diff --git a/mlir/lib/Dialect/Vector/IR/VectorOps.cpp b/mlir/lib/Dialect/Vector/IR/VectorOps.cpp --- a/mlir/lib/Dialect/Vector/IR/VectorOps.cpp +++ b/mlir/lib/Dialect/Vector/IR/VectorOps.cpp @@ -4188,12 +4188,46 @@ } }; +/// Pattern to rewrite a ShapeCast(Broadcast) -> Broadcast. +/// This only applies when the shape of the broadcast source is a suffix of the +/// shape of the result (i.e. when broadcast without reshape is expressive +/// enough to capture the result in a single op). +class ShapeCastBroadcastFolder final : public OpRewritePattern { +public: + using OpRewritePattern::OpRewritePattern; + + LogicalResult matchAndRewrite(ShapeCastOp shapeCastOp, + PatternRewriter &rewriter) const override { + auto broadcastOp = + shapeCastOp.getSource().getDefiningOp(); + if (!broadcastOp) + return failure(); + + auto broadcastSourceVectorType = + broadcastOp.getSourceType().dyn_cast(); + auto broadcastSourceShape = broadcastSourceVectorType + ? broadcastSourceVectorType.getShape() + : ArrayRef{}; + auto shapeCastTargetShape = shapeCastOp.getResultVectorType().getShape(); + + // Bail if `broadcastSourceShape` is not a suffix of the result. + bool isSuffix = (broadcastSourceShape == shapeCastTargetShape.take_back( + broadcastSourceShape.size())); + if (!isSuffix) + return failure(); + + rewriter.replaceOpWithNewOp( + shapeCastOp, shapeCastOp.getResultVectorType(), + broadcastOp.getSource()); + return success(); + } +}; + } // namespace void ShapeCastOp::getCanonicalizationPatterns(RewritePatternSet &results, MLIRContext *context) { - // Pattern to rewrite a ShapeCastOp(ConstantOp) -> ConstantOp. - results.add(context); + results.add(context); } //===----------------------------------------------------------------------===// diff --git a/mlir/test/Dialect/Vector/canonicalize.mlir b/mlir/test/Dialect/Vector/canonicalize.mlir --- a/mlir/test/Dialect/Vector/canonicalize.mlir +++ b/mlir/test/Dialect/Vector/canonicalize.mlir @@ -646,10 +646,10 @@ // ----- -// CHECK-LABEL: func @dont_fold_broadcast_shapecast_scalar +// CHECK-LABEL: func @canonicalize_broadcast_shapecast_scalar // CHECK: vector.broadcast -// CHECK: vector.shape_cast -func.func @dont_fold_broadcast_shapecast_scalar(%arg0: f32) -> vector<1xf32> { +// CHECK-NOT: vector.shape_cast +func.func @canonicalize_broadcast_shapecast_scalar(%arg0: f32) -> vector<1xf32> { %0 = vector.broadcast %arg0 : f32 to vector<1x1x1xf32> %1 = vector.shape_cast %0 : vector<1x1x1xf32> to vector<1xf32> return %1 : vector<1xf32> @@ -668,6 +668,17 @@ // ----- +// CHECK-LABEL: func @canonicalize_broadcast_shapecast +// CHECK: vector.broadcast +// CHECK-NOT: vector.shape_cast +func.func @canonicalize_broadcast_shapecast(%arg0: vector<3xf32>) -> vector<8x3xf32> { + %0 = vector.broadcast %arg0 : vector<3xf32> to vector<2x4x3xf32> + %1 = vector.shape_cast %0 : vector<2x4x3xf32> to vector<8x3xf32> + return %1 : vector<8x3xf32> +} + +// ----- + // CHECK-LABEL: fold_vector_transfers func.func @fold_vector_transfers(%A: memref) -> (vector<4x8xf32>, vector<4x9xf32>) { %c0 = arith.constant 0 : index