| //===- Tiling.cpp - Implementation of tiling using TilingInterface -------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the tiling using TilingInterface. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "mlir/Dialect/SCF/Transforms/TileUsingInterface.h" |
| |
| #include "mlir/Dialect/Affine/IR/AffineOps.h" |
| #include "mlir/Dialect/Arith/IR/Arith.h" |
| #include "mlir/Dialect/Arith/Utils/Utils.h" |
| #include "mlir/Dialect/Func/IR/FuncOps.h" |
| #include "mlir/Dialect/SCF/Utils/Utils.h" |
| #include "mlir/Dialect/Tensor/IR/Tensor.h" |
| #include "mlir/Dialect/Utils/IndexingUtils.h" |
| #include "mlir/IR/Matchers.h" |
| #include "mlir/IR/PatternMatch.h" |
| #include "mlir/Interfaces/DestinationStyleOpInterface.h" |
| #include "mlir/Interfaces/TilingInterface.h" |
| #include "llvm/Support/Debug.h" |
| #include <optional> |
| |
| #define DEBUG_TYPE "tile-using-interface" |
| |
| using namespace mlir; |
| |
| scf::SCFTilingOptions & |
| scf::SCFTilingOptions::setTileSizes(ArrayRef<OpFoldResult> ts) { |
| assert(!tileSizeComputationFunction && "tile sizes already set"); |
| auto tileSizes = llvm::to_vector(ts); |
| tileSizeComputationFunction = [tileSizes](OpBuilder &b, Operation *op) { |
| return tileSizes; |
| }; |
| return *this; |
| } |
| |
| /// Helper method to adjust the interchange vector to match the iteration |
| /// domain. |
| static SmallVector<int64_t> |
| fillInterchangeVector(ArrayRef<int64_t> interchangeVector, |
| size_t iterationDomainSize) { |
| SmallVector<int64_t> filledVector = llvm::to_vector(interchangeVector); |
| if (filledVector.size() < iterationDomainSize) { |
| auto range = llvm::seq<int64_t>(filledVector.size(), iterationDomainSize); |
| filledVector.append(range.begin(), range.end()); |
| } |
| if (filledVector.size() > iterationDomainSize) |
| filledVector.resize(iterationDomainSize); |
| return filledVector; |
| } |
| |
| /// Convert a list of ops of type `SrcOpTy` to list of `Operation *`. |
| template <typename SrcOpTy> |
| static SmallVector<Operation *> getAsOperations(ArrayRef<SrcOpTy> ops) { |
| return llvm::to_vector( |
| llvm::map_range(ops, [](auto op) -> Operation * { return op; })); |
| } |
| template <typename SrcOpTy> |
| static SmallVector<Operation *> |
| getAsOperations(const SmallVector<SrcOpTy> &ops) { |
| return getAsOperations(ArrayRef<SrcOpTy>(ops)); |
| } |
| |
| /// Convert a list of `Operation *` to a list of `DstOpTy. |
| template <typename DstOpTy> |
| static SmallVector<DstOpTy> castToTypedOperations(ArrayRef<Operation *> ops) { |
| return llvm::to_vector( |
| llvm::map_range(ops, [](Operation *op) { return cast<DstOpTy>(op); })); |
| } |
| template <typename DstOpTy> |
| static SmallVector<DstOpTy> |
| castToTypedOperations(const SmallVector<Operation *> &ops) { |
| return castToTypedOperations<DstOpTy>(ArrayRef<Operation *>(ops)); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // tileUsingSCFForOp implementation. |
| //===----------------------------------------------------------------------===// |
| |
| // Check if `stride` evenly divides the trip count `size - offset`. |
| static bool tileDividesIterationDomain(Range loopRange) { |
| std::optional<int64_t> offsetAsInt = getConstantIntValue(loopRange.offset); |
| if (!offsetAsInt) |
| return false; |
| std::optional<int64_t> sizeAsInt = getConstantIntValue(loopRange.size); |
| if (!sizeAsInt) |
| return false; |
| std::optional<int64_t> strideAsInt = getConstantIntValue(loopRange.stride); |
| if (!strideAsInt) |
| return false; |
| return ((sizeAsInt.value() - offsetAsInt.value()) % strideAsInt.value() == 0); |
| } |
| |
| /// Returns the bounded tile size given the current `iv`, `loopRange` and |
| /// `tileSize`, i.e., `min(tileSize, range.end() - iv)`. |
| static OpFoldResult getBoundedTileSize(OpBuilder &b, Location loc, |
| Range loopRange, Value iv, |
| OpFoldResult tileSize) { |
| std::optional<int64_t> ts = getConstantIntValue(tileSize); |
| if (ts && ts.value() == 1) |
| return tileSize; |
| |
| if (tileDividesIterationDomain( |
| Range{loopRange.offset, loopRange.size, tileSize})) |
| return tileSize; |
| |
| // The tile size to use (to avoid out of bounds access) is minimum of |
| // `tileSize` and `ub - iv`, where `iv` is the induction variable of the tiled |
| // loop. |
| AffineExpr s0, s1, d0; |
| bindDims(b.getContext(), d0); |
| bindSymbols(b.getContext(), s0, s1); |
| AffineMap minMap = AffineMap::get(1, 2, {s0, s1 - d0}, b.getContext()); |
| Value size = getValueOrCreateConstantIndexOp(b, loc, loopRange.size); |
| return affine::makeComposedFoldedAffineMin( |
| b, loc, minMap, SmallVector<OpFoldResult>{iv, tileSize, size}); |
| } |
| |
| /// Clones the operation and updates the destination if the operation |
| /// implements the `DestinationStyleOpInterface`. |
| static Operation *cloneOpAndUpdateDestinationArgs(RewriterBase &rewriter, |
| Operation *op, |
