[Bug c/28418] [4.0/4.1/4.2 regression] ICE incrementing compound literal expression

[fjahanian at apple dot com]

------- Comment #3 from fjahanian at apple dot com  2006-07-24 23:16 -------
gcc generates two separate trees for compound literals in c and c++. As in this
test case:

struct S {
        int i,j;
};
void foo (struct S);

int main ()
{
        foo((struct S){1,1});
}


In c it generates compound_literal_expr and in c++ it generates target_expr.
But gimplifier treats them differently in the following areas:

1) in routine mostly_copy_tree_v we don;t copy target_expr but we do copy
compound_literal_expr. I see the following comment there:

    / * Similar to copy_tree_r() but do not copy SAVE_EXPR or TARGET_EXPR
nodes.
   These nodes model computations that should only be done once.  If we
   were to unshare something like SAVE_EXPR(i++), the gimplification
   process would create wrong code.  */

Shouldn't compound_literal_expr be treated same as target_expr here?

2) gimplify_target_expr can be called more than once on the same target_expr
node because first time around its TARGET_EXPR_INITIAL is set to NULL.
    This works as a guard and prevents its temporary to be added to the
temporary list more than once (when call is made to gimple_add_tmp_var).

    On the other hand, such a guard does not exist for a compound_literal_expr
and when gimple_add_tmp_var is called, it asserts. So, I added check for
    !DECL_SEEN_IN_BIND_EXPR_P (decl) in gimplify_compound_literal_expr before
call to gimple_add_tmp_var is made. As in the following diff:

% svn diff c-gimplify.c
Index: c-gimplify.c
===================================================================
--- c-gimplify.c        (revision 116462)
+++ c-gimplify.c        (working copy)
@@ -538,7 +538,7 @@
   /* This decl isn't mentioned in the enclosing block, so add it to the
      list of temps.  FIXME it seems a bit of a kludge to say that
      anonymous artificial vars aren't pushed, but everything else is.  */
-  if (DECL_NAME (decl) == NULL_TREE)
+  if (DECL_NAME (decl) == NULL_TREE && !DECL_SEEN_IN_BIND_EXPR_P (decl))
     gimple_add_tmp_var (decl);

This fixes the problem I am encouterring as well as the test case in this PR.


-- 

fjahanian at apple dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fjahanian at apple dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28418