Here is a trace of what I am doing. Note I am debugging from the IDE and
typically use the 'step over' and 'step into' buttons but to illustrate
what I am doing I have entered the following commands manaully on the
gdb console in the IDE:

When the excutable launches it stops at the line:
	Base* pBase = new Derived();

I use the 'next' command to step over to the next source line 
	pBase->hello();

next
next
22	    pBase->hello();


Then I use a series of 'stepi' commands to execute the machine
instructions to 'step into' the function hello().

stepi
stepi
0x4804081c	22	    pBase->hello();
stepi
stepi
0x48040820	22	    pBase->hello();
stepi
stepi
0x48040824	22	    pBase->hello();
stepi
stepi
0x48040828	22	    pBase->hello();
stepi
stepi
0x4804082c	22	    pBase->hello();
stepi
stepi
0xfe339f64 in MsgSendv () from
/opt/qnx632/target/qnx6/ppcbe/lib/libc.so.2

Here is the disassembly for the above:

    pBase->hello();
48040818:	81 3f 00 10 	lwz	r9,16(r31)
4804081c:	81 29 00 00 	lwz	r9,0(r9)
48040820:	81 29 00 00 	lwz	r9,0(r9)
48040824:	7d 29 03 a6 	mtctr	r9
48040828:	80 7f 00 10 	lwz	r3,16(r31)
4804082c:	4e 80 04 21 	bctrl

One interesting point, if before doing the stepi instructions above, I
insert a breakpoint on the printf() statement in hello(), the stepi
instructions will successfully step into the hello() function and halt
on the printf() function call.


-----Original Message-----
From: Aleksandar Ristovski [mailto:community-noreply@qnx.com] 
Sent: Thursday, February 19, 2009 4:18 PM
To: general-toolchain
Subject: Re: GDB (on PPC target) can't step into functions derived from
abstract class

Robert D'Attilio wrote:
> I tried launching your binary on my system (although I had to
explicitly
> download a different libcpp.so as we use the "Dinkum Abridged without
> Exceptions" version - as an aside, I thought this (the different
libcpp)
> might be the problem but it wasn't). I stepped through the disassembly
> and end up with the same behaviour as with my binary. Here is a stack
> trace (of your binary) immediately after I try to step into hello(). 

you stepped through disassembly with 'stepi', or just did 
step again once you stopped in Base::hello (or run)? If you 
could, post exact commands you issued to gdb before you got 
to this point.


> 
> #0  0xfe339f64 in MsgSendv () from
> /opt/qnx632/target/qnx6/ppcbe/lib/libc.so.2
> #1  0xfe35f14c in _devctl () from
> /opt/qnx632/target/qnx6/ppcbe/lib/libc.so.2
> #2  0xfe318f18 in isatty () from
> /opt/qnx632/target/qnx6/ppcbe/lib/libc.so.2
> #3  0xfe34dd50 in _Fbuf () from
> /opt/qnx632/target/qnx6/ppcbe/lib/libc.so.2
> #4  0xfe34e48c in _Fwprep () from
> /opt/qnx632/target/qnx6/ppcbe/lib/libc.so.2
> #5  0xfe34c0ec in fwrite () from
> /opt/qnx632/target/qnx6/ppcbe/lib/libc.so.2
> #6  0xfe34dfb8 in _Fprout () from
> /opt/qnx632/target/qnx6/ppcbe/lib/libc.so.2
> #7  0xfe351478 in _Printf () from
> /opt/qnx632/target/qnx6/ppcbe/lib/libc.so.2
> #8  0xfe34c690 in printf () from
> /opt/qnx632/target/qnx6/ppcbe/lib/libc.so.2
> #9  0x48040784 in Base::hello (this=0x48044330) at
> /home/src/testcases/derivedcpp/derived.cpp:16
> #10 0x48040830 in main (argc=1, argv=0x4803fe74) at
> /home/src/testcases/derivedcpp/derived.cpp:22
> 
> It almost seems as if we're jumping directly into the printf()
function
> call from within hello(). On a hunch, I've tried inserting additional
> 'C' statements before the printf() statement in hello() but it doesn't
> help.


Do you see any warnings about mismatched libraries at the 
beginning of debugging session (do a 'start' at the 
beginning, it will run to main and stop there. There will be 
message about libc.so.2 and warnings if any).

Be aware that I run the binary on a 6.4.0 system. It might 
have something to do...

Aleksandar:

As far as I can tell I'm not getting any mismatched library warnings
from either the build process or when launching from gdb. Is there
anywhere else I should look for these warnings?

Here is the result from my uname
# uname -a
QNX localhost 6.3.2 2006/03/16-14:18:11EST WRM_782 ppcbe


robert
-----Original Message-----
From: Aleksandar Ristovski [mailto:community-noreply@qnx.com] 
Sent: Thursday, February 19, 2009 4:34 PM
To: general-toolchain
Subject: Re: GDB (on PPC target) can't step into functions derived from
abstract class

Robert,

I just run the test on a 6.3.2 ppc target and it still works 
fine for me.

# uname -a
QNX t2ppcbe 6.3.2 2006/03/16-14:19:24EST 8555CDS ppcbe

Please make sure you are not getting any warnings about 
mismatched libraries.

Thanks,

Aleksandar


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