| ValueRange newDestArgs) { |
| Operation *clonedOp = rewriter.clone(*op); |
| if (newDestArgs.empty()) |
| return clonedOp; |
| if (auto destinationStyleOp = dyn_cast<DestinationStyleOpInterface>(clonedOp)) |
| destinationStyleOp.getDpsInitsMutable().assign(newDestArgs); |
| return clonedOp; |
| } |
| |
| /// Generate an empty loop nest that represents the tiled loop nest shell. |
| /// - `loopRanges` specifies the lb, ub and step of the untiled iteration space. |
| /// - `tileSizes` is the tile sizes to use. Zero represent untiled loops. |
| /// - In `offsets` and `sizes` return the multi-dimensional offset and size of |
| /// the tile processed within the inner most loop. |
| /// Note that this methods adds `scf.yield` operation for all but the innermost |
| /// loop. These yield the value returned by the immediately inner loop. The |
| /// caller is expected to add the scf.yield operation for the innermost loop. |
| static SmallVector<scf::ForOp> generateTileLoopNest( |
| OpBuilder &builder, Location loc, ArrayRef<Range> loopRanges, |
| ArrayRef<OpFoldResult> tileSizes, SmallVector<OpFoldResult> &offsets, |
| SmallVector<OpFoldResult> &sizes, ValueRange destinationTensors = {}) { |
| if (loopRanges.empty()) |
| return {}; |
| assert(loopRanges.size() == tileSizes.size() && |
| "expected as many tile sizes as loop ranges"); |
| OpBuilder::InsertionGuard guard(builder); |
| SmallVector<scf::ForOp> loops; |
| offsets.resize(loopRanges.size()); |
| sizes.resize(loopRanges.size()); |
| |
| for (auto loopRange : llvm::enumerate(loopRanges)) { |
| Value offset = |
| getValueOrCreateConstantIndexOp(builder, loc, loopRange.value().offset); |
| Value size = |
| getValueOrCreateConstantIndexOp(builder, loc, loopRange.value().size); |
| Value tileSize = getValueOrCreateConstantIndexOp( |
| builder, loc, tileSizes[loopRange.index()]); |
| // No loops if tile size is zero. Set offset and size to the loop |
| // offset and size. |
| if (matchPattern(tileSize, m_Zero())) { |
| offsets[loopRange.index()] = offset; |
| sizes[loopRange.index()] = size; |
| continue; |
| } |
| |
| auto loop = builder.create<scf::ForOp>( |
| loc, offset, size, tileSize, destinationTensors, |
| [&](OpBuilder &bodyBuilder, Location bodyLoc, Value iv, |
| ValueRange /*iterArgs*/) { |
| sizes[loopRange.index()] = |
| getBoundedTileSize(bodyBuilder, bodyLoc, loopRange.value(), iv, |
| getAsOpFoldResult(tileSize)); |
| }); |
| offsets[loopRange.index()] = loop.getInductionVar(); |
| loops.push_back(loop); |
| builder.setInsertionPointToEnd(loop.getBody()); |
| destinationTensors = loop.getRegionIterArgs(); |
| } |
| |
| // Add the scf.yield operations for all the outer loops. |
| if (!loops.empty()) { |
| for (auto [outerLoop, innerLoop] : |
| llvm::zip_equal(MutableArrayRef(loops).drop_back(), |
| MutableArrayRef(loops).drop_front())) { |
| builder.setInsertionPointToEnd(outerLoop.getBody()); |
| builder.create<scf::YieldOp>(outerLoop.getLoc(), innerLoop.getResults()); |
| } |
| } |
| return loops; |
| } |
| |
| /// Method to add new init values to a loop nest. Updates `loops` in-place with |
| /// new loops that use the `newInitValues`. |
| /// The outer-loops are updated to yield the new result values of the inner |
| /// loop. For the innermost loop, the call back `getNewYields` is invoked to get |
| /// the additional values to yield form the innermost loop. |
| static void addInitOperandsToLoopNest( |
| RewriterBase &rewriter, MutableArrayRef<scf::ForOp> loops, |
| ValueRange newInitValues, |
| llvm::function_ref<SmallVector<Value>(RewriterBase &rewriter, Value iv, |
| ValueRange newRegionIterArgs)> |
| getNewYieldValsFn) { |
| SmallVector<scf::ForOp> newLoops; |
| if (loops.empty()) |
| return; |
| OpBuilder::InsertionGuard g(rewriter); |
| rewriter.setInsertionPoint(loops.front()); |
| for (auto &loop : loops) { |
| rewriter.setInsertionPoint(loop); |
| |
| // Create a new loop with the new init values for this loop. |
| SmallVector<Value> newInits = llvm::to_vector(loop.getInitArgs()); |
| newInits.append(newInitValues.begin(), newInitValues.end()); |
| auto newLoop = rewriter.create<scf::ForOp>( |
| loop.getLoc(), loop.getLowerBound(), loop.getUpperBound(), |
| loop.getStep(), newInits, |
| [&](OpBuilder &b, Location loc, Value iv, ValueRange iterArgs) {}); |
| |
| // Merge the body of the new loop with the body of the old loops. |
| SmallVector<Value> sourceBlockArgs; |
| sourceBlockArgs.push_back(newLoop.getInductionVar()); |
| auto newRegionIterArgs = newLoop.getRegionIterArgs(); |
| sourceBlockArgs.append( |
| newRegionIterArgs.begin(), |
| std::next(newRegionIterArgs.begin(), loop.getNumResults())); |
| rewriter.mergeBlocks(loop.getBody(), newLoop.getBody(), sourceBlockArgs); |
| rewriter.replaceOp(loop, |
| newLoop.getResults().take_front(loop.getNumResults())); |
| loop = newLoop; |
| newInitValues = newLoop.getRegionIterArgs().take_back(newInitValues.size()); |
