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Re: [PATCH] Fix PR35607, another revenge of invariant addresses (ivopts)
On Mon, Mar 17, 2008 at 08:40, Zdenek Dvorak <email@example.com> wrote:
> You would have to rewrite all the uses of is_gimple_min_invariant in
> middle-end to some such predicate (because as far as I can tell, all the
> uses of is_gimple_min_invariant in middle-end have this different
> meaning). Also, you would have to rewrite all the uses of is_gimple_val
> in middle end, as it uses is_gimple_min_invariant. All in all, it seems
> simpler to make is_gimple_min_invariant behave the way most of people
> think it does,
Yes. When this issue came up last year, I proposed implementing
is_gimple_min_invariant in terms of a new is_gimple_const() and
TREE_INVARIANT. I was wrong about relying on TREE_INVARIANT, but we
do want to distinguish const vs invariantness for things like &a[XXX].
In that context, we want XXX to be const, to avoid things like
So, we have:
is_gimple_invariant (const_tree t)
if (TREE_CODE (t) == ADDR_EXPR)
return address_invariant_p (t);
return is_gimple_const (t);
And is_gimple_const() is the same is_gimple_min_invariant() we have
today minus ADDR_EXPR handling.