[PATCH] Fix ubsan ICE with flexible array members

[Marek Polacek]

We were missing a check that the TYPE_MAX_VALUE is not NULL.
If it is, we ICE later when gimplifying the UBSAN_BOUNDS call arguments.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2014-07-15  Marek Polacek  <pola...@redhat.com>

        * c-ubsan.c (ubsan_instrument_bounds): Don't instrument if
        TYPE_MAX_VALUE is NULL.

        * gcc.dg/ubsan/bounds-1.c: New test.

diff --git gcc/c-family/c-ubsan.c gcc/c-family/c-ubsan.c
index 3698580..ad5dd0b 100644
--- gcc/c-family/c-ubsan.c
+++ gcc/c-family/c-ubsan.c
@@ -265,7 +265,7 @@ ubsan_instrument_bounds (location_t loc, tree array, tree 
*index,
   tree type = TREE_TYPE (array);
   tree domain = TYPE_DOMAIN (type);
 
-  if (domain == NULL_TREE)
+  if (domain == NULL_TREE || TYPE_MAX_VALUE (domain) == NULL_TREE)
     return NULL_TREE;
 
   tree bound = TYPE_MAX_VALUE (domain);
diff --git gcc/testsuite/gcc.dg/ubsan/bounds-1.c 
gcc/testsuite/gcc.dg/ubsan/bounds-1.c
index e69de29..6f3cd2d 100644
--- gcc/testsuite/gcc.dg/ubsan/bounds-1.c
+++ gcc/testsuite/gcc.dg/ubsan/bounds-1.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-fsanitize=bounds" } */
+
+struct T { int c; char d[]; } t = { 1, "abcdefg" };
+
+int
+baz (int i)
+{
+  return t.d[i];
+}

        Marek