[Bug target/63223] [avr] Make jumptables work with -Wl,--section-start,.text=

[gjl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63223

--- Comment #8 from Georg-Johann Lay <gjl at gcc dot gnu.org> ---
(In reply to Jorn Wolfgang Rennecke from comment #4)
> (In reply to Georg-Johann Lay from comment #1)
> do_global_dtors is supposed to start at the start and increment from there.
> I see it used to be half-way wrong and half-way correct.
> (Starting at the start, decrementing for __AVR_HAVE_ELPM__, incrementing
> otherwise.)
> However, you now made it all the way use an incorrect order - starting at the
> end and incrementing from there.
> Is there a rationale for this?

The old code was broken as it decremented begainning at the start address.  The
flaw never came apparent for __dtors_start = __dtors_end or with simulators
that terminated in exit.

The new code uses the same traverse direction like __do_global_ctors.

Is the order of .ctors, .dtors defined in any way?  I.e. how do you express
that constructor A must run before constructor B in the C program?  Same for
destructors.