Charitha Saumya c577f91d26
[mlir][vector] Add support for linearizing Extract, ExtractStridedSlice, Shuffle VectorOps in VectorLinearize (#88204)
This PR adds support for converting `vector.extract_strided_slice` and
`vector.extract` operations to equivalent `vector.shuffle` operations
that operates on linearized (1-D) vectors. `vector.shuffle` operations
operating on n-D (n > 1) are also converted to equivalent shuffle
operations working on linearized vectors.
2024-04-18 21:13:49 +03:00

418 lines
17 KiB
C++

//===- VectorLinearize.cpp - vector linearization transforms --------------===//
//
// 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 patterns and pass for linearizing ND vectors into 1D.
//
//===----------------------------------------------------------------------===//
#include "mlir/Dialect/Arith/IR/Arith.h"
#include "mlir/Dialect/Vector/IR/VectorOps.h"
#include "mlir/Dialect/Vector/Transforms/VectorRewritePatterns.h"
#include "mlir/IR/Attributes.h"
#include "mlir/IR/BuiltinAttributes.h"
#include "mlir/IR/Operation.h"
#include "mlir/IR/PatternMatch.h"
#include "mlir/IR/TypeUtilities.h"
#include "mlir/Support/LogicalResult.h"
#include "mlir/Transforms/DialectConversion.h"
#include "llvm/ADT/ArrayRef.h"
#include <cstdint>
#include <numeric>
using namespace mlir;
static bool isLessThanTargetBitWidth(Operation *op, unsigned targetBitWidth) {
auto resultTypes = op->getResultTypes();
for (auto resType : resultTypes) {
VectorType vecType = dyn_cast<VectorType>(resType);
// Reject index since getElementTypeBitWidth will abort for Index types.
if (!vecType || vecType.getElementType().isIndex())
return false;
// There are no dimension to fold if it is a 0-D vector.
if (vecType.getRank() == 0)
return false;
unsigned trailingVecDimBitWidth =
vecType.getShape().back() * vecType.getElementTypeBitWidth();
if (trailingVecDimBitWidth >= targetBitWidth)
return false;
}
return true;
}
namespace {
struct LinearizeConstant final : OpConversionPattern<arith::ConstantOp> {
using OpConversionPattern::OpConversionPattern;
LinearizeConstant(
const TypeConverter &typeConverter, MLIRContext *context,
unsigned targetVectBitWidth = std::numeric_limits<unsigned>::max(),
PatternBenefit benefit = 1)
: OpConversionPattern(typeConverter, context, benefit),
targetVectorBitWidth(targetVectBitWidth) {}
LogicalResult
matchAndRewrite(arith::ConstantOp constOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Location loc = constOp.getLoc();
auto resType =
getTypeConverter()->convertType<VectorType>(constOp.getType());
if (resType.isScalable() && !isa<SplatElementsAttr>(constOp.getValue()))
return rewriter.notifyMatchFailure(
loc,
"Cannot linearize a constant scalable vector that's not a splat");
if (!resType)
return rewriter.notifyMatchFailure(loc, "can't convert return type");
if (!isLessThanTargetBitWidth(constOp, targetVectorBitWidth))
return rewriter.notifyMatchFailure(
loc, "Can't flatten since targetBitWidth <= OpSize");
auto dstElementsAttr = dyn_cast<DenseElementsAttr>(constOp.getValue());
if (!dstElementsAttr)
return rewriter.notifyMatchFailure(loc, "unsupported attr type");
dstElementsAttr = dstElementsAttr.reshape(resType);
rewriter.replaceOpWithNewOp<arith::ConstantOp>(constOp, resType,
dstElementsAttr);
return success();
}
private:
unsigned targetVectorBitWidth;
};
struct LinearizeVectorizable final
: OpTraitConversionPattern<OpTrait::Vectorizable> {
using OpTraitConversionPattern::OpTraitConversionPattern;
public:
LinearizeVectorizable(
const TypeConverter &typeConverter, MLIRContext *context,
unsigned targetVectBitWidth = std::numeric_limits<unsigned>::max(),
PatternBenefit benefit = 1)
: OpTraitConversionPattern(typeConverter, context, benefit),
targetVectorBitWidth(targetVectBitWidth) {}
LogicalResult
matchAndRewrite(Operation *op, ArrayRef<Value> operands,
ConversionPatternRewriter &rewriter) const override {
if (!isLessThanTargetBitWidth(op, targetVectorBitWidth))
return rewriter.notifyMatchFailure(
op->getLoc(), "Can't flatten since targetBitWidth <= OpSize");
FailureOr<Operation *> newOp =
convertOpResultTypes(op, operands, *getTypeConverter(), rewriter);
if (failed(newOp))
return failure();
rewriter.replaceOp(op, (*newOp)->getResults());
return success();
}
private:
unsigned targetVectorBitWidth;
};
/// This pattern converts the ExtractStridedSliceOp into a ShuffleOp that works
/// on a linearized vector.
