[Bug middle-end/49536] New: latent bug in FSF gcc with creation of vector of arrays

["howarth at nitro dot med.uc.edu" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49536

           Summary: latent bug in FSF gcc with creation of vector of
                    arrays
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: howarth@nitro.med.uc.edu


Duncan Sands has determined that http://llvm.org/bugs/show_bug.cgi?id=10042
exposes a bug in FSF gcc where vectors of arrays are being created. He proposes
that the following patch to FSF gcc exposes the latent issue...


Index: tree-vect-data-refs.c
===================================================================
--- tree-vect-data-refs.c    (revision 174743)
+++ tree-vect-data-refs.c    (working copy)
@@ -2734,6 +2734,10 @@
       scalar_type = TREE_TYPE (DR_REF (dr));
       STMT_VINFO_VECTYPE (stmt_info) =
                 get_vectype_for_scalar_type (scalar_type);
+      gcc_assert(!STMT_VINFO_VECTYPE (stmt_info) ||
+                 TREE_CODE (STMT_VINFO_VECTYPE (stmt_info)) != VECTOR_TYPE ||
+                 TREE_CODE (TREE_TYPE (STMT_VINFO_VECTYPE (stmt_info)))
+                 != ARRAY_TYPE);
       if (!STMT_VINFO_VECTYPE (stmt_info))
         {
           if (vect_print_dump_info (REPORT_UNVECTORIZED_LOCATIONS))

by triggering an assertion failure when the tree-vectorizer tries to form a
vector of arrays.