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Fix strtod overflow detection (bug 23279).
As shown by bug 23279, strtod's round_and_return has an off-by-one error in its overflow detection, only counting an exponent greater than MAX_EXP as overflowing when an exponent of MAX_EXP also means overflow (recall the ISO C definition of DBL_MAX_EXP etc. is based on a floating-point model where 2^exp is multiplied by a value in the interval [0.5, 1), so 2^MAX_EXP is not representable). For decimal arguments to strtod, a separate overflow check in the main implementation covers the case where the integer part of the argument (truncated to the nearest integer towards zero) has more than MAX_EXP bits, meaning that this issue in round_and_return only affects cases (arguments with absolute value strictly between the maximum representable value and 2^MAX_EXP) where overflow depends on the rounding mode; in such cases, the returned value would still have been correct on overflow but without the overflow exception being raised or errno being set to ERANGE. For hex float arguments, however, other cases can arise, as shown in bug 23279, where a value with exponent already set to MAX_EXP is passed into round_and_return and a result can wrongly end up being NaN, or infinity instead of the largest finite value. This patch fixes the off-by-one error, adds testing of overflow exceptions to the tst-strtod-round framework, and adds tests of these issues. Tested for x86_64. Also ran the tst-strtod-round tests for powerpc to make sure the new tests didn't introduce any new failures for IBM long double. [BZ #23279] * stdlib/strtod_l.c (round_and_return): Handle an exponent of MAX_EXP as overflowing. * stdlib/gen-tst-strtod-round.c (string_to_fp): Clear MPFR overflow flag. (round_str): Output also whether result overflows in each rounding mode. * stdlib/tst-strtod-round-data: Add more tests. * stdlib/tst-strtod-round-data.h: Regenerated. * stdlib/tst-strtod-round-skeleton.c (_XNTRY): Update comment. (TEST): Handle extra arguments for overflow flags. (struct test_overflow): New type. [!FE_OVERFLOW] (FE_OVERFLOW): Define to 0. (GEN_ONE_TEST): Clear all exceptions. Test overflow flag. (test_in_one_mode): Take argument with overflow information. (do_test): Update calls to test_in_one_mode.
This commit is contained in:
Joseph Myers
parent
a745c837cb
commit
fcd6b5ac36
19
ChangeLog
19
ChangeLog
@ -1,3 +1,22 @@
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2018-06-13 Joseph Myers <joseph@codesourcery.com>
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[BZ #23279]
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* stdlib/strtod_l.c (round_and_return): Handle an exponent of
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MAX_EXP as overflowing.
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* stdlib/gen-tst-strtod-round.c (string_to_fp): Clear MPFR
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overflow flag.
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(round_str): Output also whether result overflows in each rounding
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mode.
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* stdlib/tst-strtod-round-data: Add more tests.
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* stdlib/tst-strtod-round-data.h: Regenerated.
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* stdlib/tst-strtod-round-skeleton.c (_XNTRY): Update comment.
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(TEST): Handle extra arguments for overflow flags.
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(struct test_overflow): New type.
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[!FE_OVERFLOW] (FE_OVERFLOW): Define to 0.
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(GEN_ONE_TEST): Clear all exceptions. Test overflow flag.
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(test_in_one_mode): Take argument with overflow information.
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(do_test): Update calls to test_in_one_mode.
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2018-06-12 Carlos O'Donell <carlos@redhat.com>
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* elf/dl-load (_dl_dst_substitute): Correct comment.
