Files
clang-p2996/mlir/lib/Dialect/Linalg/Transforms/DataLayoutPropagation.cpp
Lorenzo Chelini 30d542f9b2 [MLIR][Tensor] Introduce a pattern to propagate through tensor.pad
Introduce a pattern to 'push down' a `tensor.unpack` through a
`tensor.pad`. The propagation happens if the unpack does not touch the
padded dimensions.

Reviewed By: hanchung

Differential Revision: https://reviews.llvm.org/D143907
2023-02-15 08:48:55 +01:00

534 lines
22 KiB
C++

//===- DataLayoutPropagation.cpp -----------------------------------------===///
//
// 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/Passes.h"
#include "mlir/Dialect/Affine/IR/AffineOps.h"
#include "mlir/Dialect/Linalg/IR/Linalg.h"
#include "mlir/Dialect/Linalg/Transforms/Transforms.h"
#include "mlir/Dialect/Linalg/Utils/Utils.h"
#include "mlir/Dialect/Tensor/IR/Tensor.h"
#include "mlir/Dialect/Tensor/Utils/Utils.h"
#include "mlir/Dialect/Utils/IndexingUtils.h"
#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
#include "llvm/Support/Debug.h"
#include <optional>
namespace mlir {
#define GEN_PASS_DEF_LINALGDATALAYOUTPROPAGATION
#include "mlir/Dialect/Linalg/Passes.h.inc"
} // namespace mlir
using namespace mlir;
using namespace mlir::linalg;
#define DEBUG_TYPE "linalg-data-layout-propagation"
namespace {
// The struct contains the infomation about mapping packing information to
// the iteration domain of Linalg ops.
struct PackInfo {
int64_t getNumTiledLoops() const { return tileToPointMapping.size(); };
// InnerDimsPos on iteration domain, which follows the order in pack ops.
SmallVector<int64_t> tiledDimsPos;
// The sizes of tiling data dimensions on iteration domain.
llvm::DenseMap<int64_t, OpFoldResult> domainDimAndTileMapping;
// The mapping from a dimension of iteration domain to the corresponding inner
// tiling dimension on iteration domain.
llvm::DenseMap<int64_t, int64_t> tileToPointMapping;
// The permutation of outer dims (on domain).
SmallVector<int64_t> outerDimsOnDomainPerm;
};
template <typename OpTy>
static PackInfo getPackingInfoFromOperand(AffineMap indexingMap,
OpTy packOrUnPackOp) {
static_assert(llvm::is_one_of<OpTy, tensor::PackOp, tensor::UnPackOp>::value,
"applies to only pack or unpack operations");
LLVM_DEBUG(
{ llvm::dbgs() << "--- Construct PackInfo From an operand ---\n"; });
PackInfo packInfo;
int64_t origNumDims = indexingMap.getNumDims();
SmallVector<AffineExpr> exprs(indexingMap.getResults());
ArrayRef<int64_t> innerDimsPos = packOrUnPackOp.getInnerDimsPos();
for (auto [index, innerDimPos, tileSize] :
llvm::zip_equal(llvm::seq<unsigned>(0, innerDimsPos.size()),
innerDimsPos, packOrUnPackOp.getMixedTiles())) {
int64_t domainDimPos =
exprs[innerDimPos].template cast<AffineDimExpr>().getPosition();
packInfo.tiledDimsPos.push_back(domainDimPos);
packInfo.domainDimAndTileMapping[domainDimPos] = tileSize;
packInfo.tileToPointMapping[domainDimPos] = origNumDims + index;
LLVM_DEBUG({
llvm::dbgs() << "map innerDimPos=" << innerDimPos
<< " to iteration dimension (d" << domainDimPos << ", d"
<< packInfo.tileToPointMapping[domainDimPos]
<< "), which has size=("
<< packInfo.domainDimAndTileMapping[domainDimPos] << ")\n";
});
}
for (auto dim : packOrUnPackOp.getOuterDimsPerm())
packInfo.outerDimsOnDomainPerm.push_back(indexingMap.getDimPosition(dim));
if (!packInfo.outerDimsOnDomainPerm.empty()) {
LLVM_DEBUG({
llvm::dbgs() << "map outer dimsDimsPerm to ";
for (auto dim : packInfo.outerDimsOnDomainPerm)
llvm::dbgs() << dim << " ";
llvm::dbgs() << "\n";
});
}
return packInfo;
}
static SmallVector<int64_t> computeOuterDims(ArrayRef<int64_t> perm,
ArrayRef<AffineExpr> exprs) {
// Compute `outer_dims_perm`. See example:
// current exprs : (d0, d1, d2, d3) -> (d2, d3)
// perm : [0, 3, 1, 2]
// First map d2, d3 with their position in the array as:
// currentPositionTileLoops: dim | pos
// d2 | 0
// d3 | 1
// then scan `perm` in order and get the `outer_dims_perm`
// to be used, here it would be [1, 0].
