updated debugger description

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Torsten Ruger 2018-04-17 16:20:45 +03:00
parent 7fb9d9cfba
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3 changed files with 139 additions and 67 deletions

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.menu
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.blog_nav
.next , .prev
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= render "pages/rubyx/menu"
%h1= title "Register Level Debugger / simulator"
%h1= title "Register Level Debugger / Interpreter"
%h2#views Views
%h2 Interpreter
%p
To understand and debug RubyX better, an Interpreter was created for the Risc layer.
Risc defines a relatively easy abstraction, that is both far away from the language
level, yet still machine independent.
%p
Risc has only 12 registers and almost as little instructions. Mostly moving data around,
jumping and testing.
%p
But since it is so simple, it it a little challenging to understand what is happening
in terms of ruby language constructs, or even the Mom abstraction.
%p
Many test use the Interpreter to test conversion output also dynamically. But to test
successfully, one does need to know what
%em should
be happening.
%p
To understand the Risc layer even better. A Graphical User Interface was created.
%h2 Visual Debugger
%h3 Web - tech
%p
The application is implemented with web technology, in essence it is a JavaScript
One Page Application. Luckily
=ext_link "opal" , "http://opalrb.com/"
came to the rescue, and so not only the
%b whole of Rubyx
is running in the browser, but also all the application code is in ruby.
%p
The app is so small it defines is own micro framework (2 classes), and basically
only shows different list views.
%p
From left to right there are several views showing different data and controls.
All of the green boxes are in fact pop-up menus and can show more information.
All of the boxes with green border are in fact pop-up menus and can show more
information. They represent memory/objects and by hovering one can
%br/
Most of these are implemented as a single class with the name reflecting what part.
I wrote 2 base classes that handle element generation (ie there is hardly any html involved, just elements)
I wrote 2 base classes that handle element generation (ie there is no static
html involved, just elements)
%h3 Code switch view
%p
%img{:alt => "Debugger", :src => "https://raw.githubusercontent.com/ruby-x/rubyx-debugger/master/static/debugger.png", :width => "100%"}/
%h3#switch-view Switch view
Top left at the top is a little control to switch programs.
Currently there is a short hardcoded list of tiny tiny programs.
%p
Top left at the top is a little control to switch files.
The files need to be in the repository, but at least one can have several and switch between
them without stopping the debugger.
When one is selected, the Ruby is parsed and, Risc machine booted,
the Interpreter (re)started and one can use the buttons to step through
the code at various speeds.
%h3 Status View
%p
Parsing is the only thing that opal chokes on, so the files are parsed by a server script and the
ast is sent to the browser.
%h3#classes-view Classes View
The last view at the top right show the status of the interpreter, the
instruction count, flags and any stdout.
%p
The first column on the left is a list of classes in the system. Like on all boxes one can hover
over a name to look at the class and its instance variables (recursively)
%h3#source-view Source View
Current controls include stepping and three speeds of running the program.
%ul
%li
Next (first green button) will execute exactly one instruction when clicked.
Mostly useful when debugging the compiler, ie inspecting the generated code.
%li
Run (second button) runs the program at a higher speed where register instruction
fly by, but one can still follow the source view. Mainly used to verify that the
source executes as expected and also to get to a specific place in the
program (in the absence of breakpoints).
%li
Wizz (third button) makes the program run so fast that its only useful function
is to fast forward in the code (while debugging). One can follow the program counter
to get to the same position as a previous session.
%p.debug_pic
=image_tag "debugger"
%h3 Space View
%p
Next is a view of the Soml source. The Source is reconstructed from the ast as html.
Soml (RubyX object machine language) is is a statically typed language,
maybe in spirit close to c++ (without the c). In the future RubyX will compile ruby to soml.
%p While stepping through the code, those parts of the code that are active get highlighted in blue.
The second down on the left gives a view of the Space. It is the only instance of the
class and the only global being used. It carries classes, types, singleton objects
and some linked lists.
%p
Currently stepping is done only in register instructions, which means that depending on the source
constructs it may take many steps for the cursor to move on.
