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//===- VectorDropLeadUnitDim.cpp - Conversion within the Vector dialect ---===//
//
// 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 <numeric>
#include "mlir/Dialect/Utils/StructuredOpsUtils.h"
#include "mlir/Dialect/Vector/IR/VectorOps.h"
#include "mlir/Dialect/Vector/Transforms/VectorRewritePatterns.h"
#include "mlir/Dialect/Vector/Transforms/VectorTransforms.h"
#include "mlir/Dialect/Vector/Utils/VectorUtils.h"
#include "mlir/IR/Builders.h"
#include "mlir/IR/TypeUtilities.h"
#define DEBUG_TYPE "vector-drop-unit-dim"
using namespace mlir;
using namespace mlir::vector;
// Trims leading one dimensions from `oldType` and returns the result type.
// Returns `vector<1xT>` if `oldType` only has one element.
static VectorType trimLeadingOneDims(VectorType oldType) {
ArrayRef<int64_t> oldShape = oldType.getShape();
ArrayRef<int64_t> newShape = oldShape;
ArrayRef<bool> oldScalableDims = oldType.getScalableDims();
ArrayRef<bool> newScalableDims = oldScalableDims;
while (!newShape.empty() && newShape.front() == 1 &&
!newScalableDims.front()) {
newShape = newShape.drop_front(1);
newScalableDims = newScalableDims.drop_front(1);
}
// Make sure we have at least 1 dimension per vector type requirements.
if (newShape.empty()) {
newShape = oldShape.take_back();
newScalableDims = oldType.getScalableDims().take_back();
}
return VectorType::get(newShape, oldType.getElementType(), newScalableDims);
}
/// Return a smallVector of size `rank` containing all zeros.
static SmallVector<int64_t> splatZero(int64_t rank) {
return SmallVector<int64_t>(rank, 0);
}
namespace {
// Casts away leading one dimensions in vector.extract_strided_slice's vector
// input by inserting vector.broadcast.
struct CastAwayExtractStridedSliceLeadingOneDim
: public OpRewritePattern<vector::ExtractStridedSliceOp> {
using OpRewritePattern::OpRewritePattern;
LogicalResult matchAndRewrite(vector::ExtractStridedSliceOp extractOp,
PatternRewriter &rewriter) const override {
// vector.extract_strided_slice requires the input and output vector to have
// the same rank. Here we drop leading one dimensions from the input vector
// type to make sure we don't cause mismatch.
VectorType oldSrcType = extractOp.getSourceVectorType();
VectorType newSrcType = trimLeadingOneDims(oldSrcType);
if (newSrcType.getRank() == oldSrcType.getRank())
return failure();
int64_t dropCount = oldSrcType.getRank() - newSrcType.getRank();
VectorType oldDstType = extractOp.getType();
VectorType newDstType =
VectorType::get(oldDstType.getShape().drop_front(dropCount),
oldDstType.getElementType(),
oldDstType.getScalableDims().drop_front(dropCount));
Location loc = extractOp.getLoc();
Value newSrcVector = rewriter.create<vector::ExtractOp>(
loc, extractOp.getVector(), splatZero(dropCount));
// The offsets/sizes/strides attribute can have a less number of elements
// than the input vector's rank: it is meant for the leading dimensions.
auto newOffsets = rewriter.getArrayAttr(
extractOp.getOffsets().getValue().drop_front(dropCount));
auto newSizes = rewriter.getArrayAttr(
extractOp.getSizes().getValue().drop_front(dropCount));
auto newStrides = rewriter.getArrayAttr(
extractOp.getStrides().getValue().drop_front(dropCount));
auto newExtractOp = rewriter.create<vector::ExtractStridedSliceOp>(
loc, newDstType, newSrcVector, newOffsets, newSizes, newStrides);
rewriter.replaceOpWithNewOp<vector::BroadcastOp>(extractOp, oldDstType,
newExtractOp);
return success();
}
};
// Casts away leading one dimensions in vector.insert_strided_slice's vector
// inputs by inserting vector.broadcast.
