Recently we've put a lot of effort into improving ifcvt to use CSEL on AArch64.

Recently we've put a lot of effort into improving ifcvt to use CSEL on AArch64.

In  https://gcc.gnu.org/ml/gcc-patches/2015-11/msg01639.html James determined
the best value for AArch64 code generation.  Although this setting is used when
explicitly targeting Cortex cores, it is not otherwise used.  This means by
default GCC will not use (F)CSEL in many common cases.

Change the generic_branch_cost to be the same as cortexa57_branch_cost so that
all supported cores benefit from CSEL.  This is generally faster and smaller.
On one benchmark the new setting fixes a regression since GCC6 and improves
performance by 49%.

    gcc/
	* config/aarch64/aarch64.c (generic_branch_cost):
	Copy cortexa57_branch_cost.

From-SVN: r246397