[Bug rtl-optimization/86087] New: ICE in rtl_verify_fallthru, at cfgrtl.c:2911 (error: verify_flow_info: Incorrect fallthru 8->9; error: wrong insn in the fallthru edge)

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86087

            Bug ID: 86087
           Summary: ICE in rtl_verify_fallthru, at cfgrtl.c:2911 (error:
                    verify_flow_info: Incorrect fallthru 8->9; error:
                    wrong insn in the fallthru edge)
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---
            Target: powerpc-*-linux-gnu*

gcc-9.0.0-alpha20180603 snapshot (r261132) ICEs when compiling the following
snippet w/ -O3 (-Ofast) -floop-parallelize-all -frename-registers
-freorder-blocks-and-partition -ftrapv -ftree-parallelize-loops=2
-fno-expensive-optimizations -fno-tree-coalesce-vars -fno-tree-dce
-fno-tree-loop-im:

long long int
bp (int *tp, int o3, int lv)
{
  int cs = 0;
  long long int nn = lv;

  while (tp[0] + lv + nn != 0)
    nn = tp[0] + 1;

  while (cs < o3)
    {
      nn |= (tp[cs] + 1) / (!!tp[0] + 1);
      ++cs;
    }

  return nn;
}

% powerpc-e300c3-linux-gnu-gcc-9.0.0-alpha20180603 -O3 -floop-parallelize-all
-frename-registers -freorder-blocks-and-partition -ftrapv
-ftree-parallelize-loops=2 -fno-expensive-optimizations -fno-tree-coalesce-vars
-fno-tree-dce -fno-tree-loop-im -c l1fi3pyz.c                                   
l1fi3pyz.c: In function 'bp':
l1fi3pyz.c:17:1: error: verify_flow_info: Incorrect fallthru 8->9
 }
 ^
l1fi3pyz.c:17:1: error: wrong insn in the fallthru edge
(barrier 549 513 362)
during RTL pass: bbro
l1fi3pyz.c:17:1: internal compiler error: in rtl_verify_fallthru, at
cfgrtl.c:2911
0x556c7c _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-9.0.0_alpha20180603/work/gcc-9-20180603/gcc/rtl-error.c:108
0x751063 rtl_verify_fallthru
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-9.0.0_alpha20180603/work/gcc-9-20180603/gcc/cfgrtl.c:2911
0x751063 rtl_verify_flow_info
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-9.0.0_alpha20180603/work/gcc-9-20180603/gcc/cfgrtl.c:3012
0x73061b verify_flow_info()
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-9.0.0_alpha20180603/work/gcc-9-20180603/gcc/cfghooks.c:263
0x74e581 checking_verify_flow_info
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-9.0.0_alpha20180603/work/gcc-9-20180603/gcc/cfghooks.h:198
0x74e581 cfg_layout_finalize()
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-9.0.0_alpha20180603/work/gcc-9-20180603/gcc/cfgrtl.c:4333
0x1376de1 execute
       
/var/tmp/portage/cross-powerpc-e300c3-linux-gnu/gcc-9.0.0_alpha20180603/work/gcc-9-20180603/gcc/bb-reorder.c:2646