The following makes us never consider vector(1) T types for
vectorization and ensures this during SLP build. This is a
long-standing issue for BB vectorization and when we remove
early loop vector type setting we lose the single place we have
that rejects this for loops.
Once we implement partial loop vectorization we should revisit
this, but then use the original scalar types for the unvectorized
parts.
Bootstrapped and tested on x86_64-unknown-linux-gnu. I'll see
if there's any surprises from the CI, but otherwise I'll go
ahead with this.
Richard.
* tree-vect-slp.cc (vect_build_slp_tree_1): Reject
single-lane vector types.
---
gcc/tree-vect-slp.cc | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index ad75386926a..d2ce4ffaa4f 100644
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -1114,6 +1114,15 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char
*swap,
matches[0] = false;
return false;
}
+ if (known_le (TYPE_VECTOR_SUBPARTS (vectype), 1U))
+ {
+ if (dump_enabled_p ())
+ dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+ "Build SLP failed: not using single lane "
+ "vector type %T\n", vectype);
+ matches[0] = false;
+ return false;
+ }
/* Record nunits required but continue analysis, producing matches[]
as if nunits was not an issue. This allows splitting of groups
to happen. */
--
2.43.0