| } |
| |
| // Update the loop body of the innermost loop to get new yield values. |
| scf::ForOp innerMostLoop = loops.back(); |
| auto innerMostYieldOp = |
| cast<scf::YieldOp>(innerMostLoop.getBody()->getTerminator()); |
| rewriter.setInsertionPoint(innerMostYieldOp); |
| SmallVector<Value> newYieldVals = |
| getNewYieldValsFn(rewriter, innerMostLoop.getInductionVar(), |
| innerMostLoop.getRegionIterArgs()); |
| SmallVector<Value> newYieldOperands = |
| llvm::to_vector(innerMostYieldOp->getOperands()); |
| newYieldOperands.append(newYieldVals); |
| rewriter.replaceOpWithNewOp<scf::YieldOp>(innerMostYieldOp, newYieldOperands); |
| |
| // Make all other loops except the innermost loops yield the values returned |
| // by the inner loop. |
| for (auto [outerLoop, innerLoop] : |
| llvm::zip_equal(loops.drop_back(), loops.drop_front())) { |
| auto outerLoopYield = |
| cast<scf::YieldOp>(outerLoop.getBody()->getTerminator()); |
| SmallVector<Value> newYields = |
| llvm::to_vector(outerLoopYield.getOperands()); |
| ValueRange additionalYields = |
| innerLoop.getResults().take_back(newInitValues.size()); |
| newYields.append(additionalYields.begin(), additionalYields.end()); |
| rewriter.setInsertionPoint(outerLoopYield); |
| rewriter.replaceOpWithNewOp<scf::YieldOp>(outerLoopYield, newYields); |
| } |
| } |
| |
| /// Implementation of tiling transformation of `op` that implements the |
| /// `TilingInterface` using `scf.for` to iterate over the tiles. |
| FailureOr<scf::SCFTilingResult> |
| mlir::scf::tileUsingSCFForOp(RewriterBase &rewriter, TilingInterface op, |
| const scf::SCFTilingOptions &options) { |
| OpBuilder::InsertionGuard guard(rewriter); |
| rewriter.setInsertionPointAfter(op); |
| |
| if (!options.tileSizeComputationFunction) { |
| return rewriter.notifyMatchFailure( |
| op, "missing tile size computation function"); |
| } |
| |
| // 1. Get the range of the loops that are represented by the operation. |
| SmallVector<Range> iterationDomain = op.getIterationDomain(rewriter); |
| size_t numLoops = iterationDomain.size(); |
| if (numLoops == 0) { |
| return rewriter.notifyMatchFailure( |
| op, "unable to tile op with no iteration domain"); |
| } |
| // 2. Materialize the tile sizes. Enforce the convention that "tiling by zero" |
| // skips tiling a particular dimension. This convention is significantly |
| // simpler to handle instead of adjusting affine maps to account for missing |
| // dimensions. |
| SmallVector<OpFoldResult> tileSizeVector = |
| options.tileSizeComputationFunction(rewriter, op); |
| if (tileSizeVector.size() < iterationDomain.size()) { |
| auto zero = rewriter.getIndexAttr(0); |
| tileSizeVector.append(numLoops - tileSizeVector.size(), zero); |
| } |
| |
| // 3. Find the destination tensors to use for the operation. |
| SmallVector<Value> destinationTensors; |
| if (failed(tensor::getOrCreateDestinations(rewriter, op.getLoc(), op, |
| destinationTensors))) { |
| return rewriter.notifyMatchFailure(op, |
| "unable to create destination tensors"); |
| } |
| |
| SmallVector<OpFoldResult> offsets, sizes; |
| SmallVector<scf::ForOp> forLoops; |
| { |
| // If there is an interchange specified, permute the iteration domain and |
| // the tile sizes. |
| SmallVector<int64_t> interchangeVector; |
| if (!options.interchangeVector.empty()) { |
| interchangeVector = fillInterchangeVector(options.interchangeVector, |
| iterationDomain.size()); |
| } |
| if (!interchangeVector.empty()) { |
| if (!isPermutationVector(interchangeVector)) { |
| return rewriter.notifyMatchFailure( |
| op, "invalid intechange vector, not a permutation of the entire " |
| "iteration space"); |
| } |
| |
| applyPermutationToVector(iterationDomain, interchangeVector); |
| applyPermutationToVector(tileSizeVector, interchangeVector); |
| } |
| |
| // 4. Materialize an empty loop nest that iterates over the tiles. These |
| // loops for now do not return any values even if the original operation has |
| // results. |
| forLoops = generateTileLoopNest(rewriter, op.getLoc(), iterationDomain, |
| tileSizeVector, offsets, sizes, |
| destinationTensors); |
| |
| if (!interchangeVector.empty()) { |
| auto inversePermutation = invertPermutationVector(interchangeVector); |
| applyPermutationToVector(offsets, inversePermutation); |
| applyPermutationToVector(sizes, inversePermutation); |
| } |
| } |
| |
| LLVM_DEBUG({ |
| if (!forLoops.empty()) { |
| llvm::dbgs() << "LoopNest shell :\n"; |
| forLoops.front().dump(); |
| llvm::dbgs() << "\n"; |
| } |
| }); |
| |
| // 5. Generate the tiled implementation within the inner most loop. |
| SmallVector<Value> clonedOpDestination = destinationTensors; |
| if (!forLoops.empty()) { |
| rewriter.setInsertionPointToEnd(forLoops.back().getBody()); |
| clonedOpDestination = |
| llvm::map_to_vector(forLoops.back().getRegionIterArgs(), |
