The compiler FrontEnd is now finished!

Hello again! As I promised last time, I have two big announcements to make. Even though summer has been warm and beautiful, I’ve been working very hard on CoolBasic compiler for the past few weeks. We’re talking about something like 8 hours aday on average, but there were also a few of those days during which I coded 11 hours pretty much non-stop. And it’s been great! Even though most of the work has been nothing but bug fixes, my motivation has all but diminished. Some people might think otherwise, but I actually get encouraged by intriguing bugs that take 24 hours to track down because it’s very rewarding to ultimately fix those.

I don’t normally mention about bugs I’ve found and fixed, but be it exception this time: I had a medium-sized architectural issue regarding method invocation and how the reference is passed to them. Static methods and structure methods add an extra twist. The original implementation had fixed stack position for the reference – which ultimately proved to not work out for complex dot notations that involve static members in the middle. I fixed the problem by re-writing the part that is responsible for recognizing valid references and injecting them into the final code. References are now always at the same relative location they appear in the original statement. Even static methods now have them although those don’t necessarily point to anything. Long and complex dot notation paths in general have been giving me quite a lot of work recently.

The first announcement
I’m proud to announce that I have now finished the Intermediate Language (later referred to as “IL”) entirely. This effectively concludes Pass#2 and thus the compiler FrontEnd is now considered “finished”. It’s been of a long road, and reaching this major milestone is a great relief to me. What this means in terms of progress? The IL still needs yet another transformation, but this time it’ll be final. So basically there’s just one process to make for the compiler, and then I can start working on the runtime. Also, it’s July already, and I think the devTeam won’t be assembled this summer but in autumn perhaps. There just is so much work to do, sorry. I’m about a month late of the original schedule I had. But I’d say it’s normal because in program of this nature surprises tend to emerge. Some of which force medium-to-large re-writes of existing code. Modifications always affect somewhere else and thus extensive testing needs to be done after architectural changes – be it minor or major. Thankfully, I didn’t have to implement major changes to anything (atleast not just yet).

I spent 5 days (there were quite many bug discoveries and fixes involved) to write an extensive array of Unit Tests. A Unit Test is basically a standalone fragment of code that responds to input and output; they are used to test program functionality isolated from the big picture, and each test runs in its own sandbox. These small programs I wrote, test all CoolBasic programming language features. After compilation I examined the emitted IL in detail and ensured that everything went well and that the IL was correct. As a result of this process, I gathered interesting data and statistics I’d like to share with you. I think the numbers speak for themselves:

Test Program:

– Code size: 2547 lines in 7 files, 62 kb in total
– Composition: natural mix of comments, declarations and executing code. All language features
– Symbol table size: 1150 identifiers
– Emitted IL: 7410 lines

Testing Platform:

– HP HDX18-1000EO (Laptop)
– T9400 processor
– 4GB memory
– Windows Vista (64-bit)

Results:

– Number of compilations: 20
– Average compile time: 105 milliseconds
– Fastest compile time: 97 milliseconds

That’s pretty fast compilation considering the complexity of the process. Overall I’m happy with the outcome and that “pressure test”. I’ll be using the same gigantic Unit Test program to validate everything when any new feature gets added later on.

The second announcement
Now that the pressure is mostly gone, there’s something completely different I need to do: I still haven’t finished my thesis, so I’m technically still a student. That’s something I’ll soon need to take care of as the official time limit of graduation is closing to its end (and I don’t wish to extend it). As some of you may know, I already work as professional software engineer, so that’s taken some time and focus off the studies. The only thing remaining (and the only reason I’m still in their register as “pending graduation”) is the unfinished thesis. So I’ll take a few weeks off CoolBasic, and finish up my studies in Bachelor of Business Administration in Information Technology. Graduation and receival of the official “shiny paper” will also be a great relief, and after that I can fully focus on CoolBasic once again. I will start the thesis from a blank table very soon. During this time, however, I will be watching the forums, and am available via IRC (nothing new there). My four-week summer holiday is starting on 20th July so I have lots of resources to use on the thesis (although I don’t wish to spend all the summer indoors). I will also be participating in Assembly Summer 2009 this year!

Some random thoughts
I reviewed CoolBasic V3 manual. After careful consideration, I came to conclusion that the black theme is unfitting to such material that is to become the primary textual source of information for Coolbasic V3. Although silver text is still very readable on black background, you can actually read dark text on white background longer without the eyes growing tired. I’ve taken a little more MSDN-like approach although I plan to enhance the visual look and feel.

It’d be cool to allow the online manual to be somewhat interactive and more dynamic. Features such as User Comments, Version History, Multilinguality, and linking to outside sources as well as flexible Maintainability will basically require a database. Thus, online version of the manual is best to separate from offline version. I’d still like to use XSLT for the offline manual, but then the end users couldn’t use Firefox to view it – or otherwise I’d have to make the manual very dull looking basically ignoring text styling within paragraphs. So there’s still some open questions to the offline version, but database approach for the online manual certainly looks quite promising. Either way, it’s always possible to generate the offline manual directly from the database. Database design, however, will be a challenge!

Enjoy the summer, folks!

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