From 511a1db4f308fdaf954c11285bb1682b99631ddd Mon Sep 17 00:00:00 2001
From: "A. Unique TensorFlower" <gardener@tensorflow.org>
Date: Mon, 31 May 2021 12:00:41 -0700
Subject: [PATCH] [MLIR][HLO] Use canonicalization patterns in broadcast
 propagation pass

Replace local canonicalization patterns with those from upstream.

PiperOrigin-RevId: 376708719
---
 .../move_up_dynamic_broadcasts_for_fusion.cc  | 58 ++++++++++++++++++-
 1 file changed, 57 insertions(+), 1 deletion(-)

diff --git a/lib/Dialect/mhlo/transforms/move_up_dynamic_broadcasts_for_fusion.cc b/lib/Dialect/mhlo/transforms/move_up_dynamic_broadcasts_for_fusion.cc
index 0ac6fcd..51576a7 100644
--- a/lib/Dialect/mhlo/transforms/move_up_dynamic_broadcasts_for_fusion.cc
+++ b/lib/Dialect/mhlo/transforms/move_up_dynamic_broadcasts_for_fusion.cc
@@ -306,6 +306,61 @@ struct MergeAssumingOpsPattern : public OpRewritePattern<shape::AssumingOp> {
   }
 };
 
+// Eliminate casted extent tensors. Instead, produce the concrete extent tensor
+// type where possible.
+struct CanonicalizeCastedShapeOfOpPattern
+    : public OpRewritePattern<tensor::CastOp> {
+  using OpRewritePattern<tensor::CastOp>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(tensor::CastOp op,
+                                PatternRewriter &rewriter) const override {
+    // Only merge tensor cast into `shape_of` ops.
+    auto shape_of_op = op.source().getDefiningOp<shape::ShapeOfOp>();
+    if (!shape_of_op) return failure();
+
+    // Desired type must be an extent tensor type.
+    auto result_ty = op.getType().dyn_cast<RankedTensorType>();
+    if (!result_ty || result_ty.getRank() != 1 ||
+        !result_ty.getElementType().isIndex())
+      return failure();
+
+    rewriter.replaceOpWithNewOp<shape::ShapeOfOp>(op, result_ty,
+                                                  shape_of_op.arg());
+    if (shape_of_op->getUses().empty()) rewriter.eraseOp(shape_of_op);
+    return success();
+  }
+};
+
+// TODO(frgossen): Remove this once it has landed upstream.
+struct CanonicalizeBroadcastPattern
+    : public OpRewritePattern<shape::BroadcastOp> {
+  using OpRewritePattern<shape::BroadcastOp>::OpRewritePattern;
+
+  LogicalResult matchAndRewrite(shape::BroadcastOp op,
+                                PatternRewriter &rewriter) const override {
+    // Only concretize dynamic extent tensor result types.
+    auto resultTy = op.getType().dyn_cast<RankedTensorType>();
+    if (!resultTy || !resultTy.isDynamicDim(0)) return failure();
+
+    // Infer resulting shape rank if possible.
+    int64_t maxRank = 0;
+    for (Value shape : op.shapes()) {
+      if (auto extentTensorTy = shape.getType().dyn_cast<RankedTensorType>()) {
+        // Cannot infer resulting shape rank if any operand is dynamically
+        // ranked.
+        if (extentTensorTy.isDynamicDim(0)) return failure();
+        maxRank = std::max(maxRank, extentTensorTy.getDimSize(0));
+      }
+    }
+
+    auto newOp = rewriter.create<shape::BroadcastOp>(
+        op.getLoc(), RankedTensorType::get({maxRank}, rewriter.getIndexType()),
+        op.shapes());
+    rewriter.replaceOpWithNewOp<tensor::CastOp>(op, op.getType(), newOp);
+    return success();
+  }
+};
+
 // TODO(frgossen): Only move up broadcasting operations if there is a consumer.
 struct MoveUpBroadcastInDimOpPattern
     : public OpRewritePattern<DynamicBroadcastInDimOp> {
@@ -377,6 +432,8 @@ void PopulateMoveUpDynamicBroadcastsForFusionPatterns(
     MLIRContext *context, OwningRewritePatternList *patterns) {
   // clang-format off
   patterns->insert<
+      CanonicalizeBroadcastPattern,
+      CanonicalizeCastedShapeOfOpPattern,
       InlineBroadcastedShapeOperandsPattern<shape::CstrBroadcastableOp>,
       MergeAssumingOpsPattern,
       MoveIntoAssumingOpPattern<shape::ShapeOfOp>,
@@ -386,7 +443,6 @@ void PopulateMoveUpDynamicBroadcastsForFusionPatterns(
       MoveUpBroadcastInDimOpPattern,
       ShapeReificationPattern>(context);
   // clang-format on
-  shape::BroadcastOp::getCanonicalizationPatterns(*patterns, context);
   tensor::CastOp::getCanonicalizationPatterns(*patterns, context);
 }