Fix possible segfault in load/store-lane analysis

The following fixes a segfault that appeared with a patch applying
additional permutes to a reduction SLP instance root.

	* tree-vect-loop.cc (vect_analyze_loop_2): Deal with NULL
	element in SLP_TREE_SCALAR_STMTS.

diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 9320bf8e878d22faa5e202311649ffc05dbd6094..bc01e12f05bc3cebe5e10535355e5ef1d3b4bd56 100644 (file)
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -2598,7 +2598,7 @@ again:
 
       stmt_vec_info vinfo;
       vinfo = SLP_TREE_SCALAR_STMTS (SLP_INSTANCE_TREE (instance))[0];
-      if (! STMT_VINFO_GROUPED_ACCESS (vinfo))
+      if (!vinfo || !STMT_VINFO_GROUPED_ACCESS (vinfo))
        continue;
       vinfo = DR_GROUP_FIRST_ELEMENT (vinfo);
       unsigned int size = DR_GROUP_SIZE (vinfo);