Fw: Scheduling an early complete loop unrolling pass?

Ayal Zaks ZAKS@il.ibm.com
Wed Feb 7 21:21:00 GMT 2007


>Ah, right... I wonder if we can keep the loop structure in place, even
>after completely unrolling the loop  - I mean the 'struct loop' in
>'current_loops' (not the actual CFG), so that the "SLP in loops" would
>a chance to at least consider vectorizing this "loop".

Having a "loop" structure for a piece of CFG that is not a loop, was used
in some other compiler we worked with - the notion of 'region' was such
that it corresponded to loops, and in addition the entire function belonged
to a "universal" region (Peter - please correct if I'm wrong). But I think
you were looking for some marking of a basic block saying "this used to be
a loop but got completely unrolled". I wonder how much such a "dummy" loop
structure can really help the vectorizer, except for (convenience of)
keeping intact the driver that traverses all such structures or the hanging
of additional data off of them.


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