tree-optimization/109609 - correctly interpret arg size in fnspec
By majority vote and a hint from the API name which is
arg_max_access_size_given_by_arg_p this interprets a memory access
size specified as given as other argument such as for strncpy
in the testcase which has "1cO313" as specifying the _maximum_
size read/written rather than the exact size. There are two
uses interpreting it that way already and one differing. The
following adjusts the differing and clarifies the documentation.
PR tree-optimization/109609
* attr-fnspec.h (arg_max_access_size_given_by_arg_p):
Clarify semantics.
* tree-ssa-alias.cc (check_fnspec): Correctly interpret
the size given by arg_max_access_size_given_by_arg_p as
maximum, not exact, size.