| [](BlockArgument b) -> Value { return b; }); |
| } |
| |
| // 5a. Clone the operation within the loop body. |
| auto clonedOp = cast<TilingInterface>( |
| cloneOpAndUpdateDestinationArgs(rewriter, op, clonedOpDestination)); |
| |
| // 5b. Early return cloned op if tiling is not happening. We can not return |
| // the original op because it could lead to |
| // `rewriter.replaceOp(op, op->getResults())` and user would get crash. |
| if (llvm::all_of(tileSizeVector, isZeroIndex)) { |
| return scf::SCFTilingResult{/*tiledOps=*/{clonedOp}, /*loops=*/{}, |
| clonedOp->getResults()}; |
| } |
| |
| // 5c. Tile the cloned operation. |
| FailureOr<TilingResult> tiledImplementation = |
| clonedOp.getTiledImplementation(rewriter, offsets, sizes); |
| if (failed(tiledImplementation)) { |
| return rewriter.notifyMatchFailure(op, "failed to tile operation"); |
| } |
| |
| // 5d. Delete the cloned operation. |
| rewriter.eraseOp(clonedOp); |
| |
| // If loops are empty, the tiled op is used as the replacement for the untiled |
| // op. |
| if (forLoops.empty()) { |
| return scf::SCFTilingResult{tiledImplementation->tiledOps, |
| getAsOperations(forLoops), |
| tiledImplementation->tiledValues}; |
| } |
| |
| if (op->getNumResults() == 0) { |
| // The innermost loop does not have a `scf.yield` yet. There is nothing to |
| // return, so generate an empty `scf.yield` operation. |
| rewriter.setInsertionPointToEnd(forLoops.back().getBody()); |
| rewriter.create<scf::YieldOp>(op->getLoc()); |
| return scf::SCFTilingResult{ |
| tiledImplementation->tiledOps, getAsOperations(forLoops), {}}; |
| } |
| |
| // 6. Yield all the results of the tiled operation. |
| int64_t numResults = op->getNumResults(); |
| SmallVector<SmallVector<OpFoldResult>> resultOffsetsList(numResults), |
| resultSizesList(numResults); |
| SmallVector<Value> yieldedValues; |
| for (auto [index, tiledValue] : |
| llvm::enumerate(tiledImplementation->tiledValues)) { |
| SmallVector<OpFoldResult> resultOffsets, resultSizes; |
| if (failed(op.getResultTilePosition(rewriter, index, offsets, sizes, |
| resultOffsets, resultSizes))) { |
| return rewriter.notifyMatchFailure( |
| op, "failed to get slice of result produced"); |
| } |
| SmallVector<OpFoldResult> resultStrides(resultOffsets.size(), |
| rewriter.getIndexAttr(1)); |
| auto insertSlice = rewriter.create<tensor::InsertSliceOp>( |
| op->getLoc(), tiledValue, clonedOpDestination[index], resultOffsets, |
| resultSizes, resultStrides); |
| yieldedValues.push_back(insertSlice); |
| } |
| rewriter.create<scf::YieldOp>(op->getLoc(), yieldedValues); |
| |
| SmallVector<Value> replacements = llvm::map_to_vector( |
| forLoops.front().getResults(), [](OpResult r) -> Value { return r; }); |
| LLVM_DEBUG({ |
| if (!forLoops.empty()) { |
| llvm::dbgs() << "After tiled implementation :\n"; |
| forLoops.front().dump(); |
| llvm::dbgs() << "\n"; |
| } |
| }); |
| return scf::SCFTilingResult{tiledImplementation->tiledOps, |
| getAsOperations(forLoops), replacements}; |
| } |
| |
| FailureOr<scf::SCFReductionTilingResult> |
| mlir::scf::tileReductionUsingScf(RewriterBase &b, |
| PartialReductionOpInterface op, |
| ArrayRef<OpFoldResult> tileSizes) { |
| Location loc = op.getLoc(); |
| // Ops implementing PartialReductionOpInterface are expected to implement |
| // TilingInterface. |
| auto tilingInterfaceOp = cast<TilingInterface>(op.getOperation()); |
| SmallVector<Range> iterationDomain = tilingInterfaceOp.getIterationDomain(b); |
| auto tileSizesVector = llvm::to_vector(tileSizes); |
| if (tileSizesVector.size() < iterationDomain.size()) { |
| auto zero = b.getIndexAttr(0); |
| tileSizesVector.append(iterationDomain.size() - tileSizesVector.size(), |
| zero); |
| } |
| if (op->getNumResults() != 1) |
| return b.notifyMatchFailure( |
| op, "don't support ops with multiple results for now"); |
| SmallVector<utils::IteratorType> iterators = |
| tilingInterfaceOp.getLoopIteratorTypes(); |
| |
| SmallVector<int> reductionDims; |
| for (auto [idx, iteratorType] : |
| llvm::enumerate(tilingInterfaceOp.getLoopIteratorTypes())) { |
| if (iteratorType == utils::IteratorType::reduction) |
| reductionDims.push_back(idx); |
| } |
| |
| // 2. create the inital tensor value. |
| FailureOr<Operation *> identityTensor = |
| op.generateInitialTensorForPartialReduction(b, loc, tileSizesVector, |
| reductionDims); |
| if (failed(identityTensor)) |
| return b.notifyMatchFailure(op, |
| "cannot create a tensor of identity value."); |
| // 3. Create the nested loops. |
| SmallVector<OpFoldResult> offsets, sizes; |
| SmallVector<scf::ForOp> loops = |
| generateTileLoopNest(b, loc, iterationDomain, tileSizesVector, offsets, |
| sizes, identityTensor.value()->getResults()); |
| |
| // 4. Generate the tiled implementation within the inner most loop. |
| // 4a. Clone the operation within the loop body. |
| SmallVector<Value> clonedOpDestination = |
