This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug tree-optimization/51848] GCC is not able to vectorize when a constant value is also added to the sum of array expression inside a loop.
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 16 Jan 2012 10:14:08 +0000
- Subject: [Bug tree-optimization/51848] GCC is not able to vectorize when a constant value is also added to the sum of array expression inside a loop.
- Auto-submitted: auto-generated
- References: <bug-51848-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51848
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
CC| |rguenth at gcc dot gnu.org
Component|middle-end |tree-optimization
--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-16 10:14:08 UTC ---
(In reply to comment #2)
> We don't recognize this as reduction because we look for:
>
> a1 = phi < a0, a2 >
> a3 = ...
> a2 = operation (a3, a1)
>
> and here we have
>
> a1 = phi < a0, a2 >
> a3 = ...
> a4 = operation (a3, a1)
> a2 = a4 + 1
It seems reassociation should "fix" this. IIRC we had some special code
in there that was supposed to handle this.