struct CastAwayInsertStridedSliceLeadingOneDim
: public OpRewritePattern<vector::InsertStridedSliceOp> {
using OpRewritePattern::OpRewritePattern;
LogicalResult matchAndRewrite(vector::InsertStridedSliceOp insertOp,
PatternRewriter &rewriter) const override {
VectorType oldSrcType = insertOp.getSourceVectorType();
VectorType newSrcType = trimLeadingOneDims(oldSrcType);
VectorType oldDstType = insertOp.getDestVectorType();
VectorType newDstType = trimLeadingOneDims(oldDstType);
int64_t srcDropCount = oldSrcType.getRank() - newSrcType.getRank();
int64_t dstDropCount = oldDstType.getRank() - newDstType.getRank();
if (srcDropCount == 0 && dstDropCount == 0)
return failure();
// Trim leading one dimensions from both operands.
Location loc = insertOp.getLoc();
Value newSrcVector = rewriter.create<vector::ExtractOp>(
loc, insertOp.getValueToStore(), splatZero(srcDropCount));
Value newDstVector = rewriter.create<vector::ExtractOp>(
loc, insertOp.getDest(), splatZero(dstDropCount));
auto newOffsets = rewriter.getArrayAttr(
insertOp.getOffsets().getValue().take_back(newDstType.getRank()));
auto newStrides = rewriter.getArrayAttr(
insertOp.getStrides().getValue().take_back(newSrcType.getRank()));
auto newInsertOp = rewriter.create<vector::InsertStridedSliceOp>(
loc, newDstType, newSrcVector, newDstVector, newOffsets, newStrides);
rewriter.replaceOpWithNewOp<vector::BroadcastOp>(insertOp, oldDstType,
newInsertOp);
return success();
}
};
// Casts away leading one dimensions in vector.insert's vector inputs by
// inserting vector.broadcast.
struct CastAwayInsertLeadingOneDim : public OpRewritePattern<vector::InsertOp> {
using OpRewritePattern::OpRewritePattern;
LogicalResult matchAndRewrite(vector::InsertOp insertOp,
PatternRewriter &rewriter) const override {
Type oldSrcType = insertOp.getValueToStoreType();
Type newSrcType = oldSrcType;
int64_t oldSrcRank = 0, newSrcRank = 0;
if (auto type = dyn_cast<VectorType>(oldSrcType)) {
newSrcType = trimLeadingOneDims(type);
oldSrcRank = type.getRank();
newSrcRank = cast<VectorType>(newSrcType).getRank();
}
VectorType oldDstType = insertOp.getDestVectorType();
VectorType newDstType = trimLeadingOneDims(oldDstType);
int64_t srcDropCount = oldSrcRank - newSrcRank;
int64_t dstDropCount = oldDstType.getRank() - newDstType.getRank();
if (srcDropCount == 0 && dstDropCount == 0)
return failure();
// Trim leading one dimensions from both operands.
Location loc = insertOp.getLoc();
Value newSrcVector = insertOp.getValueToStore();
if (oldSrcRank != 0) {
newSrcVector = rewriter.create<vector::ExtractOp>(
loc, insertOp.getValueToStore(), splatZero(srcDropCount));
}
Value newDstVector = rewriter.create<vector::ExtractOp>(
loc, insertOp.getDest(), splatZero(dstDropCount));
// New position rank needs to be computed in two steps: (1) if destination
// type has leading unit dims, we also trim the position array accordingly,
// then (2) if source type also has leading unit dims, we need to append
// zeroes to the position array accordingly.
