S/390: Fix PR89952 incorrect CFI

S/390: Fix PR89952 incorrect CFI

This patch fixes a cases where inconsistent CFI is generated.

After restoring the hard frame pointer (r11) from an FPR we have to
set the CFA register.  In order to be able to set it back to the stack
pointer (r15) we have to make sure that r15 has been restored already.

The patch also adds a scheduler dependency to prevent the instruction
scheduler from swapping the r11 and r15 restore again.

gcc/ChangeLog:

2019-04-24  Andreas Krebbel  <krebbel@linux.ibm.com>

	PR target/89952
	* config/s390/s390.c (s390_restore_gprs_from_fprs): Restore GPRs
    	from FPRs in reverse order.  Generate REG_CFA_DEF_CFA note also
    	for restored hard frame pointer.
	(s390_sched_dependencies_evaluation): Implement new target hook.
	(TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK): New macro definition.

gcc/testsuite/ChangeLog:

2019-04-24  Andreas Krebbel  <krebbel@linux.ibm.com>

	PR target/89952
	* gcc.target/s390/pr89952.c: New test.

From-SVN: r270544