diff --git a/gcc/testsuite/gcc.target/i386/pr92645-6.c b/gcc/testsuite/gcc.target/i386/pr92645-6.c
new file mode 100644
index 000000000000..c5c5f8f8df2f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr92645-6.c
@@ -0,0 +1,34 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target lp64 } */
+/* { dg-options "-O3 -msse2" } */
+
+typedef long v2di __attribute__((vector_size(16)));
+typedef int v4si __attribute__((vector_size(16)));
+
+void foo (v4si *p, v2di *q)
+{
+  union { v2di a; v4si b; } u;
+  u.a = *q;
+  (*p)[0] = u.b[0];
+  (*p)[1] = u.b[2];
+  (*p)[2] = u.b[1];
+  (*p)[3] = u.b[3];
+}
+
+void bar (v4si *p, __int128_t *q)
+{
+  union { __int128_t a; v4si b; } u;
+  u.a = *q;
+  (*p)[0] = u.b[1];
+  (*p)[1] = u.b[2];
+  (*p)[2] = u.b[1];
+  (*p)[3] = u.b[3];
+}
+
+/* Both functions should end up with sth like
+     [v]pshufd $val, (%esi), %xmm0
+     [v]movdqa %xmm0, (%edi)
+     ret
+   recognized by SLP vectorization involving an existing "vector".  */
+/* { dg-final { scan-assembler-not "punpck" } } */
+/* { dg-final { scan-assembler-times "pshufd" 2 } } */
diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
index 65b7a27e1e88..f7f656a48102 100644
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -1105,7 +1105,8 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char *swap,
 	      tree vec = TREE_OPERAND (gimple_assign_rhs1 (stmt), 0);
 	      if (!is_a <bb_vec_info> (vinfo)
 		  || TREE_CODE (vec) != SSA_NAME
-		  || !types_compatible_p (vectype, TREE_TYPE (vec)))
+		  || !operand_equal_p (TYPE_SIZE (vectype),
+				       TYPE_SIZE (TREE_TYPE (vec))))
 		{
 		  if (dump_enabled_p ())
 		    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -1642,7 +1643,11 @@ vect_build_slp_tree_2 (vec_info *vinfo, slp_tree node,
 	  lperm.safe_push (std::make_pair (0, (unsigned)lane));
 	}
       slp_tree vnode = vect_create_new_slp_node (vNULL);
-      SLP_TREE_VECTYPE (vnode) = TREE_TYPE (vec);
+      /* ???  We record vectype here but we hide eventually necessary
+	 punning and instead rely on code generation to materialize
+	 VIEW_CONVERT_EXPRs as necessary.  We instead should make
+	 this explicit somehow.  */
+      SLP_TREE_VECTYPE (vnode) = vectype;
       SLP_TREE_VEC_DEFS (vnode).safe_push (vec);
       /* We are always building a permutation node even if it is an identity
 	 permute to shield the rest of the vectorizer from the odd node
@@ -5671,6 +5676,18 @@ vectorizable_slp_permutation (vec_info *vinfo, gimple_stmt_iterator *gsi,
 	      slp_tree first_node = SLP_TREE_CHILDREN (node)[first_vec.first];
 	      tree first_def
 		= vect_get_slp_vect_def (first_node, first_vec.second);
+	      /* ???  We SLP match existing vector element extracts but
+		 allow punning which we need to re-instantiate at uses
+		 but have no good way of explicitely representing.  */
+	      if (!types_compatible_p (TREE_TYPE (first_def), vectype))
+		{
+		  gassign *conv_stmt;
+		  conv_stmt = gimple_build_assign (make_ssa_name (vectype),
+						   build1 (VIEW_CONVERT_EXPR,
+							   vectype, first_def));
+		  vect_finish_stmt_generation (vinfo, NULL, conv_stmt, gsi);
+		  first_def = gimple_assign_lhs (conv_stmt);
+		}
 	      gassign *perm_stmt;
 	      tree perm_dest = make_ssa_name (vectype);
 	      if (!identity_p)
@@ -5679,6 +5696,16 @@ vectorizable_slp_permutation (vec_info *vinfo, gimple_stmt_iterator *gsi,
 		    = SLP_TREE_CHILDREN (node)[second_vec.first];
 		  tree second_def
 		    = vect_get_slp_vect_def (second_node, second_vec.second);
+		  if (!types_compatible_p (TREE_TYPE (second_def), vectype))
+		    {
+		      gassign *conv_stmt;
+		      conv_stmt = gimple_build_assign (make_ssa_name (vectype),
+						       build1
+							 (VIEW_CONVERT_EXPR,
+							  vectype, second_def));
+		      vect_finish_stmt_generation (vinfo, NULL, conv_stmt, gsi);
+		      second_def = gimple_assign_lhs (conv_stmt);
+		    }
 		  tree mask_vec = vect_gen_perm_mask_checked (vectype, indices);
 		  perm_stmt = gimple_build_assign (perm_dest, VEC_PERM_EXPR,
 						   first_def, second_def,