[Bug tree-optimization/83361] New: [8 Regression] ICE: verify_flow_info failed (error: non-cold basic block 3 reachable only by paths crossing the cold partition) on 32-bit BE powerpc targets

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83361

            Bug ID: 83361
           Summary: [8 Regression] ICE: verify_flow_info failed (error:
                    non-cold basic block 3 reachable only by paths
                    crossing the cold partition) on 32-bit BE powerpc
                    targets
           Product: gcc
           Version: 8.0
            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: ---
            Target: powerpc-*-linux-gnu, powerpcspe-*-linux-gnu

gcc-8.0.0-alpha20171210 snapshot (r255534) ICEs when compiling the following
snippet w/ -O2 (-O3, -Ofast) -freorder-blocks-and-partition:

#include <limits.h>

int yz;

void
tq (int z3)
{
  unsigned long long int n8 = (unsigned long long int)INT_MAX + 1;
  int *ey = &yz;

  if (yz == 0)
    {
      int bc;

      yz = 1;
      while (yz != 0)
        {
          *ey *= bc;
          n8 = !!(1 / ((unsigned long long int)yz == n8));
          ey = &z3;
        }

      while (z3 != 0)
        {
        }
    }

  z3 = (n8 != 0) && (*ey != 0);
  z3 = yz / z3;
  if (z3 < 0)
    {
      if (yz != 0)
        yz = 0;
      yz /= 0;
    }
}

% powerpc-e300c3-linux-gnu-gcc-8.0.0-alpha20171210 -O2
-freorder-blocks-and-partition -w -c yb4mx7hn.c
yb4mx7hn.c: In function 'tq':
yb4mx7hn.c:36:1: error: non-cold basic block 3 reachable only by paths crossing
the cold partition
 }
 ^
during RTL pass: ce3
yb4mx7hn.c:36:1: internal compiler error: verify_flow_info failed
0x71c61a verify_flow_info()
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-8.0.0_alpha20171210/work/gcc-8-20171210/gcc/cfghooks.c:265
0x13db5d8 checking_verify_flow_info
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-8.0.0_alpha20171210/work/gcc-8-20171210/gcc/cfghooks.h:198
0x13db5d8 if_convert
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-8.0.0_alpha20171210/work/gcc-8-20171210/gcc/ifcvt.c:5449
0x13dd2fc execute
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-8.0.0_alpha20171210/work/gcc-8-20171210/gcc/ifcvt.c:5549