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[MLIR][Vector] Extend elementwise pattern to support unrolling from higher rank to lower rank #162515

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[MLIR][Vector] Extend elementwise pattern to support unrolling from higher rank to lower rank #162515

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f854b2d
Extend elementwise to support unrolling from higher rank to lower rank
nbpatel Oct 8, 2025
01357d9
remove reshape before insertStride
nbpatel Oct 9, 2025
d59390b
Unused variable
nbpatel Oct 9, 2025
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49 changes: 35 additions & 14 deletions mlir/lib/Dialect/Vector/Transforms/VectorUnroll.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -468,38 +468,59 @@ struct UnrollElementwisePattern : public RewritePattern {
auto dstVecType = cast<VectorType>(op->getResult(0).getType());
SmallVector<int64_t> originalSize =
*cast<VectorUnrollOpInterface>(op).getShapeForUnroll();
// Bail-out if rank(source) != rank(target). The main limitation here is the
// fact that `ExtractStridedSlice` requires the rank for the input and
// output to match. If needed, we can relax this later.
if (originalSize.size() != targetShape->size())
return rewriter.notifyMatchFailure(
op, "expected input vector rank to match target shape rank");

Location loc = op->getLoc();

// Handle rank mismatch by adding leading unit dimensions to targetShape
SmallVector<int64_t> adjustedTargetShape = *targetShape;
if (originalSize.size() > targetShape->size()) {
// Add leading unit dimensions to targetShape
int64_t rankDiff = originalSize.size() - targetShape->size();
adjustedTargetShape.insert(adjustedTargetShape.begin(), rankDiff, 1);
}

// Prepare the result vector.
Value result = arith::ConstantOp::create(rewriter, loc, dstVecType,
rewriter.getZeroAttr(dstVecType));
SmallVector<int64_t> strides(targetShape->size(), 1);
VectorType newVecType =
SmallVector<int64_t> strides(adjustedTargetShape.size(), 1);
VectorType computeVecType =
VectorType::get(*targetShape, dstVecType.getElementType());

// Create the unrolled computation.
for (SmallVector<int64_t> offsets :
StaticTileOffsetRange(originalSize, *targetShape)) {
StaticTileOffsetRange(originalSize, adjustedTargetShape)) {
SmallVector<Value> extractOperands;
for (OpOperand &operand : op->getOpOperands()) {
auto vecType = dyn_cast<VectorType>(operand.get().getType());
if (!vecType) {
extractOperands.push_back(operand.get());
continue;
}
extractOperands.push_back(
rewriter.createOrFold<vector::ExtractStridedSliceOp>(
loc, operand.get(), offsets, *targetShape, strides));
Value extracted = rewriter.createOrFold<vector::ExtractStridedSliceOp>(
loc, operand.get(), offsets, adjustedTargetShape, strides);

// Reshape to remove leading unit dims if needed
if (adjustedTargetShape.size() > targetShape->size()) {
extracted = rewriter.createOrFold<vector::ShapeCastOp>(
loc, VectorType::get(*targetShape, vecType.getElementType()),
extracted);
}
extractOperands.push_back(extracted);
}

Operation *newOp = cloneOpWithOperandsAndTypes(
rewriter, loc, op, extractOperands, newVecType);
rewriter, loc, op, extractOperands, computeVecType);

Value computeResult = newOp->getResult(0);

// Use strides sized to targetShape for proper insertion
SmallVector<int64_t> insertStrides =
(adjustedTargetShape.size() > targetShape->size())
? SmallVector<int64_t>(targetShape->size(), 1)
: strides;

result = rewriter.createOrFold<vector::InsertStridedSliceOp>(
loc, newOp->getResult(0), result, offsets, strides);
loc, computeResult, result, offsets, insertStrides);
}
rewriter.replaceOp(op, result);
return success();
Expand Down
55 changes: 49 additions & 6 deletions mlir/test/Dialect/Vector/vector-unroll-options.mlir
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Original file line number Diff line number Diff line change
Expand Up @@ -188,15 +188,37 @@ func.func @vector_fma(%a: vector<4x4xf32>, %b: vector<4x4xf32>, %c: vector<4x4xf
// CHECK-LABEL: func @vector_fma
// CHECK-COUNT-4: vector.fma %{{.+}}, %{{.+}}, %{{.+}} : vector<2x2xf32>

