[v8,7/7] stdlib: Add more qsort{_r} coverage

This patch adds a qsort and qsort_r to trigger the worst case
scenario for the quicksort (which glibc current lacks coverage).
The test is done with random input, dfferent internal types (uint8_t,
uint16_t, uint32_t, uint64_t, large size), and with
different set of element numbers.

Checked on x86_64-linux-gnu and i686-linux-gnu.
---
 stdlib/Makefile     |   1 +
 stdlib/tst-qsort3.c | 366 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 367 insertions(+)
 create mode 100644 stdlib/tst-qsort3.c

On Tue, Oct 3, 2023 at 7:23 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
> This patch adds a qsort and qsort_r to trigger the worst case
> scenario for the quicksort (which glibc current lacks coverage).
> The test is done with random input, dfferent internal types (uint8_t,
> uint16_t, uint32_t, uint64_t, large size), and with
> different set of element numbers.
>
> Checked on x86_64-linux-gnu and i686-linux-gnu.
> ---
>  stdlib/Makefile     |   1 +
>  stdlib/tst-qsort3.c | 366 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 367 insertions(+)
>  create mode 100644 stdlib/tst-qsort3.c
>
> diff --git a/stdlib/Makefile b/stdlib/Makefile
> index 095518eef4..6af606136e 100644
> --- a/stdlib/Makefile
> +++ b/stdlib/Makefile
> @@ -214,6 +214,7 @@ tests := \
>    tst-on_exit \
>    tst-qsort \
>    tst-qsort2 \
> +  tst-qsort3 \
>    tst-quick_exit \
>    tst-rand48 \
>    tst-rand48-2 \
> diff --git a/stdlib/tst-qsort3.c b/stdlib/tst-qsort3.c
> new file mode 100644
> index 0000000000..421560d744
> --- /dev/null
> +++ b/stdlib/tst-qsort3.c
> @@ -0,0 +1,366 @@
> +/* qsort(_r) tests to trigger worst case for quicksort.
> +   Copyright (C) 2023 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <array_length.h>
> +#include <errno.h>
> +#include <getopt.h>
> +#include <stdbool.h>
> +#include <stdint.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <support/check.h>
> +#include <support/support.h>
> +#include <support/test-driver.h>
> +
> +typedef enum
> +{
> +  Sorted,
> +  Random,
> +  Repeated,
> +  Bitonic,
> +  Duplicated,
> +} arraytype_t;
> +
> +/* Ratio of total of elements which will be repeated.  */
> +static const double RepeatedRatio = 0.2;
> +
> +/* Ratio of duplicated element .  */
> +static const double DuplicatedRatio = 0.4;
> +
> +struct array_t
> +{
> +  arraytype_t type;
> +  const char *name;
> +} static const arraytypes[] =
> +{
> +  { Sorted,       "Sorted" },
> +  { Random,       "Random" },
> +  { Repeated,     "Repeated" },
> +  { Bitonic,      "Bitonic" },
> +  { Duplicated,   "Duplicated" },
> +};
> +
> +/* Return the index of BASE as interpreted as an array of elements
> +   of size SIZE.  */
> +static inline void *
> +arr (void *base, size_t idx, size_t size)
> +{
> +  return (void*)((uintptr_t)base + (idx * size));
> +}
> +
> +/* Functions used to check qsort.  */
> +static int
> +uint8_t_cmp (const void *a, const void *b)
> +{
> +  uint8_t ia = *(uint8_t*)a;
> +  uint8_t ib = *(uint8_t*)b;
> +  return (ia > ib) - (ia < ib);
> +}
> +
> +static int
> +uint16_t_cmp (const void *a, const void *b)
> +{
> +  uint16_t ia = *(uint16_t*)a;
> +  uint16_t ib = *(uint16_t*)b;
> +  return (ia > ib) - (ia < ib);
> +}
> +
> +static int
> +uint32_t_cmp (const void *a, const void *b)
> +{
> +  uint32_t ia = *(uint32_t*)a;
> +  uint32_t ib = *(uint32_t*)b;
> +  return (ia > ib) - (ia < ib);
> +}
> +
> +static int
> +uint64_t_cmp (const void *a, const void *b)
> +{
> +  uint64_t ia = *(uint64_t*)a;
> +  uint64_t ib = *(uint64_t*)b;
> +  return (ia > ib) - (ia < ib);
> +}
> +
> +#define LARGE_SIZE 47
> +
> +static int
> +large_cmp (const void *a, const void *b)
> +{
> +  return memcmp (a, b, LARGE_SIZE);
> +}
> +
> +/* Function used to check qsort_r.  */
> +typedef enum
> +{
> +  UINT8_CMP_T,
> +  UINT16_CMP_T,
> +  UINT32_CMP_T,
