llvm-project/mlir/lib/Dialect/Linalg/Transforms/ConvertToDestinationStyle.cpp
Matthias Springer 758329dc7c [mlir][NFC] reifyResultShapes: Add extra error checking
This change adds a new helper function `mlir::reifyResultShapes` that calls the corresponding interface method and also checks the result produced by the implementation when running in debug mode. Bugs due to incorrect interface implementations can be difficult to debug.

This helper function also reduces the amount of code needed at call sites: the cast to `ReifyRankedShapedTypeOpInterface` is done in the helper function.

Differential Revision: https://reviews.llvm.org/D145777
2023-03-10 11:37:54 +01:00

384 lines
16 KiB
C++

//===- ConvertToDestinationStyle.cpp - Convert non-DPS to DPS ops ---------===//
//
// 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 contains patterns to convert non-DPS ops to DPS ops. New
// tensor.empty ops are inserted as a destination. Such tensor.empty can be
// eliminated with "empty tensor elimination", allowing them to bufferize
// without an allocation (assuming there are no further conflicts).
//
//===----------------------------------------------------------------------===//
//
#include "mlir/Dialect/Arith/IR/Arith.h"
#include "mlir/Dialect/Arith/Utils/Utils.h"
#include "mlir/Dialect/Bufferization/IR/BufferizableOpInterface.h"
#include "mlir/Dialect/Bufferization/IR/Bufferization.h"
#include "mlir/Dialect/Linalg/IR/Linalg.h"
#include "mlir/Dialect/Linalg/Transforms/Transforms.h"
#include "mlir/Dialect/Tensor/IR/Tensor.h"
#include "mlir/Dialect/Utils/StaticValueUtils.h"
#include "mlir/IR/Matchers.h"
#include "mlir/IR/PatternMatch.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Debug.h"
using namespace mlir;
using namespace mlir::tensor;
// Implements backtracking to traverse indices of the output buffer while
// iterating over op.elements().
static Value createInserts(RewriterBase &rewriter, Location loc, int dim,
Value destination, ArrayRef<int64_t> shape,
ArrayRef<Value> constants,
OperandRange::iterator &elementIt,
SmallVectorImpl<Value> &indices) {
if (dim == static_cast<int>(shape.size()) - 1) {
for (int i = 0; i < shape.back(); ++i) {
indices.back() = constants[i];
destination = rewriter.create<tensor::InsertOp>(loc, *elementIt,
destination, indices);
++elementIt;
}
return destination;
}
for (int i = 0; i < shape[dim]; ++i) {
indices[dim] = constants[i];
destination = createInserts(rewriter, loc, dim + 1, destination, shape,
constants, elementIt, indices);
}
return destination;
}
static Operation *movePaddingToFillOrGenericOp(RewriterBase &rewriter,
Location loc, PadOp padOp,
Value dest) {
OpBuilder::InsertionGuard g(rewriter);
RankedTensorType resultType = padOp.getResultType();
// Examine the yielded value to decide if a linalg.generic is neede or a
// linalg.fill is sufficient.
Value yieldedValue =
cast<tensor::YieldOp>(padOp.getBody()->getTerminator()).getValue();
Attribute constYieldedValue;
// Is the yielded value a bbArg defined outside of the PadOp?
bool outsideBbArg =
yieldedValue.isa<BlockArgument>() &&
yieldedValue.cast<BlockArgument>().getOwner()->getParentOp() !=
padOp.getOperation();
// Is the yielded value an OpResult defined outside of the PadOp?
bool outsideOpResult =
yieldedValue.isa<OpResult>() &&
yieldedValue.getDefiningOp()->getParentOp() != padOp.getOperation();
bool invariantYieldedValue = outsideBbArg || outsideOpResult;
if (matchPattern(yieldedValue, m_Constant(&constYieldedValue))) {
// Padding with a constant: Create linalg.fill.
Dialect *arithDialect =
rewriter.getContext()->getLoadedDialect<arith::ArithDialect>();
Value fillValue =
arithDialect
->materializeConstant(rewriter, constYieldedValue,
yieldedValue.getType(), yieldedValue.getLoc())
->getResult(0);
auto fillOp = rewriter.create<linalg::FillOp>(loc, ValueRange(fillValue),
ValueRange(dest));
return fillOp;
}
if (invariantYieldedValue) {
// Padding with an invariant value.
auto fillOp = rewriter.create<linalg::FillOp>(loc, ValueRange(yieldedValue),
ValueRange(dest));
return fillOp;
}
// Create linalg.generic.
