I don't know how you might find out directly. You could try perl -V which will give you a complete configuration summary for your version of perl. Its kind of indirect evidence but often informative.
using perl -V, you will get osname, osversion and archname which should give you a good idea of what platform your version of perl was compiled for. "use64bitint", "use64bitall", "intsize" will all help determine how you can use perl on the platform (use 64bitint = undef for 32 bit platform and intsize = 8 for 64 bit).