This is the mail archive of the glibc-cvs@sourceware.org mailing list for the glibc project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

GNU C Library master sources branch master updated. glibc-2.19-285-gaa5f0ff


This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "GNU C Library master sources".

The branch, master has been updated
       via  aa5f0ff11ad2cc85277c64cf65c723a9664e1149 (commit)
      from  bb9c256fb01b09bc13a58ada3ea045ac9efd4834 (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=aa5f0ff11ad2cc85277c64cf65c723a9664e1149

commit aa5f0ff11ad2cc85277c64cf65c723a9664e1149
Author: Alan Modra <amodra@gmail.com>
Date:   Wed Apr 16 19:33:32 2014 +0930

    Correct IBM long double frexpl.
    
    Besides fixing the bugzilla, this also fixes corner-cases where the high
    and low double differ greatly in magnitude, and handles a denormal
    input without resorting to a fp rescale.
    
    	[BZ #16740]
    	[BZ #16619]
    	* sysdeps/ieee754/ldbl-128ibm/s_frexpl.c (__frexpl): Rewrite.
    	* math/libm-test.inc (frexp_test_data): Add tests.

diff --git a/ChangeLog b/ChangeLog
index 2a8cc57..9f70d63 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2014-04-16  Alan Modra  <amodra@gmail.com>
+
+	[BZ #16740]
+	[BZ #16619]
+	* sysdeps/ieee754/ldbl-128ibm/s_frexpl.c (__frexpl): Rewrite.
+	* math/libm-test.inc (frexp_test_data): Add tests.
+
 2014-04-15  Siddhesh Poyarekar  <siddhesh@redhat.com>
 
 	* benchtests/Makefile: Depend on libraries in build directory.
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 5e6789f..a4bf0b8 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -7186,6 +7186,15 @@ static const struct test_f_f1_data frexp_test_data[] =
 
     TEST_fI_f1 (frexp, 12.8L, 0.8L, 4, NO_INEXACT_EXCEPTION),
     TEST_fI_f1 (frexp, -27.34L, -0.854375L, 5, NO_INEXACT_EXCEPTION),
+
+#if defined TEST_LDOUBLE && LDBL_MANT_DIG >= 106
+    TEST_fI_f1 (frexp, 1.0L-0x1p-106L, 1.0L-0x1p-106L, 0, NO_INEXACT_EXCEPTION),
+    TEST_fI_f1 (frexp, 1.0L, 0.5L, 1, NO_INEXACT_EXCEPTION),
+    TEST_fI_f1 (frexp, 1.0L+0x1p-105L, 0.5L+0x1p-106L, 1, NO_INEXACT_EXCEPTION),
+    TEST_fI_f1 (frexp, -1.0L+0x1p-106L, -1.0L+0x1p-106L, 0, NO_INEXACT_EXCEPTION),
+    TEST_fI_f1 (frexp, -1.0L, -0.5L, 1, NO_INEXACT_EXCEPTION),
+    TEST_fI_f1 (frexp, -1.0L-0x1p-105L, -0.5L-0x1p-106L, 1, NO_INEXACT_EXCEPTION),
+#endif
   };
 
 static void
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_frexpl.c b/sysdeps/ieee754/ldbl-128ibm/s_frexpl.c
index 7e40663..a644f92 100644
--- a/sysdeps/ieee754/ldbl-128ibm/s_frexpl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/s_frexpl.c
@@ -31,57 +31,115 @@ static char rcsid[] = "$NetBSD: $";
 #include <math_private.h>
 #include <math_ldbl_opt.h>
 
-static const long double
-two107 = 162259276829213363391578010288128.0; /* 0x4670000000000000, 0 */
-
 long double __frexpl(long double x, int *eptr)
 {
-	uint64_t hx, lx, ix, ixl;
-	int64_t explo;
-	double xhi, xlo;
+  uint64_t hx, lx, ix, ixl;
+  int64_t explo, expon;
+  double xhi, xlo;
+
+  ldbl_unpack (x, &xhi, &xlo);
+  EXTRACT_WORDS64 (hx, xhi);
+  EXTRACT_WORDS64 (lx, xlo);
+  ixl = 0x7fffffffffffffffULL & lx;
+  ix  = 0x7fffffffffffffffULL & hx;
+  expon = 0;
+  if (ix >= 0x7ff0000000000000ULL || ix == 0)
+    {
+      /* 0,inf,nan.  */
+      *eptr = expon;
+      return x;
+    }
+  expon = ix >> 52;
+  if (expon == 0)
+    {
+      /* Denormal high double, the low double must be 0.0.  */
+      int cnt;
+
+      /* Normalize.  */
+      if (sizeof (ix) == sizeof (long))
+	cnt = __builtin_clzl (ix);
+      else if ((ix >> 32) != 0)
+	cnt = __builtin_clzl ((long) (ix >> 32));
+      else
+	cnt = __builtin_clzl ((long) ix) + 32;
+      cnt = cnt - 12;
+      expon -= cnt;
+      ix <<= cnt + 1;
+    }
+  expon -= 1022;
+  ix &= 0x000fffffffffffffULL;
+  hx &= 0x8000000000000000ULL;
+  hx |= (1022LL << 52) | ix;
 