> +  UINT64_CMP_T,
> +  LARGE_CMP_T
> +} type_cmp_t;
> +
> +static type_cmp_t
> +uint_t_cmp_type (size_t sz)
> +{
> +  switch (sz)
> +    {
> +      case sizeof (uint8_t):  return UINT8_CMP_T;
> +      case sizeof (uint16_t): return UINT16_CMP_T;
> +      case sizeof (uint64_t): return UINT64_CMP_T;
> +      case sizeof (uint32_t): return UINT32_CMP_T;
> +      default:                return LARGE_CMP_T;
> +    }
> +}
> +
> +static int
> +uint_t_cmp (const void *a, const void *b, void *arg)
> +{
> +  type_cmp_t type = *(type_cmp_t*) arg;
> +  switch (type)
> +    {
> +    case UINT8_CMP_T:  return uint8_t_cmp (a, b);
> +    case UINT32_CMP_T: return uint32_t_cmp (a, b);
> +    case UINT16_CMP_T: return uint16_t_cmp (a, b);
> +    case UINT64_CMP_T: return uint64_t_cmp (a, b);
> +    default:           return large_cmp (a, b);
> +    }
> +}
> +
> +static void
> +seq (void *elem, size_t type_size, int value)
> +{
> +  if (type_size == sizeof (uint8_t))
> +    *(uint8_t*)elem = value;
> +  else if (type_size == sizeof (uint16_t))
> +    *(uint16_t*)elem = value;
> +  else if (type_size == sizeof (uint32_t))
> +    *(uint32_t*)elem = value;
> +  else if (type_size == sizeof (uint64_t))
> +    *(uint64_t*)elem = value;
> +  else
> +    memset (elem, value, type_size);
> +}
> +
> +static void
> +fill_array (void *array, void *refarray, size_t nmemb, size_t type_size,
> +           arraytype_t type)
> +{
> +  size_t size = nmemb * type_size;
> +
> +  switch (type)
> +    {
> +    case Sorted:
> +      for (size_t i = 0; i < nmemb; i++)
> +       seq (arr (array, i, type_size), type_size, i);
> +      break;
> +
> +    case Random:
> +      arc4random_buf (array, size);
> +      break;
> +
> +    case Repeated:
> +      {
> +        arc4random_buf (array, size);
> +
> +       void *randelem = xmalloc (type_size);
> +       arc4random_buf (randelem, type_size);
> +
> +       /* Repeat REPEATED elements (based on RepeatRatio ratio) in the random
> +          array.  */
> +        size_t repeated = (size_t)(nmemb * RepeatedRatio);
> +       for (size_t i = 0; i < repeated; i++)
> +         {
> +           size_t pos = arc4random_uniform (nmemb - 1);
> +           memcpy (arr (array, pos, type_size), randelem, type_size);
> +         }
> +       free (randelem);
> +      }
> +      break;
> +
> +    case Bitonic:
> +      {
> +       size_t i;
> +        for (i = 0; i < nmemb / 2; i++)
> +         seq (arr (array, i, type_size), type_size, i);
> +        for (     ; i < nmemb;     i++)
> +         seq (arr (array, i, type_size), type_size, (nmemb - 1) - i);
> +      }
> +      break;
> +
> +    case Duplicated:
> +      {
> +       int randelem1 = arc4random ();
> +       for (size_t i = 0; i < nmemb; i++)
> +         seq (arr (array, i, type_size), type_size, randelem1);
> +
> +       size_t duplicates = (size_t)(nmemb * DuplicatedRatio);
> +       int randelem2 = arc4random ();
> +       for (size_t i = 0; i < duplicates; i++)
> +         {
> +           size_t pos = arc4random_uniform (nmemb - 1);
> +           seq (arr (array, pos, type_size), type_size, randelem2);
> +         }
> +      }
> +      break;
> +    }
> +
> +  memcpy (refarray, array, size);
> +}
> +
> +typedef int (*cmpfunc_t)(const void *, const void *);
> +
> +/* Simple insertion sort to use as reference sort.  */
> +static void
> +qsort_r_ref (void *p, size_t n, size_t s, __compar_d_fn_t cmp, void *arg)
> +{
> +  if (n <= 1)
> +    return;
> +
> +  int i = 1;
> +  char tmp[s];
> +  while (i < n)
> +    {
> +      memcpy (tmp, arr (p, i, s), s);
> +      int j = i - 1;
> +      while (j >= 0 && cmp (arr (p, j, s), tmp, arg) > 0)
> +       {
> +         memcpy (arr (p, j + 1, s), arr (p, j, s), s);
> +         j = j - 1;
> +       }
> +      memcpy (arr (p, j + 1, s), tmp, s);
> +      i = i + 1;
> +    }
> +}
> +