/// Following,
/// vector.extract_strided_slice %source
/// { offsets = [..], strides = [..], sizes = [..] }
/// is converted to :
/// %source_1d = vector.shape_cast %source
/// %out_1d = vector.shuffle %source_1d, %source_1d [ shuffle_indices_1d ]
/// %out_nd = vector.shape_cast %out_1d
/// `shuffle_indices_1d` is computed using the offsets and sizes of the
/// extraction.
struct LinearizeVectorExtractStridedSlice final
: public mlir::OpConversionPattern<mlir::vector::ExtractStridedSliceOp> {
using OpConversionPattern::OpConversionPattern;
LinearizeVectorExtractStridedSlice(
const TypeConverter &typeConverter, MLIRContext *context,
unsigned targetVectBitWidth = std::numeric_limits<unsigned>::max(),
PatternBenefit benefit = 1)
: OpConversionPattern(typeConverter, context, benefit),
targetVectorBitWidth(targetVectBitWidth) {}
LogicalResult
matchAndRewrite(vector::ExtractStridedSliceOp extractOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Type dstType = getTypeConverter()->convertType(extractOp.getType());
assert(!(extractOp.getVector().getType().isScalable() ||
dstType.cast<VectorType>().isScalable()) &&
"scalable vectors are not supported.");
if (!isLessThanTargetBitWidth(extractOp, targetVectorBitWidth))
return rewriter.notifyMatchFailure(
extractOp, "Can't flatten since targetBitWidth <= OpSize");
ArrayAttr offsets = extractOp.getOffsets();
ArrayAttr sizes = extractOp.getSizes();
ArrayAttr strides = extractOp.getStrides();
if (!isConstantIntValue(strides[0], 1))
return rewriter.notifyMatchFailure(
extractOp, "Strided slice with stride != 1 is not supported.");
Value srcVector = adaptor.getVector();
// If kD offsets are specified for nD source vector (n > k), the granularity
// of the extraction is greater than 1. In this case last (n-k) dimensions
// form the extraction granularity.
// Example :
// vector.extract_strided_slice %src {
// offsets = [0, 0], sizes = [2, 2], strides = [1, 1]} :
// vector<4x8x8xf32> to vector<2x2x8xf32>
// Here, extraction granularity is 8.
int64_t extractGranularitySize = 1;
int64_t nD = extractOp.getSourceVectorType().getRank();
int64_t kD = (int64_t)offsets.size();
int64_t k = kD;
while (k < nD) {
extractGranularitySize *= extractOp.getSourceVectorType().getShape()[k];
++k;
}
// Get total number of extracted slices.
int64_t nExtractedSlices = 1;
for (Attribute size : sizes) {
nExtractedSlices *= size.cast<IntegerAttr>().getInt();
}
// Compute the strides of the source vector considering first k dimensions.
llvm::SmallVector<int64_t, 4> sourceStrides(kD, extractGranularitySize);
for (int i = kD - 2; i >= 0; --i) {
sourceStrides[i] = sourceStrides[i + 1] *
extractOp.getSourceVectorType().getShape()[i + 1];
}
// Final shuffle indices has nExtractedSlices * extractGranularitySize
// elements.
llvm::SmallVector<int64_t, 4> indices(nExtractedSlices *
extractGranularitySize);
// Compute the strides of the extracted kD vector.
llvm::SmallVector<int64_t, 4> extractedStrides(kD, 1);
// Compute extractedStrides.
for (int i = kD - 2; i >= 0; --i) {
extractedStrides[i] =
extractedStrides[i + 1] * sizes[i + 1].cast<IntegerAttr>().getInt();
}
// Iterate over all extracted slices from 0 to nExtractedSlices - 1
// and compute the multi-dimensional index and the corresponding linearized
// index within the source vector.
for (int64_t i = 0; i < nExtractedSlices; ++i) {
int64_t index = i;
// Compute the corresponding multi-dimensional index.
