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Re: Limited success with 3.0 branch on AIX
- To: David Edelsohn <dje at watson dot ibm dot com>
- Subject: Re: Limited success with 3.0 branch on AIX
- From: Elena Zannoni <ezannoni at cygnus dot com>
- Date: Thu, 17 May 2001 00:29:22 -0400
- Cc: Elena Zannoni <ezannoni at cygnus dot com>, Kevin Buettner <kevinb at cygnus dot com>, "Zack Weinberg" <zackw at Stanford dot EDU>, Matthew Conway <matt_conway at i2 dot com>, Mark Mitchell <mark at codesourcery dot com>, gcc-patches at gcc dot gnu dot org, gdb at sources dot redhat dot com
- References: <ezannoni@cygnus.com><15106.54023.177141.275660@kwikemart.cygnus.com><200105162006.QAA25648@makai.watson.ibm.com>
David Edelsohn writes:
> First, I agree that the XFT_CV field of the File Auxilliary Entry
> for C_FILE Symbols is the optimal location for this type of GCC DBX
> Marker. We just do not have a way of accessing that field with the
> current tools.
>
> What exactly is the "gcc2_compiled." symbol used to enable in GDB?
> How much will it hurt if GDB debugs a GCC-compiled application and does
> not know it was compiled with GCC?
It is looked for in dbxread.c and os9kread.c only. It is used to set
the processing_gcc_compilation variable (which in other platforms is
set using different debug information). Such variable is then used in
VARIABLES_INSIDE_BLOCK (which I didn't notice before) defined for
sparc and arm, and for USE_STRUCT_CONVENTION (only the generic version
of the macro).
With regard to the first macro, I don't know if something running on
arm can have xcoff debug info, if not then, not being able to
distinguish between gcc 2 vs. older versions vs. native compilers
wouldn't be a problem.
About the the second macro, if the AIX targets don't use the generic
version of use_struct_convention, then it is already a non-problem.
>
> We seem to have the following options:
>
> 1) Do not include "gcc2_compiled." symbol in AIX XCOFF files until
> assembler provides feature to access XFT_CV field.
> 2) Always use compatible assembler feature available now, e.g. C_GSYM.
> 3) Use XFT_CV field if assembler supports the feature, otherwise fallback
> to C_GSYM. Have GDB look in both locations, in addition to historical
> "gcc2_compiled." label.
>
I would prefer to do option 3, so that it would work no matter what.
But if we all agree that we can take the risk of not having gcc2_compiled
defined at all, then we are off the hook.
Elena
> David
>