> +static void
> +qsort_ref (void *b, size_t n, size_t s, __compar_fn_t cmp)
> +{
> +  return qsort_r_ref (b, n, s, (__compar_d_fn_t) cmp, NULL);
> +}
> +
> +/* Check if ARRAY of total NMEMB element of size SIZE is sorted
> +   based on CMPFUNC.  */
> +static void
> +check_array (void *array, void *refarray, size_t nmemb, size_t type_size,
> +            cmpfunc_t cmpfunc)
> +{
> +  for (size_t i = 1; i < nmemb; i++)
> +    {
> +      int ret = cmpfunc (arr (array, i,   type_size),
> +                        arr (array, i-1, type_size));
> +      TEST_VERIFY_EXIT (ret >= 0);
> +    }
> +
> +  size_t size = nmemb * type_size;
> +  TEST_COMPARE_BLOB (array, size, refarray, size);
> +}
> +
> +static void
> +check_qsort (void *buf, void *refbuf, size_t nelem, size_t type_size,
> +            arraytype_t type, cmpfunc_t cmpfunc)
> +{
> +  fill_array (buf, refbuf, nelem, type_size, type);
> +
> +  qsort (buf, nelem, type_size, cmpfunc);
> +  qsort_ref (refbuf, nelem, type_size, cmpfunc);
> +
> +  check_array (buf, refbuf, nelem, type_size, cmpfunc);
> +}
> +
> +static void
> +check_qsort_r (void *buf, void *refbuf, size_t nelem, size_t type_size,
> +              arraytype_t type, cmpfunc_t cmpfunc)
> +{
> +  fill_array (buf, refbuf, nelem, type_size, type);
> +
> +  type_cmp_t typecmp = uint_t_cmp_type (type_size);
> +
> +  qsort_r (buf, nelem, type_size, uint_t_cmp, &typecmp);
> +  qsort_r_ref (refbuf, nelem, type_size, uint_t_cmp, &typecmp);
> +
> +  check_array (buf, refbuf, nelem, type_size, cmpfunc);
> +}
> +
> +static int
> +do_test (void)
> +{
> +  /* Some random sizes.  */
> +  static const size_t nelems[] = { 0, 1, 7, 20, 32, 100, 256, 1024, 4256 };
> +  size_t max_nelems = 0;
> +  for (int i = 0; i < array_length (nelems); i++)
> +    if (nelems[i] > max_nelems)
> +      max_nelems = nelems[i];
> +
> +  static const struct test_t
> +    {
> +      size_t type_size;
> +      cmpfunc_t cmpfunc;
> +    }
> +  tests[] =
> +    {
> +      { sizeof (uint8_t),  uint8_t_cmp },
> +      { sizeof (uint16_t), uint16_t_cmp },
> +      { sizeof (uint32_t), uint32_t_cmp },
> +      { sizeof (uint64_t), uint64_t_cmp },
> +      /* Test swap with large elements.  */
> +      { LARGE_SIZE,        large_cmp },
> +    };
> +  size_t max_type_size = 0;
> +  for (int i = 0; i < array_length (tests); i++)
> +    if (tests[i].type_size > max_type_size)
> +      max_type_size = tests[i].type_size;
> +
> +  void *buf = reallocarray (NULL, max_nelems, max_type_size);
> +  TEST_VERIFY_EXIT (buf != NULL);
> +  void *refbuf = reallocarray (NULL, max_nelems, max_type_size);
> +  TEST_VERIFY_EXIT (refbuf != NULL);
> +
> +  for (const struct test_t *test = tests; test < array_end (tests); ++test)
> +    {
> +      if (test_verbose > 0)
> +       printf ("info: testing qsort with type_size=%zu\n", test->type_size);
> +      for (const struct array_t *arraytype = arraytypes;
> +          arraytype < array_end (arraytypes);
> +          ++arraytype)
> +       {
> +         if (test_verbose > 0)
> +            printf ("  distribution=%s\n", arraytype->name);
> +         for (const size_t *nelem = nelems;
> +              nelem < array_end (nelems);
> +              ++nelem)
> +           {
> +             if (test_verbose > 0)
> +               printf ("    nelem=%zu, total size=%zu\n", *nelem,
> +                       *nelem * test->type_size);
> +
> +             check_qsort (buf, refbuf, *nelem, test->type_size,
> +                          arraytype->type, test->cmpfunc);
> +             check_qsort_r (buf, refbuf, *nelem, test->type_size,
> +                            arraytype->type, test->cmpfunc);
> +          }
> +       }
> +    }
> +
> +  free (buf);
> +  free (refbuf);
> +
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
> --
> 2.34.1
>

LGTM
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>