter.replaceOp(padOp, newResult.getValue());
522 
523     // Do not apply hoist padding to the newly introduced transpose operations.
524     for (GenericOp transposeOp : transposeOps)
525       filter.replaceLinalgTransformationFilter(rewriter, transposeOp);
526   }
527 
528   // Replace the original operation to pad.
529   rewriter.replaceOp(linalgOp, newResults.getValue());
530   filter.replaceLinalgTransformationFilter(rewriter, paddedOp);
531 
532   return paddedOp;
533 }
534 
535 /// Linalg tile and fuse tensor ops pattern.
536 mlir::linalg::LinalgTileAndFuseTensorOpsPattern::
537     LinalgTileAndFuseTensorOpsPattern(MLIRContext *context,
538                                       LinalgTilingAndFusionOptions options,
539                                       LinalgTransformationFilter f,
540                                       PatternBenefit benefit)
541     : RewritePattern(MatchAnyOpTypeTag(), benefit, context),
542       filter(std::move(f)), options(std::move(options)) {}
543 
544 mlir::linalg::LinalgTileAndFuseTensorOpsPattern::
545     LinalgTileAndFuseTensorOpsPattern(StringRef opName, MLIRContext *context,
546                                       LinalgTilingAndFusionOptions options,
547                                       LinalgTransformationFilter f,
548                                       PatternBenefit benefit)
549     : RewritePattern(opName, benefit, context), filter(std::move(f)),
550       options(std::move(options)) {}
551 
552 LogicalResult mlir::linalg::LinalgTileAndFuseTensorOpsPattern::matchAndRewrite(
553     Operation *op, PatternRewriter &rewriter) const {
554   LinalgOp rootOp = dyn_cast<LinalgOp>(op);
555   if (!rootOp)
556     return failure();
557   if (failed(filter.checkAndNotify(rewriter, op)))
558     return failure();
559 
560   // Check `tileSizes` contains a tile size for every `rootOp` loop dimension.
561   if (options.tileSizes.size() < rootOp.getNumLoops())
562     return rewriter.notifyMatchFailure(op, "expect #tile sizes >= #loops");
563 
564   // Check `tileInterchange` contains no entries or as many as `tileSizes`.
565   if (!options.tileInterchange.empty() &&
566       options.tileInterchange.size() != options.tileSizes.size())
567     return rewriter.notifyMatchFailure(
568         op, "expect the number of tile sizes and interchange dims to match");
569 
570   // Copy the `tileSizes` and `tileInterchange` prefixes needed for `rootOp`.
571   SmallVector<int64_t> rootTileSizes(options.tileSizes.begin(),
572                                      options.tileSizes.begin() +
573                                          rootOp.getNumLoops());
574   SmallVector<int64_t> rootInterchange =
575       options.tileInterchange.empty()
576           ? llvm::to_vector<6>(llvm::seq<int64_t>(0, rootOp.getNumLoops()))
577           : SmallVector<int64_t>(options.tileInterchange.begin(),
578                                  options.tileInterchange.begin() +
579                                      rootOp.getNumLoops());
580 
581   // Check `rootTileSizes` contains non-zero tile sizes.
582   if (llvm::count(rootTileSizes, 0) == static_cast<long>(rootTileSizes.size()))
583     return rewriter.notifyMatchFailure(
584         op, "expect at least one non-zero tile size");
585 
586   // Check `rootInterchange` is a permutation of the `rootOp` loop dimensions.
587   // It has to be a permutation since the tiling cannot tile the same loop
588   // dimension multiple times.
589   if (!isPermutation(rootInterchange))
590     return rewriter.notifyMatchFailure(
591         op, "expect the tile interchange permutes the root loops");
592 
593   // Tile `rootOp` and fuse its producers.
594   FailureOr<TileLoopNest> tileLoopNest =
595       tileConsumerAndFuseProducers(rewriter, rootOp, rootTileSizes,
596                                    rootInterchange, options.tileDistribution);
597   if (failed(tileLoopNest))
598     return rewriter.notifyMatchFailure(
599         op, "tileConsumerAndFuseProducers failed unexpectedly");
600 
601   // Replace all uses of the tiled loop operation.
