llvm-project/mlir/lib/Dialect/Linalg/Transforms/TilingInterfaceImpl.cpp
zhicong zhong eec9d0b681
[mlir][Linalg] use linalg.reduce to simplify the mergeReductions in partialReductionInterface (#94579)
The current implementation of `mergeReduction` in
`LinalgOpPartialReductionInterface` builds a `linalg.generic` from
scratch. While we already have `linalg.reduce` op which has the same
semantic as this generic op, this PR replaces the generic op with
`linalg.reduce` to simplify the implementation.
2024-06-28 08:50:18 +08:00

503 lines
21 KiB
C++

//===- TilingInterfaceImpl.cpp - Implementation of 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
//
//===----------------------------------------------------------------------===//
#include "mlir/Dialect/Linalg/Transforms/TilingInterfaceImpl.h"
#include "mlir/Analysis/SliceAnalysis.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/Linalg/IR/Linalg.h"
#include "mlir/Dialect/Linalg/Utils/Utils.h"
#include "mlir/Dialect/MemRef/IR/MemRef.h"
#include "mlir/Dialect/Tensor/IR/Tensor.h"
#include "mlir/Dialect/Utils/StaticValueUtils.h"
#include "mlir/Interfaces/TilingInterface.h"
#include <optional>
using namespace mlir;
using namespace mlir::linalg;
//===----------------------------------------------------------------------===//
// Utility methods for implementation of Tiling Interface for Linalg ops
//===----------------------------------------------------------------------===//
/// Return the SSA values that represent the data point accessed using a given
/// `indexingMap` for a given point in the iteration space represented by `ivs`.
static SmallVector<Value> getIndicesForAccess(OpBuilder &b, Location loc,
AffineMap indexingMap,
ValueRange ivs) {
SmallVector<Value> indices;
indices.reserve(indexingMap.getNumResults());
for (auto result : indexingMap.getResults()) {
AffineMap m = AffineMap::get(indexingMap.getNumDims(),
indexingMap.getNumSymbols(), result);
Value v = b.create<affine::AffineApplyOp>(loc, m, ivs);
indices.push_back(v);
}
return indices;
}
/// Method to inline the payload of a `linalgOp` given the iteration space
/// point and values for the arguments of the payload.
static LogicalResult inlinePayload(OpBuilder &b, LinalgOp linalgOp,
ValueRange ivs, ValueRange argValues) {
Block *body = linalgOp.getBlock();
IRMapping map;
map.map(body->getArguments(), argValues);
for (auto &op : body->without_terminator()) {
if (auto indexOp = dyn_cast<IndexOp>(&op)) {
map.map(indexOp.getResult(), ivs[indexOp.getDim()]);
continue;
}
b.clone(op, map);
}
Operation *terminator = body->getTerminator();
Location loc = terminator->getLoc();
for (const auto &operand : llvm::enumerate(terminator->getOperands())) {
Value toStore = map.lookupOrDefault(operand.value());
OpOperand *storeInto = linalgOp.getDpsInitOperand(operand.index());
auto indices = getIndicesForAccess(
b, loc, linalgOp.getMatchingIndexingMap(storeInto), ivs);
b.create<memref::StoreOp>(
loc, toStore, linalgOp.getDpsInitOperand(operand.index())->get(),
indices);
}
return success();
}
//===----------------------------------------------------------------------===//
// External Model for implementing `TilingInterface` for `LinalgOp`s.
//===----------------------------------------------------------------------===//
namespace {
/// External model implementation of TilingInterface for LinalgOps. An external
/// model implementation is used for now till the use of `TilingInterface` is
/// on-par with the current Linalg tiling + fusion patterns. Once it is
/// maybe possible to move this into the op-definition (though there are
/// advantages to leaving it as an external model)
template <typename LinalgOpTy>
struct LinalgOpTilingInterface
: public TilingInterface::ExternalModel<LinalgOpTilingInterface<LinalgOpTy>,
LinalgOpTy> {
/// Return the loop iterator type.
SmallVector<utils::IteratorType> getLoopIteratorTypes(Operation *op) const {
LinalgOpTy concreteOp = cast<LinalgOpTy>(op);
return concreteOp.getIteratorTypesArray();
}
/// Return the iteration domain range.
