Tuesday, December 2, 2025

Previous | Next

• Video series showcases Values in Action

• Giving thanks on Giving Tuesday
• Chengnian Sun and colleagues receive Most Influential Paper Award
• Notes on the last day of lectures

Video series showcases Values in Action

By Michael Dorr and Melanie Will.

Waterloo is full of people who think differently, act with purpose and work together, and over the past year we have been inspired by the number of stories that showcase our values in action. Since the launch of the Waterloo Values last summer, individuals and teams from across campus have been showcasing our values in ways that are truly shaping our culture and reinforcing our leadership in education, scholarship, innovation, entrepreneurship and so much more.

These stories inspired us to bring together a group of Waterloo employees for an unscripted and open conversation about what the values mean to them: in their work, in their decision-making and in the everyday moments that make this community what it is. The discussions were honest, energizing and often surprisingly fun.

Today, we’re excited to share the result: introducing the Values in Action video series filmed in the beautiful Humanities Theatre and featuring six incredible ambassadors who reflect on the values shaping their work and their Waterloo experience. Check out all four videos here:

• Why values matter
• Think differently
• Act with purpose
• Work together

A huge “thank you” to the talented Creative Studio team (special shout-out to Matt Regehr), the Marketing & Brand team, the Humanities Theatre and (most importantly) to our six ambassadors:

• Pavol Chvala, Director A.I. Innovation and System Development, IST
• Martin Cooke, Assistant Vice President, Leadership and Strategy Initiatives
• Yessenia Guerrera, Associate Director, Response, EDI-R
• Derek Rayside, Associate Professor and Associate Dean, Co-op Education and Professional Affairs (Eng)
• Amanda St. Marie, Indigenous Initiatives Manager (Env)
• Caitlin Vaux, Project Manager, Office of the President

Do you have your own “values in action” story?  We’d love to hear it. Share your ideas, photos or videos with the Values Working Team.

Giving thanks on Giving Tuesday

A message from Advancement.

Today is Giving Tuesday — a global celebration of generosity and community.

At Waterloo, that spirit shines every day through you — our faculty, staff and retirees. You’ve guided, taught and supported our students in countless ways — through your work, your experience and your care. Whether in your time on campus or in the years since, you’ve helped generations of students learn, grow and gain the confidence to take on the world.

This past May, we launched our first-ever UWaterloo Giving Day, a powerful moment of community and generosity — with more than $780,000 raised in support of 177 unique funds — all fueling the projects, programs and dreams of our students.

If you missed Giving Day, there’s still time to keep the momentum going. Before year’s end, you can make a gift to the area you care about most and continue supporting the students and programs that make Waterloo extraordinary.

And mark your calendars for our second UWaterloo Giving Day in May 2026. We can’t wait to celebrate with you again!

Thank you for being such an important part of our donor community, and for everything you make possible.

Chengnian Sun and colleagues receive Most Influential Paper Award

This article was originally published on the Cheriton School of Computer Science.

Professor Chengnian Sun and his collaborators Vu Le and Zhendong Su have received the Most Influential Paper Award at OOPSLA 2025, part of the ACM SIGPLAN SPLASH conference. Their paper, Finding Deep Compiler Bugs via Guided Stochastic Program Mutation, presented originally at OOPSLA 2015, was recognized for introducing a novel Equivalence Modulo Inputs mutation strategy that exposed previously undetected bugs in production compilers.

The research was conducted when Professor Sun was a postdoctoral researcher and Vu Le a PhD student, both advised by Professor Su at the University of California, Davis. The award recognizes a paper from ten years earlier that has made a lasting impact on the field of programming languages.

In its citation, the OOPSLA award committee wrote, “This paper has made substantial contributions in establishing systematic and automated test generation as a widely-used technique for ensuring compiler robustness in practice, through an extension of the Equivalence Modulo Inputs (EMI) technique. EMI-based compiler testing observes which code is unexecuted for a given program and input to that program, modifies the unexecuted code, and then checks that the resulting program behaves identically to the original program on the same input. The key innovation of the paper was to insert new unexecuted code into the program, leveraging a Markov-Chain-Monte-Carlo search to generate diverse mutants more likely to expose compiler bugs. Compiler testing techniques building on this new EMI-based technique have exposed over 1,000 bugs in the GCC and LLVM compilers that were reported and fixed by the developers, as well as bugs in compilers for a variety of other languages.”