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@ -45,6 +45,7 @@
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static int
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string_to_fp (mpfr_t f, const char *s, mpfr_rnd_t rnd)
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{
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mpfr_clear_overflow ();
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#ifdef WORKAROUND
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mpfr_t f2;
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mpfr_init2 (f2, 100000);
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@ -73,34 +74,45 @@ static void
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round_str (FILE *fout, const char *s, int prec, int emin, int emax,
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bool ibm_ld)
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{
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mpfr_t max_value;
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mpfr_t f;
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mpfr_set_default_prec (prec);
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mpfr_set_emin (emin);
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mpfr_set_emax (emax);
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mpfr_init (f);
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int r = string_to_fp (f, s, MPFR_RNDD);
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bool overflow = mpfr_overflow_p () != 0;
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if (ibm_ld)
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{
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assert (prec == 106 && emin == -1073 && emax == 1024);
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/* The maximum value in IBM long double has discontiguous
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mantissa bits. */
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mpfr_t max_value;
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mpfr_init2 (max_value, 107);
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mpfr_set_str (max_value, "0x1.fffffffffffff7ffffffffffffcp+1023", 0,
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MPFR_RNDN);
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if (mpfr_cmpabs (f, max_value) > 0)
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r = 1;
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mpfr_clear (max_value);
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{
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r = 1;
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overflow = true;
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}
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}
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mpfr_fprintf (fout, "\t%s,\n", r ? "false" : "true");
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print_fp (fout, f, ",\n");
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print_fp (fout, f, overflow ? ", true,\n" : ", false,\n");
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string_to_fp (f, s, MPFR_RNDN);
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print_fp (fout, f, ",\n");
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overflow = (mpfr_overflow_p () != 0
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|| (ibm_ld && mpfr_cmpabs (f, max_value) > 0));
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print_fp (fout, f, overflow ? ", true,\n" : ", false,\n");
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string_to_fp (f, s, MPFR_RNDZ);
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print_fp (fout, f, ",\n");
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overflow = (mpfr_overflow_p () != 0
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|| (ibm_ld && mpfr_cmpabs (f, max_value) > 0));
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print_fp (fout, f, overflow ? ", true,\n" : ", false,\n");
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string_to_fp (f, s, MPFR_RNDU);
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print_fp (fout, f, "");
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overflow = (mpfr_overflow_p () != 0
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|| (ibm_ld && mpfr_cmpabs (f, max_value) > 0));
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print_fp (fout, f, overflow ? ", true" : ", false");
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mpfr_clear (f);
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if (ibm_ld)
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mpfr_clear (max_value);
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}
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static void
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@ -310,7 +310,7 @@ round_and_return (mp_limb_t *retval, intmax_t exponent, int negative,
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}
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}
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if (exponent > MAX_EXP)
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if (exponent >= MAX_EXP)
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goto overflow;
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bool half_bit = (round_limb & (((mp_limb_t) 1) << round_bit)) != 0;
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@ -343,7 +343,7 @@ round_and_return (mp_limb_t *retval, intmax_t exponent, int negative,
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exponent = MIN_EXP - 1;
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}
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if (exponent > MAX_EXP)
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if (exponent >= MAX_EXP)
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overflow:
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return overflow_value (negative);
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File diff suppressed because one or more lines are too long
File diff suppressed because it is too large
Load Diff
@ -121,7 +121,8 @@
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#define ENTRY(...) \
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GEN_TEST_STRTOD_FOREACH (_ENTRY, __VA_ARGS__)
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/* Selector for boolean exact tag of expected results. */
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/* Selector for boolean exact tag of expected results and that for
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overflow. */
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#define _XNTRY(FSUF, FTYPE, FTOSTR, LSUF, CSUF, ...) \
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CHOOSE_ ## FSUF (__VA_ARGS__),
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#define XNTRY(...) \
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@ -136,22 +137,32 @@
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/* This macro is used in conjunction with the output from the
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gen-tst-strtod-round utility to select the appropriately
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rounded long double value for a given format. */
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#define TEST(s, \
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fx, fd, fn, fz, fu, \
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dx, dd, dn, dz, du, \
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ld64ix, ld64id, ld64in, ld64iz, ld64iu, \
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ld64mx, ld64md, ld64mn, ld64mz, ld64mu, \
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ld106x, ld106d, ld106n, ld106z, ld106u, \
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ld113x, ld113d, ld113n, ld113z, ld113u) \
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{ \
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L_ (s), \
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{ XNTRY (fx, dx, ld64ix, ld64mx, ld106x, ld113x) }, \
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{ \
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{ ENTRY (fn, dn, ld64in, ld64mn, ld106n, ld113n) }, \
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{ ENTRY (fd, dd, ld64id, ld64md, ld106d, ld113d) }, \
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{ ENTRY (fz, dz, ld64iz, ld64mz, ld106z, ld113z) }, \
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{ ENTRY (fu, du, ld64iu, ld64mu, ld106u, ld113u) } \
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} \
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#define TEST(s, \
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fx, fd, fdo, fn, fno, fz, fzo, fu, fuo, \
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dx, dd, ddo, dn, dno, dz, dzo, du, duo, \
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ld64ix, ld64id, ld64ido, ld64in, ld64ino, \
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ld64iz, ld64izo, ld64iu, ld64iuo, \
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ld64mx, ld64md, ld64mdo, ld64mn, ld64mno, \
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ld64mz, ld64mzo, ld64mu, ld64muo, \
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ld106x, ld106d, ld106do, ld106n, ld106no, \
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ld106z, ld106zo, ld106u, ld106uo, \
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ld113x, ld113d, ld113do, ld113n, ld113no, \
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ld113z, ld113zo, ld113u, ld113uo) \