SmallVector<Range> getIterationDomain(Operation *op, OpBuilder &b) const {
OpBuilder::InsertionGuard g(b);
b.setInsertionPoint(op);
Location loc = op->getLoc();
LinalgOp linalgOp = cast<LinalgOp>(op);
SmallVector<OpFoldResult> allShapesSizes =
linalgOp.createFlatListOfOperandDims(b, loc);
AffineMap map = linalgOp.getShapesToLoopsMap();
return llvm::to_vector(
llvm::map_range(map.getResults(), [&](AffineExpr loopExpr) {
OpFoldResult ofr = affine::makeComposedFoldedAffineApply(
b, loc, loopExpr, allShapesSizes);
return Range{b.getIndexAttr(0), ofr, b.getIndexAttr(1)};
}));
}
/// Instantiate the tiled implementation of the operation.
FailureOr<TilingResult>
getTiledImplementation(Operation *op, OpBuilder &b,
ArrayRef<OpFoldResult> offsets,
ArrayRef<OpFoldResult> sizes) const {
// Leave the `sizeBounds` value empty. That is only needed when the `sizes`
// specified could lead to out of bounds accesses.
Location loc = op->getLoc();
LinalgOp linalgOp = cast<LinalgOp>(op);
SmallVector<Value> valuesToTile = linalgOp->getOperands();
SmallVector<Value, 4> tiledOperands = makeTiledShapes(
b, loc, linalgOp, valuesToTile, offsets, sizes, {}, true);
SmallVector<Type> resultTensorTypes =
getTensorOutputTypes(linalgOp, tiledOperands);
Operation *tiledOp = clone(b, linalgOp, resultTensorTypes, tiledOperands);
offsetIndices(b, cast<LinalgOp>(tiledOp), offsets);
return TilingResult{{tiledOp}, SmallVector<Value>(tiledOp->getResults())};
}
/// Utility to fetch the offsets and sizes when applied as per the indexing
/// map of the linalg op. This helps in fusing the linalg op as a consumer of
/// a given slice op.
void
getMappedOffsetAndSize(LinalgOp linalgOp, OpBuilder &b, AffineMap indexingMap,
ArrayRef<OpFoldResult> offsets,
ArrayRef<OpFoldResult> sizes,
SmallVectorImpl<OpFoldResult> &mappedOffsets,
SmallVectorImpl<OpFoldResult> &mappedSizes) const {
unsigned numLoops = linalgOp.getNumLoops();
auto tilingInterfaceOp = cast<TilingInterface>(linalgOp.getOperation());
mappedOffsets.resize(numLoops);
mappedSizes.resize(numLoops);
if (!indexingMap.isPermutation()) {
SmallVector<Range> iterationDomain =
tilingInterfaceOp.getIterationDomain(b);
for (const auto &&[index, value] : llvm::enumerate(iterationDomain)) {
mappedOffsets[index] = value.offset;
mappedSizes[index] = value.size;
}
}
for (const auto &&[index, value] :
llvm::enumerate(indexingMap.getResults())) {
unsigned dimPosition = cast<AffineDimExpr>(value).getPosition();
mappedOffsets[dimPosition] = offsets[index];
mappedSizes[dimPosition] = sizes[index];
}
}
/// Method to return the position of the result tile computed by the tiled
/// operation.
LogicalResult getIterationDomainTileFromOperandTile(
Operation *op, OpBuilder &b, unsigned operandNumber,
ArrayRef<OpFoldResult> offsets, ArrayRef<OpFoldResult> sizes,
SmallVectorImpl<OpFoldResult> &iterDomainOffsets,
SmallVectorImpl<OpFoldResult> &iterDomainSizes) const {
auto linalgOp = cast<LinalgOp>(op);
// Check that the indexing map used for the operand is a projected
// permutation. This could be relaxed with a more general approach that can
// map the offsets and sizes from the operand to iteration space tiles
// (filling in full extent for dimensions not used to access the result).
AffineMap indexingMap =
linalgOp.getMatchingIndexingMap(&op->getOpOperand(operandNumber));
if (!indexingMap.isProjectedPermutation()) {
return op->emitError()
<< "unhandled get iter domain position when operand is not "
"accessed using a permuted projection";
}
getMappedOffsetAndSize(linalgOp, b, indexingMap, offsets, sizes,
iterDomainOffsets, iterDomainSizes);
return success();
}
/// Return the details of the output tile generated by the tiled
/// implementation.