// TODO: We should be able to unroll this like the example above - this will require extending UnrollElementwisePattern.
func.func @negative_vector_fma_3d(%a: vector<3x2x2xf32>) -> vector<3x2x2xf32>{
func.func @vector_fma_3d(%a: vector<3x2x2xf32>) -> vector<3x2x2xf32>{
%0 = vector.fma %a, %a, %a : vector<3x2x2xf32>
return %0 : vector<3x2x2xf32>
}
// CHECK-LABEL: func @negative_vector_fma_3d
// CHECK-NOT: vector.extract_strided_slice
// CHECK: %[[R0:.*]] = vector.fma %{{.+}} : vector<3x2x2xf32>
// CHECK: return
// CHECK-LABEL: func @vector_fma_3d
// CHECK: %[[CST:.*]] = arith.constant dense<0.000000e+00> : vector<3x2x2xf32>
// CHECK: %[[E0:.*]] = vector.extract_strided_slice %{{.*}} {offsets = [0, 0, 0], sizes = [1, 2, 2], strides = [1, 1, 1]} : vector<3x2x2xf32> to vector<1x2x2xf32>
// CHECK: %[[S0:.*]] = vector.shape_cast %[[E0]] : vector<1x2x2xf32> to vector<2x2xf32>
// CHECK: %[[E1:.*]] = vector.extract_strided_slice %{{.*}} {offsets = [0, 0, 0], sizes = [1, 2, 2], strides = [1, 1, 1]} : vector<3x2x2xf32> to vector<1x2x2xf32>
// CHECK: %[[S1:.*]] = vector.shape_cast %[[E1]] : vector<1x2x2xf32> to vector<2x2xf32>
// CHECK: %[[E2:.*]] = vector.extract_strided_slice %{{.*}} {offsets = [0, 0, 0], sizes = [1, 2, 2], strides = [1, 1, 1]} : vector<3x2x2xf32> to vector<1x2x2xf32>
// CHECK: %[[S2:.*]] = vector.shape_cast %[[E2]] : vector<1x2x2xf32> to vector<2x2xf32>
// CHECK: %[[FMA0:.*]] = vector.fma %[[S0]], %[[S1]], %[[S2]] : vector<2x2xf32>
// CHECK: %[[I0:.*]] = vector.insert_strided_slice %[[FMA0]], %[[CST]] {offsets = [0, 0, 0], strides = [1, 1]} : vector<2x2xf32> into vector<3x2x2xf32>
// CHECK: %[[E3:.*]] = vector.extract_strided_slice %{{.*}} {offsets = [1, 0, 0], sizes = [1, 2, 2], strides = [1, 1, 1]} : vector<3x2x2xf32> to vector<1x2x2xf32>
// CHECK: %[[S3:.*]] = vector.shape_cast %[[E3]] : vector<1x2x2xf32> to vector<2x2xf32>
// CHECK: %[[E4:.*]] = vector.extract_strided_slice %{{.*}} {offsets = [1, 0, 0], sizes = [1, 2, 2], strides = [1, 1, 1]} : vector<3x2x2xf32> to vector<1x2x2xf32>
// CHECK: %[[S4:.*]] = vector.shape_cast %[[E4]] : vector<1x2x2xf32> to vector<2x2xf32>
// CHECK: %[[E5:.*]] = vector.extract_strided_slice %{{.*}} {offsets = [1, 0, 0], sizes = [1, 2, 2], strides = [1, 1, 1]} : vector<3x2x2xf32> to vector<1x2x2xf32>
// CHECK: %[[S5:.*]] = vector.shape_cast %[[E5]] : vector<1x2x2xf32> to vector<2x2xf32>
// CHECK: %[[FMA1:.*]] = vector.fma %[[S3]], %[[S4]], %[[S5]] : vector<2x2xf32>
// CHECK: %[[I1:.*]] = vector.insert_strided_slice %[[FMA1]], %[[I0]] {offsets = [1, 0, 0], strides = [1, 1]} : vector<2x2xf32> into vector<3x2x2xf32>
// CHECK: %[[E6:.*]] = vector.extract_strided_slice %{{.*}} {offsets = [2, 0, 0], sizes = [1, 2, 2], strides = [1, 1, 1]} : vector<3x2x2xf32> to vector<1x2x2xf32>
// CHECK: %[[S6:.*]] = vector.shape_cast %[[E6]] : vector<1x2x2xf32> to vector<2x2xf32>
// CHECK: %[[E7:.*]] = vector.extract_strided_slice %{{.*}} {offsets = [2, 0, 0], sizes = [1, 2, 2], strides = [1, 1, 1]} : vector<3x2x2xf32> to vector<1x2x2xf32>
// CHECK: %[[S7:.*]] = vector.shape_cast %[[E7]] : vector<1x2x2xf32> to vector<2x2xf32>
// CHECK: %[[E8:.*]] = vector.extract_strided_slice %{{.*}} {offsets = [2, 0, 0], sizes = [1, 2, 2], strides = [1, 1, 1]} : vector<3x2x2xf32> to vector<1x2x2xf32>
// CHECK: %[[S8:.*]] = vector.shape_cast %[[E8]] : vector<1x2x2xf32> to vector<2x2xf32>
// CHECK: %[[FMA2:.*]] = vector.fma %[[S6]], %[[S7]], %[[S8]] : vector<2x2xf32>
// CHECK: %[[I2:.*]] = vector.insert_strided_slice %[[FMA2]], %[[I1]] {offsets = [2, 0, 0], strides = [1, 1]} : vector<2x2xf32> into vector<3x2x2xf32>
// CHECK: return %[[I2]] : vector<3x2x2xf32>

