[PATCH v2] IPA: Provide a mechanism to register static DTORs via cxa_atexit.
Sat Nov 13 15:16:11 GMT 2021
> sheesh … EWRONGREVISEDPATCH
> > On 5 Nov 2021, at 13:08, Iain Sandoe <firstname.lastname@example.org> wrote:
> > I tried enabling this on x86-64-linux (just for interest) and it seems to work
> > OK there too - but that testing revealed a thinko that didn’t show with a
> > a normal regstrap.
> … now with the correct patch.
> [PATCH v2] IPA: Provide a mechanism to register static DTORs via
> For at least one target (Darwin) the platform convention is to
> register static destructors (i.e. __attribute__((destructor)))
> with __cxa_atexit rather than placing them into a list that is
> run by some other mechanism.
> This patch provides a target hook that allows a target to opt
> into this and handling for the process in ipa_cdtor_merge ().
> When the mode is enabled (dtors_from_cxa_atexit is set) we:
> * Generate new CTORs to register static destructors with
> __cxa_atexit and add them to the existing list of CTORs;
> we then process the revised CTORs list.
> * We sort the DTORs into priority and then TU order, this
> means that they are registered in that order with
> __cxa_atexit () and therefore will be run in the reverse
> * Likewise, CTORs are sorted into priority and then TU order,
> which means that they will run in that order.
> This matches the behavior of using init/fini (or
> mod_init_func/mod_term_func) sections.
> Signed-off-by: Iain Sandoe <email@example.com>
> * config/darwin.h (TARGET_DTORS_FROM_CXA_ATEXIT): New.
> * doc/tm.texi: Regenerated.
> * doc/tm.texi.in: Add TARGET_DTORS_FROM_CXA_ATEXIT hook.
> * ipa.c (ipa_discover_variable_flags):
> (cgraph_build_static_cdtor_1): Return the built function
> (build_cxa_atexit_decl): New.
> (build_dso_handle_decl): New.
> (build_cxa_dtor_registrations): New.
> (compare_cdtor_tu_order): New.
> (build_cxa_atexit_fns): New.
> (ipa_cdtor_merge): If dtors_from_cxa_atexit is set,
> process the DTORs/CTORs accordingly.
> (pass_ipa_cdtor_merge::gate): Also run if
> dtors_from_cxa_atexit is set.
> * target.def (dtors_from_cxa_atexit): New hook.
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