[RFC/ARM] Prefer branches over conditional execution for Cortex-A15.

[Matthew Gretton-Dann <matthew dot gretton-dann at arm dot com>]

The attached patch tunes the costs of conditional execution and branches
for Cortex-A15 to be the same as that for Cortex-A5.

This gives an average improvement of over 6% on a popular embedded
benchmark.

Note that the tuning parameter structure added for Cortex-A15 is only tuned
for branch costs, and otherwise takes the generic values.  Tuning for other
optimisations (notably preload insertion) is still to be done.

Thanks,

Matt

gcc/ChangeLog:

2012-01-06  Matthew Gretton-Dann  <matthew.gretton-dann@arm.com>

	* config/arm/arm-cores.def (cortex-a15): Use cortex_a15_tune for
	tuning parameters.
	* config/arm/arm.c (arm_cortex_a15_tune): New static variable.
-- 
Matthew Gretton-Dann
Principal Engineer, PD Software, ARM Ltd.

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