[Bug c++/70018] [4.9/5/6 Regression] Possible issue around IPO and C++ comdats discovered as pure/const

["hubicka at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70018

Jan Hubicka <hubicka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |jason at redhat dot com

--- Comment #9 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
To properly track possible loads/stores w/o any optimizations we probably need
an info from Frontend, because we optimize out things prior gimplification.
Jason, how feasible it is to do that?

For pure/const a workaround is -fno-ipa-pure-const. The bug also affects
nothrow at least with -fnoncall-exceptions and nothrow discovery is not
controled by a flag.

Fixing this correctly will need bit of work, because we really want to track
nothrow/pure/const for the inline functions and make us of it when we know the
call bids to current def. This can change during the optimization queue, so we
probably want two sets of these flags.