[PATCH][ARM] Fix checking RTL error in cortex_a9_sched_adjust_cost

[Kyrill Tkachov <kyrylo.tkachov@arm.com>]

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Hi all,

An arm-none-eabi build with RTL checking and --with-cpu=cortex-a9 fails because
cortex_a9_sched_adjust_cost tries to access the SET_DEST of a PARALLEL.
The correct thing to do is to call single_set on dep, which will return a simple SET
that we can take the SET_DEST of or NULL if there's more than one SET.

This patch does that.
The arm-none-eabi build passes.
Bootstrapped and tested on arm-none-linux-gnueabihf.

Ok for trunk?

Thanks,
Kyrill

2015-10-29  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

     * config/arm/arm.c (cortex_a9_sched_adjust_cost): Use reg_set_p to
     check for dependencies.

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commit bef3ba20485085d702b9a6c8683683db49b547f0
Author: Kyrylo Tkachov <kyrylo.tkachov@arm.com>
Date:   Tue Oct 27 18:09:29 2015 +0000

    [ARM] Fix checking RTL error in cortex_a9_sched_adjust_cost

diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 08a852d..452b23d 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -11649,9 +11649,7 @@ cortex_a9_sched_adjust_cost (rtx_insn *insn, rtx link, rtx_insn *dep, int * cost
 		       case. However this gets modeled as an true
 		       dependency and hence all these checks.  */
 		    if (REG_P (SET_DEST (PATTERN (insn)))
-			&& REG_P (SET_DEST (PATTERN (dep)))
-			&& reg_overlap_mentioned_p (SET_DEST (PATTERN (insn)),
-						    SET_DEST (PATTERN (dep))))
+			&& reg_set_p (SET_DEST (PATTERN (insn)), dep))
 		      {
 			/* FMACS is a special case where the dependent
 			   instruction can be issued 3 cycles before