On 27/07/2021 09:39, Richard Biener wrote:
> Yes, that's true - there could be a one-to-many relationship there. But then
> I
> wonder in which case such lookup in the DIE tree would be the correct thing
> to do. If I lookup a variable from the parent then the concrete
> instance of that
> should be found by unwinding unless it is a static variable in which case
> the lookup can be done in any of the concrete instances.
>
> But then the original issue that the consumer skips the function if it doesn't
> have a PC range and thus skips over childs looks like an invalid optimization.
>
> Btw, the situation you run into can be simulated by
>
> int main(int argc, char **argv)
> {
> void foo ()
> {
> __builtin_puts ("bar");
> }
> foo ();
> return 0;
> }
>
> and compiling with -g -flto -flto-partition=max which forces main and foo
> into different LTRANS units and get's us
>
> <1><114>: Abbrev Number: 2 (DW_TAG_subprogram)
> <115> DW_AT_abstract_origin: <0x155>
> <2><119>: Abbrev Number: 3 (DW_TAG_subprogram)
> <11a> DW_AT_abstract_origin: <0x179>
> <11e> DW_AT_low_pc : 0x400515
> <126> DW_AT_high_pc : 0x19
> <12e> DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa)
> <130> DW_AT_static_link : 4 byte block: 91 68 6 6 (DW_OP_fbreg:
> -2
>
> gdb then fails to see 'foo' at all (cannot break on it) and the lookup of
> 'argc'
> inside it fails (setting a breakpoint also fails without -flto-partition=max,
> but I can print argc just fine).
>
> I suggest you file a bug with gdb and see how that resolves.
I have filed https://sourceware.org/bugzilla/show_bug.cgi?id=28147 for this
issue.
Thanks,
--
Hafiz Abid Qadeer
Mentor, a Siemens Business
