[RFA] dwarf2_physname
Keith Seitz
keiths@redhat.com
Tue Sep 15 15:53:00 GMT 2009
On 09/15/2009 06:32 AM, Daniel Jacobowitz wrote:
> Oh, I see. Is there any other differentiation in the ICC output
> between the two relevant cases? Namely bar and baz in:
>
> class foo {
> void bar();
> static void baz(foo*);
> };
In this case, the DWARF output looks pretty much as expected. There is
only one DIE defining foo::baz, and that is in the class definition. One
quirk: the parameter's DW_AT_name is "$01".
I played with this a bit, and it seems that only ctors and dtors have
DIEs outside the class definition (ignoring "normal" C functions).
However, in every case I tried, ICC does not output DW_AT_artificial for
ANY class method's first parameter. Does ICC not use hidden parameter
passing to implement method calls? It seems odd that it would do this
for ctors/dtors and no other methods.
In any case, once again, DW_AT_name for method formal parameters is also
generated ("$02", "$03", etc). It seems that the only time I see a
useful DW_AT_name for anything function-like is for the ctor/dtor (all
parameters, not just hidden "this") and C functions.
[Anecdote: Every time I run readelf -w on an ICC-generated object, it
complains of "Bogus end-of-siblings marker" -- perhaps there are some
bytes in the debuginfo (which readelf/gdb cannot read/interpret) which
helps mitigate some of these problems?]
> From discussions on the dwarf-discuss list, I've gathered that pretty
> much every debugger is full of compiler-specific quirking. In
> practice, to provide a good user experience, we have to interpret the
> DWARF in our best understanding of each compiler's intentions rather
> than just through the standard.
Sure, that doesn't really surprise me. But these three quirks
(conflicting DIEs for same object, missing DW_AT_artificial, nonsensical
DW_AT_name) would seem truly unnecessary and fairly trivial to fix.
> Of course, that relies on someone wanting to do the work for ICC support.
It may just be useful to provide (yet another) switch to turn on
DW_AT_MIPS_linkage_name processing (and disable the proposed physname
work). We could do this switch manually (set dwarf-linkage-name on?)
and/or by producer (turn it on for ICC by default).
Keith
More information about the Gdb-patches
mailing list