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Re: Loop induction variable optimization question
- From: Steve Ellcey <sellcey at mips dot com>
- To: Oleg Endo <oleg dot endo at t-online dot de>
- Cc: <gcc at gcc dot gnu dot org>
- Date: Mon, 17 Jun 2013 13:42:12 -0700
- Subject: Re: Loop induction variable optimization question
- References: <b7b6a86d-04ee-4336-8c2b-2e1c3daea77e at BAMAIL02 dot ba dot imgtec dot org> <1371497810 dot 2356 dot 4 dot camel at yam-132-YW-E178-FTW>
On Mon, 2013-06-17 at 21:36 +0200, Oleg Endo wrote:
>
> Sorry for not having an answer. I got curious, because just yesterday I
> was looking at this one
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55190
> and thought that this is related, although it doesn't seem to.
> I've tried the two functions of yours on SH and there it produces the
> same machine code with -O2. -O3 results in a call to memcpy, while
> -O3 -fno-tree-loop-distribute-patterns again results in the same code.
>
> Cheers,
> Oleg
Thanks for the pointer. It made me realize I should try running my test
with -fno-ivopts. That got rid of the '-4' usage and I wound up getting
the code that I was after. I still hope someone can help me understand
why ivopts made the transformation it did though. I am afraid that just
turning off ivopts may have a larger affect then I am after.
Steve Ellcey
sellcey@mips.com