[Bug middle-end/52329] New: Invalid MEM_REF encountered in set_mem_attributes_minus_bitpos

[jamborm at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52329

             Bug #: 52329
           Summary: Invalid MEM_REF encountered in
                    set_mem_attributes_minus_bitpos
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: jamb...@gcc.gnu.org
                CC: ja...@gcc.gnu.org
              Host: x86_64-suse-linux
            Target: x86_64-suse-linux
             Build: x86_64-suse-linux


Created attachment 26716
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26716
Preprocessed source

Bootstrapping revision 184388 with the following patch

Index: gcc/emit-rtl.c
===================================================================
--- gcc/emit-rtl.c      (revision 184388)
+++ gcc/emit-rtl.c      (working copy)
@@ -1681,6 +1681,7 @@ set_mem_attributes_minus_bitpos (rtx ref
       MEM_NOTRAP_P (ref) = !tree_could_trap_p (t);

       base = get_base_address (t);
+      gcc_assert (base);
       if (base && DECL_P (base)
          && TREE_READONLY (base)
          && (TREE_STATIC (base) || DECL_EXTERNAL (base))

causes an ICE when compiling libstdc++-v3/src/c++98/complex_io.cc
because get_base_address stumbles upon encountering an invalid
MEM_REF

MEM[(struct basic_stringbuf *)&__s._M_stringbuf]._M_string

and returns NULL.

This expression is passed to it by expand_debug_expr via
set_mem_attributes.

Attached is the preprocessed testcase, invocation flags
are -g -O2 -S