Ping. > -----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. >
Is it OK? Thanks