2019-05-21  Richard Biener  <rguenther@suse.de>

	PR middle-end/90510
	* fold-const.c (fold_read_from_vector): New function.
	* fold-const.h (fold_read_from_vector): Declare.
	* match.pd (VEC_PERM_EXPR): Build BIT_INSERT_EXPRs for
	single-element insert permutations.  Canonicalize selector
	further and fix issue with last commit.

	* gcc.target/i386/pr90510.c: New testcase.

From-SVN: r271463