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PDR: Docs: LLDB Command Summary

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Assembly-specific commands

  • stepi: step one MACHINE instruction (i.e. assembly instruction), instead of one C++ instruction (which is what step does)
  • registers read: display the values in the registers
  • settings set target.x86-disassembly-flavor intel: set the assembly output format to what we are used to in class (and what we are programming in)
  • disassemble: like list, but displays the lines of assembly code currently being executed.
  • disassemble --name (function): prints the assembly code for the supplied function (up until the next label)

Program execution

  • run: starts a program execution, and continues until it exits, crashes, or hits a breakpoint
  • bt: prints a back trace, which is the list of function calls that got to the current point
  • f: shows the lines of source code before and after the point at which the program paused
  • list (function): prints the lines of code around (function) or the current breakpoint otherwise if no (function) is provided.
  • up: move up the back trace function stack list
  • down: move down the back trace function stack list
  • step (or just s): step INTO the next line of code to execute
  • next (or just n): step OVER the next line of code to execute
  • continue (or just c): continue execution
  • finish: finishes executing the current function and then pauses
  • quit: exits the debugger

Breakpoints

  • b (pos) (or break (pos)): set a breakpoint at (pos). A breakpoint can be a function name (e.g., b GetMax), a line number (e.g., b 22), or either of the above preceded by a file name (e.g., b lab2.cpp:22 or b lab2.cpp:GetMax)
  • tbreak (pos): set a temporary breakpoint (only breaks the first time)
  • breakpoint list: show breakpoints
  • breakpoint delete (or just br del): deletes all breakpoints
  • breakpoint delete (num): delete the breakpoint indicated by (num)

Examining data

  • print (var) (or p): print the value in the given variable
  • print &(var): print the address that the given variable is located
  • print *(ptr): print the destination of a pointer
  • x/(format) (var/address): format controls how the memory should be displayed, and consists of (up to) 3 components: a numeric count of how many elements to display; a single-character format, indicating how to interpret and display each element -- e.g. a few of the flags are x/x displays in hex, x/d displays in signed decimals, x/c displays in characters, x/i displays in instructions, and x/s displays in C strings; and a single-character size, indicating the size of each element to display -- e.g. b, h, w, and g, for one-, two-, four-, and eight-byte blocks, respectively. You can have multiple at a time, e.g. x/30x (var/address) will display 30 elements in hexidecimal from the provided var/address OR if no var/address is provided, from the top of the stack.
  • frame variable: display all the args and the local variables and their values for their current frame
  • display (var): always display the value in (var) whenever the program pauses
  • display: show the variables that have been entered with display and their numeric IDs
  • undisplay (num): stop displaying the variable with numeric ID num
  • print function_call(params): execute the function, and print the result
  • expr (var) = (value): set the variable (var) to the value (value) -- e.g. expr foo = 5
  • up and down: moves up a frame or down a frame in the backtrace (bt) of a crashed or paused program