llvm::SmallVector<int64_t, 4> multiDimIndex(kD, 0);
for (int64_t j = 0; j < kD; ++j) {
multiDimIndex[j] = (index / extractedStrides[j]);
index -= multiDimIndex[j] * extractedStrides[j];
}
// Compute the corresponding linearized index in the source vector
// i.e. shift the multiDimIndex by the offsets.
int64_t linearizedIndex = 0;
for (int64_t j = 0; j < kD; ++j) {
linearizedIndex +=
(offsets[j].cast<IntegerAttr>().getInt() + multiDimIndex[j]) *
sourceStrides[j];
}
// Fill the indices array form linearizedIndex to linearizedIndex +
// extractGranularitySize.
for (int64_t j = 0; j < extractGranularitySize; ++j) {
indices[i * extractGranularitySize + j] = linearizedIndex + j;
}
}
// Perform a shuffle to extract the kD vector.
rewriter.replaceOpWithNewOp<vector::ShuffleOp>(
extractOp, dstType, srcVector, srcVector,
rewriter.getI64ArrayAttr(indices));
return success();
}
private:
unsigned targetVectorBitWidth;
};
/// This pattern converts the ShuffleOp that works on nD (n > 1)
/// vectors to a ShuffleOp that works on linearized vectors.
/// Following,
/// vector.shuffle %v1, %v2 [ shuffle_indices ]
/// is converted to :
/// %v1_1d = vector.shape_cast %v1
/// %v2_1d = vector.shape_cast %v2
/// %out_1d = vector.shuffle %v1_1d, %v2_1d [ shuffle_indices_1d ]
/// %out_nd = vector.shape_cast %out_1d
// `shuffle_indices_1d` is computed using the sizes and `shuffle_indices`
/// of the original shuffle operation.
struct LinearizeVectorShuffle final
: public OpConversionPattern<vector::ShuffleOp> {
using OpConversionPattern::OpConversionPattern;
LinearizeVectorShuffle(
const TypeConverter &typeConverter, MLIRContext *context,
unsigned targetVectBitWidth = std::numeric_limits<unsigned>::max(),
PatternBenefit benefit = 1)
: OpConversionPattern(typeConverter, context, benefit),
targetVectorBitWidth(targetVectBitWidth) {}
LogicalResult
matchAndRewrite(vector::ShuffleOp shuffleOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Type dstType = getTypeConverter()->convertType(shuffleOp.getType());
assert(!(shuffleOp.getV1VectorType().isScalable() ||
shuffleOp.getV2VectorType().isScalable() ||
dstType.cast<VectorType>().isScalable()) &&
"scalable vectors are not supported.");
if (!isLessThanTargetBitWidth(shuffleOp, targetVectorBitWidth))
return rewriter.notifyMatchFailure(
shuffleOp, "Can't flatten since targetBitWidth <= OpSize");
Value vec1 = adaptor.getV1();
Value vec2 = adaptor.getV2();
int shuffleSliceLen = 1;
int rank = shuffleOp.getV1().getType().getRank();
// If rank > 1, we need to do the shuffle in the granularity of slices
// instead of scalars. Size of the slice is equal to the rank-1 innermost
// dims. Mask of the shuffle op specifies which slice to take from the
// outermost dim.
if (rank > 1) {
llvm::ArrayRef<int64_t> shape = shuffleOp.getV1().getType().getShape();
for (unsigned i = 1; i < shape.size(); ++i) {
shuffleSliceLen *= shape[i];
}
}
// For each value in the mask, we generate the indices of the source vectors
// that needs to be shuffled to the destination vector. If shuffleSliceLen >
// 1 we need to shuffle the slices (consecutive shuffleSliceLen number of
// elements) instead of scalars.
ArrayAttr mask = shuffleOp.getMask();
int64_t totalSizeOfShuffledElmnts = mask.size() * shuffleSliceLen;
llvm::SmallVector<int64_t, 2> indices(totalSizeOfShuffledElmnts);
for (auto [i, value] :
llvm::enumerate(mask.getAsValueRange<IntegerAttr>())) {
int64_t v = value.getZExtValue();
std::iota(indices.begin() + shuffleSliceLen * i,
indices.begin() + shuffleSliceLen * (i + 1),
shuffleSliceLen * v);
}
rewriter.replaceOpWithNewOp<vector::ShuffleOp>(
shuffleOp, dstType, vec1, vec2, rewriter.getI64ArrayAttr(indices));
return success();
}
private:
unsigned targetVectorBitWidth;
};
/// This pattern converts the ExtractOp to a ShuffleOp that works on a
/// linearized vector.
