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Re: [PATCH GCC][5/5]Enable tree loop distribution at -O3 and above optimization levels.

On 06/07/2017 02:07 AM, Bin.Cheng wrote:
> On Tue, Jun 6, 2017 at 6:47 PM, Jeff Law <> wrote:
>> On 06/02/2017 05:52 AM, Bin Cheng wrote:
>>> Hi,
>>> This patch enables -ftree-loop-distribution by default at -O3 and above optimization levels.
>>> Bootstrap and test at O2/O3 on x86_64 and AArch64.  is it OK?
>>> Note I don't have strong opinion here and am fine with either it's accepted or rejected.
>>> Thanks,
>>> bin
>>> 2017-05-31  Bin Cheng  <>
>>>       * opts.c (default_options_table): Enable OPT_ftree_loop_distribution
>>>       for -O3 and above levels.
>> I think the question is how does this generally impact the performance
>> of the generated code and to a lesser degree compile-time.
>> Do you have any performance data?
> Hi Jeff,
> At this stage of the patch, only hmmer is impacted and improved
> obviously in my local run of spec2006 for x86_64 and AArch64.  In long
> term, loop distribution is also one prerequisite transformation to
> handle bwaves (at least).  For these two impacted cases, it helps to
> resolve the gap against ICC.  I didn't check compilation time slow
> down, we can restrict it to problem with small partition number if
> that's a problem.
Just a note. I know you've iterated further with Richi -- I'm not
objecting to the patch, nor was I ready to approve.

Are you and Richi happy with this as-is or are you looking to submit
something newer based on the conversation the two of you have had?


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