On Thu, Oct 17, 2019 at 06:07:37PM -0600, Martin Sebor wrote:
> On 10/17/19 1:00 AM, Jakub Jelinek wrote:
> > Hi!
> >
> > The following bug has been introduced when cond_expr_object_size has been
> > added in 2007. We want to treat a COND_EXPR like a PHI with 2 arguments,
> > and PHI is handled in a loop that breaks if the lhs value is unknown, and
> > then does the if (TREE_CODE (arg) == SSA_NAME) merge_object_sizes else
> > expr_object_size which is used even in places that handle just a single
> > operand (with the lhs value initialized to the opposite value of unknown
> > first). At least expr_object_size asserts that the lhs value is not
> > unknown at the start.
> >
> > Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
> > trunk?
>
> I'm not sure the other change (r277134) it the right way to fix
> the problem with the missing initialization. It was introduced
> with the merger of the sprintf pass. The latter still calls
> init_object_sizes in get_destination_size. I think the call
> should be moved from there into the new combined sprintf/strlen
> printf_strlen_execute function that also calls fini_object_sizes,
> and the one from determine_min_objsize should be removed. I can
> take care of it unless you think it needs to stay the way it is
> now for some reason.
Why? As I said, init_object_sizes is designed to be called multiple times
and is cheap (load + comparison + early return) if it has been already
called, so is meant to be called only when needed, rather than at the
beginning of a pass just in case something appears. The objsz pass does the
same. No need to allocate bitmaps/vectors if nothing will need them.
Jakub