| llvm::map_to_vector(identityTensor.value()->getResults(), |
| [](OpResult res) -> Value { return res; }); |
| if (!loops.empty()) { |
| b.setInsertionPointToEnd(loops.back().getBody()); |
| clonedOpDestination = |
| llvm::map_to_vector(loops.back().getRegionIterArgs(), |
| [](BlockArgument b) -> Value { return b; }); |
| } |
| auto clonedOp = cast<PartialReductionOpInterface>( |
| cloneOpAndUpdateDestinationArgs(b, op, clonedOpDestination)); |
| |
| // 4b. Tile the cloned operation. |
| Operation *parallelOp = clonedOp.tileToPartialReduction( |
| b, loc, clonedOpDestination, offsets, sizes, reductionDims); |
| // 4c. Delete the cloned operation. |
| b.eraseOp(clonedOp); |
| |
| SmallVector<OpFoldResult> outSizes; |
| for (size_t i = 0; i < offsets.size(); i++) { |
| outSizes.push_back( |
| tensor::getMixedSize(b, loc, parallelOp->getResult(0), i)); |
| } |
| SmallVector<OpFoldResult> outOffsets(offsets.size(), b.getIndexAttr(0)); |
| SmallVector<OpFoldResult> outStrides(outOffsets.size(), b.getIndexAttr(1)); |
| SmallVector<Value> yieldedVals; |
| auto bbArgs = loops.back().getRegionIterArgs(); |
| for (auto [result, bbArg] : llvm::zip(parallelOp->getResults(), bbArgs)) { |
| Value insert = b.create<tensor::InsertSliceOp>( |
| loc, result, bbArg, outOffsets, outSizes, outStrides); |
| yieldedVals.push_back(insert); |
| } |
| b.create<scf::YieldOp>(loc, yieldedVals); |
| |
| SmallVector<Value> replacements = llvm::map_to_vector( |
| loops.front().getResults(), [](OpResult r) -> Value { return r; }); |
| |
| // 5. Apply the merge reduction to combine all the partial values. |
| b.setInsertionPointAfter(*loops.begin()); |
| Operation *mergeOp = op.mergeReductions(b, loc, replacements, reductionDims); |
| b.replaceOp(op, mergeOp->getResults()); |
| |
| SCFReductionTilingResult results; |
| results.initialOp = *identityTensor; |
| results.loops = std::move(loops); |
| results.parallelTiledOp = parallelOp; |
| results.mergeOp = mergeOp; |
| return results; |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // tileConsumerAndFuseProducerGreedilyUsingSCFForOp implementation. |
| //===----------------------------------------------------------------------===// |
| |
| /// Return the untiled producer whose slice is used in a tiled consumer. The |
| /// method traverses the tile loop nest (`loops`) if needed, and returns the |
| /// `iter_args` of the outer most that is encountered. Traversing the iter_args |
| /// indicates that this is a destination operand of the consumer. If there was |
| /// no loop traversal needed, the second value of the returned tuple is empty. |
| static std::tuple<OpResult, std::optional<OpOperand *>> |
| getUntiledProducerFromSliceSource(OpOperand *source, |
| ArrayRef<scf::ForOp> loops) { |
| std::optional<OpOperand *> destinationIterArg; |
| auto loopIt = loops.rbegin(); |
| while (auto iterArg = dyn_cast<BlockArgument>(source->get())) { |
| scf::ForOp loop = *loopIt; |
| if (iterArg.getOwner()->getParentOp() != loop) |
| break; |
| source = loop.getTiedLoopInit(iterArg); |
| loopIt++; |
| } |
| if (loopIt == loops.rend()) |
| destinationIterArg = source; |
| return {dyn_cast<OpResult>(source->get()), destinationIterArg}; |
| } |
| |
| /// Implementation of fusing producer of a single slice by computing the |
| /// slice of the producer in-place. |
| std::optional<scf::SCFFuseProducerOfSliceResult> |
| mlir::scf::tileAndFuseProducerOfSlice(RewriterBase &rewriter, |
| tensor::ExtractSliceOp candidateSliceOp, |
| MutableArrayRef<scf::ForOp> loops) { |
| // 1. Get the producer of the source (potentially walking through |
| // `iter_args` of nested `scf.for`) |
| auto [fusableProducer, destinationInitArg] = |
| getUntiledProducerFromSliceSource(&candidateSliceOp.getSourceMutable(), |
| loops); |
| if (!fusableProducer) |
| return std::nullopt; |
| unsigned resultNumber = fusableProducer.getResultNumber(); |
| |
| OpBuilder::InsertionGuard g(rewriter); |
| rewriter.setInsertionPoint(candidateSliceOp); |
| |
| // 2. Clone the fused producer |
| // 2a. Compute the destination operands to use for the cloned operation. |
| SmallVector<Value> origDestinationTensors, clonedOpDestinationTensors; |
| Operation *fusableProducerOp = fusableProducer.getOwner(); |
| if (isa<DestinationStyleOpInterface>(fusableProducerOp) && |
| failed(tensor::getOrCreateDestinations( |
| rewriter, fusableProducerOp->getLoc(), fusableProducerOp, |
| origDestinationTensors))) |
| return std::nullopt; |
| |
| clonedOpDestinationTensors = origDestinationTensors; |
| if (destinationInitArg && |
| isa<DestinationStyleOpInterface>(fusableProducerOp)) { |
| // 2b. If the producer is also destination style, then to maintain the |
| // destination passing style, update the destination of the producer to be |
| // the source of the slice. |
| clonedOpDestinationTensors[resultNumber] = candidateSliceOp.getSource(); |
| } |
