https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101466
--- Comment #12 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #11)
> With some hand-waving we could generate
>
> void square(unsigned t, int *tt)
> {
> if (t<=4) __builtin_abort();
> tt[0] = 0;
> tt[1] = 0;
> tt[2] = 0;
> tt[3] = 0;
> tt[4] = 0;
> }
>
> but I don't see how it fits any existing transform? The "hand-waving"
> would be that __builtin_abort () since it's a known function cannot
> observe the dropped side-effects like tt[0] = 0 when t > 0.
That is, we'd sink the stores across the abort ()s because they are
not uses of them, then we arrive at
if (t<=0) __builtin_abort();
if (t<=1) __builtin_abort();
if (t<=2) __builtin_abort();
if (t<=3) __builtin_abort();
if (t<=4) __builtin_abort();
tt[0] = 0;
tt[1] = 0;
tt[2] = 0;
tt[3] = 0;
tt[4] = 0;
where we'd somehow "thread" to a single condition (PRE tail merging
merges the abort () blocks and reassoc way after it manages to merge
the controlling conditions).
