[Bug ipa/95558] Invalid IPA optimizations based on weak definition

[amonakov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95558

Alexander Monakov <amonakov at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |amonakov at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org
          Component|middle-end                  |ipa
           Keywords|                            |wrong-code

--- Comment #1 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
All functions are incorrectly discovered to be pure, and then the loop that
only makes calls to non-weak pure functions is eliminated.

Minimal testcase for the root issue, wrong warning with -O2
-Wsuggest-attribute=pure:

static void dummy(){}

void weak() __attribute__((weak,alias("dummy")));

int foo()
{
    weak();
    return 0;
}