Rasmus Munk LarsenandRasmus Munk Larsen
8a3d61c790
libeigen/eigen!2509 Closes #2868 Co-authored-by: Rasmus Munk Larsen <rmlarsen@gmail.com>
55 lines
2.0 KiB
C++
55 lines
2.0 KiB
C++
// This file is part of Eigen, a lightweight C++ template library
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// for linear algebra.
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//
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// Copyright (C) 2026 The Eigen Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla
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// Public License v. 2.0. If a copy of the MPL was not distributed
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// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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// SPDX-License-Identifier: MPL-2.0
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#include "main.h"
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#include <Eigen/Tensor>
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using Eigen::DefaultDevice;
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using Eigen::Tensor;
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using Eigen::TensorEvaluator;
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// Regression: TensorCwiseNullaryOp must report bytes_loaded == 0.
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// NullaryOps (constants, Zero, Identity, Random, sequence generators)
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// produce values from registers or minimal state without loading from
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// memory. If they reported nonzero bytes_loaded, expressions dominated
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// by constants (e.g. Horner-form polynomials) would be misclassified as
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// memory-bound and the threadpool cost model would over-restrict
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// parallelism. See TensorEvaluator.h, the CwiseNullaryOp specialization
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// of costPerCoeff().
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template <typename Scalar>
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static void test_nullary_zero_bytes_loaded() {
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Tensor<Scalar, 1> shape(/*size=*/16);
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auto zeros = shape.constant(Scalar(0));
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auto sevens = shape.constant(Scalar(7));
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using ZeroEval = TensorEvaluator<const decltype(zeros), DefaultDevice>;
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using ConstEval = TensorEvaluator<const decltype(sevens), DefaultDevice>;
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DefaultDevice device;
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ZeroEval zero_eval(zeros, device);
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ConstEval const_eval(sevens, device);
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for (bool vectorized : {false, true}) {
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const auto zero_cost = zero_eval.costPerCoeff(vectorized);
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const auto const_cost = const_eval.costPerCoeff(vectorized);
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VERIFY_IS_EQUAL(zero_cost.bytes_loaded(), 0.0);
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VERIFY_IS_EQUAL(zero_cost.bytes_stored(), 0.0);
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VERIFY_IS_EQUAL(const_cost.bytes_loaded(), 0.0);
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VERIFY_IS_EQUAL(const_cost.bytes_stored(), 0.0);
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}
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}
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EIGEN_DECLARE_TEST(tensor_cost_model) {
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CALL_SUBTEST(test_nullary_zero_bytes_loaded<float>());
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CALL_SUBTEST(test_nullary_zero_bytes_loaded<double>());
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CALL_SUBTEST(test_nullary_zero_bytes_loaded<int>());
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}
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