assert(!perm.empty() && "expect perm not to be empty");
assert(!exprs.empty() && "expect exprs not to be empty");
if (exprs.size() == 1)
return {};
SmallVector<int64_t> outerDimsPerm;
DenseMap<int64_t, int64_t> currentPositionTileLoops;
for (auto [pos, expr] : llvm::enumerate(exprs)) {
unsigned posInDomain = expr.cast<AffineDimExpr>().getPosition();
currentPositionTileLoops[posInDomain] = pos;
}
for (int64_t loopIdx : perm) {
if (currentPositionTileLoops.count(loopIdx))
outerDimsPerm.push_back(currentPositionTileLoops.lookup(loopIdx));
}
return outerDimsPerm;
}
/// Returns a tuple for packed operand and indexing_map with the assumptions:
/// 1) The generic op is the producer of the pack op.
/// 2) The generic op has only one result.
/// If the operand is a scalar or packing dimensions are all irrelevant to the
/// operand, the operand and the updated indexing map will be returned.
/// Otherwise, it returns the packed operand and the updated indexing map. E.g.,
///
/// #map0 = affine_map<(d0, d1) -> (d0, d1)>
/// #map1 = affine_map<(d0, d1) -> (d0)>
/// #map2 = affine_map<(d0, d1) -> (d1)>
/// %0 = linalg.generic {indexing_maps = [#map1, #map2, #map0],
/// iterator_types = ["parallel", "parallel"]}
/// ins(%arg0, %arg1 : tensor<?xf32>, tensor<?xf32>)
/// outs(%init : tensor<?x?xf32>) {
/// ^bb0(%arg3: f32, %arg4: f32, %arg5: f32):
/// %4 = arith.addf %arg3, %arg4 : f32
/// linalg.yield %4 : f32
/// } -> tensor<?x?xf32>
/// %1 = tensor.pack %0
/// inner_dims_pos = [0, 1]
/// inner_tiles = [8, 2]
/// into %dest : tensor<?x?xf32> -> tensor<?x?x8x2xf32>
///
/// Taking the first input operand as an example, the inner tile size of d1 is
/// 8. Thus, the below operation and `affine_map<(d0, d1, d2, d3)> ->
/// affine_map<(d1, d3)>` will be returned.
///
/// %pack = tensor.pack %arg0
/// inner_dims_pos = [0]
/// inner_tiles = [8]
/// into %init : tensor<?xf32> -> tensor<?x8xf32>
static std::tuple<Value, AffineMap>
getOrCreatePackedViewOfOperand(OpBuilder &b, Location loc, PackInfo packInfo,
GenericOp genericOp, OpOperand *opOperand) {
int64_t numOrigLoops = genericOp.getNumLoops();
int64_t numInnerLoops = packInfo.getNumTiledLoops();
int64_t numLoops = numOrigLoops + numInnerLoops;
AffineMap origIndexingMap = genericOp.getMatchingIndexingMap(opOperand);
llvm::DenseMap<int64_t, int64_t> domainDimToOperandDim;
SmallVector<AffineExpr> exprs(origIndexingMap.getResults());
if (genericOp.isScalar(opOperand))
return std::make_tuple(opOperand->get(),
AffineMap::get(numLoops, 0, exprs, b.getContext()));
// Step 1. Construct the information of packing data dimensions; append inner
// dimensions to the indexing maps for the operand.
for (auto [index, expr] : llvm::enumerate(exprs)) {
int64_t dimPos = expr.cast<AffineDimExpr>().getPosition();
domainDimToOperandDim[dimPos] = index;
}
SmallVector<int64_t> innerDimsPos;
SmallVector<OpFoldResult> innerTileSizes;
for (auto dimPos : packInfo.tiledDimsPos) {
if (!domainDimToOperandDim.count(dimPos))
continue;
int64_t index = domainDimToOperandDim[dimPos];
innerTileSizes.push_back(packInfo.domainDimAndTileMapping[dimPos]);
innerDimsPos.push_back(index);
exprs.push_back(b.getAffineDimExpr(packInfo.tileToPointMapping[dimPos]));
}
// Step 2. Handle outer dim permutations.
