how to debug mruby (rubyconftw2014)

How to debug mrubyHow to debug mruby

RubyConf.tw 2014RubyConf.tw 2014Team YamanekkoTeam Yamanekko

Yurie Yamane / Masayoshi TakahashiYurie Yamane / Masayoshi Takahashi

自我介紹Who are we?

Who are we

●やまね　ゆりえ (Yurie Yamane)●高橋征義 (Masayoshi Takahashi)●ちー (Chie)

Team Yamanekko

Who are we

http://mrb.h2so5.net/

電子書出版社

http://tatsu-zine.com/

Tatsu-zine Publishing Inc.

http://ruby-no-kai.org/

http://rubykaigi.org/2014

http://rubykaigi.org/2015

CFP will be opened soon

公開徵求講者

our talks

到現在的經歷

Our talks

RubyConf.tw 2012

Our talks

OSDC.tw 2013

RubyConf 2013

https://www.flickr.com/photos/igaiga/10836637785/

Demo

演示

STM32F4的演示

Push Button

Push Button

Power ON

blinkingmode

tilt sensormode

Our problem

我們的問題

mruby core

*.rb (stdlib)

*.rb (your code)

C/C++libmruby.a

Bytecode(C String)

mrbgems

Bytecode(C String)

mruby core

*.rb (stdlib)

*.rb (your code)

C/C++

mrbgems

Ruby

C

mrb_led_toggle

debugging in C → Eclipse+CDT

debugging in Ruby → ???

add breakpoint in C

● aaa● Bbb●

mrbc

breakpoint

mrbgems

C part inApplication

add breakpoint in Ruby

● aaa● Bbb●

mrbc

breakpoint

Today's Topic

今天的主題

Debug

除錯

https://www.flickr.com/photos/monkeymashbutton/7618269720/https://www.flickr.com/photos/monkeymashbutton/7618269720/

CRuby的除錯

Debugging in CRuby

Debugging in CRuby● p || printf● irb● ruby-debug || bybug

Debugging in CRuby● p || printf● irb● ruby-debug || bybug

mruby/src/vm.c

STDIO is an option in mruby

Debugging in CRuby

● p || printf● irb● ruby-debug || bybug

Debugging in CRuby

● p || printf● irb● ruby-debug || bybug

Debugging in CRuby

● p || printf● irb● ruby-debug || bybug

mruby has no debugger (yet)– 田中先生 will develop mruby debugger (in this year?)

Issues in mruby

● embedding into C/C++ apps– mruby's code is just a part of application– We need to debug C/C++ code AND ruby code

● ruby-debug is only Ruby-level debugger– GDB && ruby-debug ??

What we want to do● adding breakpoint in Ruby AND C● step over/into/return in Ruby AND C● show stacktrace in Ruby AND C● show variable in Ruby AND C

– it's different from ruby-debug

We can do them in C level

https://www.sourceware.org/gdb/

our solution

● “hybrid debugger”– C-level debugger + Ruby-level extension– Ruby debugger on GDB

How to debug mrubyHow to debug mruby

RubyConf.tw 2014RubyConf.tw 2014Team YamanekkoTeam Yamanekko

Yurie Yamane / Masayoshi TakahashiYurie Yamane / Masayoshi Takahashi

make a debugger tomake a debugger to

Our debugger status

● just started (not finished yet Orz)● We talk how it works, showing simple demo with gdb and Eclipse plugin

m

http://ruby-hacking-guide.github.io/

mrbc and mrubyVM

*.rb *.mrb mrubyVMmrbc

Compile

Ruby Bytecode

Execute

mrbc and mrubyVM

*.rb *.mrb mrubyVMmrbc

Compile

Ruby Bytecode

Execute

mruby VM don't seeoriginal code in Ruby

bytecode structure

● We made mruby bytecode parser– mrb_parser (v0.0.1)– http://rubygems.org/gems/mrb_parser– https://github.com/yamanekko/mrb_parser

bytecode structure

RITE Section (Header)

IREP Section

END Section

IREP Record

*.mrb

http://commons.wikimedia.org/wiki/File:Dialog-warning-orange.svg

without -g option,mrbc doesn't generate mappings between line numbers of ruby souce code and bytecodes.

mrbc and mrubyVM

*.rb *.mrb

Compile

RubyBytecode withdebug section

Executemrbc -g

mrbc mrubyVM

bytecode structure

RITE Section(Header)

IREP Section

END Section

IREP Record

DEBUG SectionDEBUG Info

*.mrb

corresponding

bytecode structure

RITE Section

IREP Section

END Section

IREP Record

DEBUG SectionDEBUG Info

*.mrb

corresponding

i=1+2

p i

http://commons.wikimedia.org/wiki/File:Dialog-warning-orange.svg

number of byte code ≠line number of Ruby code

not 1 to 1 mapping

mruby VM

mruby VM

● src/vm.c● mrb_context_run()● ≒ case statements within loops

mrb_context_run()

http://commons.wikimedia.org/wiki/File:Dialog-warning-orange.svg

You should defineENABLE_DEBUGin mrbconf.h

ENABLE_DEBUG in mrbconf.h

mrb_state has code_fetch_hook

setting code_fetch_hook function

GDB demo

Eclipse

Eclipse + CDT

● CDT = C/C++ Development Tooling– support various toolchains– standard make build– source navigation– various source knowledge tools

Eclipse + CDT meets mruby

Eclipse Platform

DSF-GDB

target application(+mruby)

GDB/MI

DSFCDT

mrubydebugger

Demo

演示

Conclusion

結語

Conclusion●programming in mruby is fun●debugging in mruby is hard

●making debugger is harder than that

●Cool tool helps you and makes less hard

TODO● step into/step over● show backtrace● show variables

Kernel#local_variables

TODO● extending *.mrb

● adding LVAR section???

Thanks!Happy mruby Hacking!

special thanks to: