[Bug middle-end/59037] [4.8/4.9 Regression] ICE when accessing invalid element (nelts + 1) of vector

[vries at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59037

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |glisse at gcc dot gnu.org,
                   |                            |vries at gcc dot gnu.org

--- Comment #4 from vries at gcc dot gnu.org ---
Tentative patch:
...
diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
index 93b8970..6f2b4fb 100644
--- a/gcc/tree-ssa-forwprop.c
+++ b/gcc/tree-ssa-forwprop.c
@@ -3046,6 +3046,8 @@ simplify_bitfield_ref (gimple_stmt_iterator *gsi)
       if (TREE_CODE (m) != VECTOR_CST)
    return false;
       nelts = VECTOR_CST_NELTS (m);
+      if (idx >= nelts)
+       return false;
       idx = TREE_INT_CST_LOW (VECTOR_CST_ELT (m, idx));
       idx %= 2 * nelts;
       if (idx < nelts)
...