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[mlir][mesh] Add TableGen deffinitions of more collective ops (#73842)
Add definitions for broadcast, gather, receive, reduce, scatter, send and shift.
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‎mlir/docs/Dialects/Mesh.md‎

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@@ -15,14 +15,17 @@ explanation.
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The main addition is that the collectives in this dialect have mesh
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semantics.
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### Device groups
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The operation attributes `mesh` and `mesh_axes` specifies a list of device mesh
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axes that partition the devices into disjoint groups.
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The collective operation is performed between devices in the same group.
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Devices that have the same coordinates outside of axes `mesh_axes` are in the
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same group.
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A group is described by its multi-index along the axes outside of `mesh_axes`.
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For example if we have a device mesh of size `2x3x4x5` and the partition mesh
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axes list is `[0, 1]` then devices are partitioned into the groups
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`{ { (i, j, k, m) | 0<=i<2, 0<=j<3 } | 0<=k<4, 0<=m<5 }`.
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The device groups would be `{ (k, m) | 0<=k<4, 0<=m<5 }`.
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Devices (1, 0, 2, 3) and (1, 1, 2, 3) will be in the same group.
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Device (1, 0, 2, 4) will be in another group.
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Some collective operations like all-to-all and all-gather care about the
@@ -33,6 +36,17 @@ The axes are ordered from outer to inner.
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If we have an axis list `[3, 1]` then device `(i, 1, k, 0)` will precede
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both devices `(i, 0, k, 1)` and `(i, 2, k, 0)`.
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### In-group Device
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Some operations like `broadcast`, `scatter` and `send` specify devices in each
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device-group.
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These devices are represented with their multi-index over the mesh axes that
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are not constant within a device group.
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These are the axes specified by `mesh_axes` attribute.
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For Example on a 3D mesh an operation with `mesh_axes = [0, 2]` would specify
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an in-group device with `(i, j)`. Then for each group with index `g` on the
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second axis, the in-group device would be `(i, g, j)`.
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## Operations
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‎mlir/include/mlir/Dialect/Mesh/IR/MeshOps.td‎

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@@ -339,6 +339,185 @@ def Mesh_AllToAllOp : Mesh_CollectiveCommunicationOpBase<"all_to_all", [
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let hasCanonicalizer = 1;
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}
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def Mesh_BroadcastOp : Mesh_CollectiveCommunicationOpBase<"broadcast", [
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AllShapesMatch<["input", "result"]>,
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AllElementTypesMatch<["input", "result"]>
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]> {
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let summary = "Broadcast over a device mesh.";
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let description = [{
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Broadcast the tensor on `root` to all devices in each respective group.
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The operation broadcasts along mesh axes `mesh_axes`.
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The `root` device specifies the in-group multi-index that is broadcast to
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all other devices in the group.
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Example:
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```
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mesh.cluster @mesh0(rank = 2, dim_sizes = [2, 2])
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%1 = mesh.broadcast %0 on @mesh0
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mesh_axes = [0]
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root = [0]
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: (tensor<2xi8>) -> tensor<2xi8>
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```
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Input:
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```
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+-------+-------+ | broadcast
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device (0, 0) -> | 1 2 | 3 4 | <- device (0, 1) | along axis 0
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+-------+-------+ ↓
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device (1, 0) -> | | | <- device (1, 1)
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+-------+-------+
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```
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Output:
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```
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+-------+-------+
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device (0, 0) -> | 1 2 | 3 4 | <- device (0, 1)
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+-------+-------+
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device (1, 0) -> | 1 2 | 3 4 | <- device (1, 1)
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+-------+-------+
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```
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}];
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let arguments = !con(commonArgs, (ins
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AnyRankedTensor:$input,
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DenseI64ArrayAttr:$root,
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Variadic<Index>:$root_dynamic
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));
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let results = (outs
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AnyRankedTensor:$result
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);
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let assemblyFormat = [{
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$input `on` $mesh (`mesh_axes` `=` $mesh_axes^)?
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`root` `=` custom<DynamicIndexList>($root_dynamic, $root)
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attr-dict `:` functional-type(operands, results)
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}];
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}
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def Mesh_GatherOp : Mesh_CollectiveCommunicationOpBase<"gather", [
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AllRanksMatch<["input", "result"]>,
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AllElementTypesMatch<["input", "result"]>
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]> {
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let summary = "Gather over a device mesh.";
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let description = [{
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Gathers on device `root` along the `gather_axis` tensor axis.
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`root` specifies the coordinates of a device along `mesh_axes`.
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It uniquely identifies the root device for each device group.
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The result tensor on non-root devices is undefined.
