* GCC, GDB v6 and -fomit-frame-pointer
@ 2003-10-09 9:51 Alex Hornby
2003-10-09 12:39 ` Daniel Jacobowitz
0 siblings, 1 reply; 5+ messages in thread
From: Alex Hornby @ 2003-10-09 9:51 UTC (permalink / raw)
To: gcc
Does the new DWARF2 call frame in gdb 6.0 support mean programs compiled
with GCC and -fomit-frame-pointer can now be debugged? That would be
great as -fomit-frame-pointer provides quite a performance boost on x86.
Assuming this is possible, what GCC and binutils versions would be
needed to take advantage of this?
Cheers,
Alex.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: GCC, GDB v6 and -fomit-frame-pointer
2003-10-09 9:51 GCC, GDB v6 and -fomit-frame-pointer Alex Hornby
@ 2003-10-09 12:39 ` Daniel Jacobowitz
2003-10-09 12:42 ` Jakub Jelinek
0 siblings, 1 reply; 5+ messages in thread
From: Daniel Jacobowitz @ 2003-10-09 12:39 UTC (permalink / raw)
To: Alex Hornby; +Cc: gcc
On Thu, Oct 09, 2003 at 10:43:22AM +0100, Alex Hornby wrote:
>
> Does the new DWARF2 call frame in gdb 6.0 support mean programs compiled
> with GCC and -fomit-frame-pointer can now be debugged? That would be
> great as -fomit-frame-pointer provides quite a performance boost on x86.
>
> Assuming this is possible, what GCC and binutils versions would be
> needed to take advantage of this?
In general yes. Backtraces should work. Ultra-accurate argument and
local variable printing requires -fvar-tracking in GCC so it's a little
flaky now, but unwinding should be fine.
Anything recent. I think 3.2, 3.3 are fine.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: GCC, GDB v6 and -fomit-frame-pointer
2003-10-09 12:39 ` Daniel Jacobowitz
@ 2003-10-09 12:42 ` Jakub Jelinek
2003-10-09 12:55 ` Daniel Jacobowitz
0 siblings, 1 reply; 5+ messages in thread
From: Jakub Jelinek @ 2003-10-09 12:42 UTC (permalink / raw)
To: Daniel Jacobowitz; +Cc: Alex Hornby, gcc
On Thu, Oct 09, 2003 at 08:33:00AM -0400, Daniel Jacobowitz wrote:
> On Thu, Oct 09, 2003 at 10:43:22AM +0100, Alex Hornby wrote:
> >
> > Does the new DWARF2 call frame in gdb 6.0 support mean programs compiled
> > with GCC and -fomit-frame-pointer can now be debugged? That would be
> > great as -fomit-frame-pointer provides quite a performance boost on x86.
> >
> > Assuming this is possible, what GCC and binutils versions would be
> > needed to take advantage of this?
>
> In general yes. Backtraces should work. Ultra-accurate argument and
> local variable printing requires -fvar-tracking in GCC so it's a little
> flaky now, but unwinding should be fine.
>
> Anything recent. I think 3.2, 3.3 are fine.
Even without CFI info? With the exception of IA-64/AMD64, GCC doesn't
generate unwind info by default, only when -fasynchronous-unwind-tables.
Jakub
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: GCC, GDB v6 and -fomit-frame-pointer
2003-10-09 12:42 ` Jakub Jelinek
@ 2003-10-09 12:55 ` Daniel Jacobowitz
2003-10-09 18:00 ` Jakub Jelinek
0 siblings, 1 reply; 5+ messages in thread
From: Daniel Jacobowitz @ 2003-10-09 12:55 UTC (permalink / raw)
To: Jakub Jelinek; +Cc: Alex Hornby, gcc
On Thu, Oct 09, 2003 at 12:36:08PM +0200, Jakub Jelinek wrote:
> On Thu, Oct 09, 2003 at 08:33:00AM -0400, Daniel Jacobowitz wrote:
> > On Thu, Oct 09, 2003 at 10:43:22AM +0100, Alex Hornby wrote:
> > >
> > > Does the new DWARF2 call frame in gdb 6.0 support mean programs compiled
> > > with GCC and -fomit-frame-pointer can now be debugged? That would be
> > > great as -fomit-frame-pointer provides quite a performance boost on x86.
> > >
> > > Assuming this is possible, what GCC and binutils versions would be
> > > needed to take advantage of this?
> >
> > In general yes. Backtraces should work. Ultra-accurate argument and
> > local variable printing requires -fvar-tracking in GCC so it's a little
> > flaky now, but unwinding should be fine.
> >
> > Anything recent. I think 3.2, 3.3 are fine.
>
> Even without CFI info? With the exception of IA-64/AMD64, GCC doesn't
> generate unwind info by default, only when -fasynchronous-unwind-tables.
Sorry, unstated assumption. This only works if you build with
debugging information. GDB parses both .eh_frame and .debug_frame, and
all the necessary CFI should be in .debug_frame with -gdwarf-2.
If debugging info bothers you, use objcopy --add-gnu-debuglink :)
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: GCC, GDB v6 and -fomit-frame-pointer
2003-10-09 12:55 ` Daniel Jacobowitz
@ 2003-10-09 18:00 ` Jakub Jelinek
0 siblings, 0 replies; 5+ messages in thread
From: Jakub Jelinek @ 2003-10-09 18:00 UTC (permalink / raw)
To: Alex Hornby, gcc
On Thu, Oct 09, 2003 at 08:42:08AM -0400, Daniel Jacobowitz wrote:
> > Even without CFI info? With the exception of IA-64/AMD64, GCC doesn't
> > generate unwind info by default, only when -fasynchronous-unwind-tables.
>
> Sorry, unstated assumption. This only works if you build with
> debugging information. GDB parses both .eh_frame and .debug_frame, and
> all the necessary CFI should be in .debug_frame with -gdwarf-2.
>
> If debugging info bothers you, use objcopy --add-gnu-debuglink :)
Ok, true. Now just stuff like backtrace (3) or libSegFault.so will be
very upset about -fo-f-p (and there .debug_frame doesn't help, only
.eh_frame could).
Jakub
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2003-10-09 17:41 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2003-10-09 9:51 GCC, GDB v6 and -fomit-frame-pointer Alex Hornby
2003-10-09 12:39 ` Daniel Jacobowitz
2003-10-09 12:42 ` Jakub Jelinek
2003-10-09 12:55 ` Daniel Jacobowitz
2003-10-09 18:00 ` Jakub Jelinek
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