Module 9 - Debuggers

GDB

To compile for debugging, use -g command line argument - compiler keeps copy of source code for use by debugger
Within gdb for a program:
- layout src - turn on TUI mode
- set style enable off - turns off syntax highlighting
- quit - quit gdb
- run - explicitly runs program, program runs to completion if program does not halt due to errors.
  - note that run also supports command line arguments/io redirection, e.g. run Hello 123 < file.in
- we can add breakpoints to pause execution - step through code line at a time
- break <function name | line number | [file:line](file:line) number> - create a breakpoint
- continue - continue execution after pause
- info breakpoints - see list of breakpoints setup
- delete <id num> - delete breakpoint with given id
- enable <id num> - enables breakpoint
- disable <id num> - disables breakpoint with id
- next - executes one statement in current context, src window will show line of code to be executed next
  - next statement is for current context - will not jump into function calls
- step - like next, but steps into contexts
- refresh - refresh screen
- list - useful if you are not using TUI mode - shows some number of surrounding statements
  - can change number of surrounding statements with set listsize [count]
- focus - brings to focus a specific window, e.g. focus cmd - brings focus to gdb command window
- print <variable> - prints some variable
  - if printing something like an array, we use arr@num to display num number of array elements
- display/undisplay/enable display/disable display - tell GDB to display the value of a particular variable, expressions, address, etc.
  - undisplay - stop displaying value
  - alternative to display is setting up watchpoints - watch variable for changes

Stack Navigation and Going in Reverse

backtrace - displays one line for the stack frames in current call stack - provide summary info of how you got to this point in the program
up/down - navigate up/down call stack
record, reverse-next, reverse-step
- execute record after you execute - basically where to start recording from
- reverse-next, reverse-step - like next, step, but in reverse
To debug recursive functions: consider finish - executes all of the function calls and stops once the current stack frame is popped

More Features, Reference Sheet

set var - set variable during debugging, e.g. set var name=value
some other commands:
- layout - lists different options available
- focus - put cmd window in focus
- dinheight - change winheight, first argument is window, second argument can be: number of lines for window, +count if we want to increase number of lines for window, -count if we want to decrease number of lines for window
- set style - configure how gdb styles stuff
- set logging - can help log results of gdb
  - can use set logging file [filename] - set file to which all output should be logged
  - enable logging with set logging enabled on

Command	Abbreviation	Description
run	r	Runs the selected program until the next Breakpoint or Watch
break	b	Sets a breakpoint at a line or function (Current line by default)
watch	wa	Sets a watchpoint
next	n	Steps through next line of code (Does not enter function call)
step	s	Steps into next line of code (Enters function call if any)
continue	c	Run from current point to next Breakpoint or Watch
info breakpoints	i b	List out all breakpoints and watchpoints
delete	d	Delete breakpoint or watchpoint with given id
print	p	Prints out the value of the given variable
whatis	what	Prints out the type of the given variable
display	disp	Print out the value of a variable at each step
undisplay	undisp	Undo a "display" command
up	up	Move up the call stack
down	do	Move down the call stack
backtrace	bt	Print a trace of the current call stack
finish	fin	Run to the end of the current function call
record	record	Begin recording additional information to enable reverse debugging (must be called after run)
reverse-next	rn	Steps backward through code (Does not enter function call)
reverse-step	rs	Steps backward through code (Enters function call if any)
set var	set var	Modify the value stored in a variable during execution

oh yeah you can set up breakpoints in vscode as well lmao