LogicalResult
getResultTilePosition(Operation *op, OpBuilder &b, unsigned resultNumber,
ArrayRef<OpFoldResult> offsets,
ArrayRef<OpFoldResult> sizes,
SmallVector<OpFoldResult> &resultOffsets,
SmallVector<OpFoldResult> &resultSizes) const {
Location loc = op->getLoc();
LinalgOp linalgOp = cast<LinalgOp>(op);
AffineExpr d0;
bindDims(b.getContext(), d0);
SmallVector<OpFoldResult> subShapeSizes =
llvm::to_vector(llvm::map_range(sizes, [&](OpFoldResult ofr) {
return affine::makeComposedFoldedAffineApply(b, loc, d0 - 1, ofr);
}));
OpOperand *outOperand = linalgOp.getDpsInitOperand(resultNumber);
SliceParameters sliceParams = computeSliceParameters(
b, loc, outOperand->get(), sizes,
linalgOp.getMatchingIndexingMap(outOperand), offsets,
/*ubs*/ {}, subShapeSizes, true);
resultOffsets = sliceParams.offsets;
resultSizes = sliceParams.sizes;
return success();
}
FailureOr<TilingResult>
generateResultTileValue(Operation *op, OpBuilder &b, unsigned resultNumber,
ArrayRef<OpFoldResult> offsets,
ArrayRef<OpFoldResult> sizes) const {
auto linalgOp = cast<LinalgOp>(op);
// Check that the indexing map used for the output is a projected
// permutation. This could be relaxed with a more general approach that can
// map the offsets and sizes from the result to iteration space tiles
// (filling in full extent for dimensions not used to access the result).
AffineMap indexingMap =
linalgOp.getIndexingMapMatchingResult(op->getResult(resultNumber));
if (!indexingMap.isProjectedPermutation()) {
return op->emitOpError(
"unhandled tiled implementation generation when result is not "
"accessed using a permuted projection");
}
SmallVector<OpFoldResult> mappedOffsets, mappedSizes;
getMappedOffsetAndSize(linalgOp, b, indexingMap, offsets, sizes,
mappedOffsets, mappedSizes);
auto tilingInterfaceOp = cast<TilingInterface>(op);
FailureOr<TilingResult> tilingResult =
tilingInterfaceOp.getTiledImplementation(b, mappedOffsets, mappedSizes);
if (failed(tilingResult))
return failure();
if (tilingResult->tiledOps.size() != 1)
return op->emitOpError("failed to generate tiled implementation");
return TilingResult{
tilingResult->tiledOps,
SmallVector<Value>{tilingResult->tiledValues[resultNumber]}};
}
/// Method to generate the tiled implementation of an operation from the tile
/// of the operand.
FailureOr<TilingResult> getTiledImplementationFromOperandTile(
Operation *op, OpBuilder &b, unsigned operandNumber,
ArrayRef<OpFoldResult> offsets, ArrayRef<OpFoldResult> sizes) const {
SmallVector<OpFoldResult> mappedOffsets, mappedSizes;
if (failed(getIterationDomainTileFromOperandTile(
op, b, operandNumber, offsets, sizes, mappedOffsets,
mappedSizes))) {
return failure();
}
return getTiledImplementation(op, b, mappedOffsets, mappedSizes);
}
LogicalResult generateScalarImplementation(Operation *op, OpBuilder &builder,
Location loc,
ValueRange ivs) const {
auto linalgOp = cast<LinalgOp>(op);
if (!linalgOp.hasPureBufferSemantics())
return op->emitOpError("expected operation to have buffer semantics");
SmallVector<Value> indexedValues;
indexedValues.reserve(linalgOp->getNumOperands());
Location linalgOpLoc = op->getLoc();
/// Load the data corresponding to the block arguments that
/// represent input operands.
for (OpOperand &operand : linalgOp->getOpOperands()) {
if (!linalgOp.payloadUsesValueFromOperand(&operand)) {
indexedValues.push_back(nullptr);
continue;
}
if (linalgOp.isScalar(&operand)) {
indexedValues.push_back(operand.get());
continue;
}
SmallVector<Value> indices = getIndicesForAccess(
builder, linalgOpLoc, linalgOp.getMatchingIndexingMap(&operand), ivs);
Value load =
builder.create<memref::LoadOp>(linalgOpLoc, operand.get(), indices);
indexedValues.push_back(load);
}
/// Inline the op payload and store the result.
return inlinePayload(builder, linalgOp, ivs, indexedValues);
}
};
//===----------------------------------------------------------------------===//
// External Model for implementing `PartialReductionInterface` for `LinalgOp`s.
