[Bug tree-optimization/92185] New: ICE when perform condition reduction vectorization on uchar ind var

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92185

            Bug ID: 92185
           Summary: ICE when perform condition reduction vectorization on
                    uchar ind var
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: linkw at gcc dot gnu.org
  Target Milestone: ---

TESTCASE:

#include "tree-vect.h"

extern void abort (void) __attribute__ ((noreturn));

#define N 27


unsigned char
condition_reduction (short *a, short min_v)
{
  unsigned char last = 0;

  for (unsigned char i = 0; i < 27; i++)
    if (a[i] < min_v)
      last = i;

  return last;
}

int
main (void)
{
  short a[27] = {
  11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
  1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
  21, 22, 23, 24, 25, 26, 27
  };

  check_vect ();

  int ret = condition_reduction (a, 10);
  if (ret != 18)
    abort ();

  return 0;
}

BTW, tree-vect.h is from gcc/testsuite/gcc.dg/vect/tree-vect.h

Options: -Ofast -fno-inline -fdump-tree-vect-details
-fvect-cost-model=unlimited

ICE backtrace:
   13 | condition_reduction (short *a, short min_v)
      | ^~~~~~~~~~~~~~~~~~~
0x115016ff vect_create_epilog_for_reduction
        /home/linkw/gcc/gcc-git-fix/gcc/tree-vect-loop.c:4252
0x1150ccb3 vectorizable_live_operation(_stmt_vec_info*, gimple_stmt_iterator*,
_slp_tree*, _slp_instance*, int, bool, vec<stmt_info_for_cost, va_heap,
vl_ptr>*)
        /home/linkw/gcc/gcc-git-fix/gcc/tree-vect-loop.c:7478
0x114df9bf can_vectorize_live_stmts
        /home/linkw/gcc/gcc-git-fix/gcc/tree-vect-stmts.c:10578
0x114e1933 vect_transform_stmt(_stmt_vec_info*, gimple_stmt_iterator*,
_slp_tree*, _slp_instance*)
        /home/linkw/gcc/gcc-git-fix/gcc/tree-vect-stmts.c:11031
0x1150e9d7 vect_transform_loop_stmt
        /home/linkw/gcc/gcc-git-fix/gcc/tree-vect-loop.c:7918
0x1150f73f vect_transform_loop(_loop_vec_info*)
        /home/linkw/gcc/gcc-git-fix/gcc/tree-vect-loop.c:8133
0x1154acc7 try_vectorize_loop_1
        /home/linkw/gcc/gcc-git-fix/gcc/tree-vectorizer.c:982
0x1154aff3 try_vectorize_loop
        /home/linkw/gcc/gcc-git-fix/gcc/tree-vectorizer.c:1035
0x1154b243 vectorize_loops()
        /home/linkw/gcc/gcc-git-fix/gcc/tree-vectorizer.c:1115
0x1132976f execute
        /home/linkw/gcc/gcc-git-fix/gcc/tree-ssa-loop.c:414