On i386, gcc truncates long double constants to double precision

at compile time regardless of the dynamic precision, and there's
no way to disable this misfeature at compile time. Hence, it's
impossible to generate the appropriate tables of constants for the
long double inverse trig functions in a straightforward way on i386;
this change hacks around the problem by encoding the underlying bits
in the table.

Note that these functions won't pass the regression test on i386,
even with the FPU set to extended precision, because the regression
test is similarly damaged by gcc. However, the tests all pass when
compiled with a modified version of gcc.

Reported by:  	bde
This commit is contained in:
David Schultz 2008-08-02 03:56:22 +00:00
parent 75accfd97d
commit 1192a80ed1
Notes: svn2git 2020-12-20 02:59:44 +00:00
svn path=/head/; revision=181152
4 changed files with 127 additions and 8 deletions

86
lib/msun/i387/invtrig.c Normal file
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@ -0,0 +1,86 @@
/*-
* Copyright (c) 2008 David Schultz <das@FreeBSD.ORG>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <stdint.h>
#define STRUCT_DECLS
#include "invtrig.h"
/*
* asinl() and acosl()
*/
const LONGDOUBLE
pS0 = { 0xaaaaaaaaaaaaaaa8ULL, 0x3ffcU }, /* 1.66666666666666666631e-01L */
pS1 = { 0xd5271b6699b48bfaULL, 0xbffdU }, /* -4.16313987993683104320e-01L */
pS2 = { 0xbcf67ca9e9f669cfULL, 0x3ffdU }, /* 3.69068046323246813704e-01L */
pS3 = { 0x8b7baa3d15f9830dULL, 0xbffcU }, /* -1.36213932016738603108e-01L */
pS4 = { 0x92154b093a3bff1cULL, 0x3ff9U }, /* 1.78324189708471965733e-02L */
pS5 = { 0xe5dd76401964508cULL, 0xbff2U }, /* -2.19216428382605211588e-04L */
pS6 = { 0xee69c5b0fdb76951ULL, 0xbfedU }, /* -7.10526623669075243183e-06L */
qS1 = { 0xbcaa2159c01436a0ULL, 0xc000U }, /* -2.94788392796209867269e+00L */
qS2 = { 0xd17a73d1e1564c29ULL, 0x4000U }, /* 3.27309890266528636716e+00L */
qS3 = { 0xd767e411c9cf4c2cULL, 0xbfffU }, /* -1.68285799854822427013e+00L */
qS4 = { 0xc809c0dfb9b0d0b7ULL, 0x3ffdU }, /* 3.90699412641738801874e-01L */
qS5 = { 0x80c3a2197c8ced57ULL, 0xbffaU }; /* -3.14365703596053263322e-02L */
/*
* atanl()
*/
const LONGDOUBLE atanhi[] = {
{ 0xed63382b0dda7b45ULL, 0x3ffdU }, /* 4.63647609000806116202e-01L */
{ 0xc90fdaa22168c235ULL, 0x3ffeU }, /* 7.85398163397448309628e-01L */
{ 0xfb985e940fb4d900ULL, 0x3ffeU }, /* 9.82793723247329067960e-01L */
{ 0xc90fdaa22168c235ULL, 0x3fffU }, /* 1.57079632679489661926e+00L */
};
const LONGDOUBLE atanlo[] = {
{ 0xdfc88bd978751a07ULL, 0x3fbcU }, /* 1.18469937025062860669e-20L */
{ 0xece675d1fc8f8cbbULL, 0xbfbcU }, /* -1.25413940316708300586e-20L */
{ 0xf10f5e197793c283ULL, 0x3fbdU }, /* 2.55232234165405176172e-20L */
{ 0xece675d1fc8f8cbbULL, 0xbfbdU }, /* -2.50827880633416601173e-20L */
};
const LONGDOUBLE aT[] = {
{ 0xaaaaaaaaaaaaaa9fULL, 0x3ffdU }, /* 3.33333333333333333017e-01L */
{ 0xcccccccccccc62bcULL, 0xbffcU }, /* -1.99999999999999632011e-01L */
{ 0x9249249248b81e3fULL, 0x3ffcU }, /* 1.42857142857046531280e-01L */
{ 0xe38e38e3316f3de5ULL, 0xbffbU }, /* -1.11111111100562372733e-01L */
{ 0xba2e8b8dc280726aULL, 0x3ffbU }, /* 9.09090902935647302252e-02L */
{ 0x9d89d5b4c6847ec4ULL, 0xbffbU }, /* -7.69230552476207730353e-02L */
{ 0x8888461d3099c677ULL, 0x3ffbU }, /* 6.66661718042406260546e-02L */
{ 0xf0e8ee0f5328dc29ULL, 0xbffaU }, /* -5.88158892835030888692e-02L */
{ 0xd73ea84d24bae54aULL, 0x3ffaU }, /* 5.25499891539726639379e-02L */
{ 0xc08fa381dcd9213aULL, 0xbffaU }, /* -4.70119845393155721494e-02L */
{ 0xa54a26f4095f2a3aULL, 0x3ffaU }, /* 4.03539201366454414072e-02L */
{ 0xeea2d8d059ef3ad6ULL, 0xbff9U }, /* -2.91303858419364158725e-02L */
{ 0xcc82292ab894b051ULL, 0x3ff8U }, /* 1.24822046299269234080e-02L */
};
const LONGDOUBLE
pi_lo = { 0xece675d1fc8f8cbbULL, 0xbfbeU }; /* -5.01655761266833202345e-20L */