SmallVector<int64_t> outerDimsPerm;
if (!packInfo.outerDimsOnDomainPerm.empty()) {
outerDimsPerm = computeOuterDims(packInfo.outerDimsOnDomainPerm, exprs);
// Step 2.1: Fold transpose into the linalg.generic.
SmallVector<int64_t> inversedOuterPerm =
invertPermutationVector(packInfo.outerDimsOnDomainPerm);
for (auto i : llvm::seq<unsigned>(0, origIndexingMap.getNumResults())) {
int64_t dimPos = exprs[i].cast<AffineDimExpr>().getPosition();
exprs[i] = b.getAffineDimExpr(inversedOuterPerm[dimPos]);
}
// Step 2.2: Undo the transposition on `exprs` and propagate the
// transposition on the pack using outerDimsPerm.
if (!outerDimsPerm.empty()) {
SmallVector<AffineExpr> auxVec = exprs;
for (const auto &en : enumerate(outerDimsPerm))
auxVec[en.index()] = exprs[en.value()];
exprs = auxVec;
}
}
auto indexingMap = AffineMap::get(numLoops, 0, exprs, b.getContext());
// The operand does not have dimensions that relates to pack op.
if (innerDimsPos.empty())
return std::make_tuple(opOperand->get(), indexingMap);
auto empty = tensor::PackOp::createDestinationTensor(
b, loc, opOperand->get(), innerTileSizes, innerDimsPos, outerDimsPerm);
auto packedOperand = b.create<tensor::PackOp>(
loc, opOperand->get(), empty, innerDimsPos, innerTileSizes,
/*padding=*/std::nullopt, outerDimsPerm);
return std::make_tuple(packedOperand, indexingMap);
}
/// Pack an element-wise genericOp and return it.
static GenericOp packElementWiseOp(RewriterBase &rewriter, GenericOp genericOp,
Value dest, AffineMap packedOutIndexingMap,
const PackInfo &packInfo) {
Location loc = genericOp.getLoc();
SmallVector<Value> inputOperands;
SmallVector<AffineMap> indexingMaps;
for (OpOperand *inputOperand : genericOp.getDpsInputOperands()) {
auto [packedOperand, packedIndexingMap] = getOrCreatePackedViewOfOperand(
rewriter, loc, packInfo, genericOp, inputOperand);
inputOperands.push_back(packedOperand);
indexingMaps.push_back(packedIndexingMap);
}
int64_t numInnerLoops = packInfo.getNumTiledLoops();
SmallVector<utils::IteratorType> iterTypes =
genericOp.getIteratorTypesArray();
iterTypes.append(numInnerLoops, utils::IteratorType::parallel);
indexingMaps.push_back(packedOutIndexingMap);
auto newGenericOp = rewriter.create<linalg::GenericOp>(
loc, dest.getType(), inputOperands, dest, indexingMaps, iterTypes,
/*bodyBuild=*/nullptr, linalg::getPrunedAttributeList(genericOp));
rewriter.cloneRegionBefore(genericOp.getRegion(), newGenericOp.getRegion(),
newGenericOp.getRegion().begin());
return newGenericOp;
}
/// Bubbles up tensor.pack op through elementwise generic op. This
/// swap pack(generic) to generic(pack). The new generic op works on packed
/// domain; pack ops are created for input and output operands. E.g.,
///
/// #map0 = affine_map<(d0, d1) -> (d0, d1)>
/// %0 = tensor.dim %arg0, %c0 : tensor<?x?xf32>
/// %1 = tensor.dim %arg0, %c1 : tensor<?x?xf32>
/// %2 = tensor.empty(%0, %1) : tensor<?x?xf32>
/// %3 = linalg.generic {indexing_maps = [#map0, #map0],
/// iterator_types = ["parallel", "parallel"]}
/// ins(%arg0 : tensor<?x?xf32>)
/// outs(%2 : tensor<?x?xf32>) {
/// ^bb0(%arg3: f32, %arg4: f32):
/// %4 = arith.addf %arg3, %arg3 : f32
/// linalg.yield %4 : f32
/// } -> tensor<?x?xf32>
/// %4 = tensor.pack %3
