If you've ever attended a seminar about weak memory models, chances are good that you've been shown a small concurrent program and asked to ponder what is allowed to happen if its threads are executed on two or three different cores of a multicore CPU. For instance, you might be shown this program: // Thread… Continue reading Understanding the memory semantics of multi-threaded CPU/FPGA programs
This post is about a paper by Matt Windsor, Ally Donaldson, and myself that will presented shortly at the ACM SIGSOFT International Symposium on Software Testing and Analysis (ISSTA) conference, in the tool demonstrations track. Compilers are a central pillar of our computing infrastructure, so it's really important that they work correctly. There's been a… Continue reading Introducing C4: the C Compiler Concurrency Checker
High-level synthesis – the automatic compilation of a software program into a custom hardware design – is an increasingly important technology. It's attractive because it lets software engineers harness the computational power and energy-efficiency of custom hardware devices such as FPGAs. It's also attractive to hardware designers because it allows them to enter their designs… Continue reading Fuzzing High-Level Synthesis Tools
Your task is to write down a sequence of English words that, after possibly moving around the spaces between the words, become their German translations. As stated, this is pretty easy: for instance, I could write down the single English word SAND which translates to the single German word SAND. Or I could be a… Continue reading A translation puzzle
T-diagrams (or tombstone diagrams) are widely used by teachers to explain how compilers and interpreters can be composed together to build and execute software. In this blog post, Paul Brunet and I revisit these diagrams, and show how they can be redesigned for better readability. We demonstrate how they can be applied to explain compiler… Continue reading Diagrams for Composing Compilers
If I visit an exotic destination, I would surely do some sightseeing. I would cycle to that destination and I would use Google Maps for navigation. At most crossroads, I need to know in which direction I should turn. Other apps running on my phone might delay the indications provided by Google Maps and therefore I can mistakenly make a wrong turn and possibly be eaten by some large animal.
The reason why this is happening is that on all modern multicore processors, applications on different cores of the system are competing for the shared resources. This is not a problem in most applications but it can be in time-sensitive ones. If we design any such time-sensitive programs, we need to know what to expect in terms of interference so that we can accommodate for the delays. The most common approach for evaluating delays in multicore systems is to run…
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Here are a few personal highlights from the FPGA 2020 conference, which took place this week in Seaside, California. (Main photo credit: George Constantinides.) Jakub Szefer's invited talk on "Thermal and Voltage Side Channels and Attacks in Cloud FPGAs" described a rather nifty side-channel through which secrets could be leaked in the context of cloud-based… Continue reading Highlights from FPGA 2020
The concept of "odd" and "even" functions is quite important in areas such as Fourier analysis. An odd function is one that has 2-fold rotational symmetry around the origin; examples include $latex y=x$, $latex y=x^3$, and $latex y=\sin x$. $latex y=x^3$ is an example of an "odd" function An even function is one that has… Continue reading New names for odd and even functions
When you want to do some computation on an FPGA, it is traditional to enter your design in a language like Verilog, and then to use automatic synthesis tools to turn your Verilog design into a "configuration bitstream" that can be fed to your FPGA to make it perform the computation you want. These synthesis… Continue reading Fuzzing FPGA synthesis tools
In this post, I'd like to share some thoughts I've accumulated over the past few years about how to draw better graphs. To get straight to the point, I have two concrete recommendations: normalised data should usually be plotted on a logarithmic scale, andscatter plots can be easier to understand than bar charts. I'll now… Continue reading A plot twist! Drawing better graphs in PL papers
