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Re: stabs difference gcc 2.95.3 -> 3.4.3
- From: Daniel Jacobowitz <drow at false dot org>
- To: Fabian Cenedese <Cenedese at indel dot ch>
- Cc: gdb at sourceware dot org
- Date: Thu, 30 Mar 2006 09:00:23 -0500
- Subject: Re: stabs difference gcc 2.95.3 -> 3.4.3
- References: <5.2.0.9.1.20060330083638.01f6da00@NT_SERVER>
On Thu, Mar 30, 2006 at 09:12:26AM +0200, Fabian Cenedese wrote:
> This is the working file of gcc 2.95.3, looking up _TASK_CLASS_NAME_::Action:
> GNU gdb 6.2.50_2004-10-14-cvs
First of all, this is an older GDB. You might want to try a current
one.
Secondly, since you're trying to debug C++ with stabs, the basic
reaction is that you'll get what you deserve - the stabs produced
by GCC are missing a lot of information that's available in the default
DWARF-2 format.
> We now wanted to upgrade and tried the same with gcc 3.4.3. To stay
> as much compatible to our other tools as possible we use -gstabs+ even
> if this is not the default format. However this gives some different results.
>
> Now doing the same with the result of gcc 3.4.3:
> GNU gdb 6.2.50_2004-10-14-cvs
> Copyright 2004 Free Software Foundation, Inc.
> This GDB was configured as "--host=i686-pc-cygwin --target=powerpc-eabi"...
> (gdb) info address _TASK_CLASS_NAME_::Action
> Symbol "_TASK_CLASS_NAME_::Action" is at 0x1650 in a file compiled without debugging.
> (gdb) info line '_TASK_CLASS_NAME_::Action()'
> Line 128 of "N:\Indel-PPC\Tests\gcc3\bin343\CTaskTemplateClass.s"
> starts at address 0x1650 <_ZN17_TASK_CLASS_NAME_6ActionEv> and ends at 0x1668 <_ZN17_TASK_CLASS_NAME_6ActionEv+24>.
>
> First thing: why does gdb say that the function is in a file compiled without
> debugging when it still knows where to find it?
We'd need a testcase, sorry. But this is likely to be related to...
> Second thing: why is the assembler file given as source file? Of course it
> _is_ the source file given our two steps compiling. But the same was true
> with the old tool chain where it worked fine. Also, in the generated assembler
> file is the first line a directive:
> .file "CTaskTemplateClass.cpp"
> so it should be clear where this code comes from.
... this. Probably gas has been passed the -g option, and generated
its own debug information, which caused GDB to see debug info for the
assembly file instead of for the source file. You might want to check
that.
> Is there sense in posting this to the gcc list?
Unlikely, since you're using such old compilers.
> Just for checking if this would work better I also tried -gdwarf-2. Got even worse:
> GNU gdb 6.2.50_2004-10-14-cvs
> This GDB was configured as "--host=i686-pc-cygwin --target=powerpc-eabi"...Dwarf Error: Could not find abbrev number 128
> [in module /cygdrive/n/IMD/Bin/Gnu32_new/gcc3.x]
Either this is a linker bug, or a GDB bug. In either case, it is
almost certainly fixed in current versions of either. The current
releases are GCC 4.1.0, binutils 2.16.1, and GDB 6.4.
--
Daniel Jacobowitz
CodeSourcery