> Am 03.12.2025 um 06:05 schrieb Andrew MacLeod <[email protected]>:
>
>
>> On 12/2/25 20:09, Andrew Pinski wrote:
>>> On Tue, Dec 2, 2025 at 1:37 PM Andrew MacLeod <[email protected]> wrote:
>>> The record() and register_relation() routines in the relation oracle
>>> and folding routines currently return void. They are called when there
>>> is a relation to register and there has not been a need for feedback on
>>> whether one was registered or not.
>>>
>>> The patch which caused this PR recognized that and on-demand calculation
>>> of something in the middle of the IL may not have access to relations
>>> which are not yet registered. When that relation is added later
>>> during the DOM walk, and then the statement encountered again, the
>>> original cached version is used and any benefit of the now known
>>> relation is lost.
>>>
>>> This was resolved by updating the timestamp of the 2 ssa-names in the
>>> relation when it is registered. When a statement using those names is
>>> re-examined, the use timestamp will be newer than the definition and the
>>> statement will be recalculated with the relation available.
>>>
>>> The problem shown here is a cycle of PHIs feeding each other... and each
>>> one adding a relation potentially consumed by the other. This forces the
>>> other to be recalculated. This was done whether a relation was actually
>>> added or not. If no new relation is added, we should not update the
>>> timestamps as there is no need to recalculate.
>>>
>>> This patch changes the record() and register_relation() methods in the
>>> both the relation oracle and fold_using_range classes . These routines
>>> now return TRUE if a new relation was added, and FALSE otherwise. The
>>> timestamps are only updated now if TRUE is returned.
>>>
>>> In order for the debugging output to make sense, its been tweaked to
>>> only print that a relation is registered, not that an attempt was being
>>> made.
>>>
>>> Bootstraps on x86_64-pc-linux-gnu with no regressions. OK?
>> One minor suggestion. Mention in comments before register_relation's
>> that false means nothing changed.
>> Likewise for add_partial_equiv and equiv_oracle::record and the others.
>>
>>
> Oh yeah, forgot to add a comment didn't I ?? doh!
>
> I will do that before committing
Ok with that.
Richard
> Andrew
>