func.func @vector_multi_reduction(%v : vector<4x6xf32>, %acc: vector<4xf32>) -> vector<4xf32> {
%0 = vector.multi_reduction #vector.kind<add>, %v, %acc [1] : vector<4x6xf32> to vector<4xf32>
Expand Down Expand Up @@ -440,3 +462,24 @@ func.func @vector_step() -> vector<32xindex> {
// CHECK: %[[ADD3:.*]] = arith.addi %[[STEP]], %[[CST]] : vector<8xindex>
// CHECK: %[[INS3:.*]] = vector.insert_strided_slice %[[ADD3]], %[[INS2]] {offsets = [24], strides = [1]} : vector<8xindex> into vector<32xindex>
// CHECK: return %[[INS3]] : vector<32xindex>


func.func @elementwise(%v1: vector<2x2x2xf32>, %v2: vector<2x2x2xf32>) -> vector<2x2x2xf32> {
%0 = arith.addf %v1, %v2 : vector<2x2x2xf32>
return %0 : vector<2x2x2xf32>
}
// CHECK-LABEL: func @elementwise
// CHECK: %[[CST:.*]] = arith.constant dense<0.000000e+00> : vector<2x2x2xf32>
// CHECK: %[[E0:.*]] = vector.extract_strided_slice %{{.*}} {offsets = [0, 0, 0], sizes = [1, 2, 2], strides = [1, 1, 1]} : vector<2x2x2xf32> to vector<1x2x2xf32>
// CHECK: %[[S0:.*]] = vector.shape_cast %[[E0]] : vector<1x2x2xf32> to vector<2x2xf32>
// CHECK: %[[E1:.*]] = vector.extract_strided_slice %{{.*}} {offsets = [0, 0, 0], sizes = [1, 2, 2], strides = [1, 1, 1]} : vector<2x2x2xf32> to vector<1x2x2xf32>
// CHECK: %[[S1:.*]] = vector.shape_cast %[[E1]] : vector<1x2x2xf32> to vector<2x2xf32>
// CHECK: %[[ADD0:.*]] = arith.addf %[[S0]], %[[S1]] : vector<2x2xf32>
// CHECK: %[[I0:.*]] = vector.insert_strided_slice %[[ADD0]], %[[CST]] {offsets = [0, 0, 0], strides = [1, 1]} : vector<2x2xf32> into vector<2x2x2xf32>
// CHECK: %[[E2:.*]] = vector.extract_strided_slice %{{.*}} {offsets = [1, 0, 0], sizes = [1, 2, 2], strides = [1, 1, 1]} : vector<2x2x2xf32> to vector<1x2x2xf32>
// CHECK: %[[S2:.*]] = vector.shape_cast %[[E2]] : vector<1x2x2xf32> to vector<2x2xf32>
// CHECK: %[[E3:.*]] = vector.extract_strided_slice %{{.*}} {offsets = [1, 0, 0], sizes = [1, 2, 2], strides = [1, 1, 1]} : vector<2x2x2xf32> to vector<1x2x2xf32>
// CHECK: %[[S3:.*]] = vector.shape_cast %[[E3]] : vector<1x2x2xf32> to vector<2x2xf32>
// CHECK: %[[ADD1:.*]] = arith.addf %[[S2]], %[[S3]] : vector<2x2xf32>
// CHECK: %[[I1:.*]] = vector.insert_strided_slice %[[ADD1]], %[[I0]] {offsets = [1, 0, 0], strides = [1, 1]} : vector<2x2xf32> into vector<2x2x2xf32>
// CHECK: return %[[I1]] : vector<2x2x2xf32>