JITWatch VS SharpLab

Last time I was this blown away was with jitwatch ( https://github.com/AdoptOpenJDK/jitwatch )

FlowTracker reminds me a little of taint analysis, which is used for tracking unvalidated user inputs or secrets through a program, making sure it is not leaked or used without validation.

search keywords are "dynamic taint tracking/analysis"

https://github.com/gmu-swe/phosphor

https://github.com/soot-oss/SootUp

https://github.com/feliam/klee-taint

You can kind of do the same as DISASSEMBLE in Clojure.

There are some helper projects like https://github.com/Bronsa/tools.decompiler, and on the OpenJDK JitWatch (https://github.com/AdoptOpenJDK/jitwatch), other JVMs have similar tools as well.

It isn't as straightforward as in Lisp, but it is nonetheless doable.

As you have encapsulated the asserts inside methods, these will be called at runtime with the arguments evaluated (for example, creating that lambda). When assertions are disabled, the C1/C2 may inline the empty method call eventually, but I don't know whether it drops the lambda instantiation as well. You can use JITWatch to see what gets inlined. The general notion though is to not worry too much. Lazy log messages are a common pattern.

You can use jitwatch for this. To see the actual assembly code generated you will also need to use a debug build of the jvm.

If you use Oracle's own IDE, it will support it out of the box, as it already did on Sun's days.

Then there are other ways depending on which JVM implementation is used.

On OpenJDK's case you can load runtime plugin to do it

https://github.com/AdoptOpenJDK/jitwatch

We use https://github.com/AdoptOpenJDK/jitwatch for this.

If you already know any JVM or .NET language, the first step would be to understand the full stack, you don't need C for that.

Many of us were doing systems programming with other languages before C went mainstream.

What you need to learn is computer architecture.

Getting back to JVM or .NET, you can get hold of JIT Watch, VS debug mode or play online in SharpLab.

Get to understand how some code gets translated into MSIL/JVM, and how those bytecodes end up being converted into machine code.

https://github.com/AdoptOpenJDK/jitwatch/wiki/Screenshots

https://sharplab.io/

Languages like F# and C# allow you to leave the high level comfort and also do most of the stuff you would be doing in C.

Or just pick D, which provides the same comfort and goes even further in low level capabilities.

Use them to write a toy compiler, userspace driver, talking to GPIO pins in a PI, manipulating B-Tree data stuctures directly from inodes, a TCP/IP userspace driver.

Not advocating not to learn Zig, do it still, the more languages one learns the better.

Only advocating what might be an easier transition path into learning about systems programming concepts.

You can enable a lot of debug information about how the compiler decides what to do with your code using feature flags like -XX:+UnlockDiagnosticVMOptions -XX:+PrintInlining. If you want to dive deeper into the world of the Hotspot JIT Compiler, have a look at JITWatch.

Let's put the code into SharpLab.

It is not just practice that will help you master C#. Using tools to look under the hood will accelerate your understanding of various language features and helps you write better, more efficient code. Sharplab.io is one such tool that will help you to quickly learn and understand certain C# language features. You can use this tool to show you "lowered" C# code.

> I do likely have a biased perspective though, as I use newer C# features every day

I think that is kind of the point, though. Many of those newer features help with simplifying code and making it less boilerplate-y. To old programmers it is a simple code fix in the IDE to move from 30 lines of variable assignments in a switch to a 5 lines switch expression and they can learn that way. People new to the language typically won't even consider going the complicated route because they learned an easier way first.

I do concede that having people with less C# experience on a team where modern C# is used, there will be constructs that are not immediately obvious. SharpLab has an “Explain” mode which would be helpful in such cases, but I haven't seen anything like that in IDEs: https://sharplab.io/#v2:C4LgpgHgDgNghgSwHYBoAmIDUAfAAgBgAJcB...

However, as a personal anecdote, we've had a number of developers who have written mostly Java 1.4 (technical reasons) before switching to C# about a year ago. They took up the newer features and syntax almost without problems. Most questions I got from them were along the lines of “Can we also use this feature?” and not “What does this do?”.

AFAIK you can still use it for older frameworks. The compiler embeds the attributes into the assembly when they're known to not be part of the runtime library [−3.7]. You can do the same with the various conditional nullability attributes.

[−3.7]: https://sharplab.io/#v2:EYLgHgbALAPgAgZgARwExIMJIN4FgBQSRKyc...

Do these all compile to the exact same thing?

https://sharplab.io/#v2:CYLg1APgAgTAjAWAFBQMwAJboMLoN7LpHoCW...

Yes, so you are right.

Recently, while creating some experimental C# source code generators (xafero/csharp-generators), I was just concatenating strings together. Like you do, you know, if things have to go very quickly. If you have a simple use case, use a formatted multi-line string or some template library like scriban. But I searched for a way to generate more and more complicated logic easily - like for example, adding raw SQL handler methods to my pre-generated DBSet-like classes for my ADO.NET experiment. You could now say: Use Roslyn and that's really fine if you look everything up in a website like SharpLab, which shows immediately the syntax tree of our C# code.

One results in MOVSX, the other in MOVZX [1]. The difference thus is sign/zero extension when moving to the larger register. However, they seem to perform pretty much identical if I'm reading Agner Fog's instruction tables correctly.

[1] https://sharplab.io/#v2:C4LghgzgtgPgAgJgIwFgBQcDMACR2DC2A3ut...

If you don't have an IDE, you can use SharpLab.io or dotnet fiddle

The closest online tool I can think of would be SharpLab, but you can only choose between Roslyn's git branches instead of C# versions.