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Re: [PATCH GCC][1/2]Feed bound computation to folder in loop split
On Fri, Jun 16, 2017 at 11:49 AM, Richard Biener
<richard.guenther@gmail.com> wrote:
> On Wed, Jun 14, 2017 at 3:07 PM, Bin Cheng <Bin.Cheng@arm.com> wrote:
>> Hi,
>> Loop split forces intermediate computation to gimple operands all the time when
>> computing bound information. This is not good since folding opportunities are
>> missed. This patch fixes the issue by feeding all computation to folder and only
>> forcing to gimple operand at last.
>>
>> Bootstrap and test on x86_64 and AArch64. Is it OK?
>
> Hm? It uses gimple_build () which should do the same as fold_buildN in terms
> of simplification.
>
> So where does that not work? It is supposed to be the prefered way and no
> new code should use force_gimple_operand (unless dealing with generic
> coming from other middle-end infrastructure like SCEV or niter analysis)
Hmm, current code calls force_gimpele operand several times which
causes the inefficiency. The patch avoids that and does one call at
the end.
Thanks,
bin
>
> Richard.
>
>>
>> Thanks,
>> bin
>> 2017-06-12 Bin Cheng <bin.cheng@arm.com>
>>
>> * tree-ssa-loop-split.c (compute_new_first_bound): Feed bound
>> computation to folder, rather than force to gimple operands too
>> early.