[Bug tree-optimization/98455] New: [11 Regression] ICE: verify_gimple failed (error: invalid 'PHI' argument; error: incompatible types in 'PHI' argument 2)

[asolokha at gmx dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98455

            Bug ID: 98455
           Summary: [11 Regression] ICE: verify_gimple failed (error:
                    invalid 'PHI' argument; error: incompatible types in
                    'PHI' argument 2)
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

gcc-11.0.0-alpha20201220 snapshot (g:18e86fae2a14f78e70aae06afce6bb9853068bb1)
ICEs when compiling the following testcase w/ -O1 -fno-tree-dce --param
case-values-threshold=1:

void
n4 (int io, int vb)
{
  double uc[2] = { 1.0, 2.0, };

  if (io == 0)
    uc[0] = 0.0;

  for (;;)
    if (io == 0)
      if (vb == 0)
        uc[0] = uc[1];
      else if (vb == 1)
        uc[1] = 0.0;
}

% gcc-11.0.0 -O1 -fno-tree-dce --param case-values-threshold=1 -c y2iyiouv.c
y2iyiouv.c: In function 'n4':
y2iyiouv.c:15:1: error: invalid 'PHI' argument
   15 | }
      | ^
uc$1_12
y2iyiouv.c:15:1: error: incompatible types in 'PHI' argument 2
void

double

.MEM_2 = PHI <.MEM_3(D)(2), .MEM_2(5), uc$1_12(4), .MEM_2(3), .MEM_2(6)>
y2iyiouv.c:15:1: error: missing 'PHI' def
uc$1_12 = PHI <2.0e+0(2), uc$1_12(5), (4), uc$1_12(3), 0.0(6)>
during GIMPLE pass: iftoswitch
y2iyiouv.c:15:1: internal compiler error: verify_gimple failed
0xe4523a verify_gimple_in_cfg(function*, bool)
       
/var/tmp/portage/sys-devel/gcc-11.0.0_alpha20201220/work/gcc-11-20201220/gcc/tree-cfg.c:5467
0xd16c37 execute_function_todo
       
/var/tmp/portage/sys-devel/gcc-11.0.0_alpha20201220/work/gcc-11-20201220/gcc/passes.c:2042
0xd1764b execute_todo
       
/var/tmp/portage/sys-devel/gcc-11.0.0_alpha20201220/work/gcc-11-20201220/gcc/passes.c:2096