tree-optimization/113630 - invalid code hoisting

tree-optimization/113630 - invalid code hoisting

The following avoids code hoisting (but also PRE insertion) of
expressions that got value-numbered to another one that are not
a valid replacement (but still compute the same value).  This time
because the access path ends in a structure with different size,
meaning we consider a related access as not trapping because of the
size of the base of the access.

	PR tree-optimization/113630
	* tree-ssa-pre.cc (compute_avail): Avoid registering a
	reference with a representation with not matching base
	access size.

	* gcc.dg/torture/pr113630.c: New testcase.

(cherry picked from commit 724b64304ff5c8ac08a913509afd6fde38d7b767)