RE: [RFC, vectorizer] Allow single element vector types for vector reduction operations

[Richard Biener <rguenther at suse dot de>]

On Tue, 12 Sep 2017, Richard Biener wrote:

> On Tue, 12 Sep 2017, Tamar Christina wrote:
> 
> > Hi Jon, Richard,
> > 
> > > > >
> > > > > Testing the following instead:
> > > >
> > > > Any news on this?
> > > 
> > > Didn't work out as expected.  I think the logic in tree-vect-generic is the one
> > > to be fixed but I have to carve out some time to look into it so stay tuned.
> > 
> > In the meantime can this patch be reverted? It is causing ICEs on 
> > AArch64 and ARM Preventing us from building benchmarks and tracking the 
> > toolchain performance.
> 
> You can always locally patch things.  I have yet another patch in
> testing right now.

I've installed the following.

Bootstrapped and tested on x86_64-unknown-linux-gnu.

Richard.

2017-09-12  Richard Biener  <rguenther@suse.de>

	* tree-vect-generic.c (expand_vector_operations_1): Do nothing
	for operations we cannot scalarize.

Index: gcc/tree-vect-generic.c
===================================================================
--- gcc/tree-vect-generic.c	(revision 251997)
+++ gcc/tree-vect-generic.c	(working copy)
@@ -1638,7 +1638,11 @@ expand_vector_operations_1 (gimple_stmt_
   /* The signedness is determined from input argument.  */
   if (code == VEC_UNPACK_FLOAT_HI_EXPR
       || code == VEC_UNPACK_FLOAT_LO_EXPR)
-    type = TREE_TYPE (rhs1);
+    {
+      type = TREE_TYPE (rhs1);
+      /* We do not know how to scalarize those.  */
+      return;
+    }
 
   /* For widening/narrowing vector operations, the relevant type is of the
      arguments, not the widened result.  VEC_UNPACK_FLOAT_*_EXPR is
@@ -1655,7 +1659,11 @@ expand_vector_operations_1 (gimple_stmt_
       || code == VEC_PACK_FIX_TRUNC_EXPR
       || code == VEC_WIDEN_LSHIFT_HI_EXPR
       || code == VEC_WIDEN_LSHIFT_LO_EXPR)
-    type = TREE_TYPE (rhs1);
+    {
+      type = TREE_TYPE (rhs1);
+      /* We do not know how to scalarize those.  */
+      return;
+    }
 
   /* Choose between vector shift/rotate by vector and vector shift/rotate by
      scalar */