Xref: utzoo comp.unix.wizards:16723 comp.lang.c:19222
Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!well!pokey
From: pokey@well.UUCP (Jef Poskanzer)
Newsgroups: comp.unix.wizards,comp.lang.c
Subject: Re: Optimal for loop on the 68020.
Message-ID: <12033@well.UUCP>
Date: 6 Jun 89 23:13:32 GMT
References: <40063@cmcl2.NYU.EDU>
Reply-To: Jef Poskanzer <pokey@well.com>
Organization: Paratheo-Anametamystikhood Of Eris Esoteric, Ada Lovelace Cabal
Lines: 14

In the referenced message, edler@cmcl2.UUCP (Jan Edler) wrote:
}However, the compiler shouldn't do either of these when d0 is initialized
}to a value < 65536.

Not good enough, since the loop body might modify the index variable.
If the compiler is smart enough to do a global semantic check for this
sort of thing, then you can do this optimization; but we've already
established that cc and gcc aren't that smart.
---
Jef

   Jef Poskanzer   {ucbvax, lll-crg, sun!pacbell, apple, hplabs}!well!pokey
 "A banker is a fellow who lends you his umbrella when the sun is shining and
          wants it back the minute it begins to rain." -- Mark Twain