unsigned oldPosRank = insertOp.getNumIndices();
unsigned newPosRank = std::max<int64_t>(0, oldPosRank - dstDropCount);
SmallVector<OpFoldResult> oldPosition = insertOp.getMixedPosition();
SmallVector<OpFoldResult> newPosition =
llvm::to_vector(ArrayRef(oldPosition).take_back(newPosRank));
newPosition.resize(newDstType.getRank() - newSrcRank,
rewriter.getI64IntegerAttr(0));
auto newInsertOp = rewriter.create<vector::InsertOp>(
loc, newSrcVector, newDstVector, newPosition);
rewriter.replaceOpWithNewOp<vector::BroadcastOp>(insertOp, oldDstType,
newInsertOp);
return success();
}
};
static Value dropUnitDimsFromMask(OpBuilder &b, Location loc, Value mask,
VectorType newType, AffineMap newMap,
VectorType oldMaskType) {
// Infer the type of the new mask from the new map.
VectorType newMaskType = inferTransferOpMaskType(newType, newMap);
// If the new mask is broadcastable to the old result type, we can safely
// use a `vector.extract` to get the new mask. Otherwise the best we can
// do is shape cast.
if (vector::isBroadcastableTo(newMaskType, oldMaskType) ==
BroadcastableToResult::Success) {
int64_t dropDim = oldMaskType.getRank() - newMaskType.getRank();
return b.create<vector::ExtractOp>(loc, mask, splatZero(dropDim));
}
return b.create<vector::ShapeCastOp>(loc, newMaskType, mask);
}
// Turns vector.transfer_read on vector with leading 1 dimensions into
// vector.shape_cast followed by vector.transfer_read on vector without leading
// 1 dimensions.
struct CastAwayTransferReadLeadingOneDim
: public OpRewritePattern<vector::TransferReadOp> {
using OpRewritePattern::OpRewritePattern;
LogicalResult matchAndRewrite(vector::TransferReadOp read,
PatternRewriter &rewriter) const override {
// TODO(#78787): Not supported masked op yet.
if (cast<MaskableOpInterface>(read.getOperation()).isMasked())
return failure();
// TODO: support 0-d corner case.
if (read.getTransferRank() == 0)
return failure();
auto shapedType = cast<ShapedType>(read.getSource().getType());
if (shapedType.getElementType() != read.getVectorType().getElementType())
return failure();
VectorType oldType = read.getVectorType();
VectorType newType = trimLeadingOneDims(oldType);
if (newType == oldType)
return failure();
AffineMap oldMap = read.getPermutationMap();
ArrayRef<AffineExpr> newResults =
oldMap.getResults().take_back(newType.getRank());
AffineMap newMap =
AffineMap::get(oldMap.getNumDims(), oldMap.getNumSymbols(), newResults,
rewriter.getContext());
ArrayAttr inBoundsAttr;
if (read.getInBounds())
inBoundsAttr = rewriter.getArrayAttr(
read.getInBoundsAttr().getValue().take_back(newType.getRank()));
Value mask = Value();
if (read.getMask()) {
VectorType maskType = read.getMaskType();
mask = dropUnitDimsFromMask(rewriter, read.getLoc(), read.getMask(),
newType, newMap, maskType);
}
auto newRead = rewriter.create<vector::TransferReadOp>(
read.getLoc(), newType, read.getSource(), read.getIndices(),
AffineMapAttr::get(newMap), read.getPadding(), mask, inBoundsAttr);
rewriter.replaceOpWithNewOp<vector::BroadcastOp>(read, oldType, newRead);
return success();
}
};
// Turns vector.transfer_write on vector with leading 1 dimensions into
// vector.shape_cast followed by vector.transfer_write on vector without leading
// 1 dimensions.
struct CastAwayTransferWriteLeadingOneDim
: public OpRewritePattern<vector::TransferWriteOp> {
using OpRewritePattern::OpRewritePattern;
LogicalResult matchAndRewrite(vector::TransferWriteOp write,
PatternRewriter &rewriter) const override {
// TODO(#78787): Not supported masked op yet.
if (cast<MaskableOpInterface>(write.getOperation()).isMasked())
return failure();
// TODO: support 0-d corner case.
