------- Comment #10 from rguenth at gcc dot gnu dot org 2009-06-02 15:21
-------
C testcase:
struct X { int type; int pos; };
int foo(struct X *a, struct X *b)
{
again:
if (a->type == 0)
goto out;
if (b->type == 1)
goto out;
({ struct X *tmp = a; a = b; b = tmp; });
goto again;
out:
return a->pos + b->pos;
}
"fix":
@@ -1734,6 +1767,19 @@ phi_translate_1 (pre_expr expr, bitmap_s
if (TREE_CODE (def) == SSA_NAME)
def = VN_INFO (def)->valnum;
+ /* If we translated the name to one defined by a PHI node
+ in the same basic-block punt. This hints at cyclic
+ PHI nodes like
+ <bb 3>:
+ # this_2 = PHI <this_45(D)(2), s_4(4)>
+ # s_4 = PHI <s_39(D)(2), this_2(4)>
+ which can cause antic computation to never finis. */
+ if (TREE_CODE (def) == SSA_NAME
+ && (def_stmt = SSA_NAME_DEF_STMT (def)) != NULL
+ && gimple_code (def_stmt) == GIMPLE_PHI
+ && gimple_bb (def_stmt) == phiblock)
+ return NULL;
+
/* Handle constant. */
if (is_gimple_min_invariant (def))
return get_or_alloc_expr_for_constant (def);
Danny - any opinions here?
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |dberlin at gcc dot gnu dot
| |org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40321
