Files
clang-p2996/mlir/lib/Dialect/Linalg/Transforms/DataLayoutPropagation.cpp
Hanhan Wang 0f297cad4d [mlir][tensor][linalg] Introduce DataLayoutPropagation pass.
It introduces a pattern that swaps `linalg.generic + tensor.pack` to
`tensor.pack + linalg.generic`. It requires all the iteration types
being parallel; the indexing map of output operand is identiy. They can
all be relaxed in the future.

The user can decide whether the propagation should be applied or not by
passing a control function.

Reviewed By: mravishankar

Differential Revision: https://reviews.llvm.org/D138882
2022-12-06 15:00:07 -08:00

249 lines
10 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"
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 {
/// 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.
/// 3) The indexing map of the output operand is identity.
/// If the operand is a scalar or packing dimensions are all irrelevant to the
/// operand, the opreand 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,
tensor::PackOp packOp, GenericOp genericOp,
OpOperand *opOperand) {
int numOrigLoops = genericOp.getNumLoops();
int64_t numInnerLoops = packOp.getInnerDimsPos().size();
int64_t numLoops = numOrigLoops + numInnerLoops;
AffineMap origIndexingMap = genericOp.getMatchingIndexingMap(opOperand);
SmallVector<AffineExpr> exprs(origIndexingMap.getResults());
if (genericOp.isScalar(opOperand))
return std::make_tuple(
opOperand->get(),
AffineMap::get(numLoops, 0, exprs, packOp.getContext()));
llvm::SetVector<int64_t> innerDimsPosSet(packOp.getInnerDimsPos().begin(),
packOp.getInnerDimsPos().end());
// Mapping from AffinDimExpr of indexing maps to the operand shape dimension.
DenseMap<int64_t, int64_t> iterMapToDim;
for (auto [index, expr] : llvm::enumerate(origIndexingMap.getResults())) {
int64_t dimPos = expr.cast<AffineDimExpr>().getPosition();
if (!innerDimsPosSet.contains(dimPos))
continue;
iterMapToDim[dimPos] = index;
}
// Construct the information of packing data dimensions and new indexing maps
// for the operand.
SmallVector<int64_t> innerDimsPos;
SmallVector<OpFoldResult> innerTileSizes;
for (auto [index, value] : llvm::enumerate(
llvm::zip(packOp.getInnerDimsPos(), packOp.getMixedTiles()))) {
int64_t dimPos = std::get<0>(value);
if (!iterMapToDim.count(dimPos))
continue;
innerDimsPos.push_back(iterMapToDim[dimPos]);
innerTileSizes.push_back(std::get<1>(value));
exprs.push_back(b.getAffineDimExpr(numOrigLoops + index));
}
auto indexingMap = AffineMap::get(numLoops, 0, exprs, packOp.getContext());
SmallVector<int64_t> outerDimsPerm;
for (auto outDim : packOp.getOuterDimsPerm()) {
if (!iterMapToDim.count(outDim))
continue;
outerDimsPerm.push_back(iterMapToDim[outDim]);
}
// The operand does not have dimensions that relates to pack op.
if (innerDimsPos.empty() && outerDimsPerm.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,
packOp.getPaddingValue(), outerDimsPerm);
return std::make_tuple(packedOperand, indexingMap);
}
/// 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);
// TODO: Add support for all permutation indexing maps.
if (!genericOp.getMatchingIndexingMap(opOperand).isIdentity())
return rewriter.notifyMatchFailure(
packOp, "the result of generic op does not have identity indexing_map");
Location loc = packOp.getLoc();
SmallVector<Value> inputOperands;
SmallVector<AffineMap> indexingMaps;
for (OpOperand *inputOperand : genericOp.getDpsInputOperands()) {
auto [packedOperand, packedIndexingMap] = getOrCreatePackedViewOfOperand(
rewriter, loc, packOp, genericOp, inputOperand);
inputOperands.push_back(packedOperand);
indexingMaps.push_back(packedIndexingMap);
}
int64_t numLoops = genericOp.getNumLoops();
int64_t numInnerLoops = packOp.getInnerDimsPos().size();
int64_t newNumLoops = numLoops + numInnerLoops;
SmallVector<utils::IteratorType> iterTypes =
genericOp.getIteratorTypesArray();
iterTypes.append(numInnerLoops, utils::IteratorType::parallel);
SmallVector<AffineExpr> outExprs(
genericOp.getMatchingIndexingMap(opOperand).getResults());
for (int i = 0; i < numInnerLoops; ++i)
outExprs.push_back(rewriter.getAffineDimExpr(numLoops + i));
indexingMaps.push_back(
AffineMap::get(newNumLoops, 0, outExprs, rewriter.getContext()));
auto newGenericOp = rewriter.create<linalg::GenericOp>(
loc, packOp.getDestType(), inputOperands, packOp.getDest(), indexingMaps,
iterTypes, /*bodyBuild=*/nullptr,
linalg::getPrunedAttributeList(genericOp));
rewriter.cloneRegionBefore(genericOp.getRegion(), newGenericOp.getRegion(),
newGenericOp.getRegion().begin());
return newGenericOp;
}
// 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.value().getResults());
return success();
}
};
} // namespace
void mlir::linalg::populateDataLayoutPropagationPatterns(
RewritePatternSet &patterns) {
patterns.insert<BubbleUpPackOpThroughElemGenericOpPattern>(
patterns.getContext());
}