Summary of "Of JavaScript Ahead-Of-Time Compilation Performance" by Manuel Serrano (Strange Loop 2022)

00:00:00 - 00:35:00

In this video, Manuel Serrano discusses the potential benefits and drawbacks of writing code in a compiled language such as JavaScript. He outlines his own approach of writing code in a dynamic language and compiling it to JavaScript ahead of time. While he cannot guarantee success, he believes it is possible.

• 00:00:00 In this video, Manuel Serrano presents the results of his work on a static compiler for JavaScript. He starts by explaining the syntax of the language, which is the same as Java. However, the semantics of the program can be very different depending on the values of variables. This can make the compiler very difficult to write. He then goes on to present the results of his work, which show that a static compiler for JavaScript would be very complex.
• 00:05:00 In this video, Manuel Serrano explains how JavaScript's ahead-of-time compilation works. He starts by discussing the semantics of the language, which tells us that we need to invoke another cementing function before doing any dispatch. This other semantic function is the one that will tell us how to follow the Prototype chain. If we find the property we're looking for in an object, we will return it to the other function. However, if we don't find the property, we will follow the Prototype chain. Finally, Manuel shows an example of a function call in C and JavaScript, and how the two languages differ in terms of how the function is implemented and how the arguments are delivered to the function.
• 00:10:00 The author describes how a Hub compiler, which is a static compiler for JavaScript, can be used to improve performance. The compiler accommodates the technique of jit compilers to static compilation, uses data flow analysis and optimistic heuristic optimizations, and is able to select the most optimized version of a function based on the type of argument.
• 00:15:00 This video discusses the performance benefits of Ahead-Of-Time (AOT) compilation of JavaScript. AOT compilation is performed by finding the type for which a compiler is able to generate the best code, and selecting that type rather than inferring the most generic type. In this example, the best possible code is generated when an expression is assigned an object, an integer, or a string. Rules are applied blindly one after the other, and the resulting type is then selected. This process is demonstrated on a simple function that reverses an array of values.
• 00:20:00 The author discusses how JavaScript Ahead-Of-Time compilation can be used to improve performance when compared to traditional compile-time compilation. He shows how this is done by compiling Scheme to JavaScript, and then invoking the forage function on arrays to generate efficient code.
• 00:25:00 Manuel Serrano explains how the performance of JavaScript ahead-of-time compiled code can vary depending on the complexity of the problem being solved. He shows how the performance of different implementations of a simple recursion problem changes over time.
• 00:30:00 The author discusses how their static compiler outperforms the most efficient jit compiler, but is not as good as the jit compiler when it comes to memory footprint. They suggest trying to reuse types generated by the typescript compiler, as this may result in better performance while sacrificing less flexibility.
• 00:35:00 Manuel Serrano discusses the potential benefits and drawbacks of writing code in a compiled language such as JavaScript, before outlining his own approach of writing code in a dynamic language and compiling it to JavaScript ahead of time. While he cannot guarantee success, he believes it is possible.