[Bug tree-optimization/18754] unrolling happens too late/SRA does not happen late enough

["dberlin at dberlin dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From dberlin at gcc dot gnu dot org  2005-01-20 15:06 -------
Subject: Re:  unrolling happens too late/SRA
 does not happen late enough



On Thu, 20 Jan 2005, rguenth at tat dot physik dot uni-tuebingen dot de wrote:

>
> ------- Additional Comments From rguenth at tat dot physik dot uni-tuebingen dot de  2005-01-20 14:57 -------
> Subject: Re:  unrolling happens too late/SRA
> does not happen late enough
>
>> Note PR 18755 blocks this if we go the SRA after loop optimization which
>> seems like a better idea.
>
> I do not completely understand this sentence ;)  I argue that SRA after
> loop is a bad idea, because SRA, in my testcases, will expose new
> oportunities for selecting ivs, so we'll need to run another loop after
> SRA.

Wiat, why are we running SRA twice again at all?
I can't figure this out from the bug report, other than seeing that we 
"could sra c.array", but i don't see why that requires a loop opt first.

If you are just trying to convince it that constant indexed accesses to 
each prat of that array is actually a different element, the 
structure-aliasing branch will help (though not quite yet, because i've 
punted on array_ref until i add the code to not punt when we have constant 
indexed array_ref)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18754