Re: [patch] Fix PR tree-optimization/45902

[Ira Rosen <IRAR@il.ibm.com>]

Richard Guenther <richard.guenther@gmail.com> wrote on 11/10/2010 02:32:08
PM:

>
> On Mon, Oct 11, 2010 at 2:19 PM, Ira Rosen <IRAR@il.ibm.com> wrote:
> >
> > Hi,
> >
> > This patch fixes a bug in creation of a vector of constants in SLP. The
> > problem is in the type of created vector. It should be set to the
vector
> > type of the statement unless it's a pointer.
> >
> > Bootstrapped and tested on x86_64-suse-linux and checked that the
failure
> > is fixed on powerpc64-suse-linux.
> >
> > Committed to mainline, ok for 4.5?
>
> I don't think this makes sense.  If at all the selection of which type
> to use should be based on the operation code and the operand
> position, but not on CONSTANT_CLASS_P or pointer-type-ness.
>
> So - what operation code / operand position is currently mishandled?

This function creates vectors of constants or loop invariants. If it's a
variable (loop invariant), we know exactly the type, hence the check for
CONSTANT_CLASS_P.

I guess instead of checking the type we can check if it's POINTER_PLUS_EXPR
to catch the cases where we need the operand's type instead of the stmt's
vectype.

Does this make sense?

Index: tree-vect-slp.c
===================================================================
--- tree-vect-slp.c     (revision 165302)
+++ tree-vect-slp.c     (working copy)
@@ -1836,10 +1836,10 @@ vect_get_constant_vectors (slp_tree slp_
   VEC (tree, heap) *voprnds = VEC_alloc (tree, heap, number_of_vectors);
   bool constant_p, is_store;
   tree neutral_op = NULL;
+  enum tree_code code = gimple_assign_rhs_code (stmt);

   if (STMT_VINFO_DEF_TYPE (stmt_vinfo) == vect_reduction_def)
     {
-      enum tree_code code = gimple_assign_rhs_code (stmt);
       if (reduc_index == -1)
         {
           VEC_free (tree, heap, *vec_oprnds);
@@ -1895,18 +1895,14 @@ vect_get_constant_vectors (slp_tree slp_
     }

   if (CONSTANT_CLASS_P (op))
-    {
-      constant_p = true;
-      if (POINTER_TYPE_P (TREE_TYPE (gimple_assign_lhs (stmt))))
-        vector_type = get_vectype_for_scalar_type (TREE_TYPE (op));
-      else
-        vector_type = STMT_VINFO_VECTYPE (stmt_vinfo);
-    }
+    constant_p = true;
   else
-    {
-      constant_p = false;
-      vector_type = get_vectype_for_scalar_type (TREE_TYPE (op));
-    }
+    constant_p = false;
+
+  if (code == POINTER_PLUS_EXPR)
+    vector_type = get_vectype_for_scalar_type (TREE_TYPE (op));
+  else
+    vector_type = STMT_VINFO_VECTYPE (stmt_vinfo);

   gcc_assert (vector_type);
   nunits = TYPE_VECTOR_SUBPARTS (vector_type);

Thanks,
Ira