https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121474
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The biggest things the alias walk happens over for 3/4 is clobbers. Maybe the
limit for 3/4 should be 0 but clobbers don't count towards the limit.
For an example before forwprop4 in highway's compare_test.cc
(hwy::N_EMU128::{anonymous}::TestEquality::operator() and others), we have the
following IR
```
m.bits = "";
D.3037309 = m;
m ={v} {CLOBBER(eos)};
D.3037308 = D.3037309;
```
This happens also in forwprop3 similarly.
This should limit but allow the prop.
The reason why this only shows up in forwprop3/4 is loop distribution which
creates a memset on m.bit which is all zeros.
