Re: unoptimized dead store

[Robert Kennedy <robert@xxxxxxxxxxxxx>]

> If the mod/ref analysis in IPA concludes the variable
> a is not modified in the function glarp, the optimizer
> could still conclude the value of "a++" and dead 
> code eliminate the store "a = 2".

Definitely true, but obviously that isn't happening in this
example. Like I said, I haven't analyzed it so I have no information
about why it isn't happening. The two main possibilities are that the
info from IPA is too conservative, or that the optimizer's overly
conservative vsym assignment is responsible (my first guess is that
the glarp call has a chi for the return vsym, and "a" also aliases
with the return vsym). If it is the latter possibility, it would take
fairly major changes to fix it.

        -- Robert