SmallVector<utils::IteratorType> iteratorTypes(resultType.getRank(),
utils::IteratorType::parallel);
SmallVector<AffineMap> indexingMaps(
1, rewriter.getMultiDimIdentityMap(resultType.getRank()));
auto genericOp = rewriter.create<linalg::GenericOp>(
loc, resultType, /*inputs=*/ValueRange(),
/*outputs=*/ValueRange{dest}, /*indexingMaps=*/
indexingMaps, iteratorTypes);
Block *body = rewriter.createBlock(&genericOp->getRegion(0), {},
resultType.getElementType(), loc);
rewriter.setInsertionPointToStart(body);
SmallVector<Value> bbArgReplacements;
for (int64_t i = 0; i < resultType.getRank(); ++i)
bbArgReplacements.push_back(rewriter.create<linalg::IndexOp>(loc, i));
rewriter.mergeBlocks(padOp.getBody(), body, bbArgReplacements);
// Update terminator.
auto yieldOp = cast<tensor::YieldOp>(body->getTerminator());
rewriter.replaceOpWithNewOp<linalg::YieldOp>(yieldOp, yieldOp.getValue());
return genericOp;
}
static SmallVector<Value> reifyOrComputeDynamicSizes(OpBuilder &b,
Value value) {
auto tensorType = value.getType().cast<RankedTensorType>();
if (tensorType.hasStaticShape())
return {};
// Try to reify dynamic sizes.
ReifiedRankedShapedTypeDims reifiedShape;
if (value.isa<OpResult>() &&
succeeded(reifyResultShapes(b, value.getDefiningOp(), reifiedShape))) {
SmallVector<Value> dynSizes;
for (int64_t i = 0; i < tensorType.getRank(); ++i) {
if (tensorType.isDynamicDim(i))
dynSizes.push_back(
reifiedShape[value.cast<OpResult>().getResultNumber()][i]
.get<Value>());
}
return dynSizes;
}
// Create tensor.dim ops.
SmallVector<Value> dynSizes;
for (int64_t i = 0; i < tensorType.getRank(); ++i) {
if (tensorType.isDynamicDim(i))
dynSizes.push_back(
b.create<DimOp>(value.getLoc(), value,
b.create<arith::ConstantIndexOp>(value.getLoc(), i)));
}
return dynSizes;
}
static Value createAllocationForTensor(RewriterBase &rewriter, Location loc,
Value value,
Attribute memorySpace = {}) {
OpBuilder::InsertionGuard g(rewriter);
auto tensorType = value.getType().cast<RankedTensorType>();
// Create buffer allocation.
auto memrefType = bufferization::getMemRefTypeWithStaticIdentityLayout(
tensorType, memorySpace)
.cast<MemRefType>();
SmallVector<Value> dynamicSizes = reifyOrComputeDynamicSizes(rewriter, value);
Value alloc = rewriter.create<memref::AllocOp>(loc, memrefType, dynamicSizes);
// Place deallocation at the end of the block.
rewriter.setInsertionPoint(rewriter.getInsertionBlock()->getTerminator());
rewriter.create<memref::DeallocOp>(loc, alloc);
return alloc;
}
Value linalg::bufferizeToAllocation(RewriterBase &rewriter, PadOp padOp,
Attribute memorySpace) {
OpBuilder::InsertionGuard g(rewriter);
rewriter.setInsertionPoint(padOp);
Location loc = padOp.getLoc();
// Create buffer allocation.
Value alloc =
createAllocationForTensor(rewriter, loc, padOp.getResult(), memorySpace);
rewriter.setInsertionPointAfter(alloc.getDefiningOp());
// Create linalg.fill or linalg.generic.
Operation *fillOp = movePaddingToFillOrGenericOp(rewriter, loc, padOp, alloc);
rewriter.setInsertionPointAfter(fillOp);
// Create memref.tensor_store.
