Session

Session 2: Compilers

Moderator: Tianqi Chen



Abstract:

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Tue 6 April 11:10 - 11:30 PDT
Cortex: A Compiler for Recursive Deep Learning Models

Pratik Fegade · Tianqi Chen · Phillip Gibbons · Todd Mowry

Optimizing deep learning models is generally performed in two steps: (i) high-level graph optimizations such as kernel fusion and (ii) low level kernel optimizations such as those found in vendor libraries. This approach often leaves significant performance on the table, especially for the case of recursive deep learning models. In this paper, we present Cortex, a compiler-based approach to generate highly-efficient code for recursive models for low latency inference. Our compiler approach and low reliance on vendor libraries enables us to perform end-to-end optimizations, leading to up to 14X lower inference latencies over past work, across different backends.

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Tue 6 April 11:30 - 11:50 PDT
A Deep Learning Based Cost Model for Automatic Code Optimization

Riyadh Baghdadi · Massinissa Merouani · Mohamed-Hicham LEGHETTAS · Kamel Abdous · Taha Arbaoui · Karima BENATCHBA · Saman Amarasinghe

Enabling compilers to automatically optimize code has been a longstanding goal for the compiler community. Efficiently solving this problem requires using precise cost models. These models predict whether applying a sequence of code transformations reduces the execution time of the program. Building an analytical cost model to do so is hard in modern x86 architectures due to the complexity of the microarchitecture. In this paper, we present a novel deep learning based cost model for automatic code optimization. This model was integrated in a search method and implemented in the Tiramisu compiler to select the best code transformations. The input of the proposed model is a set of simple features representing the unoptimized code and a sequence of code transformations. The model predicts the speedup expected when the code transformations are applied. Unlike previous models, the proposed one works on full programs and does not rely on any heavy feature engineering. The proposed model has only 16% of mean absolute percentage error in predicting speedups on full programs. The proposed model enables Tiramisu to automatically find code transformations that match or are better than state-of-the-art compilers without requiring the same level of heavy feature engineering required by those compilers

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Tue 6 April 11:50 - 12:10 PDT
Learning Fitness Functions for Machine Programming

Shantanu Mandal · Todd Anderson · Javier Turek · Justin Gottschlich · Shengtian Zhou · Abdullah Muzahid

The problem of automatic software generation has been referred to as machine programming. In this work, we propose a framework based on genetic algorithms to help make progress in this domain. Although genetic algorithms (GAs) have been successfully used for many problems, one criticism is that hand-crafting GAs fitness function, the test that aims to effectively guide its evolution, can be notably challenging. Our framework presents a novel approach to learn the fitness function using neural networks to predict values of ideal fitness functions.We also augment the evolutionary process with a minimally intrusive search heuristic. This heuristic improves the framework’s ability to discover correct programs from ones that are approximately correct and does so with negligible computational overhead. We compare our approach with several state-of-the-art program synthesis methods and demonstrate that it finds more correct programs with fewer candidate program generations.

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Tue 6 April 12:10 - 12:30 PDT
CODE: Compiler-based Neuron-aware Ensemble training

Ettore M. G. Trainiti · Thanapon Noraset · David Demeter · Doug Downey · Simone Campanoni

Deep Neural Networks (DNNs) are redefining the state-of-the-art performance in a variety of tasks like speech recognition and image classification. These impressive results are often enabled by ensembling many DNNs together. Surprisingly, ensembling is often done by training several DNN instances from scratch and combining them. This paper shows that there is significant redundancy in today's way of ensembling. The novelty we propose is CODE, a compiler approach designed to automatically generate DNN ensembles while avoiding unnecessary retraining among its DNNs. For this purpose, CODE introduces neuron-level analyses and transformations aimed at identifying and removing redundant computation from the networks that compose the ensemble. Removing redundancy enables CODE to train large DNN ensembles in a fraction of the time and memory footprint needed by current techniques. These savings can be leveraged by CODE to increase the output quality of its ensembles.

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