glibc/stdlib/gen-tst-strtod-round.c
Joseph Myers d73ed2601b More thoroughly test underflow / errno in tst-strtod-round
Add tests of underflow in tst-strtod-round, and thus also test for
errno being unchanged when there is neither overflow nor underflow.
The errno setting before the function call to test for being unchanged
is adjusted to set errno to 12345 instead of 0, so that any bugs where
strtod sets errno to 0 would be detected.

This doesn't add any new test inputs for tst-strtod-round, and in
particular doesn't cover the edge cases of underflow the way
tst-strtod-underflow does (none of the existing test inputs for
tst-strtod-round actually exercise cases that have underflow with
before-rounding tininess detection but not with after-rounding
tininess detection), but at least it provides some coverage (as per
the recent discussions) that ordinary non-overflowing non-underflowing
inputs to these functions do not set errno.

Tested for x86_64.
2024-08-27 12:38:01 +00:00

235 lines
6.4 KiB
C

/* Generate table of tests in tst-strtod-round.c from
tst-strtod-round-data.
Copyright (C) 2012-2024 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
<https://www.gnu.org/licenses/>. */
/* Compile this program as:
gcc -std=gnu11 -O2 -Wall -Wextra gen-tst-strtod-round.c -lmpfr \
-o gen-tst-strtod-round
(use of current MPFR version recommended) and run it as:
gen-tst-strtod-round tst-strtod-round-data tst-strtod-round-data.h
The output file will be generated as tst-strtod-round-data.h
*/
#define _GNU_SOURCE
#include <assert.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <mpfr.h>
/* Work around incorrect ternary value from mpfr_strtofr
<https://sympa.inria.fr/sympa/arc/mpfr/2012-08/msg00005.html>. */
#define WORKAROUND
static int
string_to_fp (mpfr_t f, const char *s, mpfr_rnd_t rnd)
{
mpfr_clear_overflow ();
mpfr_clear_underflow ();
#ifdef WORKAROUND
mpfr_t f2;
mpfr_init2 (f2, 100000);
int r0 = mpfr_strtofr (f2, s, NULL, 0, rnd);
int r = mpfr_set (f, f2, rnd);
r |= mpfr_subnormalize (f, r, rnd);
mpfr_clear (f2);
r |= r0;
#else
int r = mpfr_strtofr (f, s, NULL, 0, rnd);
r |= mpfr_subnormalize (f, r, rnd);
#endif
if (r == 0)
/* The MPFR underflow flag is set for exact subnormal results,
which is not wanted here. */
mpfr_clear_underflow ();
return r;
}
void
print_fp (FILE *fout, mpfr_t f, const char *suffix)
{
if (mpfr_inf_p (f))
mpfr_fprintf (fout, "\t%sINF%s", mpfr_signbit (f) ? "-" : "", suffix);
else
mpfr_fprintf (fout, "\t%Ra%s", f, suffix);
}
static const char *
suffix_to_print (bool overflow, bool underflow, bool underflow_before_rounding,
bool with_comma)
{
if (overflow)
return with_comma ? ", true, false,\n" : ", true, false";
if (underflow)
return with_comma ? ", false, true,\n" : ", false, true";
if (underflow_before_rounding)
return (with_comma
? ", false, !TININESS_AFTER_ROUNDING,\n"
: ", false, !TININESS_AFTER_ROUNDING");
return with_comma ? ", false, false,\n" : ", false, false";
}
static void
round_str (FILE *fout, const char *s, int prec, int emin, int emax,
bool ibm_ld)
{
mpfr_t max_value;
mpfr_t f;
mpfr_set_default_prec (prec);
mpfr_set_emin (emin);