| // 2c. Clone the fused producer. |
| Operation *clonedProducerOp = cloneOpAndUpdateDestinationArgs( |
| rewriter, fusableProducerOp, clonedOpDestinationTensors); |
| // 2d. Update the source of the candidateSlice to be the cloned producer. |
| // Easier to just clone the slice with different source since replacements |
| // and DCE of cloned ops becomes easier |
| SmallVector<Value> candidateSliceOpOperands = |
| llvm::to_vector(candidateSliceOp->getOperands()); |
| candidateSliceOpOperands[0] = clonedProducerOp->getResult(resultNumber); |
| tensor::ExtractSliceOp clonedCandidateSliceOp = |
| mlir::clone(rewriter, candidateSliceOp, |
| candidateSliceOp->getResultTypes(), candidateSliceOpOperands); |
| |
| // 3. Generate the tiled implementation of the producer of the source |
| FailureOr<TilingResult> tileAndFuseResult = |
| tensor::replaceExtractSliceWithTiledProducer( |
| rewriter, clonedCandidateSliceOp, |
| clonedProducerOp->getResult(resultNumber)); |
| if (failed(tileAndFuseResult)) |
| return std::nullopt; |
| // Note: Do not delete the candidateSliceOp, since its passed in from the |
| // caller. |
| rewriter.replaceAllUsesWith(candidateSliceOp, |
| tileAndFuseResult->tiledValues[0]); |
| rewriter.eraseOp(clonedCandidateSliceOp); |
| rewriter.eraseOp(clonedProducerOp); |
| |
| // 3. If the slice is for a destination operand, for example, |
| // |
| // ```mlir |
| // %0 = linalg.init |
| // %1 = linalg.fill .. outs(%0 : ) |
| // %2 = scf.for .. iter_args(%arg0 = %1) { |
| // %3 = scf.for .. iter_args(%arg1 = %arg0) { |
| // %4 = tensor.extract_slice %arg1 [..] |
| // .. = linalg.matmul .. outs(%4 : ) |
| // } |
| // } |
| // ``` |
| // |
| // the IR is currently |
| // |
| // ``` |
| // %0 = linalg.init |
| // %1 = linalg.fill |
| // %2 = scf.for .. iter_args(%arg0 = %1 /* incorrect value */ ) { |
| // %3 = scf.for .. iter_args(%arg1 = %arg0) { |
| // %4 = tensor.extract_slice %arg1[..] |
| // %5 = linalg.fill .. outs(%4 : ) |
| // .. = linalg.matmul .. outs(%5 : ) |
| // } |
| // } |
| // ``` |
| // |
| // The untiled `linalg.fill` is still used as the `init_value` since it |
| // was originally a destination operand of the untiled `linalg.matmul`. |
| // When fusing an operand that is a destination operand, the iter_arg of |
| // the outer most loop should be changed to use the destination of the |
| // fused operation. With this the IR will be. |
| // |
| // ``` |
| // %0 = linalg.init |
| // %1 = scf.for .. iter_args(%arg0 = %0 /* corrected value */ ) { |
| // %2 = scf.for .. iter_args(%arg1 = %arg0) { |
| // %3 = tensor.extract_slice %arg1[..] |
| // %4 = linalg.fill .. outs(%3 : ) |
| // .. = linalg.matmul .. outs(%4 : ) |
| // } |
| // } |
| // ``` |
| if (destinationInitArg && |
| isa<DestinationStyleOpInterface>(fusableProducerOp) && !loops.empty()) { |
| loops.front() |
| ->getOpOperands()[destinationInitArg.value()->getOperandNumber()] |
| .set(origDestinationTensors[resultNumber]); |
| } |
| return scf::SCFFuseProducerOfSliceResult{fusableProducer, |
| tileAndFuseResult->tiledValues[0], |
| tileAndFuseResult->tiledOps}; |
| } |
| |
| /// Reconstruct the fused producer from within the tiled-and-fused code. |
| void mlir::scf::yieldReplacementForFusedProducer( |
| RewriterBase &rewriter, tensor::ExtractSliceOp sliceOp, |
| scf::SCFFuseProducerOfSliceResult fusedProducerInfo, |
| MutableArrayRef<scf::ForOp> loops) { |
| if (loops.empty()) |
| return; |
| |
| OpResult fusableProducer = fusedProducerInfo.origProducer; |
| Value tiledAndFusedProducer = fusedProducerInfo.tiledAndFusedProducer; |
| FailureOr<Value> initValue = tensor::getOrCreateDestination( |
| rewriter, fusableProducer.getOwner()->getLoc(), fusableProducer); |
| if (succeeded(initValue)) { |
| |
| auto newYieldValuesFn = |
| [&](RewriterBase &innerRewriter, Value iv, |
| ValueRange newRegionIterArgs) -> SmallVector<Value> { |
| OpBuilder::InsertionGuard g(innerRewriter); |
| if (auto tiledDestStyleOp = |
| tiledAndFusedProducer |
| .getDefiningOp<DestinationStyleOpInterface>()) { |
| rewriter.setInsertionPoint(tiledDestStyleOp); |
| BlockArgument newRegionArg = loops.back().getRegionIterArgs().back(); |
| auto destSlice = rewriter.create<tensor::ExtractSliceOp>( |
| sliceOp.getLoc(), newRegionArg, sliceOp.getMixedOffsets(), |
| sliceOp.getMixedSizes(), sliceOp.getMixedStrides()); |
| unsigned resultNumber = fusableProducer.getResultNumber(); |
| rewriter.updateRootInPlace(tiledDestStyleOp, [&]() { |
| tiledDestStyleOp.getDpsInitsMutable()[resultNumber].set(destSlice); |
| }); |
| } |
| Block *block = rewriter.getInsertionPoint()->getBlock(); |
| rewriter.setInsertionPoint(block->getTerminator()); |
| Value replacement = rewriter.create<tensor::InsertSliceOp>( |
| fusedProducerInfo.origProducer.getLoc(), |
| fusedProducerInfo.tiledAndFusedProducer, |
| loops.back().getRegionIterArgs().back(), sliceOp.getMixedOffsets(), |
