compiler study 4 - crowbar debug and code analysis

compile

debug

on mac, the gdb has been replaced with lldb, here is some debug tips.

set alias for frequently used command

I wrote a file for command aliases, here is the script:

command alias bfl breakpoint set -f %1 -l %2
bfl main.c 21

then start program :

lldb --source br_aliases crowbar test2.crb

--source would specify which file would be used.

static analysis

There is a very good tool for c code static analysis - doxygen
here is the webiste : doxygen, just follow the instruction, compile and install it. the path would be /usr/local/bin/doxygen.

how to use

• doxygen -g crowbar_config , crowbar_config is the doxygen configure file, it would generate a template config file.
• modify the config file. then some entries need to be changed are:

CALL_GRAPH      =  YES
CALLER_GRAPH    =  YES
RECURSIVE       =  YES
EXTRACT_ALL     =  YES
EXTRACT_STATIC  =  YES
OUTPUT_DIRECTORY=  ./call_graph

I make a directory named call_graph for holding all the doucments doxygen generated. be aware that you need dot, ie , graphviz as prerequsite.

• doxygen crowbar_config to generate documents.
  for ex, let's search crb_create_funcion_call_expression,
  
  we get :
  you would get call graph and caller graph. All the white box could be clicked , you would jump to the function immediately. Also the parameter list could be cliked to show you the parameter type definition. that's really a mighty tool.

dynamic analysis

using instruments

for linux user, there are some choices, such as gprof, codeviz and ncc, egypt, etc. but most of them are gnu based. on my mac, it is clang compiler so those tool could not be used. I tried to install egypt but failed, don't want to spend much time on it. so I choose use the osx instruments directly.

• open instruments on mac
• choose time profile
• click on choose a target
• select the program and input parameter
  
• click record, the program would run and all the activity would be profiled. but the profile results seems not complete, when the code runs quickly, I didn't see any method or function except for those system call. I have to run somehow a bigger code script to see the effects. still missing a lot of the function call.
• the call graph is like this :
  

this is also a good tool for analysis the code.

using graphviz and pvtrace

1. install graphviz
2. install pvtrace
3. add instrument.c into the project
4. link instrument.o ,
   
util.o\
native.o\
instrument.o\
error.o\

5. change compile flag
   
#CFLAGS = -c -g -Wall -Wswitch-enum -ansi -pedantic -DDEBUG
CFLAGS = -c -g -finstrument-functions -Wall -Wswitch-enum -ansi -pedantic -DDEBUG

   add -finstrument-functions flag
6. rebuild the project
7. run ./crowbar test/test.crb, then a file trace.txt would be generated, in this file, all the function enter and leave address is recorded.
8. pvtrace crowbar, in fact, pvtrace call addr2line to find the symbol line # . unfortunately, mac doesn't have addr2line, the alternative atos doens't work. so I have to use vmware to start an opensuse box. a file, graph.dot would be generated.
9. dot -Tpng graph.dot -o graph.png to generate a png file. it looks like this :