602   rootOp->replaceAllUsesWith(tileLoopNest->getRootOpReplacementResults());
603 
604   // Apply the filter if specified.
605   for (LinalgOp linalgOp : tileLoopNest->getAllTiledAndFusedOps())
606     filter.replaceLinalgTransformationFilter(rewriter, linalgOp);
607   return success();
608 }
609 
610 /// Linalg generic interchange pattern.
611 mlir::linalg::GenericOpInterchangePattern::GenericOpInterchangePattern(
612     MLIRContext *context, ArrayRef<unsigned> interchangeVector,
613     LinalgTransformationFilter f, PatternBenefit benefit)
614     : OpRewritePattern(context, benefit), filter(std::move(f)),
615       interchangeVector(interchangeVector.begin(), interchangeVector.end()) {}
616 
617 FailureOr<GenericOp>
618 mlir::linalg::GenericOpInterchangePattern::returningMatchAndRewrite(
619     GenericOp genericOp, PatternRewriter &rewriter) const {
620   if (failed(filter.checkAndNotify(rewriter, genericOp)))
621     return failure();
622 
623   FailureOr<GenericOp> transformedOp =
624       interchangeGenericOp(rewriter, genericOp, interchangeVector);
625   if (failed(transformedOp))
626     return failure();
627 
628   // New filter if specified.
629   filter.replaceLinalgTransformationFilter(rewriter, genericOp);
630   return transformedOp;
631 }
632 
633 /// Linalg generalization pattern.
634 mlir::linalg::LinalgGeneralizationPattern::LinalgGeneralizationPattern(
635     MLIRContext *context, LinalgTransformationFilter f, PatternBenefit benefit)
636     : OpInterfaceRewritePattern<LinalgOp>(context, benefit),
637       filter(std::move(f)) {}
638 
639 mlir::linalg::LinalgGeneralizationPattern::LinalgGeneralizationPattern(
640     StringRef opName, MLIRContext *context, LinalgTransformationFilter f,
641     PatternBenefit benefit)
642     : OpInterfaceRewritePattern<LinalgOp>(context, benefit),
643       filter(f.addOpNameFilter(opName)) {}
644 
645 FailureOr<GenericOp>
646 mlir::linalg::LinalgGeneralizationPattern::returningMatchAndRewrite(
647     LinalgOp linalgOp, PatternRewriter &rewriter) const {
648   if (failed(filter.checkAndNotify(rewriter, linalgOp)))
649     return failure();
650   FailureOr<GenericOp> genericOp = generalizeNamedOp(rewriter, linalgOp);
651   if (failed(genericOp))
652     return failure();
653   filter.replaceLinalgTransformationFilter(rewriter, *genericOp);
654   return genericOp;
655 }
656 
657 mlir::linalg::LinalgBasePromotionPattern::LinalgBasePromotionPattern(
658     MLIRContext *context, LinalgTransformationFilter f,
659     LinalgPromotionOptions options, PatternBenefit benefit)
660     : RewritePattern(MatchAnyOpTypeTag(), benefit, context),
661       filter(std::move(f)), options(std::move(options)) {}
662 
663 mlir::linalg::LinalgBasePromotionPattern::LinalgBasePromotionPattern(
664     StringRef opName, MLIRContext *context, LinalgPromotionOptions options,
665     LinalgTransformationFilter f, PatternBenefit benefit)
666     : RewritePattern(opName, benefit, context, {}), filter(std::move(f)),
667       options(std::move(options)) {}
668 
669 LogicalResult mlir::linalg::LinalgBasePromotionPattern::matchAndRewrite(
670     Operation *op, PatternRewriter &rewriter) const {
671   if (failed(filter.checkAndNotify(rewriter, op)))
672     return failure();
673   if (failed(promoteSubviewsPrecondition(op, options)))
674     return failure();
675 
676   // TODO: We cannot use root update here. This pattern is creating other ops,
677   // so if the promotion fails, those need to be cleaned up, which doesnt seem
678   // to be happening here. So to fail properly, we should be cloning the op and
679   // deleting the previous op. This needs more investigation.