| sliceOp.getMixedSizes(), sliceOp.getMixedStrides()); |
| return {replacement}; |
| }; |
| |
| addInitOperandsToLoopNest(rewriter, loops, |
| SmallVector<Value>{initValue.value()}, |
| newYieldValuesFn); |
| } |
| } |
| |
| /// Implementation of tile consumer and fuse producer greedily. |
| FailureOr<scf::SCFTileAndFuseResult> |
| mlir::scf::tileConsumerAndFuseProducerGreedilyUsingSCFForOp( |
| RewriterBase &rewriter, TilingInterface consumer, |
| const scf::SCFTileAndFuseOptions &options) { |
| // This transformation is only valid for ops that return values (i.e. not |
| // valid to use with operations that have memref operands). |
| if (!consumer->getNumResults()) { |
| return rewriter.notifyMatchFailure( |
| consumer, "invalid pattern for op with no results"); |
| } |
| |
| // 1. First tile the consumer. |
| SmallVector<scf::ForOp> forLoops; |
| SetVector<Operation *> fusedProducers, tiledAndFusedOps; |
| DenseMap<Value, Value> replacements; |
| llvm::SmallDenseMap<Value, int64_t> yieldedValueToResultNumber; |
| { |
| FailureOr<scf::SCFTilingResult> tilingResult = |
| tileUsingSCFForOp(rewriter, consumer, options.tilingOptions); |
| if (failed(tilingResult)) |
| return rewriter.notifyMatchFailure(consumer, "failed to tile consumer"); |
| for (auto *tiledOp : tilingResult->tiledOps) |
| tiledAndFusedOps.insert(tiledOp); |
| forLoops = castToTypedOperations<scf::ForOp>(tilingResult->loops); |
| for (auto [index, origValue, replacement] : |
| llvm::enumerate(consumer->getResults(), tilingResult->replacements)) { |
| replacements[origValue] = replacement; |
| yieldedValueToResultNumber[tilingResult->tiledOps.back()->getResult( |
| index)] = index; |
| } |
| } |
| |
| // If there are no loops generated, fusion is immaterial. |
| if (forLoops.empty()) { |
| return scf::SCFTileAndFuseResult{fusedProducers, tiledAndFusedOps, |
| getAsOperations(forLoops), replacements}; |
| } |
| |
| // 2. Typically, the operands of the tiled operation are slices of the |
| // operands of the untiled operation. These are expressed in IR using |
| // `tensor.extract_slice` operations with source being the operands of the |
| // untiled operation. Create a worklist of these `tensor.extract_slice` |
| // operations. If the producers of the source of the `tensor.extract_slice` |
| // can be tiled such that the tiled value is generated in-place, that |
| // effectively tiles + fuses the operations. |
| auto addCandidateSlices = [](Operation *fusedOp, |
| std::deque<tensor::ExtractSliceOp> &candidates) { |
| for (Value operand : fusedOp->getOperands()) |
| if (auto sliceOp = operand.getDefiningOp<tensor::ExtractSliceOp>()) |
| candidates.push_back(sliceOp); |
| }; |
| |
| std::deque<tensor::ExtractSliceOp> candidates; |
| addCandidateSlices(tiledAndFusedOps.back(), candidates); |
| OpBuilder::InsertionGuard g(rewriter); |
| while (!candidates.empty()) { |
| // Traverse the slices in BFS fashion. |
| tensor::ExtractSliceOp candidateSliceOp = candidates.front(); |
| candidates.pop_front(); |
| |
| // The operands of the fused producer might themselved be slices of |
| // values produced by operations that implement the `TilingInterface`. |
| // Add these operations to the worklist. |
| std::optional<scf::SCFFuseProducerOfSliceResult> fusedResult = |
| tileAndFuseProducerOfSlice(rewriter, candidateSliceOp, forLoops); |
| if (!fusedResult) |
| continue; |
| |
| if (Operation *tiledAndFusedOp = |
| fusedResult->tiledAndFusedProducer.getDefiningOp()) { |
| fusedProducers.insert(fusedResult->origProducer.getDefiningOp()); |
| tiledAndFusedOps.insert(tiledAndFusedOp); |
| addCandidateSlices(tiledAndFusedOp, candidates); |
| } |
| } |
| return scf::SCFTileAndFuseResult{fusedProducers, tiledAndFusedOps, |
| getAsOperations(forLoops), replacements}; |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // tileUsingSCFForAllOp implementation. |
| //===----------------------------------------------------------------------===// |
| |
| FailureOr<scf::SCFTilingResult> |
| mlir::scf::tileUsingSCFForallOp(RewriterBase &rewriter, TilingInterface op, |
| const scf::SCFTilingOptions &options) { |
| Location loc = op->getLoc(); |
| OpBuilder::InsertionGuard g(rewriter); |
| |
| // 1. Get the range of loops that are represented by the operation. |
| SmallVector<Range> loopRanges = op.getIterationDomain(rewriter); |
| if (loopRanges.empty()) |
| return op->emitOpError("expected non-empty loop ranges"); |
| auto hasStrideOne = [](Range r) { return !isConstantIntValue(r.stride, 1); }; |
| if (llvm::any_of(loopRanges, hasStrideOne)) |
| return op->emitOpError("only stride-1 supported atm"); |
| |
| // 2. Get the tile sizes. If tile size is 0, it is not tiled and distributed. |
| // To make it easier, pad the tile sizes to loopRanges.size with value 0. |
| SmallVector<OpFoldResult> tileSizeVector = |
| options.tileSizeComputationFunction(rewriter, op); |