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Using it will result in undefined behavior.
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Example:
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```mlir
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mesh.cluster @mesh0(rank = 2, dim_sizes = [2, 2])
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...
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%1 = mesh.gather %0 on @mesh0 mesh_axes = [1]
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gather_axis = 1 root = [1]
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: (tensor<2x2xi8>) -> tensor<2x4xi8>
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```
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Input:
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```
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gather tensor
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axis 1
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------------>
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+-------+-------+
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device (0, 0) -> | 1 2 | 5 6 | <- device (0, 1)
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| 3 4 | 7 8 |
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+-------+-------+
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device (1, 0) -> | 9 10 | 13 14 | <- device (1, 1)
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| 11 12 | 15 16 |
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+-------+-------+
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```
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Result:
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```
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+-------------+
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| 1 2 5 6 | <- devices (0, 1)
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| 3 4 7 8 |
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+-------------+
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| 9 10 13 14 | <- devices (1, 1)
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| 11 12 15 16 |
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+-------------+
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```
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Devices `(0, 0)` and `(1, 0)` have undefined result.
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}];
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let arguments = !con(commonArgs, (ins
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AnyNon0RankedTensor:$input,
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IndexAttr:$gather_axis,
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DenseI64ArrayAttr:$root,
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Variadic<Index>:$root_dynamic
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));
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let results = (outs
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AnyNon0RankedTensor:$result
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);
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let assemblyFormat = [{
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$input `on` $mesh (`mesh_axes` `=` $mesh_axes^)?
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`gather_axis` `=` $gather_axis
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`root` `=` custom<DynamicIndexList>($root_dynamic, $root)
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attr-dict `:` functional-type(operands, results)
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}];
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}
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def Mesh_RecvOp : Mesh_CollectiveCommunicationOpBase<"recv", [
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AllShapesMatch<["input", "result"]>,
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AllElementTypesMatch<["input", "result"]>
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]> {
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let summary = "Send over a device mesh.";
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let description = [{
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Receive from a device within a device group.
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}];
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let arguments = !con(commonArgs, (ins
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AnyNon0RankedTensor:$input,
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OptionalAttr<DenseI64ArrayAttr>:$source,
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Variadic<Index>:$source_dynamic
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));
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let results = (outs
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AnyRankedTensor:$result
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);
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let assemblyFormat = [{
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$input `on` $mesh (`mesh_axes` `=` $mesh_axes^)?
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(`source` `=` custom<DynamicIndexList>($source_dynamic, $source)^)?
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attr-dict `:` functional-type(operands, results)
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}];
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}
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def Mesh_ReduceOp : Mesh_CollectiveCommunicationOpBase<"reduce", [
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AllShapesMatch<["input", "result"]>
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]> {
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let summary = "Reduce over a device mesh.";
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let description = [{
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Reduces on device `root` within each device group.
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`root` specifies the coordinates of a device along `mesh_axes`.
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It uniquely identifies the root device within its device group.
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The accumulation element type is specified by the result type and
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it does not need to match the input element type.
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The input element is converted to the result element type before
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performing the reduction.
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Attributes:
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`reduction`: Indicates the reduction method.
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Example:
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```
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%1 = mesh.reduce %0 on @mesh0 mesh_axes = [1, 0]
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reduction = <max> root = [2, 3]
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: (tensor<3x4xf32>) -> tensor<3x4xf64>
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```
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}];
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let arguments = !con(commonArgs, (ins
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AnyRankedTensor:$input,
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DefaultValuedAttr<Mesh_PartialAttr, "::mlir::mesh::Partial::Sum">:$reduction,
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DenseI64ArrayAttr:$root,
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Variadic<Index>:$root_dynamic
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));
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let results = (outs
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AnyRankedTensor:$result
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);
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let assemblyFormat = [{
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$input `on` $mesh (`mesh_axes` `=` $mesh_axes^)?
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(`reduction` `=` $reduction^)?
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`root` `=` custom<DynamicIndexList>($root_dynamic, $root)
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attr-dict `:` functional-type(operands, results)
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}];
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}
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def Mesh_ReduceScatterOp : Mesh_CollectiveCommunicationOpBase<"reduce_scatter", [
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SameOperandsAndResultRank]> {
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let summary = "Reduce-scatter over a device mesh.";
@@ -400,4 +579,154 @@ def Mesh_ReduceScatterOp : Mesh_CollectiveCommunicationOpBase<"reduce_scatter",
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let hasCanonicalizer = 1;
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}
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def Mesh_ScatterOp : Mesh_CollectiveCommunicationOpBase<"scatter", [
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AllRanksMatch<["input", "result"]>,
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AllElementTypesMatch<["input", "result"]>
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]> {
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let summary = "Scatter over a device mesh.";
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let description = [{
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For each device group split the input tensor on the `root` device along
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axis `scatter_axis` and scatter the parts across the group devices.
