PowerPC: remove wrong nearbyintl implementation for PPC64

The nearbyintl assembly implementation
(sysdeps/powerpc/powerpc64/fpu/s_nearbyintl.S)
returns wrong results for some inputs where first double is a exact
integer and the precision is determined by second long double.

Checking on implementation comments and history, I am very confident the
assembly implementation was based on a version before commit
5c68d401698a58cf7da150d9cce769fa6679ba5f that fixes BZ#2423 (Errors in
long double (ldbl-128ibm) rounding functions in glibc-2.4).

By just removing the implementation and make the build select
sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c instead fixes the failing
math.

Fixes BZ#16706.

diff --git a/ChangeLog b/ChangeLog
index 5db859e..f43bbf4 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2014-03-14  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
 
+       [BZ #16706]
+       * sysdeps/powerpc/powerpc64/fpu/s_nearbyintl.S: Remove wrong
+       implementation.
+       * math/libm-test.inc (nearbyint_test_data): Add more tests.
+
+2014-03-14  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
+
        [BZ #16701]
        * sysdeps/powerpc/powerpc64/fpu/s_ceill.S: Remove wrong
        implementation.

diff --git a/NEWS b/NEWS
index 16a17c8..c9bfcb8 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -11,7 +11,7 @@ Version 2.20
 
   15347, 15804, 15894, 16447, 16532, 16545, 16574, 16600, 16609, 16610,
   16611, 16613, 16623, 16632, 16639, 16642, 16670, 16674, 16677, 16683,
-  16689, 16695, 16701.
+  16689, 16695, 16701, 16706.
 
 * The am33 port, which had not worked for several years, has been removed
   from ports.

diff --git a/math/libm-test.inc b/math/libm-test.inc
index c151b7d..1d602eb 100644 (file)
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -9521,6 +9521,16 @@ static const struct test_f_f_data nearbyint_test_data[] =
     TEST_f_f (nearbyint, -562949953421312.75, -562949953421313.0, NO_INEXACT_EXCEPTION),
     TEST_f_f (nearbyint, -1125899906842624.75, -1125899906842625.0, NO_INEXACT_EXCEPTION),
 #endif
+#ifdef TEST_LDOUBLE
+    /* Check cases where first double is a exact integer higher than 2^52 and
+       the precision is determined by second long double for IBM long double.  */
+    TEST_f_f (nearbyint,  34503599627370498.515625L, 34503599627370499.0L),
+    TEST_f_f (nearbyint, -34503599627370498.515625L, -34503599627370499.0L),
+# if LDBL_MANT_DIG >= 106
+    TEST_f_f (nearbyint,  1192568192774434123539907640624.484375L, 1192568192774434123539907640624.0L),
+    TEST_f_f (nearbyint, -1192568192774434123539907640624.484375L, -1192568192774434123539907640624.0L),
+# endif
+#endif
   };
 