680   rewriter.startRootUpdate(op);
681   Optional<LinalgOp> promotedOp = promoteSubViews(rewriter, op, options);
682   if (!promotedOp) {
683     rewriter.cancelRootUpdate(op);
684     return op->emitError("subview promotion failed");
685   }
686   rewriter.finalizeRootUpdate(op);
687   filter.replaceLinalgTransformationFilter(rewriter, op);
688   return success();
689 }
690 
691 mlir::linalg::LinalgVectorizationPattern::LinalgVectorizationPattern(
692     MLIRContext *context, LinalgTransformationFilter f,
693     LinalgVectorizationOptions options, PatternBenefit benefit)
694     : OpInterfaceRewritePattern<LinalgOp>(context, benefit),
695       filter(std::move(f)) {}
696 
697 mlir::linalg::LinalgVectorizationPattern::LinalgVectorizationPattern(
698     StringRef opName, MLIRContext *context, LinalgVectorizationOptions options,
699     LinalgTransformationFilter f, PatternBenefit benefit)
700     : OpInterfaceRewritePattern<LinalgOp>(context, benefit),
701       filter(f.addOpNameFilter(opName)) {}
702 
703 LogicalResult mlir::linalg::LinalgVectorizationPattern::matchAndRewrite(
704     LinalgOp linalgOp, PatternRewriter &rewriter) const {
705   if (failed(filter.checkAndNotify(rewriter, linalgOp)))
706     return failure();
707   return vectorize(rewriter, linalgOp);
708 }
709 
710 LogicalResult mlir::linalg::CopyVectorizationPattern::matchAndRewrite(
711     memref::CopyOp copyOp, PatternRewriter &rewriter) const {
712   return vectorizeCopy(rewriter, copyOp);
713 }
714 
715 LogicalResult mlir::linalg::applyStagedPatterns(
716     Operation *op, ArrayRef<FrozenRewritePatternSet> stage1Patterns,
717     const FrozenRewritePatternSet &stage2Patterns,
718     function_ref<LogicalResult(Operation *)> stage3Lambda) {
719   unsigned iteration = 0;
720   (void)iteration;
721   for (const auto &patterns : stage1Patterns) {
722     LLVM_DEBUG(DBGS() << "Before 1st stage, iter: " << ++iteration << "\n"
723                       << *op);
724     if (failed(applyPatternsAndFoldGreedily(op, patterns))) {
725       LLVM_DEBUG(DBGS() << "Underlying first stage rewrite did not converge");
726       return failure();
727     }
728     LLVM_DEBUG(DBGS() << "After 1st stage, iter: " << ++iteration << "\n"
729                       << *op);
730     if (failed(applyPatternsAndFoldGreedily(op, stage2Patterns))) {
731       LLVM_DEBUG(DBGS() << "Underlying 2nd stage rewrite did not converge");
732       return failure();
733     }
734     LLVM_DEBUG(DBGS() << "After 2nd stage, iter : " << iteration << "\n"
735                       << *op);
736     if (stage3Lambda) {
737       if (failed(stage3Lambda(op)))
738         return failure();
739       LLVM_DEBUG(DBGS() << "After 3rd stage, iter : " << iteration << "\n"
740                         << *op);
741     }
742   }
743   return success();
744 }
745 
746 static SmallVector<StringRef> getNParallelLoopsAttrs(unsigned nParallelLoops) {
747   return SmallVector<StringRef>(nParallelLoops, getParallelIteratorTypeName());
748 }
749 
750 /// Rewrite a tensor::PadOp into a sequence of InitTensorOp, FillOp (to
751 /// initialize with pad_val) and GenericOp (to copy contents).
752 LogicalResult
753 PadOpTransformationPattern::matchAndRewrite(tensor::PadOp padOp,
754                                             PatternRewriter &rewriter) const {
755 
756   auto inputShapedType = padOp.source().getType().cast<ShapedType>();
757   auto resultShapedType = padOp.result().getType().cast<ShapedType>();
758 
759   // Bail on non-static shapes.
760   if (!inputShapedType.hasStaticShape())
761     return failure();
762   if (!resultShapedType.hasStaticShape())
763     return failure();
764 
765   // Only support padding with a constant for now, i.e. either:
766   //   1. A BBarg from a different block.
767   //   2. A value defined outside of the current block.