/// inner_dims_pos = [0, 1]
/// inner_tiles = [8, 2]
/// into %dest : tensor<?x?xf32> -> tensor<?x?x8x2xf32>
///
/// will be converted to
///
/// #map = affine_map<()[s0] -> (s0 ceildiv 8)>
/// #map1 = affine_map<()[s0] -> (s0 ceildiv 2)>
/// #map2 = affine_map<(d0, d1, d2, d3) -> (d0, d1, d2, d3)>
/// %dim = tensor.dim %arg0, %c0 : tensor<?x?xf32>
/// %dim_0 = tensor.dim %arg0, %c1 : tensor<?x?xf32>
/// %0 = affine.apply #map()[%dim]
/// %1 = affine.apply #map1()[%dim_0]
/// %2 = tensor.empty(%0, %1) : tensor<?x?x8x2xf32>
/// %pack = tensor.pack %arg0
/// inner_dims_pos = [0, 1]
/// inner_tiles = [8, 2]
/// into %2 : tensor<?x?xf32> -> tensor<?x?x8x2xf32>
/// %3 = linalg.generic {indexing_maps = [#map2, #map2],
/// iterator_types = ["parallel", "parallel", "parallel", "parallel"]}
/// ins(%pack : tensor<?x?x8x2xf32>)
/// outs(%arg1 : tensor<?x?x8x2xf32>) {
/// ^bb0(%in: f32, %out: f32):
/// %4 = arith.addf %in, %in : f32
/// linalg.yield %4 : f32
/// } -> tensor<?x?x8x2xf32>
static FailureOr<GenericOp>
bubbleUpPackOpThroughElemGenericOp(RewriterBase &rewriter,
tensor::PackOp packOp) {
auto genericOp = packOp.getSource().getDefiningOp<GenericOp>();
if (!genericOp)
return failure();
if (!isElementwise(genericOp))
return failure();
// TODO: Relax the restriction. We are able to bubble up the pack op through
// multi-result generic op. It just needs more work.
if (genericOp.getNumResults() != 1)
return failure();
// TODO: Add an option for allowing padding values. It could introduce
// undefined behavior if we unconditionally propagate pack op through all
// the ops. E.g., if the padding value is zero and there are division ops in
// a generic op. Some values of padding area could be NaN (0/0).
if (packOp.getPaddingValue())
return failure();
OpOperand *opOperand = genericOp.getDpsInitOperand(0);
auto packInfo = getPackingInfoFromOperand(
genericOp.getMatchingIndexingMap(opOperand), packOp);
// Rebuild the indexing map for the corresponding init operand.
auto [packedOutOperand, packedOutIndexingMap] =
getOrCreatePackedViewOfOperand(rewriter, genericOp.getLoc(), packInfo,
genericOp, opOperand);
// We'll replace the init operand with the destination of pack op if the init
// operand has not users in the body of the linalg.generic (pure elementwise).
// If it has users we need to pack the init operand too and replace the init
// with the packing result.
Value dest = (genericOp.getRegionOutputArgs()[0].use_empty())
? packOp.getDest()
: packedOutOperand;
return packElementWiseOp(rewriter, genericOp, dest, packedOutIndexingMap,
packInfo);
}
/// Wrapper pattern that applies bubbleUpPackOpThroughElemGenericOp method.
struct BubbleUpPackOpThroughElemGenericOpPattern
: public OpRewritePattern<tensor::PackOp> {
using OpRewritePattern<tensor::PackOp>::OpRewritePattern;
LogicalResult matchAndRewrite(tensor::PackOp packOp,
PatternRewriter &rewriter) const override {
auto genericOp = bubbleUpPackOpThroughElemGenericOp(rewriter, packOp);
if (failed(genericOp))
return failure();
rewriter.replaceOp(packOp, genericOp->getResults());
return success();
}
};
// TODO: Relax this restriction. We should unpack an elementwise also
// in the presence of multiple unpack ops as producers.
