re PR tree-optimization/81723 (fortran build doesn't terminate on 64bit targets)

re PR tree-optimization/81723 (fortran build doesn't terminate on 64bit targets)

2017-08-08  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/81723
	* tree-vect-slp.c (struct bst_traits): New hash traits.
	(bst_fail): New global.
	(vect_build_slp_tree_2): New worker, split out from ...
	(vect_build_slp_tree): ... this now wrapping it with using
	bst_fail set to cache SLP tree build fails.  Properly handle
	max_tree_size.
	(vect_analyze_slp_instance): Allocate and free bst_fail.

	* gfortran.dg/pr81723.f: New testcase.

From-SVN: r250953