768   Block &block = padOp.region().front();
769   auto yieldOp = cast<tensor::YieldOp>(block.getTerminator());
770   Value padValue = yieldOp.value();
771   Operation *definingOp = padValue.getDefiningOp();
772   if (definingOp && definingOp->getBlock() == &block)
773     return failure();
774   if (!definingOp && padValue.cast<BlockArgument>().getOwner() == &block)
775     return failure();
776 
777   // Create tensor with the padded shape
778   Location loc = padOp.getLoc();
779   SmallVector<Value> indices(resultShapedType.getRank(),
780                              rewriter.create<arith::ConstantIndexOp>(loc, 0));
781   Value initTensor = rewriter.create<InitTensorOp>(
782       loc, resultShapedType.getShape(), resultShapedType.getElementType());
783 
784   // Initialize tensor with the pad value
785   Value tmpTensor =
786       rewriter.create<linalg::FillOp>(loc, padValue, initTensor).result();
787 
788   // Copy original contents into new tensor
789   // Uses linalg.generic, but could be done with tensor.insert_slice
790   SmallVector<AffineExpr, 4> outputExprs;
791   for (unsigned i = 0; i < resultShapedType.getRank(); ++i) {
792     outputExprs.push_back(getAffineDimExpr(i, rewriter.getContext()) +
793                           padOp.static_low()[i].cast<IntegerAttr>().getInt());
794   }
795 
796   SmallVector<AffineMap, 2> transferMaps = {
797       rewriter.getMultiDimIdentityMap(inputShapedType.getRank()),
798       AffineMap::get(resultShapedType.getRank(),
799                      /*symbolCount=*/0, outputExprs, rewriter.getContext())};
800 
801   rewriter.replaceOpWithNewOp<linalg::GenericOp>(
802       padOp, resultShapedType, padOp.source(), tmpTensor, transferMaps,
803       getNParallelLoopsAttrs(resultShapedType.getRank()),
804       [&](OpBuilder &nestedBuilder, Location nestedLoc, ValueRange args) {
805         nestedBuilder.create<linalg::YieldOp>(nestedLoc, args[0]);
806       });
807 
808   return success();
809 }
810 
811 /// Filling `dest` using FillOp constant padding value if possible.
812 /// Otherwise, generate a tensor::GenerateOp.
813 Value GeneralizePadOpPattern::createFillOrGenerateOp(
814     PatternRewriter &rewriter, tensor::PadOp padOp, Value dest,
815     const SmallVector<Value> &dynSizes) const {
816   auto padValue = padOp.getConstantPaddingValue();
817   if (padValue)
818     return rewriter.create<FillOp>(padOp.getLoc(), padValue, dest).result();
819 
820   // Fill could not be optimized: Lower to tensor::GenerateOp with region.
821   auto generateOp = rewriter.create<tensor::GenerateOp>(
822       padOp.getLoc(), padOp.getResultType(), dynSizes);
823   // Copy region to new op.
824   BlockAndValueMapping bvm;
825   padOp.region().cloneInto(&generateOp.getRegion(), bvm);
826   return generateOp;
827 }
828 
829 LogicalResult
830 GeneralizePadOpPattern::matchAndRewrite(tensor::PadOp padOp,
831                                         PatternRewriter &rewriter) const {
832   // Given an OpFoldResult, return an index-typed value.
833   auto getIdxValue = [&](OpFoldResult ofr) {
834     if (auto val = ofr.dyn_cast<Value>())
835       return val;
836     return rewriter
837         .create<arith::ConstantIndexOp>(
838             padOp.getLoc(), ofr.get<Attribute>().cast<IntegerAttr>().getInt())
839         .getResult();
840   };
841 
842   auto resultType = padOp.getResultType();
843   // Compute size of InitTensorOp. Any combination of static/dynamic is
844   // supported.
845   SmallVector<Value> dynSizes;
846   SmallVector<int64_t> staticSizes;
847   for (unsigned dim = 0; dim < resultType.getRank(); ++dim) {
848     if (resultType.isDynamicDim(dim)) {
849       auto srcSize = rewriter.createOrFold<tensor::DimOp>(padOp.getLoc(),
850                                                           padOp.source(), dim);
851       // Add low and high padding value.
