[Bug tree-optimization/78224] [5/6/7 Regression] g++ ICE at -O2(-O1 on gcc6) and above in verify_loop_structure, at cfgloop.c:1646

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78224

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2016-11-07
          Component|middle-end                  |tree-optimization
      Known to work|                            |4.7.4
   Target Milestone|---                         |5.5
            Summary|g++ v4.8+ ICE at -O2(-O1 on |[5/6/7 Regression] g++ ICE
                   |gcc6) and above in          |at -O2(-O1 on gcc6) and
                   |verify_loop_structure, at   |above in
                   |cfgloop.c:1646              |verify_loop_structure, at
                   |                            |cfgloop.c:1646
     Ever confirmed|0                           |1
      Known to fail|                            |4.8.5, 4.9.4, 5.4.0, 6.2.0,
                   |                            |7.0

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.

t.ii: In function ‘void the_game(float)’:
t.ii:35:6: error: missing PHI def
 void the_game(float turn_amount)
      ^
first_18 = PHI <0(9), 1(2), (7)>

t.ii:35:6: internal compiler error: verify_gimple failed

on the GCC 6 branch and

t.ii:35:6: error: loop with header 3 not in loop tree
 void the_game(float turn_amount)
      ^~~~~~~~
t.ii:35:6: internal compiler error: in verify_loop_structure, at cfgloop.c:1646
0xbd58e6 verify_loop_structure()
        /space/rguenther/src/svn/trunk/gcc/cfgloop.c:1646
0xf27531 checking_verify_loop_structure
        /space/rguenther/src/svn/trunk/gcc/cfgloop.h:611
0xf276e4 loop_optimizer_init(unsigned int)
        /space/rguenther/src/svn/trunk/gcc/loop-init.c:129
0x1346b7d tree_ssa_cs_elim
        /space/rguenther/src/svn/trunk/gcc/tree-ssa-phiopt.c:116

on trunk.