> -----Original Message----- > From: Joern Rennecke [mailto:joern.renne...@embecosm.com] > Sent: Monday, March 25, 2013 8:53 PM > To: Bin Cheng > Cc: gcc-patches@gcc.gnu.org > Subject: Re: [PATCH GCC]Relax the probability condition in CE pass when > optimizing for code size > > Quoting Bin Cheng <bin.ch...@arm.com>: > > > During the work I observed passes before combine might interfere with > > CE pass, so this patch is enabled for ce2/ce3 after combination pass. > > > > It is tested on x86/thumb2 for both normal and Os. Is it ok for trunk? > > There are bound to be target and application specific variations on which > scaling factors work best. > > > 2013-03-25 Bin Cheng <bin.ch...@arm.com> > > > > * ifcvt.c (ifcvt_after_combine): New static variable. > > It would make more sense to pass in the scale factor as a an argument to > if_convert. And get the respective values from a set of gcc parameters, so > they can be tweaked by ports and/or by a user/ML learning framework (e.g. > Milepost) supplying the appropriate --param option.
I agree it would be more flexible to pass the factor as parameter, but not sure how useful to users it will be because: firstly it has already been target specific by the BRANCH_COST heuristic; for code size, the heuristic should be tuned to achieve an overall good results, I doubt to which extend it depends on specific target/application. Hi Jeff, This is based on your heuristic tuning in ifcvt, would you help us on this issue with some suggestions? Thanks very much.
