Hi!

This patch adds new field in tune_params to indicate if LDRD/STRD are
preferred over PUSH/POP in prologue/epilogue of specific core.
It also creates new tune for cortex-A15 and updates tunes for other
cores to set new field to default value. 

Changelog entry for Patch to create tune for cortex-a15:

2011-10-11  Sameera Deshpande
<sameera.deshpande@arm.com>                                             
        
        * config/arm/arm-cores.def (cortex_a15): Update.
        * config/arm/arm-protos.h (struct tune_params): Add new field...
          (arm_gen_ldrd_strd): ... this.
        * config/arm/arm.c (arm_slowmul_tune): Add 
          arm_gen_ldrd_strd field settings.
          (arm_fastmul_tune): Likewise.
          (arm_strongarm_tune): Likewise.
          (arm_xscale_tune): Likewise.
          (arm_9e_tune): Likewise.
          (arm_v6t2_tune): Likewise.
          (arm_cortex_tune): Likewise.
          (arm_cortex_a5_tune): Likewise.
          (arm_cortex_a9_tune): Likewise.
          (arm_fa726te_tune): Likewise. 
          (arm_cortex_a15_tune): New variable.
-- 


On Tue, 2011-10-11 at 10:08 +0100, Sameera Deshpande wrote:
> This series of 5 patches generate LDRD/STRD instead of POP/PUSH in
> epilogue/prologue for ARM and Thumb-2 mode of A15.
> 
> Patch [1/5] introduces new field in tune which can be used to indicate
> whether LDRD/STRD are preferred over POP/PUSH by the specific core.
> 
> Patches [2-5/5] use this field to determine if LDRD/STRD can be
> generated instead of PUSH/POP in ARM and Thumb-2 mode.
> 
> Patch [2/5] generates LDRD instead of POP for Thumb-2 epilogue in A15.
> This patch depends on patch [1/5].
> 
> Patch [3/5] generates STRD instead of PUSH for Thumb-2 prologue in A15.
> This patch depends for variables, functions and patterns defined in
> [1/5] and [2/5].
> 
> Patch [4/5] generates STRD instead of PUSH for ARM prologue in A15. This
> patch depends on [1/5].
> 
> Patch [5/5] generates LDRD instead of POP for ARM epilogue in A15. This
> patch depends for variables, functions and patterns defined in [1/5] and
> [4/5].
> 
> All these patches depend upon the Thumb2/ARM RTL epilogue patches
> http://gcc.gnu.org/ml/gcc-patches/2011-09/msg01854.html,
> http://gcc.gnu.org/ml/gcc-patches/2011-09/msg01855.html submitted for
> review.
> 
> All these patches are applied in given order and tested with check-gcc,
> check-gdb and bootstrap without regression. 
> 
> In case of ARM mode, significant performance improvement can be seen on
> some parts of a popular embedded consumer benchmark (~26%). 
> However, in most of the cases, not much effect is seen on performance.
> (~ 3% improvement) 
> 
> In case of thumb2, the performance improvement observed on same parts
> the benchmark is ~11% (2.5% improvement). 
>