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[MLIR][XeGPU] Distribute load_gather/store_scatter op from Wg To Sg #154420

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Merged
merged 11 commits into from
Sep 1, 2025
Merged

[MLIR][XeGPU] Distribute load_gather/store_scatter op from Wg To Sg #154420

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b94a37f
Add pattern for load_gather and store_scatter ops
nbpatel Aug 18, 2025
4f490ef
Merge branch 'main' into xegpu-scatter-ops-backup
nbpatel Aug 19, 2025
459e98a
Add tests
nbpatel Aug 19, 2025
e3c02a6
Merge branch 'main' into xegpu-scatter-ops
nbpatel Aug 22, 2025
a25c40d
Feedback
nbpatel Aug 28, 2025
bdbf14f
Cleanup
nbpatel Aug 28, 2025
c93090f
Add check
nbpatel Aug 28, 2025
a7b780d
Feedback
nbpatel Aug 29, 2025
21f1f4f
Add check
nbpatel Aug 29, 2025
73204b7
Merge branch 'main' into xegpu-scatter-ops
nbpatel Aug 29, 2025
efc211b
use updated api's for layout attr
nbpatel Aug 30, 2025
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12 changes: 12 additions & 0 deletions mlir/include/mlir/Dialect/XeGPU/IR/XeGPUOps.td
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Original file line number Diff line number Diff line change
Expand Up @@ -828,6 +828,12 @@ def XeGPU_LoadGatherOp : XeGPU_Op<"load", [MemoryEffects<[MemRead]>]> {

let builders = [
OpBuilder<(ins "Type": $value, "Value": $source, "Value": $mask,
"xegpu::CachePolicyAttr": $l1_hint,
"xegpu::CachePolicyAttr": $l2_hint,
"xegpu::CachePolicyAttr": $l3_hint)>,
OpBuilder<(ins "Type": $value, "Value": $source,
"ArrayRef<OpFoldResult>": $offsets, "Value": $mask,
"IntegerAttr": $chunk_size,
"xegpu::CachePolicyAttr": $l1_hint,
"xegpu::CachePolicyAttr": $l2_hint,
"xegpu::CachePolicyAttr": $l3_hint)>
Expand Down Expand Up @@ -936,6 +942,12 @@ def XeGPU_StoreScatterOp : XeGPU_Op<"store", [MemoryEffects<[MemWrite]>]> {

let builders = [
OpBuilder<(ins "Value": $value, "Value": $dest, "Value": $mask,
"xegpu::CachePolicyAttr": $l1_hint,
"xegpu::CachePolicyAttr": $l2_hint,
"xegpu::CachePolicyAttr": $l3_hint)>,
OpBuilder<(ins "Value": $value, "Value": $dest,
"ArrayRef<OpFoldResult>": $offsets, "Value": $mask,
"IntegerAttr": $chunk_size,
"xegpu::CachePolicyAttr": $l1_hint,
"xegpu::CachePolicyAttr": $l2_hint,
"xegpu::CachePolicyAttr": $l3_hint)>
Expand Down
34 changes: 34 additions & 0 deletions mlir/lib/Dialect/XeGPU/IR/XeGPUOps.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -796,6 +796,22 @@ void LoadGatherOp::build(OpBuilder &builder, OperationState &state,
l1_hint, l2_hint, l3_hint);
}

void LoadGatherOp::build(OpBuilder &builder, OperationState &state,
Type valueType, Value source,
ArrayRef<OpFoldResult> offsets, Value mask,
IntegerAttr chunk_size, xegpu::CachePolicyAttr l1_hint,
xegpu::CachePolicyAttr l2_hint,
xegpu::CachePolicyAttr l3_hint) {
auto loc = source.getLoc();
int64_t size = static_cast<int64_t>(offsets.size());
auto type = VectorType::get(size, builder.getIndexType());
auto values = getValueOrCreateConstantIndexOp(builder, loc, offsets);
auto offset = vector::FromElementsOp::create(builder, loc, type, values);

build(builder, state, valueType, source, offset, mask, chunk_size, l1_hint,
l2_hint, l3_hint);
}