/// Return the unpacked operand, if present, for the current generic op.
static FailureOr<OpOperand *> getUnPackedOperand(GenericOp genericOp) {
OpOperand *unPackedOperand = nullptr;
for (OpOperand &operand : genericOp->getOpOperands()) {
auto unPackOp = operand.get().getDefiningOp<tensor::UnPackOp>();
if (!unPackOp)
continue;
if (unPackedOperand)
return failure();
unPackedOperand = &operand;
}
if (!unPackedOperand)
return failure();
return unPackedOperand;
}
/// Push down a tensor.unpack op through elementwise generic op.
/// The new generic op works on packed domain; pack ops are created for input
/// and output operands. A tensor.unpack op is inserted right after the packed
/// generic. E.g.
///
/// #map = affine_map<(d0, d1, d2, d3) -> (d0, d1, d2, d3)>
///
/// %arg0 = tensor<12x2x56x56x32xf32> // packed arg.
///
/// %0 = tensor.empty() : tensor<12x56x56x64xf32>
/// %1 = tensor.unpack %arg0 outer_dims_perm = [0, 3, 1, 2]
/// inner_dims_pos = [3] inner_tiles = [32] into %0
/// %2 = linalg.generic {indexing_maps = [#map],
/// iterator_types = ["parallel", "parallel", "parallel", "parallel"]}
/// outs(%1 : tensor<12x56x56x64xf32>) {
/// ^bb0(%out : f32):
/// linalg.yield %out : f32
/// } -> tensor<12x56x56x64xf32>
///
/// will be converted to
///
/// #map = affine_map<(d0, d1, d2, d3, d4) -> (d0, d1, d2, d3, d4)>
///
/// %0 = tensor.empty() : tensor<12x56x56x64xf32>
/// %1 = linalg.generic {indexing_maps = [#map],
/// iterator_types = ["parallel", "parallel", "parallel",
/// "parallel", "parallel"]}
/// outs(%arg0 : tensor<12x2x56x56x32xf32>) {
/// ^bb0(%out : f32):
/// linalg.yield %out : f32
/// } -> tensor<12x2x56x56x32xf32>
/// %2 = tensor.unpack %1 outer_dims_perm = [0, 3, 1, 2]
/// inner_dims_pos = [3] inner_tiles = [32] into %0
///
static FailureOr<std::tuple<GenericOp, Value>>
pushDownUnPackOpThroughElemGenericOp(RewriterBase &rewriter,
GenericOp genericOp) {
if (!isElementwise(genericOp))
return failure();
if (genericOp.getNumResults() != 1)
return failure();
// Collect the unPacked operand, if present.
auto maybeUnPackedOperand = getUnPackedOperand(genericOp);
if (failed(maybeUnPackedOperand))
return failure();
OpOperand *unPackedOperand = *(maybeUnPackedOperand);
// Extract packing information.
tensor::UnPackOp producerUnPackOp =
unPackedOperand->get().getDefiningOp<tensor::UnPackOp>();
assert(producerUnPackOp && "expect a valid UnPackOp");
auto packInfo = getPackingInfoFromOperand(
genericOp.getMatchingIndexingMap(unPackedOperand), producerUnPackOp);
// Rebuild the indexing map for the corresponding init operand.
auto [packedOutOperand, packedOutIndexingMap] =
getOrCreatePackedViewOfOperand(rewriter, genericOp.getLoc(), packInfo,
genericOp, genericOp.getDpsInitOperand(0));
// If the dps init operand of the generic is a tensor.empty, do not pack it
// and forward the new tensor.empty as a destination.
Value dest = packedOutOperand;
if (auto initTensor = genericOp.getDpsInitOperand(0)
->get()
.getDefiningOp<tensor::EmptyOp>()) {
if (auto packOp = packedOutOperand.getDefiningOp<tensor::PackOp>())
dest = packOp.getDest();
}
// Pack the genericOp.
