2014-05-26 21:04:19 +02:00
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---
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layout: news
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author: Torsten
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---
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Both "ends", parsing and machine code, were relatively clear cut. Now it is into unknown territory.
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I had ported the Kaleidescope llvm tutorial language to ruby-llvm last year, so thee were some ideas floating.
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The idea of basic blocks, as the smallest unit of code without branches was pretty clear. Using those as jump
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2014-05-26 21:13:49 +02:00
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targets was also straight forward. But how to get from the AST to arm Intructions was not, and took some trying out.
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2014-05-26 21:04:19 +02:00
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2014-05-26 21:13:49 +02:00
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In the end, or rather now, it is the AST layer that "compiles" itself into the Vm layer. The Vm layer then assembles
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2014-05-26 21:04:19 +02:00
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itself into Instructions.
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General instructions are part of the Vm layer, but the code picks up derived classes and thus makes machine
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dependant code possible. So far so ok.
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Register allocation was (and is) another story. Argument passing and local variables do work now, but there is definately
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room for improvement there.
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To get anything out of a running program i had to implement putstring (easy) and putint (difficult). Surprisingly
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division is not easy and when pinned to 10 (divide by 10) quite strange. Still it works. While i was at writing
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assmbler i found a fibonachi in 10 or so instructions.
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To summarise, function definition and calling (including recursion) works.
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If and and while structures work and also some operators and now it's easy to add more.
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So we have a Fibonacchi in ruby using a while implementation that can be executed by crystal and outputs the
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2014-05-26 21:13:49 +02:00
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correct result. After a total of 7 weeks this is much more than expected!
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