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* [glibc] math: Use wordsize-64 version for s_logb
@ 2019-07-08 20:27 Adhemerval Zanella
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From: Adhemerval Zanella @ 2019-07-08 20:27 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=105f2ed368ed61785a0a63ddb47fc62b89b58e0d
commit 105f2ed368ed61785a0a63ddb47fc62b89b58e0d
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Thu Mar 28 19:14:04 2019 +0000
math: Use wordsize-64 version for s_logb
- The resulting binary difference on 32 bits architecture is
minimum. On i686-linux-gnu (with architecture optimization
routine removed) there is no different using logb benchtests
- It helps wordsize-64 architectures that use ldbl-opt.
- It add some code simplification with reduction of duplicated
implementations.
Checked on powerpc-linux-gnu (built without --with-cpu, with
--with-cpu=power4 and with --with-cpu=power5+ and --disable-multi-arch),
powerpc64-linux-gnu (built without --with-cp and with --with-cpu=power5+
and --disable-multi-arch).
* sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c: Move to ...
* sysdeps/ieee754/dbl-64/s_logb.c: ... here. Add work around for
powerpc32 integer 0 converting to -0.
Reviewed-by: Gabriel F. T. Gomes <gabrielftg@linux.ibm.com>
Diff:
---
ChangeLog | 4 ++
sysdeps/ieee754/dbl-64/s_logb.c | 61 ++++++++++++++---------------
sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c | 47 ----------------------
3 files changed, 33 insertions(+), 79 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 828f832..c36f8fd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
2019-07-08 Adhemerval Zanella <adhemerval.zanella@linaro.org>
+ * sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c: Move to ...
+ * sysdeps/ieee754/dbl-64/s_logb.c: ... here. Add work around for
+ powerpc32 integer 0 converting to -0.
+
* benchtests/Makefile (bench-math): Add logb.
* benchtests/logb-inputs: New file.
* benchtests/logbf-inputs: New file.
diff --git a/sysdeps/ieee754/dbl-64/s_logb.c b/sysdeps/ieee754/dbl-64/s_logb.c
index a6de1f6..e336251 100644
--- a/sysdeps/ieee754/dbl-64/s_logb.c
+++ b/sysdeps/ieee754/dbl-64/s_logb.c
@@ -1,22 +1,24 @@
-/* @(#)s_logb.c 5.1 93/09/24 */
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunPro, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice
- * is preserved.
- * ====================================================
- */
+/* Compute radix independent exponent.
+ Copyright (C) 2011-2019 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
-/*
- * double logb(x)
- * IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
- * Use ilogb instead.
- */
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ 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/>. */
#include <math.h>
+
#include <math_private.h>
#include <libm-alias-double.h>
#include <fix-int-fp-convert-zero.h>
@@ -24,28 +26,23 @@
double
__logb (double x)
{
- int32_t lx, ix, rix;
+ int64_t ix, ex;
- EXTRACT_WORDS (ix, lx, x);
- ix &= 0x7fffffff; /* high |x| */
- if ((ix | lx) == 0)
+ EXTRACT_WORDS64 (ix, x);
+ ix &= UINT64_C(0x7fffffffffffffff);
+ if (ix == 0)
return -1.0 / fabs (x);
- if (ix >= 0x7ff00000)
+ ex = ix >> 52;
+ if (ex == 0x7ff)
return x * x;
- if (__glibc_unlikely ((rix = ix >> 20) == 0))
+ if (__glibc_unlikely (ex == 0))
{
- /* POSIX specifies that denormal number is treated as
- though it were normalized. */
- int ma;
- if (ix == 0)
- ma = __builtin_clz (lx) + 32;
- else
- ma = __builtin_clz (ix);
- rix -= ma - 12;
+ int m = __builtin_clzll (ix);
+ ex -= m - 12;
}
- if (FIX_INT_FP_CONVERT_ZERO && rix == 1023)
+ if (FIX_INT_FP_CONVERT_ZERO && ex == 1023)
return 0.0;
- return (double) (rix - 1023);
+ return (double) (ex - 1023);
}
#ifndef __logb
libm_alias_double (__logb, logb)
diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c b/sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c
deleted file mode 100644
index d9b40af..0000000
--- a/sysdeps/ieee754/dbl-64/wordsize-64/s_logb.c
+++ /dev/null
@@ -1,47 +0,0 @@
-/* Compute radix independent exponent.
- Copyright (C) 2011-2019 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
- Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
-
- The GNU C Library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 2.1 of the License, or (at your option) any later version.
-
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- 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/>. */
-
-#include <math.h>
-
-#include <math_private.h>
-#include <libm-alias-double.h>
-
-
-double
-__logb (double x)
-{
- int64_t ix, ex;
-
- EXTRACT_WORDS64 (ix, x);
- ix &= UINT64_C(0x7fffffffffffffff);
- if (ix == 0)
- return -1.0 / fabs (x);
- ex = ix >> 52;
- if (ex == 0x7ff)
- return x * x;
- if (__glibc_unlikely (ex == 0))
- {
- int m = __builtin_clzll (ix);
- ex -= m - 12;
- }
- return (double) (ex - 1023);
-}
-#ifndef __logb
-libm_alias_double (__logb, logb)
-#endif
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