tree-optimization/94261 - avoid IL adjustments in SLP analysis

tree-optimization/94261 - avoid IL adjustments in SLP analysis

The remaining IL adjustment done by SLP analysis turns out harmful
since we share them in the now multiple analyses states.  It turns
out we do not actually need those apart from the case where we
reorg scalar stmts during re-arrangement when optimizing load
permutations in SLP reductions.  But that isn't needed either now
since we only need to permute non-isomorphic parts which now
reside in separate SLP nodes who are all leafs.

2020-03-23  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/94261
	* tree-vect-slp.c (vect_get_and_check_slp_defs): Remove
	IL operand swapping code.
	(vect_slp_rearrange_stmts): Do not arrange isomorphic
	nodes that would need operation code adjustments.