View Both Assembly and C code

Question

Do we have a way to view assembly and c code both using gdb.

disassemble function_name shows only assembly, I was trying to find a way to easliy map c code to assembly.

Answer 1

You can run gdb in Text User Interface (TUI) mode:

gdb -tui <your-binary>
(gdb) b main
(gdb) r
(gdb) layout split

The layout split command divides the window into two parts - one of them displaying the source code, the other one the corresponding assembly. A few others tricks:

• set disassembly-flavor intel - if your prefer intel notation
• set print asm-demangle - demangles C++ names in assembly view
• ni - next instruction
• si - step instruction

If you do not want to use the TUI mode (e.g. your terminal does not like it), you can always do:

x /12i $pc

which means print 12 instructions from current program counter address - this also works with the tricks above (demangling, stepping instructions, etc.).

The "x /12i $pc" trick works in both gdb and cgdb, whereas "layout split" only works in gdb.

Enjoy :)

Answer 2

Try disassemble /m.

Refer to http://sourceware.org/gdb/current/onlinedocs/gdb/Machine-Code.html#Machine-Code

The format is similar to that of objdump -S, and intermixes source with disassembly. Sample output excerpt:

10      int i = 0;
=> 0x0000000000400536 <+9>: movl   $0x0,-0x14(%rbp)

11      while (1) {
12          i++;
   0x000000000040053d <+16>:    addl   $0x1,-0x14(%rbp)

Answer 3

For your purpose, try

objdump -S <your_object_file>

from man objdump:

-S
--source
 Display source code intermixed with disassembly, if possible.
 Implies -d.