SmallVector<OpFoldResult> sizes =
getMixedSizes(rewriter, loc, padOp.getSource());
SmallVector<OpFoldResult> strides(padOp.getResultType().getRank(),
rewriter.getIndexAttr(1));
Value subview = rewriter.create<memref::SubViewOp>(
loc, alloc, /*offsets=*/padOp.getMixedLowPad(), sizes, strides);
rewriter.create<memref::TensorStoreOp>(loc, padOp.getSource(), subview);
// Create bufferization.to_tensor with "restrict" and "writable". The returned
// tensor is a new buffer allocation, so it does not alias with any buffer.
Value toTensorOp = rewriter.create<bufferization::ToTensorOp>(
loc, alloc, /*restrict=*/true, /*writable=*/true);
rewriter.replaceOp(padOp, toTensorOp);
return toTensorOp;
}
/// Lower tensor.from_elements to a sequence of chained tensor.insert.
FailureOr<Operation *> mlir::linalg::rewriteInDestinationPassingStyle(
RewriterBase &rewriter, tensor::FromElementsOp fromElementsOp) {
Location loc = fromElementsOp.getLoc();
RankedTensorType tensorType =
fromElementsOp.getType().cast<RankedTensorType>();
auto shape = tensorType.getShape();
// Create tensor.empty.
auto emptyOp = rewriter.create<EmptyOp>(loc, tensorType, ValueRange());
// Case: tensor<elem_type>.
if (shape.empty()) {
Operation *res = rewriter.replaceOpWithNewOp<tensor::InsertOp>(
fromElementsOp, fromElementsOp.getElements().front(),
emptyOp.getResult(), ValueRange());
return res;
}
// Create constants for the range of possible indices [0, max{shape_i}).
auto maxDim = *std::max_element(shape.begin(), shape.end());
SmallVector<Value, 2> constants;
constants.reserve(maxDim);
for (int i = 0; i < maxDim; ++i)
constants.push_back(rewriter.create<arith::ConstantIndexOp>(loc, i));
// Traverse all elements and create tensor.insert ops.
auto elementIt = fromElementsOp.getElements().begin();
SmallVector<Value, 2> indices(tensorType.getRank(), constants[0]);
Value result = createInserts(rewriter, loc, /*dim=*/0, emptyOp.getResult(),
shape, constants, elementIt, indices);
// Replace tensor.from_elements.
rewriter.replaceOp(fromElementsOp, result);
return result.getDefiningOp();
}
/// Lower tensor.generate to linalg.generic.
FailureOr<Operation *>
mlir::linalg::rewriteInDestinationPassingStyle(RewriterBase &rewriter,
tensor::GenerateOp generateOp) {
// Only ops with exactly one block are supported.
if (!generateOp.getBody().hasOneBlock())
return failure();
Location loc = generateOp.getLoc();
RankedTensorType tensorType = generateOp.getType().cast<RankedTensorType>();
// Create tensor.empty.
auto emptyOp =
rewriter.create<EmptyOp>(loc, tensorType, generateOp.getDynamicExtents());
// Create linalg.generic.
SmallVector<utils::IteratorType> iteratorTypes(tensorType.getRank(),
utils::IteratorType::parallel);
SmallVector<AffineMap> indexingMaps(
1, rewriter.getMultiDimIdentityMap(tensorType.getRank()));
auto genericOp = rewriter.create<linalg::GenericOp>(
loc, tensorType, /*inputs=*/ValueRange(),
/*outputs=*/ValueRange{emptyOp.getResult()}, /*indexingMaps=*/
indexingMaps, iteratorTypes);
Block *body = rewriter.createBlock(&genericOp->getRegion(0), {},
tensorType.getElementType(), loc);
rewriter.setInsertionPointToStart(body);
SmallVector<Value> bbArgReplacements;
for (int64_t i = 0; i < tensorType.getRank(); ++i)
bbArgReplacements.push_back(rewriter.create<linalg::IndexOp>(loc, i));
rewriter.mergeBlocks(&generateOp.getBody().front(), body, bbArgReplacements);
// Update terminator.
auto yieldOp = cast<tensor::YieldOp>(body->getTerminator());
rewriter.replaceOpWithNewOp<linalg::YieldOp>(yieldOp, yieldOp.getValue());
// Replace tensor.generate.
rewriter.replaceOp(generateOp, genericOp->getResult(0));
return genericOp.getOperation();
}
/// Lower tensor.pad to linalg.generic + tensor.insert_slice.
FailureOr<Operation *>
mlir::linalg::rewriteInDestinationPassingStyle(RewriterBase &rewriter,
tensor::PadOp padOp) {
// Only ops with exactly one block are supported.
if (!padOp.getBodyRegion().hasOneBlock())
return failure();
// Create tensor.empty.