%p Each step will show progress on the register level though (next view)
%h3#register-instruction-view Register Instruction view
like other views it updates, so when for example an integer is "allocated" one can
follow the list being relinked (the next free integer being swapped out)
%h3 Classes View
%p
RubyX defines a register machine level which is quite close to the arm machine, but with more
sensible names. It has 16 registers (below) and an instruction set that is useful for Soml.
The lower column on the left is a list of classes in the system. Like on all boxes one
can hover over a name to look at the class and it's instance type and so one, recursively.
%h3 Source View
%p
Data movement related instruction implement an indexed get and set. There is also Constant load and
integer operators and off course branches.
Instructions print their name and used registers r0-r15.
%p The next instruction to be executed is highlighted in blue. A list of previous instructions is shown.
Next is a view code to the right is currently broken, but should be the ruby code.
%p
The next view on the right is Risc Machine Instruction panel.
The are the instructions the Interpreter interprets. The next one is
highlighted in blue.
%h3 Register Instruction view
%p
RubyX defines a register machine level which is quite close to the arm machine, but
with more sensible names. It has 12 registers (below) and an instruction set that is
useful for the compiler.
%p
Data movement related instruction implement an indexed get and set. There is also
Constant load and integer operators and off course branches.
Instructions print their name and used registers r0-r11.
%p
The next instruction to be executed is highlighted in blue. A list of previous
instructions is shown.
%p One can follow the effect of instruction in the register view below.
%h3#status-view Status View
%h3 Register view
%p
The last view at the top right show the status of the machine (interpreter to be precise), the
instruction count and any stdout
%p Current controls include stepping and three speeds of running the program.
%ul
%li
Next (green button) will execute exactly one instruction when clicked. Mostly useful when
debugging the compiler, ie inspecting the generated code.
%li
Crawl (first blue button) will execute at a moderate speed. One can still follow the
logic at the register level
%li
Run (second blue button) runs the program at a higher speed where register instruction just
whizz by, but one can still follow the source view. Mainly used to verify that the source executes
as expected and also to get to a specific place in the program (in the absence of breakpoints)
%li
Wizz (third blue button) makes the program run so fast that its only useful function is to
fast forward in the code (while debugging)
%h3#register-view Register view
The bottom part of the screen is taken up by the 12 register. As we execute an
object oriented language, we show the object contents if it is an object in a register.
Data may occupy registers at this level, in which case the hex value is shown.
%p
The bottom part of the screen is taken up by the 16 register. As we execute an object oriented
language, we show the object contents if it is an object (not an integer) in a register.
The (virtual) machine only uses objects, and specifically a linked list of Message
objects to make calls. The current message is always in register 0 (analogous to a stack
pointer). All other registers are scratch for statement use.
%p
The (virtual) machine only uses objects, and specifically a linked list of Message objects to
make calls. The current message is always in register 0 (analgous to a stack pointer).
All other registers are scratch for statement use.
%p
In Soml expressions compile to the register that holds the expressions value and statements may use
all registers and may not rely on anything other than the message in register 0.
%p The Register view is now greatly improved, especially in its dynamic features:
%ul
The Register view is now greatly improved, especially in its dynamic features:
%ul
%li when the contents update the register obviously updates
%li when the object that the register holds updates, the new value is shown immediately
%li
hovering over a variable will
%strong expand that variable
\.
%li the hovering works recursively, so it is possible to drill down into objects for several levels
%strong expand that variable.
%li
the hovering works recursively, so it is possible to drill down into
objects for up to four levels
%p
The last feature of inspecting objects is show in the screenshot. This makes it possible
This last feature of inspecting objects is show in the screenshot. This makes it possible
to very quickly verify the programs behaviour. As it is a pure object system , all data is in
objects, and all objects can be inspected.
%h2 Running the debugger
%p
The debugger is online
=ext_link "here." , "/debugger"
Because of the 10k lines of code it is a bit slow to load.
%p
Also it is not yet possible to write one's own code yet. Just the basic examples.
%p
You can off course clone the debugger from
=ext_link "github" , "https://github.com/ruby-x/rubyx-debugger"
and then change the codes.