| tileSizeVector.resize(loopRanges.size(), rewriter.getIndexAttr(0)); |
| |
| // 3. Build the offsets, sizes and steps for the tile and distributed loops. |
| SmallVector<OpFoldResult> lbs, ubs, steps; |
| for (auto [tileSize, loopRange] : llvm::zip(tileSizeVector, loopRanges)) { |
| if (isConstantIntValue(tileSize, 0)) |
| continue; |
| lbs.push_back(loopRange.offset); |
| ubs.push_back(loopRange.size); |
| steps.push_back(tileSize); |
| } |
| |
| // 4. Gather destination tensors. |
| SmallVector<Value> dest; |
| if (failed(tensor::getOrCreateDestinations(rewriter, loc, op, dest))) |
| return op->emitOpError("failed to get destination tensors"); |
| |
| // 5. Build the device mapping attribute. |
| std::optional<ArrayAttr> mappingAttr; |
| if (!options.mappingVector.empty()) { |
| mappingAttr = rewriter.getArrayAttr(ArrayRef(options.mappingVector)); |
| } |
| |
| // 6. Create the ForallOp. We don't use the lambda body-builder |
| // version because we require the use of RewriterBase in the body, so we |
| // manually move the insertion point to the body below. |
| auto forallOp = |
| rewriter.create<scf::ForallOp>(loc, lbs, ubs, steps, dest, mappingAttr); |
| |
| // 7. Get the tile offset and sizes. |
| rewriter.setInsertionPoint(forallOp.getTerminator()); |
| SmallVector<OpFoldResult> tiledOffsets, tiledSizes; |
| ValueRange ivs = forallOp.getInductionVars(); |
| { |
| int materializedLoopNum = 0; |
| for (auto [tileSize, loopRange] : llvm::zip(tileSizeVector, loopRanges)) { |
| if (isConstantIntValue(tileSize, 0)) { |
| tiledOffsets.push_back(loopRange.offset); |
| tiledSizes.push_back(loopRange.size); |
| continue; |
| } |
| Value iv = ivs[materializedLoopNum++]; |
| tiledOffsets.push_back(iv); |
| tiledSizes.push_back( |
| getBoundedTileSize(rewriter, loc, loopRange, iv, tileSize)); |
| } |
| } |
| |
| // 8. Tile the operation. Clone the operation to allow fix up of destination |
| // operands. |
| ArrayRef<BlockArgument> destBbArgs = forallOp.getOutputBlockArguments(); |
| Operation *clonedOp = |
| cloneOpAndUpdateDestinationArgs(rewriter, op, destBbArgs); |
| FailureOr<TilingResult> tilingResult = |
| cast<TilingInterface>(clonedOp).getTiledImplementation( |
| rewriter, tiledOffsets, tiledSizes); |
| if (failed(tilingResult)) |
| return clonedOp->emitError("failed to tile op: "); |
| rewriter.eraseOp(clonedOp); |
| |
| // 9. Parallel insert back into the result tensor. |
| for (auto [index, tiledValue, destBBArg] : |
| llvm::enumerate(tilingResult->tiledValues, destBbArgs)) { |
| // 9.a. Partial subset information is inserted just before the terminator. |
| rewriter.setInsertionPoint(forallOp.getTerminator()); |
| |
| SmallVector<OpFoldResult> resultOffsets, resultSizes; |
| if (failed(op.getResultTilePosition(rewriter, index, tiledOffsets, |
| tiledSizes, resultOffsets, |
| resultSizes))) { |
| return op->emitOpError("output offsets couldn't be calculated"); |
| } |
| |
| SmallVector<OpFoldResult> strides(resultSizes.size(), |
| rewriter.getIndexAttr(1)); |
| // 9.b. Parallel insertions are inserted at the end of the combining |
| // terminator. |
| rewriter.setInsertionPointToEnd(forallOp.getTerminator().getBody()); |
| rewriter.create<tensor::ParallelInsertSliceOp>( |
| loc, tiledValue, destBBArg, resultOffsets, resultSizes, strides); |
| } |
| |
| // 10. Return the tiling result. |
| return scf::SCFTilingResult{ |
| tilingResult->tiledOps, |
| {forallOp.getOperation()}, |
| llvm::map_to_vector(forallOp.getResults(), |
| [](auto val) -> Value { return val; })}; |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // lowerToLoopsUsingSCFForOp implementation. |
| //===----------------------------------------------------------------------===// |
| |
| FailureOr<SmallVector<scf::ForOp>> |
| mlir::scf::lowerToLoopsUsingSCFForOp(RewriterBase &rewriter, |
| TilingInterface op) { |
| // TODO: Handle cases where the op has results if needed. |
| if (op->getNumResults() > 0) { |
| return rewriter.notifyMatchFailure( |
| op, "unable to lower to loops operations with return values"); |
| } |
| |
| SmallVector<Range> domain = op.getIterationDomain(rewriter); |
| SmallVector<Value> ivs; |
| SmallVector<scf::ForOp> loops; |
| Location loc = op.getLoc(); |
| for (auto loopRange : domain) { |
| Value offsetVal = |
| getValueOrCreateConstantIndexOp(rewriter, loc, loopRange.offset); |
| Value sizeVal = |
| getValueOrCreateConstantIndexOp(rewriter, loc, loopRange.size); |
| Value strideVal = |
| getValueOrCreateConstantIndexOp(rewriter, loc, loopRange.stride); |
| auto loop = rewriter.create<scf::ForOp>(op.getLoc(), offsetVal, sizeVal, |
| strideVal, ValueRange{}); |
| loops.push_back(loop); |
| ivs.push_back(loop.getInductionVar()); |
| rewriter.setInsertionPoint(loop.getBody()->getTerminator()); |
| } |
| if (failed(op.generateScalarImplementation(rewriter, op.getLoc(), ivs))) { |
| return failure(); |
| } |
| return loops; |
| } |