//===----------------------------------------------------------------------===//
/// External model implementation of PartialReductionInterface for LinalgOps.
template <typename LinalgOpTy>
struct LinalgOpPartialReductionInterface
: public PartialReductionOpInterface::ExternalModel<
LinalgOpPartialReductionInterface<LinalgOpTy>, LinalgOpTy> {
FailureOr<SmallVector<Value>> generateInitialTensorForPartialReduction(
Operation *op, OpBuilder &b, Location loc, ArrayRef<OpFoldResult> sizes,
ArrayRef<int> reductionDims) const {
auto linalgOp = cast<LinalgOp>(op);
OpBuilder::InsertionGuard guard(b);
if (linalgOp.hasPureBufferSemantics())
return op->emitOpError("expected operation to have tensor semantics");
SmallVector<Value> inits;
for (int initIdx = 0, e = linalgOp.getNumDpsInits(); initIdx < e;
++initIdx) {
// Insert the new parallel dimension based on the index of the reduction
// loops. This could be controlled by user for more flexibility.
SmallVector<Operation *, 4> combinerOps;
if (!matchReduction(linalgOp.getRegionOutputArgs(), initIdx,
combinerOps) ||
combinerOps.size() != 1)
return op->emitOpError("Failed to anaysis the reduction operation.");
Operation *reductionOp = combinerOps[0];
std::optional<TypedAttr> identity = arith::getNeutralElement(reductionOp);
if (!identity.has_value())
return op->emitOpError(
"Failed to get an identity value for the reduction operation.");
ArrayRef<int64_t> oldShape =
linalgOp.getShape(linalgOp.getDpsInitOperand(initIdx));
// Calculate the new shape, we insert the new dimensions based on the
// index of the reduction dimensions.
SmallVector<int64_t> newOutputShape;
SmallVector<Value> dynamicDims;
int64_t currReductionDims = 0;
DenseSet<int> reductionDimsSet(reductionDims.begin(),
reductionDims.end());
for (int64_t idx :
llvm::seq<int64_t>(0, oldShape.size() + reductionDims.size())) {
if (reductionDimsSet.contains(idx)) {
dispatchIndexOpFoldResults(sizes[idx], dynamicDims, newOutputShape);
currReductionDims++;
continue;
}
int64_t oldIdx = idx - currReductionDims;
int64_t dim = oldShape[oldIdx];
newOutputShape.push_back(dim);
if (ShapedType::isDynamic(dim))
dynamicDims.push_back(b.create<tensor::DimOp>(
loc, linalgOp.getDpsInitOperand(initIdx)->get(), oldIdx));
}
Value emptyTensor = b.create<tensor::EmptyOp>(
loc, newOutputShape,
linalgOp.getRegionOutputArgs()[initIdx].getType(), dynamicDims);
Value constantOp = b.create<arith::ConstantOp>(loc, *identity);
auto identityTensor =
b.create<linalg::FillOp>(loc, constantOp, emptyTensor);
inits.push_back(identityTensor.getResult(0));
}
return inits;
}
FailureOr<TilingResult>
tileToPartialReduction(Operation *op, OpBuilder &b, Location loc,
ValueRange init, ArrayRef<OpFoldResult> offsets,
ArrayRef<OpFoldResult> sizes,
ArrayRef<int> reductionDims) const {
OpBuilder::InsertionGuard guard(b);
auto linalgOp = cast<LinalgOp>(op);
// Step 1. Extend init maps to have reduction dimension dims, since we
// are converting them to parallel dimensions.
SmallVector<AffineMap> newInitMaps;
newInitMaps.reserve(linalgOp.getNumDpsInits());
for (int idx : llvm::seq<int>(0, linalgOp.getNumDpsInits())) {
// TODO: linalg::Generic doesn't have getDpsInitOperands. Can replace
// this with a for range loop when we have it.
AffineMap newMap =
linalgOp.getMatchingIndexingMap(linalgOp.getDpsInitOperand(idx));
for (int redPos : reductionDims) {
newMap = newMap.insertResult(b.getAffineDimExpr(redPos),
newMap.getNumResults());
}
newInitMaps.push_back(newMap);
}
// Step 2a: Extract a slice of the input operands.
SmallVector<Value, 4> tiledInputs = makeTiledShapes(
b, loc, linalgOp, linalgOp.getDpsInputs(), offsets, sizes, {}, true);
// Step 2b: Extract a slice of the init operands.