//===----------------------------------------------------------------------===//
// XeGPU_StoreScatterOp
//===----------------------------------------------------------------------===//
Expand Down Expand Up @@ -844,6 +860,24 @@ void StoreScatterOp::build(OpBuilder &builder, OperationState &state,
l2_hint, l3_hint);
}

void StoreScatterOp::build(OpBuilder &builder, OperationState &state,
Value value, Value dest,
ArrayRef<OpFoldResult> offsets, Value mask,
IntegerAttr chunk_size,
xegpu::CachePolicyAttr l1_hint,
xegpu::CachePolicyAttr l2_hint,
xegpu::CachePolicyAttr l3_hint) {
auto loc = dest.getLoc();
int64_t size = static_cast<int64_t>(offsets.size());
auto type = VectorType::get(size, builder.getIndexType());
auto values = getValueOrCreateConstantIndexOp(builder, loc, offsets);
auto offset = vector::FromElementsOp::create(builder, loc, type, values);

// Call the correct builder overload that does not expect result types.
build(builder, state, value, dest, offset, mask, chunk_size, l1_hint, l2_hint,
l3_hint);
}

//===----------------------------------------------------------------------===//
// XeGPU_UpdateOffsetOp
//===----------------------------------------------------------------------===//
Expand Down
114 changes: 112 additions & 2 deletions mlir/lib/Dialect/XeGPU/Transforms/XeGPUWgToSgDistribute.cpp
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Expand Up @@ -763,6 +763,100 @@ struct WgToSgArithConstantOp : public OpConversionPattern<arith::ConstantOp> {
}
};

// This pattern transforms the LoadGatherOp with explicit offsets to load
// subgroup data
struct WgToSgLoadGatherOpWithOffset
: public OpConversionPattern<xegpu::LoadGatherOp> {
using OpConversionPattern<xegpu::LoadGatherOp>::OpConversionPattern;
LogicalResult
matchAndRewrite(xegpu::LoadGatherOp op, OneToNOpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {

if (!op.getOffsets())
return failure();

Location loc = op.getLoc();
VectorType resultType = op.getResult().getType();
ArrayRef<int64_t> wgShape = resultType.getShape();

xegpu::LayoutAttr layout = xegpu::getLayoutAttr(op.getResult());
if (!layout || !layout.isForWorkgroup())
return failure();

SmallVector<int64_t> sgShape = getSgShapeAndCount(wgShape, layout).first;

// The offsets need to be distributed
if (dyn_cast<VectorType>(adaptor.getOffsets().front().getType())
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@chencha3 chencha3 Aug 29, 2025

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nit: it would read better if we do dyn_cast before the if. and same for the following one.

.getShape() !=
dyn_cast<VectorType>(adaptor.getMask().front().getType()).getShape()) {
return rewriter.notifyMatchFailure(op,
"offsets have not been distributed");
}

SmallVector<Value> newLoadOps;
auto chunkSizeAttr =
rewriter.getI64IntegerAttr(op.getChunkSize().value_or(1));
VectorType newTy = VectorType::get(sgShape, resultType.getElementType());
for (auto [offsets, mask] :
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@chencha3 chencha3 Aug 22, 2025

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Nit: Here the code assums the offset has been distributed by its defining op. It is not always true currently,
e.g., the offsets is from an function parameter, or non-splat arith constant. Thus, it would be better to check
whether the offsets has been distributed yet.

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@adam-smnk adam-smnk Aug 26, 2025

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+1, could you add a test for this?

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@nbpatel nbpatel Aug 28, 2025

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with the current design, its not possible to add negative tests

llvm::zip(adaptor.getOffsets(), adaptor.getMask())) {
auto newLoadOp = rewriter.create<xegpu::LoadGatherOp>(
loc, newTy, op.getSource(), offsets, mask, chunkSizeAttr,
op.getL1HintAttr(), op.getL2HintAttr(), op.getL3HintAttr());
xegpu::setLayoutAttr(newLoadOp->getResult(0),
layout.dropSgLayoutAndData());
newLoadOps.push_back(newLoadOp);
}
rewriter.replaceOpWithMultiple(op, {newLoadOps});
return success();
}
};

// This pattern transforms the StoreScatterOp with explicit offsets to store
// subgroup data
struct WgToSgStoreScatterOpWithOffset
: public OpConversionPattern<xegpu::StoreScatterOp> {
using OpConversionPattern<xegpu::StoreScatterOp>::OpConversionPattern;
LogicalResult
matchAndRewrite(xegpu::StoreScatterOp op, OneToNOpAdaptor adaptor,
ConversionPatternRewriter &rewriter) const override {

if (!op.getOffsets())
return failure();