GenericOp newGenericOp = packElementWiseOp(rewriter, genericOp, dest,
packedOutIndexingMap, packInfo);
auto unPackOp = unPackedOperand->get().getDefiningOp<tensor::UnPackOp>();
// Insert an unPackOp right after the packed generic.
Value unPackOpRes =
rewriter
.create<tensor::UnPackOp>(
genericOp.getLoc(),
newGenericOp.getTiedOpResult(newGenericOp.getDpsInitOperand(0)),
unPackOp.getDest(), producerUnPackOp.getInnerDimsPos(),
producerUnPackOp.getMixedTiles(),
producerUnPackOp.getOuterDimsPerm())
.getResult();
return std::make_tuple(newGenericOp, unPackOpRes);
}
// Wrapper pattern that applies pushDownUnPackOpThroughElemGenericOp method.
struct PushDownUnPackOpThroughElemGenericOp
: public OpRewritePattern<GenericOp> {
using OpRewritePattern<GenericOp>::OpRewritePattern;
LogicalResult matchAndRewrite(GenericOp genericOp,
PatternRewriter &rewriter) const override {
auto genericAndRepl =
pushDownUnPackOpThroughElemGenericOp(rewriter, genericOp);
if (failed(genericAndRepl))
return failure();
rewriter.replaceOp(genericOp, std::get<1>(*genericAndRepl));
return success();
}
};
/// Propagate a tensor.unpack operation through a tensor.pad. The idea is to
/// add as many zero padding dimensions in `high` and `low` based on the number
/// of point loops.
struct PushDownUnPackThroughPadOp : public OpRewritePattern<tensor::PadOp> {
using OpRewritePattern<tensor::PadOp>::OpRewritePattern;
LogicalResult matchAndRewrite(tensor::PadOp padOp,
PatternRewriter &rewriter) const override {
tensor::UnPackOp unpackOp =
padOp.getSource().getDefiningOp<tensor::UnPackOp>();
if (!unpackOp)
return failure();
Location loc = padOp.getLoc();
// Bail out if one of the padded dimension is a tiled one.
llvm::SmallBitVector paddedDims = padOp.getPaddedDims();
ArrayRef<int64_t> innerDimsPos = unpackOp.getInnerDimsPos();
llvm::SmallBitVector innerDims(paddedDims.size());
for (int64_t dim : innerDimsPos)
innerDims.flip(dim);
if (paddedDims.anyCommon(innerDims))
return failure();
Value paddingVal = padOp.getConstantPaddingValue();
if (!paddingVal)
return failure();
// If we have `outer_dims_perms` we need to adjust the padded dimensions.
ArrayRef<int64_t> outerDimsPerm = unpackOp.getOuterDimsPerm();
SmallVector<OpFoldResult> lowPad = padOp.getMixedLowPad();
SmallVector<OpFoldResult> highPad = padOp.getMixedHighPad();
if (!outerDimsPerm.empty()) {
applyPermutationToVector<OpFoldResult>(lowPad, outerDimsPerm);
applyPermutationToVector<OpFoldResult>(highPad, outerDimsPerm);
}
// Add zero padding for the point loops.
size_t pointLoopsSize = innerDimsPos.size();
lowPad.append(pointLoopsSize, rewriter.getIndexAttr(0));
highPad.append(pointLoopsSize, rewriter.getIndexAttr(0));
auto newPadOp = rewriter.create<tensor::PadOp>(
loc, /*result=*/Type(), unpackOp.getSource(), lowPad, highPad,
paddingVal, padOp.getNofold());
// Inject the tensor.unpack right after the packed padOp.
Value outputUnPack = rewriter.create<tensor::EmptyOp>(
loc, padOp.getResultType().getShape(),
padOp.getResultType().getElementType());
Value replacement = rewriter.create<tensor::UnPackOp>(
loc, newPadOp.getResult(), outputUnPack, innerDimsPos,
unpackOp.getMixedTiles(), outerDimsPerm);
rewriter.replaceOp(padOp, replacement);
return success();
}
};
} // namespace
void mlir::linalg::populateDataLayoutPropagationPatterns(
RewritePatternSet &patterns) {
patterns
.insert<BubbleUpPackOpThroughElemGenericOpPattern,
PushDownUnPackOpThroughElemGenericOp, PushDownUnPackThroughPadOp>(
patterns.getContext());
}