From 89c9aa491a7cee97bf78a29cddbf0a25c902a671 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Thu, 10 May 2012 15:11:55 -0500 Subject: [PATCH] Fix for logb/logbf/logbl (bugs 13954/13955/13956) POSIX 2008 states that if the input for 'logb[f|l]' is a subnormal number it should be treated as if it were normalized. This means the implementation should calculate the log2 of the mantissa and add it to the subnormal exponent (-126 for float and -1022 for double and IBM long double). This patch takes care of that. --- ChangeLog | 13 ++++++++ NEWS | 5 +-- math/libm-test.inc | 16 +++++++++ sysdeps/ieee754/dbl-64/s_logb.c | 37 ++++++++++++--------- sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c | 13 +++++--- sysdeps/ieee754/flt-32/s_logbf.c | 32 ++++++++++-------- sysdeps/ieee754/ldbl-128/s_logbl.c | 31 +++++++++++------ sysdeps/ieee754/ldbl-128ibm/s_logbl.c | 35 +++++++++++-------- sysdeps/ieee754/ldbl-96/s_logbl.c | 35 +++++++++++-------- 9 files changed, 143 insertions(+), 74 deletions(-) diff --git a/ChangeLog b/ChangeLog index 8bceaab8be6..6848fb4838c 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,16 @@ +2012-05-09 Adhemerval Zanella + + [BZ #13954] + [BZ #13955] + [BZ #13956] + * sysdeps/ieee754/dbl-64/s_logb.c (__logb): Fix for subnormal number. + * sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c (__logb): Likewise. + * sysdeps/ieee754/flt-32/s_logbf.c (__logf): Likewise. + * sysdeps/ieee754/ldbl-128/s_logbl.c (__logbl): Likewise. + * sysdeps/ieee754/ldbl-128ibm/s_logbl.c (__logbl): Likewise. + * sysdeps/ieee754/ldbl-96/s_logbl.c (__logbl): Likewise. + * math/libm-test.inc (logb_test) : Additional logb tests. + 2012-05-09 Andreas Schwab Andreas Jaeger diff --git a/NEWS b/NEWS index 5c90f3da281..b3a12334827 100644 --- a/NEWS +++ b/NEWS @@ -23,8 +23,9 @@ Version 2.16 13852, 13854, 13871, 13872, 13873, 13879, 13883, 13884, 13885, 13886, 13892, 13895, 13908, 13910, 13911, 13912, 13913, 13914, 13915, 13916, 13917, 13918, 13919, 13920, 13921, 13922, 13923, 13924, 13926, 13927, - 13928, 13938, 13941, 13942, 13963, 13967, 13970, 13973, 13979, 13983, - 14027, 14033, 14034, 14040, 14049, 14053, 14055, 14064, 14080, 14083 + 13928, 13938, 13941, 13942, 13954, 13955, 13956, 13963, 13967, 13970, + 13973, 13979, 13983, 14027, 14033, 14034, 14040, 14049, 14053, 14055, + 14064, 14080, 14083 * ISO C11 support: diff --git a/math/libm-test.inc b/math/libm-test.inc index 542131dc7b1..5a38dbf3a7f 100644 --- a/math/libm-test.inc +++ b/math/libm-test.inc @@ -5376,6 +5376,22 @@ logb_test (void) TEST_f_f (logb, 1024, 10); TEST_f_f (logb, -2000, 10); + TEST_f_f (logb, 0x0.1p-127, -131); + TEST_f_f (logb, 0x0.01p-127, -135); + TEST_f_f (logb, 0x0.011p-127, -135); +#ifndef TEST_FLOAT + TEST_f_f (logb, 0x0.8p-1022, -1023); + TEST_f_f (logb, 0x0.1p-1022, -1026); + TEST_f_f (logb, 0x0.00111p-1022, -1034); + TEST_f_f (logb, 0x0.00001p-1022, -1042); + TEST_f_f (logb, 0x0.000011p-1022, -1042); + TEST_f_f (logb, 0x0.0000000000001p-1022, -1074); +#endif +#if defined TEST_LDOUBLE && LDBL_MIN_EXP - LDBL_MANT_DIG <= -16400 + TEST_f_f (logb, 0x1p-16400L, -16400); + TEST_f_f (logb, 0x.00000000001p-16382L, -16426); +#endif + END (logb); } diff --git a/sysdeps/ieee754/dbl-64/s_logb.c b/sysdeps/ieee754/dbl-64/s_logb.c index 2382fbb4145..baa35e14d85 100644 --- a/sysdeps/ieee754/dbl-64/s_logb.c +++ b/sysdeps/ieee754/dbl-64/s_logb.c @@ -10,10 +10,6 @@ * ==================================================== */ -#if defined(LIBM_SCCS) && !defined(lint) -static char rcsid[] = "$NetBSD: s_logb.c,v 1.8 1995/05/10 20:47:50 jtc Exp $"; -#endif - /* * double logb(x) * IEEE 754 logb. Included to pass IEEE test suite. Not recommend. @@ -23,20 +19,29 @@ static char rcsid[] = "$NetBSD: