On 10/23/13 07:05, Richard Biener wrote:
Btw, -ftree-isolate-paths sounds a bit generic for isolating paths leading
to undefined behavior, maybe -fisolate-errorneous-paths? (please drop
'tree-' from new options, 'tree' isn't meaningful to GCC users)
Seems reasonable, particularly since I think t
On 10/23/13 01:58, Florian Weimer wrote:
Could you keep in mind that there is considerable interest in a
check_nonnull attribute which marks values (parameters, return values,
maybe even struct fields) that can be NULL and need to be checked
explictly prior to dereference? GCC would then warn if
On Mon, Oct 21, 2013 at 7:27 PM, Jeff Law wrote:
> On 10/21/13 06:19, Richard Biener wrote:
>
>>
>> I wonder why this isn't part of the regular jump-threading code - after
>> all the opportunity is to thead to __builtin_unreachable () ;) Otherwise
>> the question is always where you'd place this
On 10/22/2013 09:00 PM, Jeff Law wrote:
So I was poking at this a bit. It's trival to use infer_nonnull_range
and to teach infer_nonnull_range to use the returns_nonnull attribute to
pick up that return x in an appropriately decorated function implies
that x is non-null.
We'll need a better pl
On 10/18/13 14:31, Marc Glisse wrote:
On Fri, 18 Oct 2013, Jeff Law wrote:
On 10/18/13 12:47, Marc Glisse wrote:
* tree-vrp has a function infer_nonnull_range, do you think we could
share it? We now store the VRP ranges for integers, but not for
pointers. If we did (or maybe just a non-null bi
On 10/21/13 06:19, Richard Biener wrote:
I wonder why this isn't part of the regular jump-threading code - after
all the opportunity is to thead to __builtin_unreachable () ;) Otherwise
the question is always where you'd place this pass and whether it
enables jump threading or CSE opportunitie
On Fri, Oct 18, 2013 at 7:12 PM, Jeff Law wrote:
>
>
> Back in 2011 I wrote code to detect cases when traversing a particular path
> could be proven to trigger undefined behaviour (such as a null pointer
> dereference). That original patch would find the control dependent edges
> leading to the d
On 10/18/13 15:15, Marc Glisse wrote:
On Fri, 18 Oct 2013, Jeff Law wrote:
On 10/18/13 14:31, Marc Glisse wrote:
But once you have that pointer defined by a PHI containing a zero, you
look at all its uses, trying to find one that proves the pointer is
non-zero
What are you going to do with t
On Fri, 18 Oct 2013, Jeff Law wrote:
On 10/18/13 14:31, Marc Glisse wrote:
But once you have that pointer defined by a PHI containing a zero, you
look at all its uses, trying to find one that proves the pointer is
non-zero
What are you going to do with that information?
Uh? I must have been
On 10/18/13 14:31, Marc Glisse wrote:
But once you have that pointer defined by a PHI containing a zero, you
look at all its uses, trying to find one that proves the pointer is
non-zero
What are you going to do with that information? The only use I can see
for this pass would be discovering mo
On Fri, 18 Oct 2013, Jeff Law wrote:
On 10/18/13 12:47, Marc Glisse wrote:
* tree-vrp has a function infer_nonnull_range, do you think we could
share it? We now store the VRP ranges for integers, but not for
pointers. If we did (or maybe just a non-null bit), the pass could just
test that bit o
On 10/18/13 12:47, Marc Glisse wrote:
Maybe a new -fretroactive-undefined-behavior? (for later, obviously)
Something like that -- haven't thought much about the name.
* should cfg_altered be static (or a member of the pass class)?
At the minimum it should be static. Into the pass class woul
On Fri, 18 Oct 2013, Jeff Law wrote:
Back in 2011 I wrote code to detect cases when traversing a particular path
could be proven to trigger undefined behaviour (such as a null pointer
dereference). That original patch would find the control dependent edges
leading to the dereference and elimi
Back in 2011 I wrote code to detect cases when traversing a particular
path could be proven to trigger undefined behaviour (such as a null
pointer dereference). That original patch would find the control
dependent edges leading to the dereference and eliminate those edges.
The result being
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