------- Comment #8 from rguenth at gcc dot gnu dot org 2009-06-02 14:45 -------
Pffft. Not this again...
<bb 3>:
# this_2 = PHI <this_45(D)(2), s_4(7)>
# s_4 = PHI <s_39(D)(2), this_2(7)>
so this_2 and s_4 are equal on one edge but not on another. copyprop is
not always able to remove the PHI for some un-obvious reason.
Thus, how do we deal with that?
We enter PRE with
<bb 2>:
<bb 3>:
# this_2 = PHI <this_45(D)(2), s_4(7)>
# s_4 = PHI <s_39(D)(2), this_2(7)>
D.2149_3 = this_2->type;
if (D.2149_3 == 1)
goto <bb 4>;
else
goto <bb 6>;
<bb 6>:
goto <bb 5>;
<bb 4>:
D.2152_5 = s_4->type;
if (D.2152_5 == 0)
goto <bb 7>;
else
goto <bb 8>;
<bb 7>:
goto <bb 3>;
<bb 8>:
<bb 5>:
# this_61 = PHI <this_2(6), this_2(8)>
# s_62 = PHI <s_4(6), s_4(8)>
...
and have
Value numbers:
this_61 = this_2
s_62 = s_4
copy-prop seems confused:
Simulating statement (from ssa_edges): this_61 = PHI <this_2(3), this_2(4)>
Visiting PHI node: this_61 = PHI <this_2(3), this_2(4)>
PHI node this_61 copy-of chain: this_61 -> this_61 [NOT A COPY]
Telling the propagator to add SSA edges out of this PHI and never visit again.
but, before we fix copy-prop we probably should deal with this in PRE
by simply not phi_translating in circles.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |rguenth at gcc dot gnu dot
|dot org |org
Status|NEW |ASSIGNED
Last reconfirmed|2009-06-02 13:55:12 |2009-06-02 14:45:08
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40321