s_logb.c,v 1.8 1995/05/10 20:47:50 jtc Exp $"; #include #include -double __logb(double x) +double +__logb (double x) { - int32_t lx,ix; - EXTRACT_WORDS(ix,lx,x); - ix &= 0x7fffffff; /* high |x| */ - if((ix|lx)==0) return -1.0/fabs(x); - if(ix>=0x7ff00000) return x*x; - if((ix>>=20)==0) /* IEEE 754 logb */ - return -1022.0; - else - return (double) (ix-1023); + int32_t lx, ix, rix; + + EXTRACT_WORDS (ix, lx, x); + ix &= 0x7fffffff; /* high |x| */ + if ((ix | lx) == 0) + return -1.0 / fabs (x); + if (ix >= 0x7ff00000) + return x * x; + if (__builtin_expect ((rix = ix >> 20) == 0, 0)) + { + /* POSIX specifies that denormal number is treated as + though it were normalized. */ + int m1 = (ix == 0) ? 0 : __builtin_clz (ix); + int m2 = (lx == 0) ? 0 : __builtin_clz (lx); + int ma = (m1 == 0) ? m2 + 32 : m1; + return -1022.0 + (double)(11 - ma); + } + return (double) (rix - 1023); } weak_alias (__logb, logb) #ifdef NO_LONG_DOUBLE -strong_alias (__logb, __logbl) -weak_alias (__logb, logbl) +strong_alias (__logb, __logbl) weak_alias (__logb, logbl) #endif diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c b/sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c index 2ad6c7ddbda..474eeef36b4 100644 --- a/sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c +++ b/sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c @@ -1,5 +1,5 @@ /* Compute radix independent exponent. - Copyright (C) 2011 Free Software Foundation, Inc. + Copyright (C) 2011, 2012 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper , 2011. @@ -25,16 +25,21 @@ double __logb (double x) { - int64_t ix; + int64_t ix, ex; EXTRACT_WORDS64 (ix, x); ix &= UINT64_C(0x7fffffffffffffff); if (ix == 0) return -1.0 / fabs (x); - unsigned int ex = ix >> 52; + ex = ix >> 52; if (ex == 0x7ff) return x * x; - return ex == 0 ? -1022.0 : (double) (ex - 1023); + if (__builtin_expect (ex == 0, 0)) + { + int m = (ix == 0) ? 0 : __builtin_clzl (ix); + return -1022.0 + (double)(11 -m); + } + return (double) (ex - 1023); } weak_alias (__logb, logb) #ifdef NO_LONG_DOUBLE diff --git a/sysdeps/ieee754/flt-32/s_logbf.c b/sysdeps/ieee754/flt-32/s_logbf.c index b6aa0f057db..025c70de7ec 100644 --- a/sysdeps/ieee754/flt-32/s_logbf.c +++ b/sysdeps/ieee754/flt-32/s_logbf.c @@ -13,23 +13,27 @@ * ==================================================== */ -#if defined(LIBM_SCCS) && !defined(lint) -static char rcsid[] = "$NetBSD: s_logbf.c,v 1.4 1995/05/10 20:47:51 jtc Exp $"; -#endif - #include #include -float __logbf(float x) +float +__logbf (float x) { - int32_t ix; - GET_FLOAT_WORD(ix,x); - ix &= 0x7fffffff; /* high |x| */ - if(ix==0) return (float)-1.0/fabsf(x); - if(ix>=0x7f800000) return x*x; - if((ix>>=23)==0) /* IEEE 754 logb */ - return -126.0; - else - return (float) (ix-127); + int32_t ix, rix; + + GET_FLOAT_WORD (ix, x); + ix &= 0x7fffffff; /* high |x| */ + if (ix == 0) + return (float) -1.0 / fabsf (x); + if (ix >= 0x7f800000) + return x * x; + if (__builtin_expect ((rix = ix >> 23) == 0, 0)) + { + /* POSIX specifies that denormal number is treated as + though it were normalized. */ + int m = (ix == 0) ? 0 : __builtin_clz (ix); + return -126.0 + (float)(8 - m); + } + return (float) (rix - 127); } weak_alias (__logbf, logbf) diff --git a/sysdeps/ieee754/ldbl-128/s_logbl.c b/sysdeps/ieee754/ldbl-128/s_logbl.c index 0b09b289c2e..cf6003e055a 100644 --- a/sysdeps/ieee754/ldbl-128/s_logbl.c +++ b/sysdeps/ieee754/ldbl-128/s_logbl.c @@ -26,16 +26,27 @@ static char rcsid[] = "$NetBSD: $"; #include #include -long double __logbl(long double x) +long double +__logbl (long double x) { - int64_t lx,hx; - GET_LDOUBLE_WORDS64(hx,lx,x); - hx &= 0x7fffffffffffffffLL; /* high |x| */ - if((hx|lx)==0) return -1.0/fabs(x); - if(hx>=0x7fff000000000000LL) return x*x; - if((hx>>=48)==0) /* IEEE 754 logb */ - return -16382.0; - else - return (long double) (hx-0x3fff); + int64_t lx, hx, ex; + + GET_LDOUBLE_WORDS64 (hx, lx, x); + hx &= 0x7fffffffffffffffLL; /* high |x| */ + if ((hx | lx) == 0) + return -1.0 / fabs (x); + if (hx >= 0x7fff000000000000LL) + return x * x; + if ((ex = hx >> 48) == 0) /* IEEE 754 logb */ + { + /* POSIX specifies that denormal number is treated as + though it were normalized. */ + int m1 = (hx == 0) ? 