modulo-sched: skip loops with strange register defs [PR100225]

modulo-sched: skip loops with strange register defs [PR100225]

PR84878 fix adds an assertion which can fail, e.g. when stack pointer
is adjusted inside the loop.  We have to prevent it and search earlier
for any 'strange' instruction.  The solution is to skip the whole loop
if using 'note_stores' we found that one of hard registers is in
'df->regular_block_artificial_uses' set.

Also patch properly prohibit not single-set instruction in loop body.

gcc/ChangeLog:

	PR rtl-optimization/100225
	PR rtl-optimization/84878
	* modulo-sched.c (sms_schedule): Use note_stores to skip loops
	where we have an instruction which touches (writes) any hard
	register from df->regular_block_artificial_uses set.
	Allow not-single-set instruction only right before basic block
	tail.

gcc/testsuite/ChangeLog:

	PR rtl-optimization/100225
	PR rtl-optimization/84878
	* gcc.dg/pr100225.c: New test.

libgomp/ChangeLog:

	* testsuite/libgomp.oacc-c-c++-common/atomic_capture-3.c: New test.

(cherry picked from commit 4cf3b10f27b1994cf4a9eb12079d85412ebc7cad)