[patch] Fix EH breakage in LTO mode

[Richard Biener]

On November 9, 2017 7:03:18 PM GMT+01:00, Jan Hubicka <hubicka@ucw.cz> wrote:
>> > I am not sure I follow your argumentation here.  flag_exceptions is
>> > optimization which means that one should not test it globally. For
>that
>> > reason I would just change dwarf2out to simply trigger
>> > dwarf2out_frame_finish if any of the compiled functions needed it
>(had
>> > flag_exceptions set).
>> 
>> That's not sufficient for a partition with only EH-neutral functions.
>> 
>> > My readon of lto-wrapper is that it will set flag_exceptions for
>whole
>> > compilation unit when one of compilation units were copmiled with
>> > flag_exceptions.
>> > 
>> > How that helps the neutral functions?
>> 
>> flag_exceptions is never set in a partition with only EH-neutral
>functions.
>
>Hmm, I am still not following. By EH-neutral you mean function compiled
>with -fno-exceptions so it has no unwind info at all or one that has
>unwind
>info but does not do anything with EH?

The latter. We choose a 'neutral' EH personality for those and thus if all behave that way we fail to init EH. 

I suppose we could record a TU wide setting of options attached to the TRANSLATION_UNIT_DECL and read global flags from that? 

Richard. 

>Honza
>> 
>> -- 
>> Eric Botcazou