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{ \
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L_ (s), \
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{ XNTRY (fx, dx, ld64ix, ld64mx, ld106x, ld113x) }, \
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{ \
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{ ENTRY (fn, dn, ld64in, ld64mn, ld106n, ld113n) }, \
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{ ENTRY (fd, dd, ld64id, ld64md, ld106d, ld113d) }, \
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{ ENTRY (fz, dz, ld64iz, ld64mz, ld106z, ld113z) }, \
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{ ENTRY (fu, du, ld64iu, ld64mu, ld106u, ld113u) } \
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}, \
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{ \
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{ XNTRY (fno, dno, ld64ino, ld64mno, ld106no, ld113no) }, \
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{ XNTRY (fdo, ddo, ld64ido, ld64mdo, ld106do, ld113do) }, \
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{ XNTRY (fzo, dzo, ld64izo, ld64mzo, ld106zo, ld113zo) }, \
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{ XNTRY (fuo, duo, ld64iuo, ld64muo, ld106uo, ld113uo) } \
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} \
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}
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struct test_exactness
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@ -164,10 +175,16 @@ struct test_results
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STRUCT_FOREACH_FLOAT_FTYPE
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};
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struct test_overflow
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{
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STRUCT_FOREACH_FLOAT_BOOL
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};
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struct test {
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const CHAR *s;
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struct test_exactness exact;
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struct test_results r[4];
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struct test_overflow o[4];
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};
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/* Include the generated test data. */
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@ -181,9 +198,13 @@ struct test {
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# define FE_INEXACT 0
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#endif
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#ifndef FE_OVERFLOW
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# define FE_OVERFLOW 0
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#endif
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#define GEN_ONE_TEST(FSUF, FTYPE, FTOSTR, LSUF, CSUF) \
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{ \
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feclearexcept (FE_INEXACT); \
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feclearexcept (FE_ALL_EXCEPT); \
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FTYPE f = STRTO (FSUF) (s, NULL); \
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if (f != expected->FSUF \
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|| (copysign ## CSUF) (1.0 ## LSUF, f) \
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@ -200,25 +221,47 @@ struct test {
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else \
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printf ("ignoring this inexact result\n"); \
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} \
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else if (FE_INEXACT != 0) \
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else \
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{ \
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bool inexact_raised = fetestexcept (FE_INEXACT) != 0; \
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if (inexact_raised != !exact->FSUF) \
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if (FE_INEXACT != 0) \
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{ \
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printf (FNPFXS "to" #FSUF " (" STRM ") inexact %d " \
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"not %d\n", s, inexact_raised, !exact->FSUF); \
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if (EXCEPTION_TESTS (FTYPE)) \
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result = 1; \
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else \
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printf ("ignoring this exception error\n"); \
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bool inexact_raised = fetestexcept (FE_INEXACT) != 0; \
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if (inexact_raised != !exact->FSUF) \
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{ \
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printf (FNPFXS "to" #FSUF \
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" (" STRM ") inexact %d " \
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"not %d\n", s, inexact_raised, \
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!exact->FSUF); \
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if (EXCEPTION_TESTS (FTYPE)) \
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result = 1; \
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else \
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printf ("ignoring this exception error\n"); \
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} \
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} \
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if (FE_OVERFLOW != 0) \
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{ \
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bool overflow_raised \
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= fetestexcept (FE_OVERFLOW) != 0; \
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if (overflow_raised != overflow->FSUF) \
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{ \
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printf (FNPFXS "to" #FSUF \
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" (" STRM ") overflow %d " \
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"not %d\n", s, overflow_raised, \
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overflow->FSUF); \
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if (EXCEPTION_TESTS (FTYPE)) \
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result = 1; \
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else \
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printf ("ignoring this exception error\n"); \
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} \
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} \
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} \
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}
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static int
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test_in_one_mode (const CHAR *s, const struct test_results *expected,
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const struct test_exactness *exact, const char *mode_name,
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int rnd_mode)
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const struct test_exactness *exact,
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const struct test_overflow *overflow,
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const char *mode_name, int rnd_mode)
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{
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int result = 0;
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GEN_TEST_STRTOD_FOREACH (GEN_ONE_TEST)
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@ -252,14 +295,15 @@ do_test (void)
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for (size_t i = 0; i < sizeof (tests) / sizeof (tests[0]); i++)
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{
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result |= test_in_one_mode (tests[i].s, &tests[i].r[modes[0].rnd_i],
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&tests[i].exact, modes[0].mode_name,
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modes[0].rnd_mode);
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&tests[i].exact, &tests[i].o[modes[0].rnd_i],
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modes[0].mode_name, modes[0].rnd_mode);
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for (const struct fetestmodes *m = &modes[1]; m->mode_name != NULL; m++)
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{
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if (!fesetround (m->rnd_mode))
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{
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result |= test_in_one_mode (tests[i].s, &tests[i].r[m->rnd_i],
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&tests[i].exact, m->mode_name,
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&tests[i].exact,
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&tests[i].o[m->rnd_i], m->mode_name,
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m->rnd_mode);
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fesetround (save_round_mode);
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}
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