Re: [patch] Fix PR tree-optimization/46213

[Ira Rosen <IRAR at il dot ibm dot com>]

Richard Guenther <richard.guenther@gmail.com> wrote on 04/11/2010 04:18:34
PM:

> On Thu, Nov 4, 2010 at 12:51 PM, Ira Rosen <IRAR@il.ibm.com> wrote:
> >
> > Hi,
> >
> > MINUS_EXPR in reduction is supposed to be supported for computations of
the
> > form: res = res - a[i], and not for res = a[i] - res, but this is not
> > checked. The attached patch adds such check.
>
> We can simply support this by treating is as
>
>   tmp = -a[i];
>   res = res + tmp;

But isn't that the res = res - a[i] case? It is supported. This patch
prevents attempts to vectorize res = a[i] - res.

Ira

>
> Richard.
>
> > Bootstrapped on powerpc64-suse-linux and tested on x86_64-suse-linux.
> > Committed.
> >
> > Ira
> >
> >
> > ChangeLog:
> >
> > ? ? ? ?PR tree-optimization/46213
> > ? ? ? ?* tree-vect-loop.c (vect_is_simple_reduction_1): Handle
> > ? ? ? ?MINUS_EXPR only if the first operand is reduction operand.
> >
> > testsuite/ChangeLog:
> >
> > ? ? ? ?PR tree-optimization/46213
> > ? ? ? ?* gfortran.dg/vect/pr46213.f90: New.
> >
> >
> > Index: testsuite/gfortran.dg/vect/pr46213.f90
> > ===================================================================
> > --- testsuite/gfortran.dg/vect/pr46213.f90 ? ? ?(revision 0)
> > +++ testsuite/gfortran.dg/vect/pr46213.f90 ? ? ?(revision 0)
> > @@ -0,0 +1,25 @@
> > +! { dg-do compile }
> > +! { dg-options "-O -fno-tree-loop-ivcanon -ftree-vectorize
-fno-tree-ccp
> > -fno-tree-ch -finline-small-functions" }
> > +
> > +module foo
> > + ?INTEGER, PARAMETER :: ONE = 1
> > +end module foo
> > +program test
> > + ?use foo
> > + ?integer :: a(ONE), b(ONE), c(ONE), d(ONE)
> > + ?interface
> > + ? ?function h_ext()
> > + ? ?end function h_ext
> > + ?end interface
> > + ?c = j()
> > + ?if (any (c .ne. check)) call myabort (7)
> > +contains
> > + ?function j()
> > + ? ? integer :: j(ONE), cc(ONE)
> > + ? ? j = cc - j
> > + ?end function j
> > + ?function get_d()
> > + ?end function get_d
> > +end program test
> > +
> > +! { dg-final { cleanup-tree-dump "vect" } }
> > Index: tree-vect-loop.c
> > ===================================================================
> > --- tree-vect-loop.c ? ?(revision 166172)
> > +++ tree-vect-loop.c ? ?(working copy)
> > @@ -1800,7 +1800,11 @@ vect_is_simple_reduction_1 (loop_vec_inf
> > ? ? ?simply rewriting this into "res += -x[i]". ?Avoid changing
> > ? ? ?gimple instruction for the first simple tests and only do this
> > ? ? ?if we're allowed to change code at all. ?*/
> > - ?if (code == MINUS_EXPR && modify)
> > + ?if (code == MINUS_EXPR
> > + ? ? ?&& modify
> > + ? ? ?&& (op1 = gimple_assign_rhs1 (def_stmt))
> > + ? ? ?&& TREE_CODE (op1) == SSA_NAME
> > + ? ? ?&& SSA_NAME_DEF_STMT (op1) == phi)
> > ? ? code = PLUS_EXPR;
> >
> > ? if (check_reduction
> >
> >