 static void

diff --git a/sysdeps/powerpc/powerpc64/fpu/s_nearbyintl.S b/sysdeps/powerpc/powerpc64/fpu/s_nearbyintl.S
deleted file mode 100644 (file)
index acd95da..0000000
--- a/sysdeps/powerpc/powerpc64/fpu/s_nearbyintl.S
+++ /dev/null
@@ -1,113 +0,0 @@
-/* nearbyint long double.
-   IBM extended format long double version.
-   Copyright (C) 2004-2014 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
-   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 <sysdep.h>
-#include <math_ldbl_opt.h>
-
-       .section        ".toc","aw"
-.LC0:  /* 2**52 */
-       .tc FD_43300000_0[TC],0x4330000000000000
-       .section        ".text"
-
-/* long double [fp1,fp2] nearbyintl (long double x [fp1,fp2])
-   IEEE 1003.1 nearbyintl function.  nearbyintl is similar to the rintl
-   but does raise the "inexact" exception.  This implementation is
-   based on rintl but explicitly masks the inexact exception on entry
-   and clears any pending inexact before restoring the exception mask
-   on exit.
-
-   PowerPC64 long double uses the IBM extended format which is
-   represented two 64-floating point double values. The values are
-   non-overlapping giving an effective precision of 106 bits. The first
-   double contains the high order bits of mantissa and is always rounded
-   to represent a normal rounding of long double to double. Since the
-   long double value is sum of the high and low values, the low double
-   normally has the opposite sign to compensate for the this rounding.
-
-   For long double there are two cases:
-   1) |x| < 2**52, all the integer bits are in the high double.
-      floor the high double and set the low double to -0.0.
-   2) |x| >= 2**52, Rounding involves both doubles.
-      See the comment before label .L2 for details.
-   */
-ENTRY (__nearbyintl)
-       mffs    fp11            /* Save current FPSCR.  */
-       lfd     fp13,.LC0@toc(2)
-       fabs    fp0,fp1
-       mtfsb0  28              /* Disable "inexact" exceptions.  */
-       fsub    fp12,fp13,fp13  /* generate 0.0  */
-       fabs    fp9,fp2
-       fcmpu   cr7,fp0,fp13    /* if (fabs(x) > TWO52)  */
-       fcmpu   cr6,fp1,fp12    /* if (x > 0.0)  */
-       bnl-    cr7,.L2
-       fmr     fp2,fp12
-       bng-    cr6,.L4
-       fadd    fp1,fp1,fp13    /* x+= TWO52;  */
-       fsub    fp1,fp1,fp13    /* x-= TWO52;  */
-       b       .L9
-.L4:
-       bnl-    cr6,.L9         /* if (x < 0.0)  */
-       fsub    fp1,fp13,fp1    /* x = TWO52 - x;  */
-       fsub    fp0,fp1,fp13    /* x = - (x - TWO52);  */
-       fneg    fp1,fp0
-.L9:
-       mtfsb0  6               /* Clear any pending "inexact" exceptions.  */
-       mtfsf   0x01,fp11       /* restore exception mask.  */
-       blr
-
-/* The high double is > TWO52 so we need to round the low double and
-   perhaps the high double.  This gets a bit tricky so we use the
-   following algorithm:
-
-   tau = floor(x_high/TWO52);
-   x0 = x_high - tau;
-   x1 = x_low + tau;
-   r1 = nearbyint(x1);
-   y_high = x0 + r1;
-   y_low = r1 - tau;
-   return y;  */
-.L2:
-       fcmpu   cr7,fp9,fp13    /* if (|x_low| > TWO52)  */
-       fcmpu   cr0,fp9,fp12    /* || (|x_low| == 0.0)  */
-       bge-    cr7,.L9         /*   return x;  */
-       beq-  cr0,.L9
-       fdiv    fp8,fp1,fp13    /* x_high/TWO52  */
-       fctidz  fp0,fp8
-       fcfid   fp8,fp0         /* tau = floor(x_high/TWO52);  */
-       fsub    fp3,fp1,fp8     /* x0 = x_high - tau;  */
-       fadd    fp4,fp2,fp8     /* x1 = x_low + tau;  */
-
-       fcmpu   cr6,fp4,fp12    /* if (x1 > 0.0)  */
-       bng-    cr6,.L8
-       fadd    fp5,fp4,fp13    /* r1 = x1 + TWO52;  */
-       fsub    fp5,fp5,fp13    /* r1 = r1 - TWO52;  */
-       b       .L6
-.L8:
-       fmr     fp5,fp4
-       bge-    cr6,.L6         /* if (x1 < 0.0)  */
-       fsub    fp5,fp13,fp4    /* r1 = TWO52 - x1;  */
-       fsub    fp0,fp5,fp13    /* r1 = - (r1 - TWO52);  */
-       fneg    fp5,fp0
-.L6:
-       fadd    fp1,fp3,fp5     /* y_high = x0 + r1;  */
-       fsub    fp2,fp5,fp8     /* y_low = r1 - tau;  */
-       b       .L9
-END (__nearbyintl)
-
-long_double_symbol (libm, __nearbyintl, nearbyintl)