From: Noah Goldstein <goldstein.w.n@gmail.com>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: libc-alpha@sourceware.org, Paul Eggert <eggert@cs.ucla.edu>,
Florian Weimer <fweimer@redhat.com>
Subject: Re: [PATCH v8 7/7] stdlib: Add more qsort{_r} coverage
Date: Mon, 30 Oct 2023 14:04:51 -0500 [thread overview]
Message-ID: <CAFUsyfJknoMx2n7pysv-fj+NEOgZ-qYOAHB9EFujGxUWPBEE2w@mail.gmail.com> (raw)
In-Reply-To: <20231003122251.3325435-8-adhemerval.zanella@linaro.org>
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>
next prev parent reply other threads:[~2023-10-30 19:05 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-03 12:22 [PATCH v8 0/7] Use introsort for qsort Adhemerval Zanella
2023-10-03 12:22 ` [PATCH v8 1/7] string: Add internal memswap implementation Adhemerval Zanella
2023-10-03 17:42 ` Noah Goldstein
2023-10-27 20:23 ` Adhemerval Zanella Netto
2023-10-27 22:47 ` Gabriel Ravier
2023-10-28 1:30 ` Noah Goldstein
2023-10-30 19:02 ` Noah Goldstein
2023-10-03 12:22 ` [PATCH v8 2/7] stdlib: Optimization qsort{_r} swap implementation Adhemerval Zanella
2023-10-30 19:02 ` Noah Goldstein
2023-10-03 12:22 ` [PATCH v8 3/7] stdlib: Move insertion sort out qsort Adhemerval Zanella
2023-10-30 19:03 ` Noah Goldstein
2023-10-03 12:22 ` [PATCH v8 4/7] stdlib: qsort: Move some macros to inline function Adhemerval Zanella
2023-10-30 19:03 ` Noah Goldstein
2023-10-03 12:22 ` [PATCH v8 5/7] stdlib: Implement introsort for qsort (BZ 19305) Adhemerval Zanella
2023-10-30 19:03 ` Noah Goldstein
2023-10-03 12:22 ` [PATCH v8 6/7] stdlib: Remove use of mergesort on qsort (BZ 21719) Adhemerval Zanella
2023-10-30 19:04 ` Noah Goldstein
2023-10-03 12:22 ` [PATCH v8 7/7] stdlib: Add more qsort{_r} coverage Adhemerval Zanella
2023-10-30 19:04 ` Noah Goldstein [this message]
2023-10-03 18:13 ` [PATCH v8 0/7] Use introsort for qsort Noah Goldstein
2023-10-27 20:24 ` Adhemerval Zanella Netto
2023-10-28 1:31 ` Noah Goldstein
-- strict thread matches above, loose matches on Subject: below --
2023-10-02 19:33 Adhemerval Zanella
2023-10-02 19:33 ` [PATCH v8 7/7] stdlib: Add more qsort{_r} coverage Adhemerval Zanella
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