PR tree-optimization/86714
	PR tree-optimization/86711
	* builtins.c (c_strlen): Add arguments to call to string_constant.
	* expr.c (string_constant): Add argument.  Detect missing nul
	terminator and outermost declaration it's missing in.
	* expr.h (string_constant): Add argument.
	* fold-const.c (read_from_constant_string): Add arguments to call to
	string_constant.
	(c_getstr): Likewise.
	* tree-ssa-forwprop.c (simplify_builtin_call): Likewise.
	to string_constant.
	* tree-ssa-strlen.c (get_stridx): Likewise.

	PR tree-optimization/86714
	PR tree-optimization/86711
	* gcc.c-torture/execute/memchr-1.c: New test.
	* gcc.c-torture/execute/pr86714.c: New test.
	* gcc.c-torture/execute/widechar-3.c: New test.
	* gcc.dg/strlenopt-58.c: New test.

Co-Authored-By: Bernd Edlinger <bernd.edlinger@hotmail.de>
Co-Authored-By: Jeff Law <law@redhat.com>

From-SVN: r263963