Chengnian Sun is an Associate Professor and Cheriton Faculty Fellow at the Cheriton School of Computer Science. His research interests lie at the intersection of software engineering and programming languages, with a focus on improving software quality and enhancing developer productivity through better tools, techniques and methodologies.

He has a PhD in Computer Science from the National University of Singapore. Before joining the Cheriton School of Computer Science, he worked as a software engineer at Google in Mountain View, California, and as a postdoctoral researcher at the University of California, Davis, where he conducted this award-winning research.

More about compilers and this research

A compiler is a program that translates code written in a high-level programming language into a lower-level language such as machine code. Compiler bugs are particularly serious because they can affect all programs. These bugs may cause compilers to silently miscompile a program, leading to its incorrect executions and even security vulnerabilities in the miscompiled program. Because bugs in production compilers are relatively rare and occur only under specific circumstances, they can go undetected during software development and surface only after deployment.

This award-winning research advanced a then-emerging compiler validation approach known as Equivalence Modulo Inputs. EMI works by generating new test programs from existing ones that should behave identically under specific inputs. By comparing how a compiler processes these equivalent variants, researchers can detect miscompilations.

Earlier tools such as Orion had demonstrated EMI’s promise, uncovering numerous bugs in production compilers. But despite Orion’s success in finding bugs, its effectiveness was limited by its simple, blind mutation strategy.

To address these limitations, Professor Sun and his collaborators developed Athena, a new realization of EMI that uses guided mutation rather than random variation. By combining code insertion and deletion in unexecuted regions of a program, and applying Markov Chain Monte Carlo optimization guided by control-flow diversity, Athena generates a large number of variants for testing. This guided search allows Athena to uncover deep, complex compiler behaviours that simpler fuzzing tools cannot expose.

Over 19 months of testing, Athena discovered 72 previously unknown bugs in GCC and LLVM, two of the most widely used compilers. All 72 bugs were confirmed by developers. Seventeen of the 40 GCC bugs were marked as P1, the most severe kind of bugs that must be fixed before a new GCC release can be made.

Their experiments showed that Athena detected both shallow and deep bugs, the latter of which requires sophisticated mutation sequences that could not be done using Orion. Importantly, the study demonstrated the effectiveness of the general EMI technique and provided insight into developing effective EMI mutation-based compiler testing strategies.

Notes on the last day of lectures

Lectures and classes come to an end today on campus, with students having a couple of pre-examination study days as breathing space before the fall 2025 examination period gets going on Friday, December 5.

Fittingly, the Music department's end-of-term ensemble concert series comes to a close today with the Instrumental Chamber Ensemble performing tonight at 7:30 p.m. in the  Conrad Grebel University College Chapel. 

Directed this term by violist Judith Davenport, five different instrumental groups will perform the following pieces:

• Turina Piano Quartet in A minor;
• Chausson Piano Quartet in A major, op.30;
• Rota Trio for Flute, Violin and Piano;
• Moszkowski Suite for 2 Violins and Piano; and
• Handel Sonata for 2 Violins and Piano in G Minor.

Organizers also promise some surprise performances. Admission to the concert is free, and there will be a short reception  in the chapel lobby after the concert.

The Faculty of Engineering will be hosting a ceremony and moment of silence today at 11:00 a.m. to mark the National Day of Remembrance and Action on Violence Against Women, which is observed annually on December 6 to remember the 14 women murdered at École Polytechnique in 1989. This year, December 6 falls on a Saturday.

The ceremony will be held in the second-floor event space of the Pearl Sullivan Engineering building (formerly Engineering 7).

"Black graduate students at Waterloo are invited to apply for the Black Graduate Student Award, open until January 15, 2026," says a note from the Equity, Diversity, Inclusion, and Anti-Racism office (EDI-R). "This award celebrates academic excellence. Visit the EDI-R website for more information."