-----Original Message----- From: Bin.Cheng [mailto:amker.ch...@gmail.com] Sent: Monday, July 06, 2015 7:04 AM To: Steven Bosscher Cc: Ajit Kumar Agarwal; l...@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....@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