if (write.getTransferRank() == 0)
return failure();
auto shapedType = dyn_cast<ShapedType>(write.getSource().getType());
if (shapedType.getElementType() != write.getVectorType().getElementType())
return failure();
VectorType oldType = write.getVectorType();
VectorType newType = trimLeadingOneDims(oldType);
if (newType == oldType)
return failure();
int64_t dropDim = oldType.getRank() - newType.getRank();
AffineMap oldMap = write.getPermutationMap();
ArrayRef<AffineExpr> newResults =
oldMap.getResults().take_back(newType.getRank());
AffineMap newMap =
AffineMap::get(oldMap.getNumDims(), oldMap.getNumSymbols(), newResults,
rewriter.getContext());
ArrayAttr inBoundsAttr;
if (write.getInBounds())
inBoundsAttr = rewriter.getArrayAttr(
write.getInBoundsAttr().getValue().take_back(newType.getRank()));
auto newVector = rewriter.create<vector::ExtractOp>(
write.getLoc(), write.getVector(), splatZero(dropDim));
if (write.getMask()) {
VectorType maskType = write.getMaskType();
Value newMask = dropUnitDimsFromMask(
rewriter, write.getLoc(), write.getMask(), newType, newMap, maskType);
rewriter.replaceOpWithNewOp<vector::TransferWriteOp>(
write, newVector, write.getSource(), write.getIndices(),
AffineMapAttr::get(newMap), newMask, inBoundsAttr);
return success();
}
rewriter.replaceOpWithNewOp<vector::TransferWriteOp>(
write, newVector, write.getSource(), write.getIndices(),
AffineMapAttr::get(newMap), inBoundsAttr);
return success();
}
};
} // namespace
FailureOr<Value>
mlir::vector::castAwayContractionLeadingOneDim(vector::ContractionOp contractOp,
MaskingOpInterface maskingOp,
RewriterBase &rewriter) {
VectorType oldAccType = dyn_cast<VectorType>(contractOp.getAccType());
if (oldAccType == nullptr)
return failure();
if (oldAccType.getRank() < 2)
return failure();
if (oldAccType.getShape()[0] != 1)
return failure();
// currently we support only dropping one dim but the pattern can be applied
// greedily to drop more.
int64_t dropDim = 1;
auto oldIndexingMaps = contractOp.getIndexingMapsArray();
SmallVector<AffineMap> newIndexingMaps;
auto oldIteratorTypes = contractOp.getIteratorTypes();
SmallVector<Attribute> newIteratorTypes;
int64_t dimToDrop = oldIndexingMaps[2].getDimPosition(0);
if (!isParallelIterator(oldIteratorTypes[dimToDrop]))
// only parallel type iterators can be dropped.
return failure();
for (const auto &it : llvm::enumerate(oldIteratorTypes)) {
int64_t currDim = it.index();
if (currDim == dimToDrop)
continue;
newIteratorTypes.push_back(it.value());
}
SmallVector<Value> operands = {contractOp.getLhs(), contractOp.getRhs(),
contractOp.getAcc()};
SmallVector<Value> newOperands;
auto loc = contractOp.getLoc();
for (const auto &it : llvm::enumerate(oldIndexingMaps)) {
// Check if the dim to be dropped exists as a leading dim in the operand
// if it does then we use vector.extract to drop it.
bool validExtract = false;
SmallVector<AffineExpr> results;
auto map = it.value();
int64_t orginalZeroDim = it.value().getDimPosition(0);
if (orginalZeroDim != dimToDrop) {
// There are two reasons to be in this path, 1. We need to
// transpose the operand to make the dim to be dropped
// leading. 2. The dim to be dropped does not exist and in
// that case we dont want to add a unit transpose but we must
// check all the indices to make sure this is the case.
bool transposeNeeded = false;
SmallVector<int64_t> perm;
SmallVector<AffineExpr> transposeResults;
for (int64_t i = 0, e = map.getNumResults(); i < e; ++i) {
int64_t currDim = map.getDimPosition(i);
if (currDim == dimToDrop) {
transposeNeeded = true;
perm.insert(perm.begin(), i);
auto targetExpr = rewriter.getAffineDimExpr(currDim);
transposeResults.insert(transposeResults.begin(), targetExpr);
} else {
perm.push_back(i);
auto targetExpr = rewriter.getAffineDimExpr(currDim);
transposeResults.push_back(targetExpr);
}
}
// Checks if only the outer, unit dimensions (of size 1) are permuted.
