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math: Fix incorrect results of exp10m1f with some GCC versions 

On GCC 11 (x86-64), the previous code produced test failures like
this one:

Failure: Test: exp10m1_towardzero (-0x1.1p+4)
Result:
 is:         -1.00000000e+00  -0x1.000000p+0
 should be:  -9.99999940e-01  -0x1.fffffep-1
 difference:  5.96046447e-08   0x1.000000p-24
 ulp       :  1.0000
 max.ulp   :  0.0000

Apply a similar fix to exp2m1f.

Co-authored-by: Paul Zimmermann <Paul.Zimmermann@inria.fr>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer 2024-11-06 16:09:05 +01:00
parent ff254cabd6
commit ba60be8735
2 changed files with 2 additions and 2 deletions
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2
sysdeps/ieee754/flt-32/s_exp10m1f.c
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@ -40,7 +40,7 @@ __exp10m1f (float x)
{ /* x < -7.52575 */
if (ax > (0xffu << 23))
return x + x; /* nan */
return (ux == 0xff800000) ? -0x1p+0 : -0x1p+0 + 0x1p-26f;
return (ux == 0xff800000) ? -0x1p+0f : -0x1p+0f + 0x1p-26f;
}
else if (__glibc_unlikely (ax > 0x421a209au))
{ /* x > 38.5318 */

2
sysdeps/ieee754/flt-32/s_exp2m1f.c
View File

@ -41,7 +41,7 @@ __exp2m1f (float x)
{ /* x <= -25 */
if (ax > (0xffu << 23))
return x + x; /* nan */
return (ux == 0xff800000) ? -0x1p+0 : -0x1p+0 + 0x1p-26f;
return (ux == 0xff800000) ? -0x1p+0f : -0x1p+0f + 0x1p-26f;
}
else if (__glibc_unlikely (ax >= 0x43000000u))
{ /* x >= 128 */