852       auto plusLow = rewriter.createOrFold<arith::AddIOp>(
853           padOp.getLoc(), srcSize, getIdxValue(padOp.getMixedLowPad()[dim]));
854       auto plusHigh = rewriter.createOrFold<arith::AddIOp>(
855           padOp.getLoc(), plusLow, getIdxValue(padOp.getMixedHighPad()[dim]));
856       dynSizes.push_back(plusHigh);
857     }
858     staticSizes.push_back(resultType.getDimSize(dim));
859   }
860 
861   // Init tensor and fill it with padding.
862   Value init = rewriter.create<InitTensorOp>(
863       padOp.getLoc(), dynSizes, staticSizes, resultType.getElementType());
864   Value fill = createFillOrGenerateOp(rewriter, padOp, init, dynSizes);
865 
866   // Try optimize the copy of source.
867   if (optimizeCopyFn && optimizeCopyFn(rewriter, padOp, fill).succeeded())
868     return success();
869 
870   // tensor::PadOps cannot be optimized. Generate a InsertSliceOp instead
871   // for copying the PadOp source.
872   auto sourceType = padOp.getSourceType();
873   // Compute size of source of tensor::PadOp.
874   SmallVector<OpFoldResult> srcSizes;
875   for (unsigned dim = 0; dim < sourceType.getRank(); ++dim) {
876     if (sourceType.isDynamicDim(dim)) {
877       srcSizes.push_back(rewriter.createOrFold<tensor::DimOp>(
878           padOp.getLoc(), padOp.source(), dim));
879     } else {
880       srcSizes.push_back(rewriter.getIndexAttr(sourceType.getDimSize(dim)));
881     }
882   }
883   // Strides of InsertSliceOp are all 1.
884   SmallVector<OpFoldResult> strides(sourceType.getRank(),
885                                     rewriter.getIndexAttr(1));
886   rewriter.replaceOpWithNewOp<tensor::InsertSliceOp>(
887       padOp, padOp.source(), fill, padOp.getMixedLowPad(), srcSizes, strides);
888 
889   return success();
890 }
891 
892 LogicalResult ExtractSliceOfPadTensorSwapPattern::matchAndRewrite(
893     tensor::ExtractSliceOp sliceOp, PatternRewriter &rewriter) const {
894   if (!sliceOp.hasUnitStride())
895     return failure();
896 
897   auto padOp = sliceOp.source().getDefiningOp<tensor::PadOp>();
898   if (!padOp)
899     return failure();
900 
901   bool zeroSliceGuard = true;
902   if (controlFn) {
903     if (Optional<bool> control = controlFn(sliceOp))
904       zeroSliceGuard = control.getValue();
905     else
906       return failure();
907   }
908 
909   Operation *tiledPadOp =
910       tensor::bubbleUpPadSlice(rewriter, padOp, sliceOp.getMixedOffsets(),
911                                sliceOp.getMixedSizes(), zeroSliceGuard);
912   // All shapes are static and the data source is actually used. Rewrite into
913   // pad(extract_slice(x)).
914   rewriter.replaceOp(sliceOp, tiledPadOp->getResults());
915   return success();
916 }
917 
918 namespace {
919 // The following are patterns for downscaling convolution ops with size-1
920 // window dimensions.
921 //
922 // Note that we'd eventually want to write such transformations in a generic
923 // way, e.g., converting to linalg.generic, removing the size-1 dimensions,
924 // and then turning back to named ops. But for now it's fine to have a few
925 // patterns matching special ops to get started.
926 
927 /// Rewrites 2-D convolution ops with size-1 window dimensions into 1-D
928 /// convolution ops.
929 struct DownscaleSizeOneWindowed2DConvolution final
930     : public OpRewritePattern<Conv2DNhwcHwcfOp> {
931   DownscaleSizeOneWindowed2DConvolution(
932       MLIRContext *context,
933       LinalgTransformationFilter f = LinalgTransformationFilter(),
934       PatternBenefit benefit = 1)
935       : OpRewritePattern<Conv2DNhwcHwcfOp>(context, benefit),
936         filter(std::move(f)) {}
937 
938   LogicalResult matchAndRewrite(linalg::Conv2DNhwcHwcfOp convOp,
939                                 PatternRewriter &rewriter) const override {
940     if (failed(filter.checkAndNotify(rewriter, convOp)))
941       return failure();
942     if (convOp.hasBufferSemantics())
943       return failure(); // To be implemented
944 
945     Value input = convOp.inputs().front();
946     Value kernel = convOp.inputs().back();
947     Value output = convOp.outputs().front();
948 
949     auto inputType = input.getType().dyn_cast<RankedTensorType>();
950     auto kernelType = kernel.getType().dyn_cast<RankedTensorType>();
951     auto outputType = output.getType().dyn_cast<RankedTensorType>();
952 
953     auto kernelShape = kernelType.getShape();
954     auto outputShape = outputType.getShape();
955 
956     // Only handle the case where at least one of the window dimensions is
957     // of size 1. Other cases can rely on tiling to reduce to such cases.
