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Fix CombineContractBroadcast folding reduction iterators.
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Fix CombineContractBroadcast folding reduction iterators.

Differential Revision: https://reviews.llvm.org/D128739
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@bjacob
bjacob committed Jun 29, 2022
1 parent 079c8cc commit 694ad3e
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47 changes: 46 additions & 1 deletion mlir/lib/Dialect/Vector/Transforms/VectorTransforms.cpp
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Expand Up @@ -32,6 +32,7 @@
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
Expand Down Expand Up @@ -1126,18 +1127,62 @@ struct CombineContractBroadcast
// relaxed we can remove this case.
if (innerDimBroadcast)
continue;

// It would be incorrect to fold a broadcast onto a reduction dimension
// of non-unit size.
bool nonUnitDimReductionBroadcast = false;
for (int64_t i = 0; i < rankDiff; ++i) {
if (broadcast.getVectorType().getDimSize(i) != 1 &&
isReductionIterator(contractOp.getIteratorTypes()
.getValue()[map.getDimPosition(i)])) {
nonUnitDimReductionBroadcast = true;
break;
}
}
if (nonUnitDimReductionBroadcast)
continue;

AffineMap broadcastMap =
AffineMap::get(broadcast.getVectorType().getRank(), 0, originalDims,
contractOp.getContext());
map = broadcastMap.compose(map);
*operand = broadcast.getSource();
changed = true;
}

if (!changed)
return failure();

// Determine which dims are usused, now that the maps have been composed
// with the broadcast maps.
unsigned numDims = maps[0].getNumDims();
llvm::SmallBitVector unusedDims(numDims, true);
for (const auto &m : maps) {
for (unsigned i = 0; i < numDims; ++i) {
if (m.isFunctionOfDim(i))
unusedDims.reset(i);
}
}
// Compress unused dims.
for (auto &m : maps)
m = compressDims(m, unusedDims);
// Compute the combined iterators.
SmallVector<Attribute, 4> iterators;
for (unsigned i = 0; i < numDims; ++i) {
if (!unusedDims.test(i))
iterators.push_back(contractOp.getIteratorTypes().getValue()[i]);
}
// Check that compressing unused dims isn't removing all reduction
// iterators. For example, if the vector.contract had only one reduction
// iterator and that was a unit-dimension created by a broadcast,
// then we should bail here, otherwise we would create a contract without
// a reduction iterator.
if (!llvm::any_of(iterators, isReductionIterator))
return failure();

rewriter.replaceOpWithNewOp<vector::ContractionOp>(
contractOp, lhs, rhs, contractOp.getAcc(),
rewriter.getAffineMapArrayAttr(maps), contractOp.getIteratorTypes());
rewriter.getAffineMapArrayAttr(maps), rewriter.getArrayAttr(iterators));
return success();
}
};
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92 changes: 92 additions & 0 deletions mlir/test/Dialect/Vector/vector-reduce-to-contract.mlir
View file
Expand Up @@ -86,6 +86,98 @@ func.func @contract_broadcast(
return %1 : vector<8x32xf32>
}

// -----
// Test that CombineContractBroadcast is able to combine a broadcast that
// creates a unit dim that is consumed by a reduction iterator, dropping that
// reduction iterator, as long as there is another reduction iterator left.

#map0 = affine_map<(d0, d1, d2, d3) -> (d0, d1, d3)>
#map1 = affine_map<(d0, d1, d2, d3) -> (d0, d2, d3)>
#map2 = affine_map<(d0, d1, d2, d3) -> (d1, d2)>

// CHECK-DAG: #[[$map0:.*]] = affine_map<(d0, d1, d2) -> (d0, d2)>
// CHECK-DAG: #[[$map1:.*]] = affine_map<(d0, d1, d2) -> (d1, d2)>
// CHECK-DAG: #[[$map2:.*]] = affine_map<(d0, d1, d2) -> (d0, d1)>

// CHECK-LABEL: contract_broadcast_unit_dim_reduction
// CHECK-SAME: (%[[ARG0:.+]]: vector<8x4xi32>, %[[ARG1:.+]]: vector<8x4xi32>, %[[ARG2:.+]]: vector<8x8xi32>)
// CHECK: vector.contract
// CHECK-SAME: indexing_maps = [#[[$map0]], #[[$map1]], #[[$map2]]]
// CHECK-SAME: iterator_types = ["parallel", "parallel", "reduction"]
// CHECK-SAME: %[[ARG0]], %[[ARG1]], %[[ARG2]] : vector<8x4xi32>, vector<8x4xi32> into vector<8x8xi32>
func.func @contract_broadcast_unit_dim_reduction(%arg0 : vector<8x4xi32>, %arg1 : vector<8x4xi32>, %arg2 : vector<8x8xi32>) -> vector<8x8xi32> {
%0 = vector.broadcast %arg0 : vector<8x4xi32> to vector<1x8x4xi32>
%1 = vector.broadcast %arg1 : vector<8x4xi32> to vector<1x8x4xi32>
%result = vector.contract {
indexing_maps = [#map0, #map1, #map2],
iterator_types = ["reduction", "parallel", "parallel", "reduction"],
kind = #vector.kind<add>
} %0, %1, %arg2 : vector<1x8x4xi32>, vector<1x8x4xi32> into vector<8x8xi32>
return %result : vector<8x8xi32>
}

// -----
// Test that CombineContractBroadcast will not combine a broadcast that creates
// a non-unit dim that is consumed by a reduction iterator.
// Moreover, the affine_map's are permuting the position of that reduction
// iterator with the position of a parallel iterator to ensure that
// the logic guarding that case does not mix up dimensions here.

