[Mlir-commits] [mlir] [MLIR][Mesh] Add sharding propagation pass (PR #69665)

[Boian Petkantchin]

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+//===- ShardingInterface.cpp -------------------------------------*- C++-*-===//
+//
+// 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/Mesh/Interfaces/ShardingInterface.h"
+#include "mlir/Dialect/Mesh/IR/MeshOps.h"
+#include "mlir/Dialect/Utils/IndexingUtils.h"
+#include "mlir/IR/AffineMap.h"
+#include "mlir/Support/LLVM.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/Support/Debug.h"
+
+#include <algorithm>
+#include <utility>
+
+#define DEBUG_TYPE "sharding-interface"
+#define DBGS() (llvm::dbgs() << "[" DEBUG_TYPE << "]: ")
+
+using namespace mlir;
+using namespace mlir::mesh;
+
+#include "mlir/Dialect/Mesh/Interfaces/ShardingInterface.cpp.inc"
+
+//===----------------------------------------------------------------------===//
+// common util functions
+//===----------------------------------------------------------------------===//
+
+// This method aims to retrieve the mesh sharding attribute (MeshShardingAttr)
+// for a given operation result.
+static FailureOr<MeshShardingAttr>
+getMeshShardingAttr(OpResult result, bool useOperandSharding) {
+  Value val = result.cast<Value>();
+  bool anyShardedForDef = llvm::any_of(val.getUsers(), [](Operation *user) {
+    auto shardOp = llvm::dyn_cast<mesh::ShardOp>(user);
+    if (!shardOp)
+      return false;
+    return !shardOp.getAnnotateForUsers();
+  });
+
+  if (anyShardedForDef) {
+    // expected to have exact one use if it has a use of `mesh.shard` without
+    // unit attr annotate_for_users
+    if (!val.hasOneUse())
+      return failure();
+    auto shardOp = llvm::cast<mesh::ShardOp>(*val.getUsers().begin());
+    return shardOp.getShard();
+  } else if (useOperandSharding) {
+    bool anyShardedForUsers = llvm::any_of(val.getUsers(), [](Operation *user) {
+      auto shardOp = llvm::dyn_cast<mesh::ShardOp>(user);
+      if (!shardOp)
+        return false;
+      return shardOp.getAnnotateForUsers();
+    });
+    if (anyShardedForUsers) {
+      SmallVector<ShardOp> shardOps;
+      for (Operation *user : val.getUsers()) {
+        ShardOp shardOp = llvm::dyn_cast<ShardOp>(user);
+        if (shardOp)
+          shardOps.push_back(shardOp);
+      }
+      MeshShardingAttr shardForDef = shardOps[0].getShard();
+      for (size_t i = 1; i < shardOps.size(); ++i) {
+        // TODO: Deduce a reasonable mesh sharding attr for def when they are
+        // different
+        assert(shardOps[i].getShard() == shardForDef &&
+               "only support all shard ops have the same mesh sharding attr");
+      }
+      return shardForDef;
+    }
+  }
+
+  return failure();
+}
+
+// This method aims to retrieve the mesh sharding attribute (MeshShardingAttr)
+// for a given operation operand.
+static FailureOr<std::pair<bool, MeshShardingAttr>>
+getMeshShardingAttr(OpOperand &opOperand) {
+  Value val = opOperand.get();
+  if (ShardOp shardOp = val.getDefiningOp<ShardOp>())
+    return std::make_pair(shardOp.getAnnotateForUsers(), shardOp.getShard());
+
+  return failure();
+}
+
+static LogicalResult
+checkOperandAffineExprRecursively(AffineExpr expr,
+                                  SmallVectorImpl<bool> &seenIds) {
+  switch (expr.getKind()) {
+  case AffineExprKind::Add: {
+    auto binOpExpr = expr.cast<AffineBinaryOpExpr>();
+    AffineExpr lhs = binOpExpr.getLHS();
+    AffineExpr rhs = binOpExpr.getRHS();
+    if (failed(checkOperandAffineExprRecursively(lhs, seenIds)))
+      return failure();
+    if (failed(checkOperandAffineExprRecursively(rhs, seenIds)))
+      return failure();
+    return success();
+  }
+  case AffineExprKind::Mul: {
+    auto binOpExpr = expr.cast<AffineBinaryOpExpr>();
+    AffineExpr lhs = binOpExpr.getLHS();
+    AffineExpr rhs = binOpExpr.getRHS();
+    AffineExpr dimExpr;
+    if (lhs.getKind() == AffineExprKind::DimId) {
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sogartar wrote:

Is it certain that the left-hand side would be the dimension operand?

https://github.com/llvm/llvm-project/pull/69665