/// Following,
/// vector.extract %source [ position ]
/// is converted to :
/// %source_1d = vector.shape_cast %source
/// %out_1d = vector.shuffle %source_1d, %source_1d [ shuffle_indices_1d ]
/// %out_nd = vector.shape_cast %out_1d
/// `shuffle_indices_1d` is computed using the position of the original extract.
struct LinearizeVectorExtract final
: public OpConversionPattern<vector::ExtractOp> {
using OpConversionPattern::OpConversionPattern;
LinearizeVectorExtract(
const TypeConverter &typeConverter, MLIRContext *context,
unsigned targetVectBitWidth = std::numeric_limits<unsigned>::max(),
PatternBenefit benefit = 1)
: OpConversionPattern(typeConverter, context, benefit),
targetVectorBitWidth(targetVectBitWidth) {}
LogicalResult
matchAndRewrite(vector::ExtractOp extractOp, OpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {
Type dstTy = getTypeConverter()->convertType(extractOp.getType());
assert(!(extractOp.getVector().getType().isScalable() ||
dstTy.cast<VectorType>().isScalable()) &&
"scalable vectors are not supported.");
if (!isLessThanTargetBitWidth(extractOp, targetVectorBitWidth))
return rewriter.notifyMatchFailure(
extractOp, "Can't flatten since targetBitWidth <= OpSize");
// Dynamic position is not supported.
if (extractOp.hasDynamicPosition())
return rewriter.notifyMatchFailure(extractOp,
"dynamic position is not supported.");
llvm::ArrayRef<int64_t> shape = extractOp.getVector().getType().getShape();
int64_t size = extractOp.getVector().getType().getNumElements();
// Compute linearized offset.
int64_t linearizedOffset = 0;
llvm::ArrayRef<int64_t> offsets = extractOp.getStaticPosition();
for (auto [i, off] : llvm::enumerate(offsets)) {
size /= shape[i];
linearizedOffset += offsets[i] * size;
}
llvm::SmallVector<int64_t, 2> indices(size);
std::iota(indices.begin(), indices.end(), linearizedOffset);
rewriter.replaceOpWithNewOp<vector::ShuffleOp>(
extractOp, dstTy, adaptor.getVector(), adaptor.getVector(),
rewriter.getI64ArrayAttr(indices));
return success();
}
private:
unsigned targetVectorBitWidth;
};
} // namespace
void mlir::vector::populateVectorLinearizeTypeConversionsAndLegality(
TypeConverter &typeConverter, RewritePatternSet &patterns,
ConversionTarget &target, unsigned targetBitWidth) {
typeConverter.addConversion([](VectorType type) -> std::optional<Type> {
if (!isLinearizableVector(type))
return type;
return VectorType::get(type.getNumElements(), type.getElementType(),
type.isScalable());
});
auto materializeCast = [](OpBuilder &builder, Type type, ValueRange inputs,
Location loc) -> Value {
if (inputs.size() != 1 || !isa<VectorType>(inputs.front().getType()) ||
!isa<VectorType>(type))
return nullptr;
return builder.create<vector::ShapeCastOp>(loc, type, inputs.front());
};
typeConverter.addArgumentMaterialization(materializeCast);
typeConverter.addSourceMaterialization(materializeCast);
typeConverter.addTargetMaterialization(materializeCast);
target.markUnknownOpDynamicallyLegal(
[=](Operation *op) -> std::optional<bool> {
if ((isa<arith::ConstantOp>(op) ||
op->hasTrait<OpTrait::Vectorizable>())) {
return (isLessThanTargetBitWidth(op, targetBitWidth)
? typeConverter.isLegal(op)
: true);
}
return std::nullopt;
});
patterns.add<LinearizeConstant, LinearizeVectorizable>(
typeConverter, patterns.getContext(), targetBitWidth);
}
void mlir::vector::populateVectorLinearizeShuffleLikeOpsPatterns(
TypeConverter &typeConverter, RewritePatternSet &patterns,
ConversionTarget &target, unsigned int targetBitWidth) {
target.addDynamicallyLegalOp<vector::ShuffleOp>(
[=](vector::ShuffleOp shuffleOp) -> bool {
return isLessThanTargetBitWidth(shuffleOp, targetBitWidth)
? (typeConverter.isLegal(shuffleOp) &&
shuffleOp.getResult()
.getType()
.cast<mlir::VectorType>()
.getRank() == 1)
: true;
});
patterns.add<LinearizeVectorShuffle, LinearizeVectorExtract,
LinearizeVectorExtractStridedSlice>(
typeConverter, patterns.getContext(), targetBitWidth);
}