tree-optimization/95172 - avoid mixing conditionalized and ordered SM

tree-optimization/95172 - avoid mixing conditionalized and ordered SM

The following testcase shows a missed optimization that then leads to
wrong-code when issueing SMed stores on exits.  When we were able to
compute an ordered sequence of stores for an exit we need to emit
that in the correct order and we can emit it disregarding to any
conditional for whether a store actually happened (we know it did).
We can also improve detection as of whether we need conditional
processing at all.  Both parts fix the testcase.

2020-05-18  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/95172
	* tree-ssa-loop-im.c (execute_sm): Get flag whether we
	eventually need the conditional processing.
	(execute_sm_exit): When processing an orderd sequence
	avoid doing any conditional processing.
	(hoist_memory_references): Pass down whether all edges
	have ordered processing for a ref to execute_sm.

	* gcc.dg/torture/pr95172.c: New testcase.