Location loc = padOp.getLoc();
RankedTensorType resultType = padOp.getResultType();
ReifiedRankedShapedTypeDims reifiedShape;
if (failed(reifyResultShapes(rewriter, padOp, reifiedShape)))
return rewriter.notifyMatchFailure(
padOp, "failed to reify tensor.pad op result shape");
SmallVector<Value> dynamicSizes;
for (int64_t i = 0; i < resultType.getRank(); ++i)
if (resultType.isDynamicDim(i))
dynamicSizes.push_back(reifiedShape[0][i].get<Value>());
// If the `padOp` has a nofold attribute and all paddings are known to be 0,
// explicitly insert a `linalg.copy`.
if (padOp.getNofoldAttr() &&
llvm::all_of(padOp.getMixedLowPad(), isZeroIndex) &&
llvm::all_of(padOp.getMixedHighPad(), isZeroIndex)) {
using bufferization::AllocTensorOp;
Value allocated =
rewriter.create<AllocTensorOp>(loc, resultType, dynamicSizes);
auto copyOp = rewriter.replaceOpWithNewOp<linalg::CopyOp>(
padOp, padOp.getSource(), allocated);
return copyOp.getOperation();
}
Value empty = rewriter.create<EmptyOp>(loc, resultType, dynamicSizes);
// Create linalg.fill or linalg.generic.
Operation *fillOp = movePaddingToFillOrGenericOp(rewriter, loc, padOp, empty);
rewriter.setInsertionPointAfter(fillOp);
// Create tensor::InsertSliceOp.
SmallVector<OpFoldResult> sliceSizes =
getMixedSizes(rewriter, loc, padOp.getSource());
SmallVector<OpFoldResult> sliceStrides(resultType.getRank(),
rewriter.getIndexAttr(1));
auto insertSliceOp = rewriter.replaceOpWithNewOp<tensor::InsertSliceOp>(
padOp, padOp.getSource(), fillOp->getResult(0),
/*offsets=*/padOp.getMixedLowPad(), sliceSizes, sliceStrides);
return insertSliceOp.getOperation();
}
Value linalg::bufferizeToAllocation(RewriterBase &rewriter, Value value,
Attribute memorySpace) {
// Call specialized overload for certain ops.
if (auto padOp = value.getDefiningOp<PadOp>())
return bufferizeToAllocation(rewriter, padOp, memorySpace);
// Collect all uses.
SmallVector<OpOperand *> uses = llvm::to_vector(
llvm::map_range(value.getUses(), [](OpOperand &use) { return &use; }));
OpBuilder::InsertionGuard g(rewriter);
if (auto bbArg = value.dyn_cast<BlockArgument>()) {
rewriter.setInsertionPointToStart(bbArg.getOwner());
} else {
rewriter.setInsertionPointAfter(value.getDefiningOp());
}
Location loc = value.getLoc();
// Create buffer allocation.
Value alloc = createAllocationForTensor(rewriter, loc, value, memorySpace);
// Create memref.tensor_store.
rewriter.setInsertionPointAfter(alloc.getDefiningOp());
rewriter.create<memref::TensorStoreOp>(loc, value, alloc);
// Create bufferization.to_tensor with "restrict" and "writable". The returned
// tensor is a new buffer allocation, so it does not alias with any buffer.
Value toTensorOp = rewriter.create<bufferization::ToTensorOp>(
loc, alloc, /*restrict=*/true, /*writable=*/true);
for (OpOperand *use : uses) {
rewriter.updateRootInPlace(use->getOwner(),
[&]() { use->set(toTensorOp); });
}
return toTensorOp;
}
namespace {
template <typename OpTy>
LogicalResult rewriteOpInDestinationPassingStyle(OpTy op,
PatternRewriter &rewriter) {
return linalg::rewriteInDestinationPassingStyle(rewriter, op);
}
} // namespace
void linalg::populateConvertToDestinationStylePatterns(
RewritePatternSet &patterns) {
patterns.add(rewriteOpInDestinationPassingStyle<tensor::FromElementsOp>);
patterns.add(rewriteOpInDestinationPassingStyle<tensor::GenerateOp>);
patterns.add(rewriteOpInDestinationPassingStyle<tensor::PadOp>);
}