[Bug tree-optimization/87543] Inconsistency in noticing a constant result rather than emitting code for a loop

eyalroz at technion dot ac.il gcc-bugzilla@gcc.gnu.org
Mon Oct 8 09:03:00 GMT 2018


--- Comment #2 from Eyal Rozenberg <eyalroz at technion dot ac.il> ---
(In reply to Richard Biener from comment #1)
> The issue at -O2 is etc.

That is one issue, but there is the question of the changes in behavior between
versions and when `-march` is used. I don't know if you guys are actively
maintaining 7.x or 6.x ; assuming you do, each of them should at least exhibit
coherent behavior here.

> because of the awkward IV structure PRE present us with

I assume other GCC devs will understand what this means, but for my benefit as
the lay reporter - can you define (or link to a definition of) what "PRE" is
and what is an "awkward IV structure"? (I'm guessing the acronym expands to
Induction Variable.)

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