-	ldbl_unpack (x, &xhi, &xlo);
-	EXTRACT_WORDS64 (hx, xhi);
-	EXTRACT_WORDS64 (lx, xlo);
-	ixl = 0x7fffffffffffffffULL&lx;
-	ix =  0x7fffffffffffffffULL&hx;
-	*eptr = 0;
-	if(ix>=0x7ff0000000000000ULL||ix==0) return x;	/* 0,inf,nan */
-	if (ix<0x0010000000000000ULL) {		/* subnormal */
-	    x *= two107;
-	    xhi = ldbl_high (x);
-	    EXTRACT_WORDS64 (hx, xhi);
-	    ix = hx&0x7fffffffffffffffULL;
-	    *eptr = -107;
+  if (ixl != 0)
+    {
+      /* If the high double is an exact power of two and the low
+	 double has the opposite sign, then the exponent calculated
+	 from the high double is one too big.  */
+      if (ix == 0
+	  && (int64_t) (hx ^ lx) < 0)
+	{
+	  hx += 1L << 52;
+	  expon -= 1;
 	}
-	*eptr += (ix>>52)-1022;
 
-	if (ixl != 0ULL) {
-	  explo = (ixl>>52) - (ix>>52) + 0x3fe;
-	  if ((ixl&0x7ff0000000000000ULL) == 0LL) {
-	    /* the lower double is a denormal so we need to correct its
-	       mantissa and perhaps its exponent.  */
-	    int cnt;
+      explo = ixl >> 52;
+      if (explo == 0)
+	{
+	  /* The low double started out as a denormal.  Normalize its
+	     mantissa and adjust the exponent.  */
+	  int cnt;
 
-	    if (sizeof (ixl) == sizeof (long))
-	      cnt = __builtin_clzl (ixl);
-	    else if ((ixl >> 32) != 0)
-	      cnt = __builtin_clzl ((long) (ixl >> 32));
-	    else
-	      cnt = __builtin_clzl ((long) ixl) + 32;
-	    cnt = cnt - 12;
-	    lx = (lx&0x8000000000000000ULL) | ((explo-cnt)<<52)
-	       | ((ixl<<(cnt+1))&0x000fffffffffffffULL);
-	  } else
-	    lx = (lx&0x800fffffffffffffULL) | (explo<<52);
-	} else
-	  lx = 0ULL;
+	  if (sizeof (ixl) == sizeof (long))
+	    cnt = __builtin_clzl (ixl);
+	  else if ((ixl >> 32) != 0)
+	    cnt = __builtin_clzl ((long) (ixl >> 32));
+	  else
+	    cnt = __builtin_clzl ((long) ixl) + 32;
+	  cnt = cnt - 12;
+	  explo -= cnt;
+	  ixl <<= cnt + 1;
+	}
+
+      /* With variable precision we can't assume much about the
+	 magnitude of the returned low double.  It may even be a
+	 denormal.  */
+      explo -= expon;
+      ixl &= 0x000fffffffffffffULL;
+      lx  &= 0x8000000000000000ULL;
+      if (explo <= 0)
+	{
+	  /* Handle denormal low double.  */
+	  if (explo > -52)
+	    {
+	      ixl |= 1LL << 52;
+	      ixl >>= 1 - explo;
+	    }
+	  else
+	    {
+	      ixl = 0;
+	      lx = 0;
+	      if ((hx & 0x7ff0000000000000ULL) == (1023LL << 52))
+		{
+		  /* Oops, the adjustment we made above for values a
+		     little smaller than powers of two turned out to
+		     be wrong since the returned low double will be
+		     zero.  This can happen if the input was
+		     something weird like 0x1p1000 - 0x1p-1000.  */
+		  hx -= 1L << 52;
+		  expon += 1;
+		}
+	    }
+	  explo = 0;
+	}
+      lx |= (explo << 52) | ixl;
+    }
 
-	hx = (hx&0x800fffffffffffffULL) | 0x3fe0000000000000ULL;
-	INSERT_WORDS64 (xhi, hx);
-	INSERT_WORDS64 (xlo, lx);
-	x = ldbl_pack (xhi, xlo);
-	return x;
+  INSERT_WORDS64 (xhi, hx);
+  INSERT_WORDS64 (xlo, lx);
+  x = ldbl_pack (xhi, xlo);
+  *eptr = expon;
+  return x;
 }
 #ifdef IS_IN_libm
 long_double_symbol (libm, __frexpl, frexpl);

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                              |    7 ++
 math/libm-test.inc                     |    9 ++
 sysdeps/ieee754/ldbl-128ibm/s_frexpl.c |  146 ++++++++++++++++++++++----------
 3 files changed, 118 insertions(+), 44 deletions(-)


hooks/post-receive
-- 
GNU C Library master sources


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]