[Bug tree-optimization/40219] New: iterative_hash_expr in tree.c has an out of bound reference for machine specific builtins

[meissner at linux dot vnet dot ibm dot com]

The function iterative_hash_expr uses built_in_decls to a map a builtin
function to the __builtin_ form.  It uses DECL_FUNCTION_CODE as the index.  For
machine specific builtins, the DECL_FUNCTION_CODE is defined by the backend,
instead of being the builtin number.  This means that the builtin_in_decls
reference can point to random memory.

In the power7 branch, I added quite a few more builtins, and this code causes
crashes when it looks at memory beyond the bound of builtin_in_decls.  Even if
it doesn't overflow the bounds of the array, the builtin hash might pick up the
wrong declaration.


-- 
           Summary: iterative_hash_expr in tree.c has an out of bound
                    reference for machine specific builtins
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: meissner at linux dot vnet dot ibm dot com
 GCC build triplet: powerpc64-unknown-linux-gnu
  GCC host triplet: powerpc64-unknown-linux-gnu
GCC target triplet: powerpc64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40219