958     int64_t khSize = kernelShape[0], kwSize = kernelShape[1];
959     int64_t ohSize = outputShape[1], owSize = outputShape[2];
960     bool removeH = (khSize == 1 && ohSize == 1);
961     bool removeW = (kwSize == 1 && owSize == 1);
962     if (!removeH && !removeW)
963       return failure();
964 
965     // Get new shapes and types for all operands by removing the size-1
966     // dimension.
967     using RTTBuilder = RankedTensorType::Builder;
968     RankedTensorType newInputType =
969         RTTBuilder(inputType).dropDim((removeH ? 1 : 2));
970     RankedTensorType newKernelType =
971         RTTBuilder(kernelType).dropDim((removeH ? 0 : 1));
972     RankedTensorType newOutputType =
973         RTTBuilder(outputType).dropDim(removeH ? 1 : 2);
974 
975     // Rank-reduce operands.
976     Location loc = convOp.getLoc();
977     Value newInput = tensor::createCanonicalRankReducingExtractSliceOp(
978         rewriter, loc, input, newInputType);
979     Value newKernel = tensor::createCanonicalRankReducingExtractSliceOp(
980         rewriter, loc, kernel, newKernelType);
981     Value newOutput = tensor::createCanonicalRankReducingExtractSliceOp(
982         rewriter, loc, output, newOutputType);
983 
984     // Rank-reduce strides and dilations too.
985     // TODO: dropDim 1-liner helper.
986     auto strides = llvm::to_vector<4>(convOp.strides().getValues<int64_t>());
987     strides.erase(strides.begin() + (removeH ? 0 : 1));
988     auto stridesAttr = rewriter.getI64VectorAttr(strides);
989 
990     auto dilations =
991         llvm::to_vector<4>(convOp.dilations().getValues<int64_t>());
992     dilations.erase(dilations.begin() + (removeH ? 0 : 1));
993     auto dilationsAttr = rewriter.getI64VectorAttr(dilations);
994 
995     auto conv1DOp = rewriter.create<linalg::Conv1DNwcWcfOp>(
996         loc, newOutputType, ValueRange{newInput, newKernel},
997         ValueRange{newOutput}, stridesAttr, dilationsAttr);
998 
999     // Insert back.
1000     Value inserted = tensor::createCanonicalRankReducingInsertSliceOp(
1001         rewriter, loc, conv1DOp.getResult(0), output);
1002     rewriter.replaceOp(convOp, inserted);
1003 
1004     filter.replaceLinalgTransformationFilter(rewriter, conv1DOp);
1005     return success();
1006   };
1007 
1008 private:
1009   /// LinalgTransformMarker handles special attribute manipulations.
1010   LinalgTransformationFilter filter;
1011 };
1012 
1013 /// Rewrites 2-D depthwise convolution ops with size-1 (w, kw) or (h, kh)
1014 /// dimensions into 1-D depthwise convolution ops.