// Such transposes do not materially effect the underlying vector and can
// be omitted. EG: perm [1, 0, 2] applied to vector<1x1x8xi32>
bool transposeNonOuterUnitDims = false;
auto operandShape = cast<ShapedType>(operands[it.index()].getType());
for (auto [index, dim] :
llvm::enumerate(ArrayRef<int64_t>(perm).drop_back(1))) {
if (dim != static_cast<int64_t>(index) &&
operandShape.getDimSize(index) != 1) {
transposeNonOuterUnitDims = true;
break;
}
}
// Do the transpose now if needed so that we can drop the
// correct dim using extract later.
if (transposeNeeded) {
map = AffineMap::get(map.getNumDims(), 0, transposeResults,
contractOp.getContext());
if (transposeNonOuterUnitDims) {
operands[it.index()] = rewriter.createOrFold<vector::TransposeOp>(
loc, operands[it.index()], perm);
}
}
}
// We have taken care to have the dim to be dropped be
// the leading dim. If its still not leading that means it
// does not exist in this operand and hence we do not need
// an extract.
if (map.getDimPosition(0) == dimToDrop)
validExtract = true;
for (int64_t i = 0, e = map.getNumResults(); i < e; ++i) {
int64_t currDim = map.getDimPosition(i);
if (currDim == dimToDrop)
// This is the dim we are dropping.
continue;
auto targetExpr = rewriter.getAffineDimExpr(
currDim < dimToDrop ? currDim : currDim - 1);
results.push_back(targetExpr);
}
newIndexingMaps.push_back(AffineMap::get(map.getNumDims() - 1, 0, results,
contractOp.getContext()));
// Extract if its a valid extraction, otherwise use the operand
// without extraction.
newOperands.push_back(
validExtract ? rewriter.create<vector::ExtractOp>(
loc, operands[it.index()], splatZero(dropDim))
: operands[it.index()]);
}
// Depending on whether this vector.contract is masked, the replacing Op
// should either be a new vector.contract Op or vector.mask Op.
Operation *newOp = rewriter.create<vector::ContractionOp>(
loc, newOperands[0], newOperands[1], newOperands[2],
rewriter.getAffineMapArrayAttr(newIndexingMaps),
rewriter.getArrayAttr(newIteratorTypes), contractOp.getKind());
if (maskingOp) {
auto newMask = rewriter.create<vector::ExtractOp>(loc, maskingOp.getMask(),
splatZero(dropDim));
newOp = mlir::vector::maskOperation(rewriter, newOp, newMask);
}
return rewriter
.create<vector::BroadcastOp>(loc, contractOp->getResultTypes()[0],
newOp->getResults()[0])
.getResult();
}
namespace {
/// Turns vector.contract on vector with leading 1 dimensions into
/// vector.extract followed by vector.contract on vector without leading
/// 1 dimensions. Also performs transpose of lhs and rhs operands if required
/// prior to extract.
struct CastAwayContractionLeadingOneDim
: public MaskableOpRewritePattern<vector::ContractionOp> {
using MaskableOpRewritePattern::MaskableOpRewritePattern;
FailureOr<Value>
matchAndRewriteMaskableOp(vector::ContractionOp contractOp,
MaskingOpInterface maskingOp,
PatternRewriter &rewriter) const override {
return castAwayContractionLeadingOneDim(contractOp, maskingOp, rewriter);
}
};
/// Looks at elementwise operations on vectors with at least one leading
/// dimension equal 1, e.g. vector<1x[4]x1xf32> (but not vector<2x[4]x1xf32>),
/// and cast aways the leading one dimensions (_plural_) and then broadcasts
/// the results.
