This is an issue of folding looking at SSA def stmts when SSA form
is not up-to-date. That's not safe unless the SSA name we are
looking at is not marked for update (see GIMPLE_COND folding in
cfgcleaup for another example).
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
Richard.
2012-08-20 Richard Guenther <rguent...@suse.de>
PR tree-optimization/54327
* gimple-fold.c (get_maxval_strlen): Do not walk use-def chains
if the use is registered for SSA update.
* gcc.dg/torture/pr54327.c: New testcase.
Index: gcc/gimple-fold.c
===================================================================
*** gcc/gimple-fold.c (revision 190523)
--- gcc/gimple-fold.c (working copy)
*************** get_maxval_strlen (tree arg, tree *lengt
*** 736,741 ****
--- 736,746 ----
return true;
}
+ /* If ARG is registered for SSA update we cannot look at its defining
+ statement. */
+ if (name_registered_for_update_p (arg))
+ return false;
+
/* If we were already here, break the infinite cycle. */
if (!bitmap_set_bit (visited, SSA_NAME_VERSION (arg)))
return true;
Index: gcc/testsuite/gcc.dg/torture/pr54327.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr54327.c (revision 0)
--- gcc/testsuite/gcc.dg/torture/pr54327.c (working copy)
***************
*** 0 ****
--- 1,15 ----
+ /* { dg-do compile } */
+
+ #include <string.h>
+ #include <stdlib.h>
+ void treathead ()
+ {
+ char *a = ';' == '\0' ? : 0;
+ if (*a == '=')
+ {
+ while (*a == (*a == 0) || *a == '\'')
+ a++;
+ if (strlen (a) < 2)
+ abort ();
+ }
+ }
