This backport contains 1 patch from gcc main stream tree.
The commit id of these patchs list as following in the order of time.

0001-tree-vect-slp.c-vect_build_slp_tree_2-Do-not-build-o.patch
f99d62629933adf91e7e0bc1b1ff344ffb68e1a2

diff -Nurp a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
--- a/gcc/tree-vect-slp.c	2020-08-24 21:31:24.780000000 +0800
+++ b/gcc/tree-vect-slp.c	2020-08-24 21:31:53.516000000 +0800
@@ -1326,7 +1326,7 @@ vect_build_slp_tree_2 (vec_info *vinfo,
 	      slp_tree grandchild;
 
 	      FOR_EACH_VEC_ELT (SLP_TREE_CHILDREN (child), j, grandchild)
-		if (SLP_TREE_DEF_TYPE (grandchild) == vect_internal_def)
+		if (SLP_TREE_DEF_TYPE (grandchild) != vect_external_def)
 		  break;
 	      if (!grandchild)
 		{
@@ -1486,7 +1486,7 @@ vect_build_slp_tree_2 (vec_info *vinfo,
 		  slp_tree grandchild;
 
 		  FOR_EACH_VEC_ELT (SLP_TREE_CHILDREN (child), j, grandchild)
-		    if (SLP_TREE_DEF_TYPE (grandchild) == vect_internal_def)
+		    if (SLP_TREE_DEF_TYPE (grandchild) != vect_external_def)
 		      break;
 		  if (!grandchild)
 		    {