diff options
Diffstat (limited to 'sysdeps/ieee754/flt-32/e_powf.c')
| -rw-r--r-- | sysdeps/ieee754/flt-32/e_powf.c | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/sysdeps/ieee754/flt-32/e_powf.c b/sysdeps/ieee754/flt-32/e_powf.c index ece83f0dd2..9c1902fc5b 100644 --- a/sysdeps/ieee754/flt-32/e_powf.c +++ b/sysdeps/ieee754/flt-32/e_powf.c @@ -1,5 +1,5 @@ /* Single-precision pow function. - Copyright (C) 2017-2018 Free Software Foundation, Inc. + Copyright (C) 2017-2019 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 @@ -14,9 +14,11 @@ 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/>. */ + <https://www.gnu.org/licenses/>. */ #include <math.h> +#include <math-barriers.h> +#include <math-narrow-eval.h> #include <stdint.h> #include <shlib-compat.h> #include <libm-alias-float.h> @@ -118,7 +120,8 @@ exp2_inline (double_t xd, uint32_t sign_bias) return y; } -/* Returns 0 if not int, 1 if odd int, 2 if even int. */ +/* Returns 0 if not int, 1 if odd int, 2 if even int. The argument is + the bit representation of a non-zero finite floating-point value. */ static inline int checkint (uint32_t iy) { @@ -155,9 +158,9 @@ __powf (float x, float y) if (__glibc_unlikely (zeroinfnan (iy))) { if (2 * iy == 0) - return issignalingf_inline (x) ? x + y : 1.0f; + return issignaling (x) ? x + y : 1.0f; if (ix == 0x3f800000) - return issignalingf_inline (y) ? x + y : 1.0f; + return issignaling (y) ? x + y : 1.0f; if (2 * ix > 2u * 0x7f800000 || 2 * iy > 2u * 0x7f800000) return x + y; if (2 * ix == 2 * 0x3f800000) @@ -206,7 +209,17 @@ __powf (float x, float y) { /* |y*log(x)| >= 126. */ if (ylogx > 0x1.fffffffd1d571p+6 * POWF_SCALE) + /* |x^y| > 0x1.ffffffp127. */ return __math_oflowf (sign_bias); + if (WANT_ROUNDING && WANT_ERRNO + && ylogx > 0x1.fffffffa3aae2p+6 * POWF_SCALE) + /* |x^y| > 0x1.fffffep127, check if we round away from 0. */ + if ((!sign_bias + && math_narrow_eval (1.0f + math_opt_barrier (0x1p-25f)) != 1.0f) + || (sign_bias + && math_narrow_eval (-1.0f - math_opt_barrier (0x1p-25f)) + != -1.0f)) + return __math_oflowf (sign_bias); if (ylogx <= -150.0 * POWF_SCALE) return __math_uflowf (sign_bias); #if WANT_ERRNO_UFLOW |