SmallVector<Value, 1> tiledInits;
for (auto [valueMap, valueToTile] : llvm::zip_equal(newInitMaps, init)) {
int64_t initRank = valueMap.getNumResults();
SmallVector<OpFoldResult> initOffset(initRank, b.getIndexAttr(0));
SmallVector<OpFoldResult> initStride(initRank, b.getIndexAttr(1));
SmallVector<OpFoldResult> initSizes;
for (AffineExpr dimExpr : valueMap.getResults()) {
auto dim = cast<AffineDimExpr>(dimExpr);
initSizes.push_back(sizes[dim.getPosition()]);
}
// TODO: Use SubsetExtractOpInterface here once available.
auto extractSlice = b.create<tensor::ExtractSliceOp>(
loc, valueToTile, initOffset, initSizes, initStride);
tiledInits.push_back(extractSlice);
}
// Update the indexing maps.
SmallVector<AffineMap> newMaps = linalgOp.getIndexingMapsArray();
// Change the init maps.
for (int idx : llvm::seq<int>(0, linalgOp.getNumDpsInits())) {
// TODO: linalg::Generic doesn't have getDpsInitOperands. Can replace
// this with a for range loop when we have it.
OpOperand *initOperand = linalgOp.getDpsInitOperand(idx);
int64_t mapIdx = linalgOp.getIndexingMapIndex(initOperand);
newMaps[mapIdx] = newInitMaps[idx];
}
// Step 3. Change the reduction dim iterator types.
SmallVector<utils::IteratorType> newIteratorTypes =
linalgOp.getIteratorTypesArray();
for (int dim : reductionDims)
newIteratorTypes[dim] = utils::IteratorType::parallel;
// Step 4. Create the new generic op.
auto genericOp =
b.create<GenericOp>(loc, ValueRange(tiledInits).getTypes(), tiledInputs,
tiledInits, newMaps, newIteratorTypes);
IRMapping mapping;
op->getRegion(0).cloneInto(&genericOp.getRegion(),
genericOp.getRegion().begin(), mapping);
return TilingResult{
{genericOp.getOperation()},
llvm::map_to_vector(genericOp->getResults(),
[](OpResult r) -> Value { return r; })};
}
FailureOr<MergeResult> mergeReductions(Operation *op, OpBuilder &b,
Location loc, ValueRange partialReduce,
ArrayRef<int> reductionDims) const {
auto linalgOp = cast<LinalgOp>(op);
SmallVector<int64_t> reductionDimsInt64(reductionDims.begin(),
reductionDims.end());
auto reduction = b.create<linalg::ReduceOp>(
loc, partialReduce, linalgOp.getDpsInits(), reductionDimsInt64,
[&linalgOp](OpBuilder &b, Location loc, ValueRange inputs) {
int64_t numInits = linalgOp.getNumDpsInits();
SmallVector<Value> yieldedValues;
for (int idx : llvm::seq<int>(0, numInits)) {
// Get the combiner op.
SmallVector<Operation *, 4> combinerOps;
matchReduction(linalgOp.getRegionOutputArgs(), idx, combinerOps);
Operation *clonedReductionOp = b.clone(*combinerOps[0]);
// Combine the input at idx and output at numInits + idx.
clonedReductionOp->setOperand(0, inputs[idx]);
clonedReductionOp->setOperand(1, inputs[numInits + idx]);
// Yield.
yieldedValues.push_back(clonedReductionOp->getResult(0));
}
b.create<linalg::YieldOp>(loc, yieldedValues);
});
return MergeResult{
{reduction.getOperation()},
llvm::map_to_vector(reduction->getResults(),
[](OpResult r) -> Value { return r; })};
}
};
} // namespace
template <typename OpType>
static void registerOne(MLIRContext *ctx) {
OpType::template attachInterface<LinalgOpTilingInterface<OpType>>(*ctx);
OpType::template attachInterface<LinalgOpPartialReductionInterface<OpType>>(
*ctx);
}
/// Variadic helper function.
template <typename... OpTypes>
static void registerAll(MLIRContext *ctx) {
(registerOne<OpTypes>(ctx), ...);
}
#define GET_OP_LIST
void mlir::linalg::registerTilingInterfaceExternalModels(
DialectRegistry &registry) {
registry.addExtension(+[](MLIRContext *ctx, linalg::LinalgDialect *dialect) {
registerOne<linalg::GenericOp>(ctx);
registerAll<
#include "mlir/Dialect/Linalg/IR/LinalgStructuredOps.cpp.inc"
>(ctx);
});
}