> > -----Original Message----- > > From: Richard Earnshaw > > Sent: Thursday, July 26, 2012 9:19 PM > > To: Andrew Pinski > > Cc: Bin Cheng; gcc-patches@gcc.gnu.org > > Subject: Re: [PATCH]Remove duplicate check on BRANCH_COST in > > fold-const.c > > > > On 26/07/12 11:27, Andrew Pinski wrote: > > > On Thu, Jul 26, 2012 at 3:20 AM, Bin Cheng <bin.ch...@arm.com> wrote: > > >> Hi, > > >> This patch removes the duplicate check on BRANCH_COST in > fold_truth_andor. > > >> The BRANCH_COST condition removed is a duplicate of the default > > >> definition of LOGICAL_OP_NON_SHORT_CIRCUIT. > > >> All current targets (mips and rs6000) that provide non-default > > >> definitions of LOGICAL_OP_SHORT_CIRCUIT set it to 0, so this patch > > >> is therefore just a code cleanup and does not change behaviour in > > >> the > compiler. > > >> > > >> I built mipsel-elf cross compiler and compared newlib/libstdc++ > > >> compiled by the patched/original compilers. > > >> > > >> Is it OK? > > > > > > Just some history here on this. The BRANCH COST check was there > > > before LOGICAL_OP_NON_SHORT_CIRCUIT was added. I will be submitting > > > a patch which changes the MIPS definition soon but it will not be > > > based on the branch cost but rather than another option. So in the > > > end it might not be redundant as it is currently. > > > > > > Thanks, > > > Andrew > > > > > > > You can always factor BRANCH_COST into LOGICAL_OP_NON_SHORT_CIRCUIT > > (as > the > > default currently does), so there's no loss of functionality from > > removing this currently redundant check. However, the current > > definition is broken > in > > that it makes it impossible to force the compiler to use this > > optimization when the branch cost is low. > > >
Hi, is this change ok? Or we need more discussion on it? Thanks very much.
