[Bug middle-end/57806] New: Waste work in propagate_nothrow()

[pchang9 at cs dot wisc.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57806

            Bug ID: 57806
           Summary: Waste work in propagate_nothrow()
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pchang9 at cs dot wisc.edu
                CC: nistor1 at illinois dot edu

The problem appears in revision 200588 in version 4.9.

In method "propagate_nothrow()" in gcc/ipa-pure-const.c, the loop on line 1432
should break immediately after "can_throw" is set to "true". All the iterations
after "can_throw" set to "true" do not perform any useful work, at best they
just set "can_throw" again to "true".