Location loc = op.getLoc();
VectorType valueType = dyn_cast<VectorType>(op.getValue().getType());
if (!valueType)
return failure();

xegpu::LayoutAttr layout = xegpu::getLayoutAttr(op.getValue());
if (!layout || !layout.isForWorkgroup())
return failure();

// The offsets need to be distributed
if (dyn_cast<VectorType>(adaptor.getOffsets().front().getType())
.getShape() !=
dyn_cast<VectorType>(adaptor.getMask().front().getType()).getShape()) {
return rewriter.notifyMatchFailure(op,
"offsets have not been distributed");
}

auto chunkSizeOpt = op.getChunkSize();
int64_t chunkSize = chunkSizeOpt ? static_cast<int64_t>(*chunkSizeOpt) : 1;
auto chunkSizeAttr = rewriter.getI64IntegerAttr(chunkSize);
for (auto [val, offs, mask] : llvm::zip(
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@chencha3 chencha3 Aug 22, 2025

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same check for offsets as above.

adaptor.getValue(), adaptor.getOffsets(), adaptor.getMask())) {
rewriter.create<xegpu::StoreScatterOp>(
loc, val, op.getDest(), offs, mask, chunkSizeAttr, op.getL1HintAttr(),
op.getL2HintAttr(), op.getL3HintAttr());
// Update the layout attribute to drop sg_layout and sg_data.
if (auto newLayout = layout.dropSgLayoutAndData())
op->setAttr("layout", newLayout);
}
rewriter.eraseOp(op);
return success();
}
};

struct WgToSgLoadMatrixOp : public OpConversionPattern<xegpu::LoadMatrixOp> {
using OpConversionPattern<xegpu::LoadMatrixOp>::OpConversionPattern;
LogicalResult
Expand Down Expand Up @@ -824,8 +918,9 @@ void populateXeGPUWgToSgDistributePatterns(RewritePatternSet &patterns) {
WgToSgUpdateNdOffsetOp, WgToSgDpasOp, WgToSgPrefetchNdOp,
WgToSgPrefetchNdOpWithOffset, UnrealizedConversionCastOpPattern,
WgToSgElementwiseOp, WgToSgVectorBroadcastOp, WgToSgConvertLayoutOp,
WgToSgArithConstantOp, WgToSgLoadMatrixOp, WgToSgStoreMatrixOp>(
patterns.getContext());
WgToSgArithConstantOp, WgToSgLoadGatherOpWithOffset,
WgToSgStoreScatterOpWithOffset, WgToSgLoadMatrixOp,
WgToSgStoreMatrixOp>(patterns.getContext());
}
} // namespace xegpu
} // namespace mlir
Expand Down Expand Up @@ -950,6 +1045,21 @@ void XeGPUWgToSgDistributePass::runOnOperation() {
return isLegal(xegpu::getLayoutAttr(op.getResult()));
});

target.addDynamicallyLegalOp<xegpu::LoadGatherOp>(
[=](xegpu::LoadGatherOp op) -> bool {
auto layout = xegpu::getLayoutAttr(op.getResult());
return isLegal(layout);
});

target.addDynamicallyLegalOp<xegpu::StoreScatterOp>(
[=](xegpu::StoreScatterOp op) -> bool {
// Check if the layout attribute is present on the result.
auto layout = op->getAttrOfType<xegpu::LayoutAttr>("layout");
if (!layout)
return true;
return isLegal(layout);
});

target.addDynamicallyLegalOp<vector::BroadcastOp>(
[=](vector::BroadcastOp op) -> bool {
return isLegal(xegpu::getLayoutAttr(op.getResult()));
Expand Down
44 changes: 44 additions & 0 deletions mlir/test/Dialect/XeGPU/xegpu-wg-to-sg-unify-ops.mlir
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Expand Up @@ -264,6 +264,50 @@ gpu.module @test_distribution {
gpu.return
}

