[COMMITTED] bpf: avoid potential NULL pointer dereference

[David Faust via Gcc-patches]

[Committed as obvious.]

If the result from SSA_NAME_DEF_STMT is NULL, we could try to
dereference it anyway and ICE. Avoid this.

gcc/ChangeLog:

        * config/bpf/bpf.c (handle_attr_preserve): Avoid calling
        is_gimple_assign with a NULL pointer.
---
 gcc/config/bpf/bpf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/config/bpf/bpf.c b/gcc/config/bpf/bpf.c
index 9d2c0bb6818..c054c1ead6b 100644
--- a/gcc/config/bpf/bpf.c
+++ b/gcc/config/bpf/bpf.c
@@ -1482,7 +1482,7 @@ handle_attr_preserve (function *fn)
                      && TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME)
                    {
                      gimple *def_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (expr, 
0));
-                     if (is_gimple_assign (def_stmt))
+                     if (def_stmt && is_gimple_assign (def_stmt))
                        expr = gimple_assign_rhs1 (def_stmt);
                    }
 
-- 
2.31.1