In the fall semester of 2019, I had the opportunity to work as a teaching assistant for the course 15-312/15-652 Foundations of Programming Languages, taught by Bob Harper. Today we wrapped up (almost) all of the work. As I have always said, the best way to build clear insight into a subject is perhaps by teaching and explaining it to the others. On the other hand, it was quite a unique experience. In addition to the usual grading and recitation, I invented a few homework problems (the DFA problem in HW2 and the entire KPCF problems) and wrote a few exam questions. There are a few things that went pretty well, and honestly some things just don’t quite go well as we would hope for. For the purpose of this post, I don’t want to (and honestly can’t) go into too much details, but focus on mainly 3 things: the philosophy behind this course, one unfortunate situation, and what it feels like working with Bob.

This is the first part of a two-part post, where I mainly talk about the philosophy of this course, as I understand it. In other words, I seek to answer the question of why study programming languages with my own experience.

Introduction

During the summer of 2019, I took an internship at NVidia’s Austin campus working with one of their CUDA compiler teams. Two teams of engineers there work on compiler related projects: the compiler verification team and the compiler development team. The compiler verification team ensures the correctness and consistent behavior of the CUDA compiler toolchain for a large number of applications on all platforms. The development team is in charge of the in-driver CUDA assembler, publicly known as ptxas. I worked under the supervision of Brian Deitrich, and mentored by Rishkul Kulkarni.

京都动画第一动画工房于2019年7月18日遭遇纵火恐怖袭击。目前已知有33人遇难，36人不同程度受伤，十多人下落不明。据传大量原稿丢失。京都动画公司体量并不大，目前遇难者接近公司总员工数五分之一，伤难者接近三分之一。此次袭击的严重程度为日本二战以后最为恶劣。

作为动画的观众，虽然我并不是京蜜，说实在对于几位监督并不是十分熟悉，但仍然感到极为心痛。说实在今天在公司一天都没有什么效率，一直在刷Twitter。看到了很多人分享京都动画的作品给他们的生活带来的正面的影响，说实在十分感动。我在这里也希望分享一下我的感受。

• 如果只是想到BAT打工当程序员，是不是一定要是CS科班出身？
• CS科班出身的程序员是不是理所应当的高人一等？
• 学校里教的技术很老旧，是不是还不如翘课自学新技术？
• 培训班和某些大V网课是不是能学到”真本事“？

这样的问题在各大网上平台中被反复地讨论，但时常这样的讨论都以双方发生大量争执而不欢而散。应该强调本文的目的不是对于以上问题给出是或者否的答案。*事实上，我对于以上（和其他没有列举的问题）的看法相当复杂。*但我仍然认为有必要对这些问题提出一些看法，并且这样的讨论是有意义的。

Sigbovik (Special Interest Group on Harry Q. Bovik) is an annual Quasi-conference held on April 1st at CMU for mostly computer science students to have “geek fun”. Papers submitted usually includes silly ideas with (often) serious execution. This year, I and @codeworm96 submitted a paper titled Precise ECG platform on Modern Processors. We won the Most Likely to Void a Warranty award from the program comittee.

本文不含剧透。

Source of image is here

Recently I’ve been taking VE475 cryptography. This is final CS course I will take here in JI. Frankly, the course is mind challenging, yet informative. It’s time well-spent in short. So there is this challenge, a bonus project, which asks student to write their own ciphers and attack against each other. Attacks are conducted through a web server. Basically you can access a website that allows you preform cryptographic attacks. Now I’ve able to discover a seriers of the security issues that eventually allows me to take full control of the server.

This post contains solutions to specific problem used in CMU 15513. If you are taking the course, please do not read further.

In this post, I will introduce you to a bug of the program. At first I thought this is a hardware bug. Then I suspect this is a compiler bug. Yet it turns out, the real issue is undefined behavior in my program. We will see how compiler makes “wrong” optimizations, when undefined behavior is involved.

I know I am supposed to make weekly updates. Sorry fellows. We both know something enourmous happenned this week. A comment on recent events is going to be published someday soon. I have almost done writing it. I need time to polish it, and more importantly make sure it will not cause any trouble. As a part of my trying to keep up with the weekly update, I’m introducing you to an interesting website, Have I been pawned?.