///
/// Example before:
/// %1 = arith.mulf %arg0, %arg1 : vector<1x4x1xf32>
/// Example after:
/// %2 = arith.mulf %0, %1 : vector<4x1xf32>
/// %3 = vector.broadcast %2 : vector<4x1xf32> to vector<1x4x1xf32>
///
/// Does support scalable vectors.
class CastAwayElementwiseLeadingOneDim : public RewritePattern {
public:
CastAwayElementwiseLeadingOneDim(MLIRContext *context,
PatternBenefit benefit = 1)
: RewritePattern(MatchAnyOpTypeTag(), benefit, context) {}
LogicalResult matchAndRewrite(Operation *op,
PatternRewriter &rewriter) const override {
if (!OpTrait::hasElementwiseMappableTraits(op) || op->getNumResults() != 1)
return failure();
auto vecType = dyn_cast<VectorType>(op->getResultTypes()[0]);
if (!vecType)
return failure();
VectorType newVecType = trimLeadingOneDims(vecType);
if (newVecType == vecType)
return failure();
int64_t dropDim = vecType.getRank() - newVecType.getRank();
SmallVector<Value, 4> newOperands;
for (Value operand : op->getOperands()) {
if (auto opVecType = dyn_cast<VectorType>(operand.getType())) {
newOperands.push_back(rewriter.create<vector::ExtractOp>(
op->getLoc(), operand, splatZero(dropDim)));
} else {
newOperands.push_back(operand);
}
}
Operation *newOp =
rewriter.create(op->getLoc(), op->getName().getIdentifier(),
newOperands, newVecType, op->getAttrs());
rewriter.replaceOpWithNewOp<vector::BroadcastOp>(op, vecType,
newOp->getResult(0));
return success();
}
};
// Drops leading 1 dimensions from vector.constant_mask and inserts a
// vector.broadcast back to the original shape.
struct CastAwayConstantMaskLeadingOneDim
: public OpRewritePattern<vector::ConstantMaskOp> {
using OpRewritePattern::OpRewritePattern;
LogicalResult matchAndRewrite(vector::ConstantMaskOp mask,
PatternRewriter &rewriter) const override {
VectorType oldType = mask.getType();
VectorType newType = trimLeadingOneDims(oldType);
if (newType == oldType)
return failure();
int64_t dropDim = oldType.getRank() - newType.getRank();
ArrayRef<int64_t> dimSizes = mask.getMaskDimSizes();
// If any of the dropped unit dims has a size of `0`, the entire mask is a
// zero mask, else the unit dim has no effect on the mask.
int64_t flatLeadingSize =
std::accumulate(dimSizes.begin(), dimSizes.begin() + dropDim + 1,
static_cast<int64_t>(1), std::multiplies<int64_t>());
SmallVector<int64_t> newDimSizes = {flatLeadingSize};
newDimSizes.append(dimSizes.begin() + dropDim + 1, dimSizes.end());
auto newMask = rewriter.create<vector::ConstantMaskOp>(
mask.getLoc(), newType, newDimSizes);
rewriter.replaceOpWithNewOp<vector::BroadcastOp>(mask, oldType, newMask);
return success();
}
};
} // namespace
void mlir::vector::populateCastAwayVectorLeadingOneDimPatterns(
RewritePatternSet &patterns, PatternBenefit benefit) {
patterns
.add<CastAwayExtractStridedSliceLeadingOneDim,
CastAwayInsertStridedSliceLeadingOneDim, CastAwayInsertLeadingOneDim,
CastAwayConstantMaskLeadingOneDim, CastAwayTransferReadLeadingOneDim,
CastAwayTransferWriteLeadingOneDim, CastAwayElementwiseLeadingOneDim,
CastAwayContractionLeadingOneDim>(patterns.getContext(), benefit);
}