1015 struct DownscaleDepthwiseConv2DNhwcHwcOp final
1016     : public OpRewritePattern<DepthwiseConv2DNhwcHwcOp> {
1017   DownscaleDepthwiseConv2DNhwcHwcOp(
1018       MLIRContext *context,
1019       LinalgTransformationFilter f = LinalgTransformationFilter(),
1020       PatternBenefit benefit = 1)
1021       : OpRewritePattern<DepthwiseConv2DNhwcHwcOp>(context, benefit),
1022         filter(std::move(f)) {}
1023 
1024   LogicalResult matchAndRewrite(DepthwiseConv2DNhwcHwcOp convOp,
1025                                 PatternRewriter &rewriter) const override {
1026     if (failed(filter.checkAndNotify(rewriter, convOp)))
1027       return failure();
1028     if (convOp.hasBufferSemantics())
1029       return failure(); // To be implemented
1030 
1031     Value input = convOp.inputs().front();
1032     Value kernel = convOp.inputs().back();
1033     Value output = convOp.outputs().front();
1034 
1035     auto inputType = input.getType().dyn_cast<RankedTensorType>();
1036     auto kernelType = kernel.getType().dyn_cast<RankedTensorType>();
1037     auto outputType = output.getType().dyn_cast<RankedTensorType>();
1038 
1039     auto kernelShape = kernelType.getShape();
1040     auto outputShape = outputType.getShape();
1041 
1042     // Only handle the case where at least one of the window dimensions is
1043     // of size 1. Other cases can rely on tiling to reduce to such cases.
1044     int64_t khSize = kernelShape[0], kwSize = kernelShape[1];
1045     int64_t ohSize = outputShape[1], owSize = outputShape[2];
1046     bool removeH = (khSize == 1 && ohSize == 1);
1047     bool removeW = (kwSize == 1 && owSize == 1);
1048     if (!removeH && !removeW)
1049       return failure();
1050 
1051     // Get new shapes and types for all operands by removing the size-1
1052     // dimension.
1053     using RTTBuilder = RankedTensorType::Builder;
1054     RankedTensorType newInputType =
1055         RTTBuilder(inputType).dropDim((removeH ? 1 : 2));
1056     RankedTensorType newKernelType =
1057         RTTBuilder(kernelType).dropDim((removeH ? 0 : 1));
1058     RankedTensorType newOutputType =
1059         RTTBuilder(outputType).dropDim(removeH ? 1 : 2);
1060 
1061     // Rank-reduce operands.
1062     Location loc = convOp.getLoc();
1063     Value newInput = tensor::createCanonicalRankReducingExtractSliceOp(
1064         rewriter, loc, input, newInputType);
1065     Value newKernel = tensor::createCanonicalRankReducingExtractSliceOp(
1066         rewriter, loc, kernel, newKernelType);
1067     Value newOutput = tensor::createCanonicalRankReducingExtractSliceOp(
1068         rewriter, loc, output, newOutputType);
1069 
1070     // Rank-reduce strides and dilations too.
1071     // TODO: dropDim 1-liner helper.
1072     auto strides = llvm::to_vector<4>(convOp.strides().getValues<int64_t>());
1073     strides.erase(strides.begin() + (removeH ? 0 : 1));
1074     auto stridesAttr = rewriter.getI64VectorAttr(strides);
1075 
1076     auto dilations =
1077         llvm::to_vector<4>(convOp.dilations().getValues<int64_t>());
1078     dilations.erase(dilations.begin() + (removeH ? 0 : 1));
1079     auto dilationsAttr = rewriter.getI64VectorAttr(dilations);
1080 
1081     auto conv1DOp = rewriter.create<DepthwiseConv1DNwcWcOp>(
1082         loc, newOutputType, ValueRange{newInput, newKernel},
1083         ValueRange{newOutput}, stridesAttr, dilationsAttr);
1084 
1085     // Insert back.
1086     Value inserted = tensor::createCanonicalRankReducingInsertSliceOp(
1087         rewriter, loc, conv1DOp.getResult(0), output);
1088     rewriter.replaceOp(convOp, inserted);
1089 
1090     filter.replaceLinalgTransformationFilter(rewriter, conv1DOp);
1091     return success();
1092   };
1093 
1094 private:
1095   /// LinalgTransformMarker handles special attribute manipulations.
1096   LinalgTransformationFilter filter;
1097 };
1098 
1099 } // namespace
1100 
1101 void linalg::populateDecomposeConvolutionPatterns(
1102     RewritePatternSet &patterns, const LinalgTransformationFilter &filter,
1103     PatternBenefit benefit) {
1104   patterns.add<DownscaleSizeOneWindowed2DConvolution,
1105                DownscaleDepthwiseConv2DNhwcHwcOp>(patterns.getContext(), filter,
1106                                                   benefit);
1107 }
1108