0 : __builtin_clzll (hx); + int m2 = (lx == 0) ? 0 : __builtin_clzll (lx); + int ma = (m1 == 0) ? m2 + 64 : m1; + return -16382.0 + (long double)(15 - ma); + } + return (long double) (ex - 16383); } + weak_alias (__logbl, logbl) diff --git a/sysdeps/ieee754/ldbl-128ibm/s_logbl.c b/sysdeps/ieee754/ldbl-128ibm/s_logbl.c index f38b1299710..678b6cad57c 100644 --- a/sysdeps/ieee754/ldbl-128ibm/s_logbl.c +++ b/sysdeps/ieee754/ldbl-128ibm/s_logbl.c @@ -13,10 +13,6 @@ * ==================================================== */ -#if defined(LIBM_SCCS) && !defined(lint) -static char rcsid[] = "$NetBSD: $"; -#endif - /* * long double logbl(x) * IEEE 754 logb. Included to pass IEEE test suite. Not recommend. @@ -27,16 +23,27 @@ static char rcsid[] = "$NetBSD: $"; #include #include -long double __logbl(long double x) +long double +__logbl (long double x) { - int64_t lx,hx; - GET_LDOUBLE_WORDS64(hx,lx,x); - hx &= 0x7fffffffffffffffLL; /* high |x| */ - if((hx|(lx&0x7fffffffffffffffLL))==0) return -1.0/fabs(x); - if(hx>=0x7ff0000000000000LL) return x*x; - if((hx>>=52)==0) /* IEEE 754 logb */ - return -1022.0; - else - return (long double) (hx-0x3ff); + int64_t lx, hx, rhx; + + GET_LDOUBLE_WORDS64 (hx, lx, x); + hx &= 0x7fffffffffffffffLL; /* high |x| */ + if ((hx | (lx & 0x7fffffffffffffffLL)) == 0) + return -1.0 / fabs (x); + if (hx >= 0x7ff0000000000000LL) + return x * x; + if (__builtin_expect ((rhx = hx >> 52) == 0, 0)) + { + /* POSIX specifies that denormal number is treated as + though it were normalized. */ + int m1 = (hx == 0) ? 0 : __builtin_clzll (hx); + int m2 = (lx == 0) ? 0 : __builtin_clzll (lx); + int ma = (m1 == 0) ? m2 + 64 : m1; + return -1022.0 + (long double)(11 - ma); + } + return (long double) (rhx - 1023); } + long_double_symbol (libm, __logbl, logbl); diff --git a/sysdeps/ieee754/ldbl-96/s_logbl.c b/sysdeps/ieee754/ldbl-96/s_logbl.c index 95b644c030f..d8ad4bcfcf9 100644 --- a/sysdeps/ieee754/ldbl-96/s_logbl.c +++ b/sysdeps/ieee754/ldbl-96/s_logbl.c @@ -14,10 +14,6 @@ * ==================================================== */ -#if defined(LIBM_SCCS) && !defined(lint) -static char rcsid[] = "$NetBSD: $"; -#endif - /* * long double logbl(x) * IEEE 754 logb. Included to pass IEEE test suite. Not recommend. @@ -27,16 +23,27 @@ static char rcsid[] = "$NetBSD: $"; #include #include -long double __logbl(long double x) +long double +__logbl (long double x) { - int32_t es,lx,ix; - GET_LDOUBLE_WORDS(es,ix,lx,x); - es &= 0x7fff; /* exponent */ - if((es|ix|lx)==0) return -1.0/fabs(x); - if(es==0x7fff) return x*x; - if(es==0) /* IEEE 754 logb */ - return -16382.0; - else - return (long double) (es-0x3fff); + int32_t es, lx, ix; + + GET_LDOUBLE_WORDS (es, ix, lx, x); + es &= 0x7fff; /* exponent */ + if ((es | ix | lx) == 0) + return -1.0 / fabs (x); + if (es == 0x7fff) + return x * x; + if (es == 0) /* IEEE 754 logb */ + { + /* POSIX specifies that denormal number is treated as + though it were normalized. */ + int m1 = (ix == 0) ? 0 : __builtin_clz (ix); + int m2 = (lx == 0) ? 0 : __builtin_clz (lx); + int ma = (m1 == 0) ? m2 + 32 : m1; + return -16382.0 - (long double)(ma); + } + return (long double) (es - 16383); } + weak_alias (__logbl, logbl) -- 2.47.2