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Re: Live on Exit renaming.
- From: "Bin.Cheng" <amker dot cheng at gmail dot com>
- To: Ajit Kumar Agarwal <ajit dot kumar dot agarwal at xilinx dot com>
- Cc: Steven Bosscher <stevenb dot gcc at gmail dot com>, "law at redhat dot com" <law at redhat dot com>, Richard Biener <richard dot guenther at gmail dot com>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>, Vinod Kathail <vinodk at xilinx dot com>, Shail Aditya Gupta <shailadi at xilinx dot com>, Vidhumouli Hunsigida <vidhum at xilinx dot com>, Nagaraju Mekala <nmekala at xilinx dot com>
- Date: Mon, 6 Jul 2015 12:56:07 +0800
- Subject: Re: Live on Exit renaming.
- Authentication-results: sourceware.org; auth=none
- References: <37378DC5BCD0EE48BA4B082E0B55DFAA41F4116D at XAP-PVEXMBX02 dot xlnx dot xilinx dot com> <CABu31nN=1EER_7JYDCFXp9MaPKsrczQ_iWA33pwgd8pLU2NYrQ at mail dot gmail dot com> <CAHFci28cWUoP=FWCh-Xi8N9oDJr0-sUfp4CzHi8r4ijz0fUEFg at mail dot gmail dot com> <37378DC5BCD0EE48BA4B082E0B55DFAA41F4166F at XAP-PVEXMBX02 dot xlnx dot xilinx dot com>
On Mon, Jul 6, 2015 at 12:02 PM, Ajit Kumar Agarwal
<ajit.kumar.agarwal@xilinx.com> wrote:
>
>
> -----Original Message-----
> From: Bin.Cheng [mailto:amker.cheng@gmail.com]
> Sent: Monday, July 06, 2015 7:04 AM
> To: Steven Bosscher
> Cc: Ajit Kumar Agarwal; law@redhat.com; Richard Biener; gcc@gcc.gnu.org; Vinod Kathail; Shail Aditya Gupta; Vidhumouli Hunsigida; Nagaraju Mekala
> Subject: Re: Live on Exit renaming.
>
> On Mon, Jul 6, 2015 at 6:02 AM, Steven Bosscher <stevenb.gcc@gmail.com> wrote:
>> On Sat, Jul 4, 2015 at 3:45 PM, Ajit Kumar Agarwal wrote:
>>> I am not sure why the above optimization is not implemented in GCC.
>>
>> -fsplit-ivs-in-unroller
>
>>>And thing might have changed. Given the condition GCC does IVO on gimple, unrolling on RTL, there is inconsistency between the two optimizer since IVO >>takes register pressure of IVs into consideration and assumes IVs will take single registers. At least for some cases, splitting live range of IVs results in bad >>code. See PR29256 for more information. As described in the comment, actually I am going to do some experiments disabling such transformation to see >>what happens.
>
> The above optimization is implemented as a part of unroller in gimple. There is an unroller pass in rtl which does not have support for this
As far as I understand, fsplit-ivs-in-unroller is a transformation in
RTL unroller.
Thanks,
bin
> optimization. Shouldn't be the fsplit-ivs-in-unroller optimization implemented in the unroller pass of rtl. I am looking at the implementation
> perspective for implementing the fsplit-ivs-in-unroller optimizations in the unroller rtl pass.
>
> Thanks & Regards
> Ajit
>
> Thanks,
> bin
>>
>> Ciao!
>> Steven