mpfr_set_emax (emax);
mpfr_init (f);
string_to_fp (f, s, MPFR_RNDZ);
bool underflow_before_rounding = mpfr_underflow_p () != 0;
int r = string_to_fp (f, s, MPFR_RNDD);
bool overflow = mpfr_overflow_p () != 0;
bool underflow = mpfr_underflow_p () != 0;
if (ibm_ld)
{
assert (prec == 106 && emin == -1073 && emax == 1024);
/* The maximum value in IBM long double has discontiguous
mantissa bits. */
mpfr_init2 (max_value, 107);
mpfr_set_str (max_value, "0x1.fffffffffffff7ffffffffffffcp+1023", 0,
MPFR_RNDN);
if (mpfr_cmpabs (f, max_value) > 0)
{
r = 1;
overflow = true;
}
}
mpfr_fprintf (fout, "\t%s,\n", r ? "false" : "true");
print_fp (fout, f,
suffix_to_print (overflow, underflow, underflow_before_rounding,
true));
string_to_fp (f, s, MPFR_RNDN);
overflow = (mpfr_overflow_p () != 0
|| (ibm_ld && mpfr_cmpabs (f, max_value) > 0));
print_fp (fout, f,
suffix_to_print (overflow, underflow, underflow_before_rounding,
true));
string_to_fp (f, s, MPFR_RNDZ);
overflow = (mpfr_overflow_p () != 0
|| (ibm_ld && mpfr_cmpabs (f, max_value) > 0));
print_fp (fout, f,
suffix_to_print (overflow, underflow, underflow_before_rounding,
true));
string_to_fp (f, s, MPFR_RNDU);
overflow = (mpfr_overflow_p () != 0
|| (ibm_ld && mpfr_cmpabs (f, max_value) > 0));
print_fp (fout, f,
suffix_to_print (overflow, underflow, underflow_before_rounding,
false));
mpfr_clear (f);
if (ibm_ld)
mpfr_clear (max_value);
}
static void
round_for_all (FILE *fout, const char *s)
{
static const struct fmt {
int prec;
int emin;
int emax;
bool ibm_ld;
} formats[] = {
{ 24, -148, 128, false },
{ 53, -1073, 1024, false },
/* This is the Intel extended float format. */
{ 64, -16444, 16384, false },
/* This is the Motorola extended float format. */
{ 64, -16445, 16384, false },
{ 106, -1073, 1024, true },
{ 113, -16493, 16384, false },
};
mpfr_fprintf (fout, " TEST (\"");
const char *p;
for (p = s; *p; p++)
{
fputc (*p, fout);
if ((p - s) % 60 == 59 && p[1])
mpfr_fprintf (fout, "\"\n\t\"");
}
mpfr_fprintf (fout, "\",\n");
int i;
int n_formats = sizeof (formats) / sizeof (formats[0]);
for (i = 0; i < n_formats; i++)
{
round_str (fout, s, formats[i].prec, formats[i].emin,
formats[i].emax, formats[i].ibm_ld);
if (i < n_formats - 1)
mpfr_fprintf (fout, ",\n");
}
mpfr_fprintf (fout, "),\n");
}
int
main (int argc, char **argv)
{
char *p = NULL;
size_t len;
ssize_t nbytes;
FILE *fin, *fout;
char *fin_name, *fout_name;
if (argc < 3)
{
fprintf (stderr, "Usage: %s <input> <output>\n", basename (argv[0]));
return EXIT_FAILURE;
}
fin_name = argv[1];
fout_name = argv[2];
fin = fopen (fin_name, "r");
if (fin == NULL)
{
perror ("Could not open input for reading");
return EXIT_FAILURE;
}
fout = fopen (fout_name, "w");
if (fout == NULL)
{
perror ("Could not open output for writing");
return EXIT_FAILURE;
}
fprintf (fout, "/* This file was generated by %s from %s. */\n",
__FILE__, fin_name);
fputs ("static const struct test tests[] = {\n", fout);
while ((nbytes = getline (&p, &len, fin)) != -1)
{
if (p[nbytes - 1] == '\n')
p[nbytes - 1] = 0;
round_for_all (fout, p);
free (p);
p = NULL;
}
fputs ("};\n", fout);
return EXIT_SUCCESS;
}