* GDB Stacktrace for optimized code!
@ 2021-04-20 5:55 Thamil K
2021-04-20 10:54 ` Hannes Domani
0 siblings, 1 reply; 2+ messages in thread
From: Thamil K @ 2021-04-20 5:55 UTC (permalink / raw)
To: gdb
Hi Geeks,
For programs compiled with -O2, where the compiler uses 'jmp' where
possible instead of 'call' or where callee doesn't push $rbp onto the
stack, gdb is still able to generate stack trace properly. But by
inspecting the $rbp and return address, I am unable to trace back the
calls. I would like to know how gdb synthesises the stack trace ? Any
pointers on documentation? Thanks in advance.
Thanks
Thamil
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: GDB Stacktrace for optimized code!
2021-04-20 5:55 GDB Stacktrace for optimized code! Thamil K
@ 2021-04-20 10:54 ` Hannes Domani
0 siblings, 0 replies; 2+ messages in thread
From: Hannes Domani @ 2021-04-20 10:54 UTC (permalink / raw)
To: gdb, Thamil K
Am Dienstag, 20. April 2021, 07:55:39 MESZ hat Thamil K via Gdb <gdb@sourceware.org> Folgendes geschrieben:
> Hi Geeks,
>
> For programs compiled with -O2, where the compiler uses 'jmp' where
> possible instead of 'call' or where callee doesn't push $rbp onto the
> stack, gdb is still able to generate stack trace properly. But by
> inspecting the $rbp and return address, I am unable to trace back the
> calls. I would like to know how gdb synthesises the stack trace ? Any
> pointers on documentation? Thanks in advance.
For tail call optimization ('call' optimized to 'jmp'), see [1].
For for frame pointer omission ($rbp) I couldn't find documentation in gdb, but this blog [2] has some explanations.
[1] https://sourceware.org/gdb/download/onlinedocs/gdb/Tail-Call-Frames.html
[2] https://yosefk.com/blog/getting-the-call-stack-without-a-frame-pointer.html
Hannes
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