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[Bug target/42542] Vectorizer produces incorrect results on max/min of unsigned intergers
- From: "sje at cup dot hp dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 11 Jan 2010 23:33:00 -0000
- Subject: [Bug target/42542] Vectorizer produces incorrect results on max/min of unsigned intergers
- References: <bug-42542-5724@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #22 from sje at cup dot hp dot com 2010-01-11 23:33 -------
I am looking at this on IA64 and fixing it for V2SI seems simple enough.
I will attach a patch. But I am not sure what to do for V4HI and V8QI.
The current code uses an 'unsigned saturating subtraction' and that
seems to be what x86 is using for V16QI and V8HI. But when I run
pr42542-2.c and pr42542-3.c (short and char) on IA64 they fail. My
patch does make pr42542-1.c (int) work. I tried handling V4HI and V8QI
in the same way as V2SI but that didn't seem to work either.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42542