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Example:
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```
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mesh.cluster @mesh0(rank = 2, dim_sizes = [2, 2])
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%1 = mesh.scatter %0 on @mesh0 mesh_axes = [0]
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scatter_axis = 0
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root = [1]
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: (tensor<2x2xi8>) -> tensor<1x2xi8>
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```
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Input:
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```
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device
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(0, 1)
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↓
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+-------+-------+ | scatter tensor
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device (0, 0) -> | | | | axis 0
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| | | ↓
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+-------+-------+
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device (1, 0) -> | 1 2 | 5 6 |
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| 3 4 | 7 8 |
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+-------+-------+
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↑
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device
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(1, 1)
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```
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Result:
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```
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device
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(0, 1)
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↓
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+-------+-------+
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device (0, 0) -> | 1 2 | 5 6 |
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+-------+-------+
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device (1, 0) -> | 3 4 | 7 8 |
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+-------+-------+
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↑
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device
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(1, 1)
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```
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}];
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let arguments = !con(commonArgs, (ins
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AnyNon0RankedTensor:$input,
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IndexAttr:$scatter_axis,
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DenseI64ArrayAttr:$root,
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Variadic<Index>:$root_dynamic
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));
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let results = (outs
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AnyRankedTensor:$result
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);
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let assemblyFormat = [{
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$input `on` $mesh (`mesh_axes` `=` $mesh_axes^)?
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`scatter_axis` `=` $scatter_axis
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`root` `=` custom<DynamicIndexList>($root_dynamic, $root)
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attr-dict `:` functional-type(operands, results)
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}];
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}
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def Mesh_SendOp : Mesh_CollectiveCommunicationOpBase<"send", [
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AllShapesMatch<["input", "result"]>,
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AllElementTypesMatch<["input", "result"]>
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]> {
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let summary = "Send over a device mesh.";
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let description = [{
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Send from one device to another within a device group.
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}];
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let arguments = !con(commonArgs, (ins
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AnyNon0RankedTensor:$input,
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DenseI64ArrayAttr:$destination,
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Variadic<Index>:$destination_dynamic
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));
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let results = (outs
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AnyRankedTensor:$result
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);
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let assemblyFormat = [{
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$input `on` $mesh (`mesh_axes` `=` $mesh_axes^)?
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`destination` `=` custom<DynamicIndexList>($destination_dynamic, $destination)
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attr-dict `:` functional-type(operands, results)
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}];
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}
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def Mesh_ShiftOp : Mesh_CollectiveCommunicationOpBase<"shift", [
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SameOperandsAndResultElementType,
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SameOperandsAndResultShape
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]> {
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let summary = "Sift over a device mesh.";
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let description = [{
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Within each device group shift along mesh axis `shift_axis` by an offset
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`offset`.
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The result on devices that do not have a corresponding source is undefined.
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`shift_axis` must be one of `mesh_axes`.
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If the `rotate` attribute is present,
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instead of a shift a rotation is done.
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Example:
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```
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mesh.cluster @mesh0(rank = 2, dim_sizes = [2, 4])
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%1 = mesh.shift on @mesh0 mesh_axes = [1]
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shift_axis = 1 offset = 2 rotate
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: tensor<2xi8> -> tensor<2xi8>
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```
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Input:
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```
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mesh axis 1
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----------->
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+----+----+----+----+
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| 1 | 2 | 3 | 4 |
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+----+----+----+----+
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| 5 | 6 | 7 | 8 |
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+----+----+----+----+
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```
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Result:
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```
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+----+----+----+----+
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| 3 | 4 | 1 | 2 |
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+----+----+----+----+
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| 7 | 8 | 5 | 6 |
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+----+----+----+----+
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```
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}];
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let arguments = !con(commonArgs, (ins
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AnyNon0RankedTensor:$input,
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IndexAttr:$shift_axis,
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I64Attr:$offset,
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UnitAttr:$rotate
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));
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let results = (outs
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AnyRankedTensor:$result
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);
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let assemblyFormat = [{
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$input `on` $mesh (`mesh_axes` `=` $mesh_axes^)?
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`shift_axis` `=` $shift_axis
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`offset` `=` $offset
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(`rotate` $rotate^)?
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attr-dict `:` type($input) `->` type($result)
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}];
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}
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#endif // MLIR_DIALECT_MESH_IR_MESHOPS_TD

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