[PATCH/AARCH64] Add issue_rate tuning field

[Andrew Pinski <pinskia at gmail dot com>]

Hi,
  While writing a scheduler for Cavium's aarch64 processor (Thunder),
I found there was no way currently to change the issue rate in
back-end.  This patch adds a field (issue_rate) to tune_params and
creates a new function that the middle-end calls.  I updated the
current two tuning variables (generic_tunings and cortexa53_tunings)
to be 1 which was the default before.

OK?  Built and tested for aarch64-elf with no regressions.

Thanks,
Andrew Pinski

ChangeLog:
* config/aarch64/aarch64-protos.h (tune_params): Add issue_rate.
* config/aarch64/aarch64.c (generic_tunings): Add issue rate of 1.
 (cortexa53_tunings): Likewise.
(aarch64_sched_issue_rate): New function.
(TARGET_SCHED_ISSUE_RATE): Define.

Attachment: addissuerate.diff.txt
Description: Text document