http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56621
--- Comment #2 from auc42 at yahoo dot com 2013-03-14 20:00:56 UTC --- Ah, I had forgotten to change "tmp" back to a long in the code snippet provided. I was experimenting to see variations of the generated assembly while using different types. The failure is present with both the 8-byte long and 4-byte int, in this case. I accept your explanation about the clobbered registers, though. I apparently misunderstood how clobber declarations worked (and in re-reading the manual, either I'm still missing something or the text isn't very clear). Placing the variables directly in the S and d registers and skipping the movX instructions eliminates the problem. I suppose that the sequence only worked by happenstance in earlier versions of gcc. (As for the reason of doing it this way: the original code was avoiding use of the C standard library and/or any include files, as a personal learning exercise toward a later program.)