#map0 = affine_map<(d0, d1, d2, d3) -> (d1, d0, d3)>
#map1 = affine_map<(d0, d1, d2, d3) -> (d1, d2, d3)>
#map2 = affine_map<(d0, d1, d2, d3) -> (d0, d2)>

// CHECK-DAG: #[[$map0:.*]] = affine_map<(d0, d1, d2, d3) -> (d1, d0, d3)>
// CHECK-DAG: #[[$map1:.*]] = affine_map<(d0, d1, d2, d3) -> (d1, d2, d3)>
// CHECK-DAG: #[[$map2:.*]] = affine_map<(d0, d1, d2, d3) -> (d0, d2)>

// CHECK-LABEL: contract_broadcast_non_unit_dim_reduction_with_permutation
// CHECK-SAME: (%[[ARG0:.+]]: vector<8x4xi32>, %[[ARG1:.+]]: vector<8x4xi32>, %[[ARG2:.+]]: vector<8x8xi32>)
// CHECK: %[[BROADCAST0:.+]] = vector.broadcast %[[ARG0]] : vector<8x4xi32> to vector<2x8x4xi32>
// CHECK: %[[BROADCAST1:.+]] = vector.broadcast %[[ARG1]] : vector<8x4xi32> to vector<2x8x4xi32>
// CHECK: vector.contract
// CHECK-SAME: indexing_maps = [#[[$map0]], #[[$map1]], #[[$map2]]]
// CHECK-SAME: iterator_types = ["parallel", "reduction", "parallel", "reduction"]
// CHECK-SAME: %[[BROADCAST0]], %[[BROADCAST1]], %[[ARG2]] : vector<2x8x4xi32>, vector<2x8x4xi32> into vector<8x8xi32>
func.func @contract_broadcast_non_unit_dim_reduction_with_permutation(%arg0 : vector<8x4xi32>, %arg1 : vector<8x4xi32>, %arg2 : vector<8x8xi32>) -> vector<8x8xi32> {
%0 = vector.broadcast %arg0 : vector<8x4xi32> to vector<2x8x4xi32>
%1 = vector.broadcast %arg1 : vector<8x4xi32> to vector<2x8x4xi32>
%result = vector.contract {
indexing_maps = [#map0, #map1, #map2],
iterator_types = ["parallel", "reduction", "parallel", "reduction"],
kind = #vector.kind<add>
} %0, %1, %arg2 : vector<2x8x4xi32>, vector<2x8x4xi32> into vector<8x8xi32>
return %result : vector<8x8xi32>
}

// -----

// Test that CombineContractBroadcast is not combining this case, as that would
// result in dropping this contract's only reduction iterator.

#map0 = affine_map<(d0, d1, d2) -> (d0, d1)>
#map1 = affine_map<(d0, d1, d2) -> (d0, d2)>
#map2 = affine_map<(d0, d1, d2) -> (d1, d2)>

// CHECK-LABEL: contract_broadcast_unit_dim_reduction_as_only_reduction
// CHECK-SAME: (%[[ARG0:.+]]: vector<8xi32>, %[[ARG1:.+]]: vector<8xi32>, %[[ARG2:.+]]: vector<8x8xi32>)
// CHECK: %[[BROADCAST0:.+]] = vector.broadcast %[[ARG0]] : vector<8xi32> to vector<1x8xi32>
// CHECK: %[[BROADCAST1:.+]] = vector.broadcast %[[ARG1]] : vector<8xi32> to vector<1x8xi32>
// CHECK: vector.contract
// CHECK-SAME: indexing_maps = [#[[$map0]], #[[$map1]], #[[$map2]]]
// CHECK-SAME: iterator_types = ["reduction", "parallel", "parallel"]
// CHECK-SAME: %[[BROADCAST0]], %[[BROADCAST1]], %[[ARG2]] : vector<1x8xi32>, vector<1x8xi32> into vector<8x8xi32>
func.func @contract_broadcast_unit_dim_reduction_as_only_reduction(%arg0 : vector<8xi32>, %arg1 : vector<8xi32>, %arg2 : vector<8x8xi32>) -> vector<8x8xi32> {
%0 = vector.broadcast %arg0 : vector<8xi32> to vector<1x8xi32>
%1 = vector.broadcast %arg1 : vector<8xi32> to vector<1x8xi32>
%result = vector.contract {
indexing_maps = [#map0, #map1, #map2],
iterator_types = ["reduction", "parallel", "parallel"],
kind = #vector.kind<add>
} %0, %1, %arg2 : vector<1x8xi32>, vector<1x8xi32> into vector<8x8xi32>
return %result : vector<8x8xi32>
}

//===----------------------------------------------------------------------===//
// Reorder casting ops and vector ops. The casting ops have almost identical
// pattern, so only arith.extsi op is tested.
Expand Down

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