Stephen Chou

PhD Student

I am a final-year PhD student affiliated with the COMMIT group in MIT CSAIL and advised by Prof. Saman Amarasinghe. I completed my undergraduate studies at the University of Waterloo, where I majored in computer engineering. I have also interned at Microsoft (working as a research intern with Drs. Minjia Zhang and Yuxiong He), Sybase (working with Dr. Anisoara Nica), OptumSoft, and IBM.

My interests lie in the area of programming languages and compilers for performance computing. I have developed various techniques to automatically generate efficient code for computing with sparse matrices and tensors that are stored in arbitrary, disparate data layouts. I am a primary contributor to TACO, a compiler for sparse tensor computations. I have also worked on Simit, a domain-specific programming language for computing on sparse systems.

Education

PhD in Computer Science, 2022 (expected)

Massachusetts Institute of Technology
SM in Computer Science, 2018

Massachusetts Institute of Technology
BASc in Computer Engineering, 2015

University of Waterloo

Projects

TACO

A compiler that generates fast code to perform sparse tensor algebra computations. I extended TACO so that it can emit code to efficiently compute with sparse tensors that are stored in a wide range of specialized data structures. I also helped maintain many other parts of the compiler, as well as developed a web interface that lets users try out TACO without having to install it on their own machines.

simit

A domain-specific programming language for computing on sparse systems using linear algebra. I implemented a new front end for the Simit compiler that was significantly more user-friendly and robust than the original one. This new front end was later also adapted for use in the compiler for GraphIt, a programming language for graph computations.

Publications

Preprints

Dynamic Sparse Tensor Algebra Compilation
Stephen Chou, Saman Amarasinghe
arXiv:2112.01394 [cs.MS], 2021.

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Conference Publications

Unified Compilation for Lossless Compression and Sparse Computing
Daniel Donenfeld, Stephen Chou, Saman Amarasinghe
Proceedings of the 2022 IEEE/ACM International Symposium on Code Generation and Optimization, 2022.

PDF

Compilation of Sparse Array Programming Models
Rawn Henry, Olivia Hsu, Rohan Yadav, Stephen Chou, Kunle Olukotun, Saman Amarasinghe, Fredrik Kjolstad
Proceedings of the ACM on Programming Languages, Volume 5, Issue OOPSLA, 2021.

PDF

A Sparse Iteration Space Transformation Framework for Sparse Tensor Algebra
Ryan Senanayake, Changwon Hong, Ziheng Wang, Amalee Wilson, Stephen Chou, Shoaib Kamil, Saman Amarasinghe, Fredrik Kjolstad
Proceedings of the ACM on Programming Languages, Volume 4, Issue OOPSLA, 2020.

PDF

Automatic Generation of Efficient Sparse Tensor Format Conversion Routines
Stephen Chou, Fredrik Kjolstad, Saman Amarasinghe
41st ACM SIGPLAN International Conference on Programming Language Design and Implementation (PLDI), 2020.

PDF Slides Video

Format Abstraction for Sparse Tensor Algebra Compilers
Stephen Chou, Fredrik Kjolstad, Saman Amarasinghe
Proceedings of the ACM on Programming Languages, Volume 2, Issue OOPSLA, 2018.

PDF Slides Video

The Tensor Algebra Compiler
Fredrik Kjolstad, Shoaib Kamil, Stephen Chou, David Lugato, Saman Amarasinghe
Proceedings of the ACM on Programming Languages, Volume 1, Issue OOPSLA, 2017.
Distinguished Paper Award

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Peer-Reviewed Short/Workshop Publications

Sparse Tensor Transpositions
Suzanne Mueller, Peter Ahrens, Stephen Chou, Fredrik Kjolstad, Saman Amarasinghe
32nd ACM Symposium on Parallelism in Algorithms and Architectures, 2020.
(brief announcement)

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Taco: compilation et génération de code d’expressions tensorielles
David Lugato, Fredrik Kjolstad, Stephen Chou, Saman Amarasinghe, Shoaib Kamil
Chocs Avancées, No. 12, 2018.

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taco: A Tool to Generate Tensor Algebra Kernels
Fredrik Kjolstad, Stephen Chou, David Lugato, Shoaib Kamil, Saman Amarasinghe
32nd IEEE/ACM International Conference on Automated Software Engineering (ASE), 2017.
(tools paper and demo)

PDF Video

Using Similarity Distance for Performance Prediction of the Query Optimization Process
Anisoara Nica, Stephen Chou
Sixth International Workshop on Testing Database Systems (DBTest), 2013.

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Other Publications

Unified Sparse Formats for Tensor Algebra Compilers
SM Thesis, Massachusetts Institute of Technology, 2018.

Patents

Resource Estimation For A Query Optimization Process
Anisoara Nica, Stephen Chou
Application number: US 13/754,596, Publication number: US9298771 B2, 2013.

Professional Service

Artifact evaluation committee member for CGO 2020
Reviewer for IEEE Transactions on Computers (2019)
Subreviewer for CGO 2017, CGO 2018, PLDI 2019, SPAA 2019, Euro-Par 2020, SPAA 2021, CGO 2022, and MLSys 2022

Awards & Honors

Distinguished Paper Award (OOPSLA, 2017)
Albert Sherwood Barber Medal for Best Overall Work Term and Academic Performance (University of Waterloo, 2015)
First in Class Engineering Scholarship for 4A term (University of Waterloo, 2015)
First in Class Engineering Scholarship for 3B term (University of Waterloo, 2014)
First in Class Engineering Scholarship for 3A term (University of Waterloo, 2013)
iAnywhere Solutions Inc. Scholarship (University of Waterloo, 2012)