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RE: Live on Exit renaming.
- From: Ajit Kumar Agarwal <ajit dot kumar dot agarwal at xilinx dot com>
- To: "Bin.Cheng" <amker dot cheng at gmail dot com>, Steven Bosscher <stevenb dot gcc at gmail dot com>
- Cc: "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 04:02:28 +0000
- Subject: RE: Live on Exit renaming.
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-----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
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