You can use the command info line
to map source lines to program
addresses (and vice versa), and the command disassemble
to display
a range of addresses as machine instructions. When run under GNU Emacs
mode, the info line
command causes the arrow to point to the
line specified. Also, info line
prints addresses in symbolic form as
well as hex.
info line linespec
list
command (see section Printing source lines).
For example, we can use info line
to discover the location of
the object code for the first line of function
m4_changequote
:
(gdb) info line m4_changequote Line 895 of "builtin.c" starts at pc 0x634c and ends at 0x6350.
We can also inquire (using *addr
as the form for
linespec) what source line covers a particular address:
(gdb) info line *0x63ff Line 926 of "builtin.c" starts at pc 0x63e4 and ends at 0x6404.
After info line
, the default address for the x
command
is changed to the starting address of the line, so that `x/i' is
sufficient to begin examining the machine code (see section Examining memory). Also, this address is saved as the value of the
convenience variable $_
(see section Convenience variables).
disassemble
The following example shows the disassembly of a range of addresses of HP PA-RISC 2.0 code:
(gdb) disas 0x32c4 0x32e4 Dump of assembler code from 0x32c4 to 0x32e4: 0x32c4 <main+204>: addil 0,dp 0x32c8 <main+208>: ldw 0x22c(sr0,r1),r26 0x32cc <main+212>: ldil 0x3000,r31 0x32d0 <main+216>: ble 0x3f8(sr4,r31) 0x32d4 <main+220>: ldo 0(r31),rp 0x32d8 <main+224>: addil -0x800,dp 0x32dc <main+228>: ldo 0x588(r1),r26 0x32e0 <main+232>: ldil 0x3000,r31 End of assembler dump.
Some architectures have more than one commonly-used set of instruction mnemonics or other syntax.
set disassembly-flavor instruction-set
disassemble
or x/i
commands.
Currently this command is only defined for the Intel x86 family. You
can set instruction-set to either intel
or att
.
The default is att
, the AT&T flavor used by default by Unix
assemblers for x86-based targets.
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