// CHECK-LABEL: @load_gather
// CHECK-SAME: %[[ARG0:.*]]: memref<?xf16>
gpu.func @load_gather(%src : memref<?xf16>) {
// CHECK: %[[CST:.*]] = arith.constant dense<0> : vector<32x4xindex>
// CHECK: %[[MASK:.*]] = arith.constant dense<true> : vector<32x4xi1>
// CHECK: %[[LOAD:.*]] = xegpu.load %[[ARG0]][%[[CST]]], %[[MASK]] <{chunk_size = 1 : i64, l1_hint = #xegpu.cache_hint<cached>}>
// CHECK-SAME: : memref<?xf16>, vector<32x4xindex>, vector<32x4xi1> -> vector<32x4xf16>
%offset = arith.constant {layout_result_0 = #xegpu.layout<sg_layout = [8, 4], sg_data = [32, 4]>} dense<0> : vector<256x16xindex>
%mask = arith.constant {layout_result_0 = #xegpu.layout<sg_layout = [8, 4], sg_data = [32, 4]>} dense<1> : vector<256x16xi1>
%load = xegpu.load %src[%offset], %mask {chunk_size = 1, layout_result_0 = #xegpu.layout<sg_layout = [8, 4], sg_data = [32, 4]>, l1_hint = #xegpu.cache_hint<cached>}
: memref<?xf16>, vector<256x16xindex>, vector<256x16xi1> -> vector<256x16xf16>
gpu.return
}

// CHECK-LABEL: @store_scatter
// CHECK-SAME: %[[ARG0:.*]]: memref<256xf16>
gpu.func @store_scatter(%dest : memref<256xf16>) {
// CHECK: %[[VAL:.*]] = arith.constant dense<2.550000e+01> : vector<8xf16>
// CHECK: %[[CST:.*]] = arith.constant dense<0> : vector<8xindex>
// CHECK: %[[MASK:.*]] = arith.constant dense<true> : vector<8xi1>
// CHECK: xegpu.store %[[VAL]], %[[ARG0]][%[[CST]]], %[[MASK]] <{chunk_size = 1 : i64, l1_hint = #xegpu.cache_hint<cached>}>
// CHECK-SAME: : vector<8xf16>, memref<256xf16>, vector<8xindex>, vector<8xi1>
%val = arith.constant {layout_result_0 = #xegpu.layout<sg_layout = [32], sg_data = [8]>} dense<25.5> : vector<256xf16>
%offset = arith.constant {layout_result_0 = #xegpu.layout<sg_layout = [32], sg_data = [8]>} dense<0> : vector<256xindex>
%mask = arith.constant {layout_result_0 = #xegpu.layout<sg_layout = [32], sg_data = [8]>} dense<1> : vector<256xi1>
xegpu.store %val, %dest[%offset], %mask {chunk_size = 1, layout = #xegpu.layout<sg_layout = [32], sg_data = [8]>, l1_hint = #xegpu.cache_hint<cached>}
: vector<256xf16>, memref<256xf16>, vector<256xindex>, vector<256xi1>
gpu.return
}

// CHECK-LABEL: @load_with_non_unit_chunk_size
// CHECK-SAME: %[[ARG0:.*]]: memref<?xf16>
gpu.func @load_with_non_unit_chunk_size(%src : memref<?xf16>) {
// CHECK: %[[CST:.*]] = arith.constant dense<0> : vector<8xindex>
// CHECK: %[[MASK:.*]] = arith.constant dense<true> : vector<8xi1>
// CHECK: %[[LOAD:.*]] = xegpu.load %[[ARG0]][%[[CST]]], %[[MASK]] <{chunk_size = 4 : i64, l1_hint = #xegpu.cache_hint<cached>}>
// CHECK-SAME: : memref<?xf16>, vector<8xindex>, vector<8xi1> -> vector<8x4xf16>
%offset = arith.constant {layout_result_0 = #xegpu.layout<sg_layout = [32], sg_data = [8]>} dense<0> : vector<256xindex>
%mask = arith.constant {layout_result_0 = #xegpu.layout<sg_layout = [32], sg_data = [8]>} dense<1> : vector<256xi1>
%load = xegpu.load %src[%offset], %mask {chunk_size = 4, layout_result_0 = #xegpu.layout<sg_layout = [32, 1], sg_data = [8, 4]>, l1_hint = #xegpu.cache_hint<cached>}
: memref<?xf16>, vector<256xindex>, vector<256xi1> -> vector<256x4xf16>
gpu.return
}

// CHECK-LABEL: distribute_load_matrix
// CHECK-SAME: [[arg0:%.+]]: memref<32768xi8, 3>
gpu.func @distribute_load_matrix(%arg0: memref<32768xi8, 3>) {
Expand Down
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