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@ -64,10 +64,21 @@
#define pio2_lo atanlo[3]
#define pio4_hi atanhi[1]
extern const long double pS0, pS1, pS2, pS3, pS4, pS5, pS6;
extern const long double qS1, qS2, qS3, qS4, qS5;
extern const long double atanhi[], atanlo[], aT[];
extern const long double pi_lo;
#ifdef STRUCT_DECLS
typedef struct longdouble {
uint64_t mant;
uint16_t expsign;
} LONGDOUBLE;
#else
typedef long double LONGDOUBLE;
#endif
extern const LONGDOUBLE pS0, pS1, pS2, pS3, pS4, pS5, pS6;
extern const LONGDOUBLE qS1, qS2, qS3, qS4, qS5;
extern const LONGDOUBLE atanhi[], atanlo[], aT[];
extern const LONGDOUBLE pi_lo;
#ifndef STRUCT_DECLS
static inline long double
P(long double x)
@ -99,3 +110,5 @@ T_odd(long double x)
return (aT[1] + x * (aT[3] + x * (aT[5] + x * (aT[7] + x * \
(aT[9] + x * aT[11])))));
}
#endif

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@ -27,9 +27,19 @@ __FBSDID("$FreeBSD$");
#include "math_private.h"
static const long double
one= 1.00000000000000000000e+00,
one= 1.00000000000000000000e+00;
#ifdef __i386__
/* XXX Work around the fact that gcc truncates long double constants on i386 */
static volatile double
pi1 = 3.14159265358979311600e+00, /* 0x1.921fb54442d18p+1 */
pi2 = 1.22514845490862001043e-16; /* 0x1.1a80000000000p-53 */
#define pi ((long double)pi1 + pi2)
#else
static const long double
pi = 3.14159265358979323846264338327950280e+00L;
#endif
long double
acosl(long double x)
{

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@ -30,8 +30,18 @@ __FBSDID("$FreeBSD$");
static volatile long double
tiny = 1.0e-300;
static const long double
zero = 0.0,
pi = 3.14159265358979323846264338327950280e+00L;
zero = 0.0;
#ifdef __i386__
/* XXX Work around the fact that gcc truncates long double constants on i386 */
static volatile double
pi1 = 3.14159265358979311600e+00, /* 0x1.921fb54442d18p+1 */
pi2 = 1.22514845490862001043e-16; /* 0x1.1a80000000000p-53 */
#define pi ((long double)pi1 + pi2)
#else
static const long double
pi = 3.14159265358979323846264338327950280e+00L;
#endif
long double
atan2l(long double y, long double x)