tree-chrec: Fix up ICE on pointer multiplication [PR107835]

tree-chrec: Fix up ICE on pointer multiplication [PR107835]

r13-254-gdd3c7873a61019e9 added an optimization for {a, +, a} (x-1),
but as can be seen on the following testcase, the way it is written
where chrec_fold_multiply is called with type doesn't work for pointers:
             res = build_int_cst (TREE_TYPE (x), 1);
             res = chrec_fold_plus (TREE_TYPE (x), x, res);
             res = chrec_convert_rhs (type, res, NULL);
             res = chrec_fold_multiply (type, chrecr, res);
while what we were doing before and what is still used if the condition
doesn't match is fine:
             res = chrec_convert_rhs (TREE_TYPE (chrecr), x, NULL);
             res = chrec_fold_multiply (TREE_TYPE (chrecr), chrecr, res);
             res = chrec_fold_plus (type, CHREC_LEFT (chrec), res);
because it performs chrec_fold_multiply on TREE_TYPE (chrecr) and converts
only afterwards.

I think the easiest fix is to ignore the new path for pointer types.

2022-11-30  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/107835
	* tree-chrec.cc (chrec_apply): Don't handle "{a, +, a} (x-1)"
	as "a*x" if type is a pointer type.

	* gcc.c-torture/compile/pr107835.c: New test.