diff options
Diffstat (limited to 'sysdeps/powerpc/power7/fpu/s_logbl.c')
| -rw-r--r-- | sysdeps/powerpc/power7/fpu/s_logbl.c | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/sysdeps/powerpc/power7/fpu/s_logbl.c b/sysdeps/powerpc/power7/fpu/s_logbl.c index ec6907efc5..192145a7a1 100644 --- a/sysdeps/powerpc/power7/fpu/s_logbl.c +++ b/sysdeps/powerpc/power7/fpu/s_logbl.c @@ -1,5 +1,5 @@ /* logbl(). PowerPC/POWER7 version. - Copyright (C) 2012-2016 Free Software Foundation, Inc. + Copyright (C) 2012-2018 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 @@ -35,14 +35,16 @@ static const union { long double __logbl (long double x) { - double xh; + double xh, xl; double ret; + int64_t hx; if (__builtin_expect (x == 0.0L, 0)) /* Raise FE_DIVBYZERO and return -HUGE_VAL[LF]. */ return -1.0L / __builtin_fabsl (x); - xh = ldbl_high (x); + ldbl_unpack (x, &xh, &xl); + EXTRACT_WORDS64 (hx, xh); /* ret = x & 0x7ff0000000000000; */ asm ( "xxland %x0,%x1,%x2\n" @@ -58,10 +60,20 @@ __logbl (long double x) { /* POSIX specifies that denormal number is treated as though it were normalized. */ - int64_t hx; - - EXTRACT_WORDS64 (hx, xh); - return (long double) (-1023 - (__builtin_clzll (hx) - 12)); + return (long double) (- (__builtin_clzll (hx & 0x7fffffffffffffffLL) \ + - 12) - 1023); + } + else if ((hx & 0x000fffffffffffffLL) == 0) + { + /* If the high part is a power of 2, and the low part is nonzero + with the opposite sign, the low part affects the + exponent. */ + int64_t lx, rhx; + EXTRACT_WORDS64 (lx, xl); + rhx = (hx & 0x7ff0000000000000LL) >> 52; + if ((hx ^ lx) < 0 && (lx & 0x7fffffffffffffffLL) != 0) + rhx--; + return (long double) (rhx - 1023); } /* Test to avoid logb_downward (0.0) == -0.0. */ return ret == -0.0 ? 0.0 : ret; |