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authorJoseph Myers <joseph@codesourcery.com>2014-02-18 14:45:41 +0000
committerJoseph Myers <joseph@codesourcery.com>2014-02-18 14:45:41 +0000
commita4fb786185fce5048a13c7879f67dfbe59ff70be (patch)
tree32d90a80cb679c5d96320ec56b92928312e1246e /math/gen-auto-libm-tests.c
parentef114eafbff80525d079d7d6fadd69a58eb8dcc3 (diff)
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Fix gen-auto-libm-tests sticky bit setting for negative results.
gen-auto-libm-tests has a bug in the logic for setting a sticky bit based on the ternary value from MPFR: it is correct for positive results, but for negative results mpz_setbit acts as if a two's complement representation is used, whereas the low bit needs setting based on the sign-magnitude representation GMP actually uses. (This showed up in converting fma tests to use auto-libm-test-in / gen-auto-libm-tests.) This patch fixes the problem by negating the mpz_t value to set its low bit. There are lots of changes to auto-libm-test-out (mainly 1ulp fixes to ldbl-128 expected results), but only a few ulps updates are needed on x86 / x86_64. In one case, a corrected expectation showed up a spurious underflow exception where the correct result is slightly outside the underflowing range. Tested x86_64 and x86 and ulps updated accordingly. * math/gen-auto-libm-tests.c (adjust_real): Ensure integers are non-negative before setting low bit. * math/auto-libm-test-in: Mark one asin test possibly having spurious underflow. * math/auto-libm-test-out: Regenerated. * sysdeps/i386/fpu/libm-test-ulps: Update. * sysdeps/x86_64/fpu/libm-test-ulps: Likewise.
Diffstat (limited to 'math/gen-auto-libm-tests.c')
-rw-r--r--math/gen-auto-libm-tests.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/math/gen-auto-libm-tests.c b/math/gen-auto-libm-tests.c
index 2f521d5c83..198d001519 100644
--- a/math/gen-auto-libm-tests.c
+++ b/math/gen-auto-libm-tests.c
@@ -987,7 +987,14 @@ adjust_real (mpfr_t r, bool inexact)
mpz_t tmp;
mpz_init (tmp);
mpfr_exp_t e = mpfr_get_z_2exp (tmp, r);
- mpz_setbit (tmp, 0);
+ if (mpz_sgn (tmp) < 0)
+ {
+ mpz_neg (tmp, tmp);
+ mpz_setbit (tmp, 0);
+ mpz_neg (tmp, tmp);
+ }
+ else
+ mpz_setbit (tmp, 0);
assert_exact (mpfr_set_z_2exp (r, tmp, e, MPFR_RNDN));
mpz_clear (tmp);
}