GNU C Library master sources branch, master, updated. glibc-2.12-191-g3e692e0

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Fri Oct 15 19:26:00 GMT 2010


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http://sources.redhat.com/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=3e692e0518b4f4679352d25102bd47cf3f85c592

commit 3e692e0518b4f4679352d25102bd47cf3f85c592
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Oct 15 15:26:06 2010 -0400

    Implement fmal, some fma bugfixes

diff --git a/math/libm-test.inc b/math/libm-test.inc
index 1bec476..ceed18d 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -2787,8 +2787,24 @@ fma_test (void)
   TEST_fff_f (fma, minus_infty, plus_infty, plus_infty, nan_value, INVALID_EXCEPTION);
   TEST_fff_f (fma, plus_infty, minus_infty, plus_infty, nan_value, INVALID_EXCEPTION);
   TEST_fff_f (fma, minus_infty, minus_infty, minus_infty, nan_value, INVALID_EXCEPTION);
+  TEST_fff_f (fma, plus_infty, 3.5L, minus_infty, nan_value, INVALID_EXCEPTION);
+  TEST_fff_f (fma, minus_infty, -7.5L, minus_infty, nan_value, INVALID_EXCEPTION);
+  TEST_fff_f (fma, -13.5L, plus_infty, plus_infty, nan_value, INVALID_EXCEPTION);
+  TEST_fff_f (fma, minus_infty, 7.5L, plus_infty, nan_value, INVALID_EXCEPTION);
 
   TEST_fff_f (fma, 1.25L, 0.75L, 0.0625L, 1.0L);
+
+  FLOAT fltmax = CHOOSE (LDBL_MAX, DBL_MAX, FLT_MAX,
+			 LDBL_MAX, DBL_MAX, FLT_MAX);
+  TEST_fff_f (fma, -fltmax, -fltmax, minus_infty, minus_infty);
+  TEST_fff_f (fma, fltmax / 2, fltmax / 2, minus_infty, minus_infty);
+  TEST_fff_f (fma, -fltmax, fltmax, plus_infty, plus_infty);
+  TEST_fff_f (fma, fltmax / 2, -fltmax / 4, plus_infty, plus_infty);
+  TEST_fff_f (fma, plus_infty, 4, plus_infty, plus_infty);
+  TEST_fff_f (fma, 2, minus_infty, minus_infty, minus_infty);
+  TEST_fff_f (fma, minus_infty, minus_infty, plus_infty, plus_infty);
+  TEST_fff_f (fma, plus_infty, minus_infty, minus_infty, minus_infty);
+
 #if defined (TEST_FLOAT) && FLT_MANT_DIG == 24
   TEST_fff_f (fma, 0x1.7ff8p+13, 0x1.000002p+0, 0x1.ffffp-24, 0x1.7ff802p+13);
   TEST_fff_f (fma, 0x1.fffp+0, 0x1.00001p+0, -0x1.fffp+0, 0x1.fffp-20);
@@ -2818,6 +2834,15 @@ fma_test (void)
   TEST_fff_f (fma, -0x1.19cab66d73e17p-959, 0x1.c7108a8c5ff51p-107, -0x0.80b0ad65d9b64p-1022, -0x0.80b0ad65d9d59p-1022);
   TEST_fff_f (fma, -0x1.d2eaed6e8e9d3p-979, -0x1.4e066c62ac9ddp-63, -0x0.9245e6b003454p-1022, -0x0.9245c09c5fb5dp-1022);
   TEST_fff_f (fma, 0x1.153d650bb9f06p-907, 0x1.2d01230d48407p-125, -0x0.b278d5acfc3cp-1022, -0x0.b22757123bbe9p-1022);
+  TEST_fff_f (fma, -0x1.fffffffffffffp-711, 0x1.fffffffffffffp-275, 0x1.fffffe00007ffp-983, 0x1.7ffffe00007ffp-983);
+#endif
+#if defined (TEST_LDOUBLE) && LDBL_MANT_DIG == 64
+  TEST_fff_f (fma, -0x8.03fcp+3696L, 0xf.fffffffffffffffp-6140L, 0x8.3ffffffffffffffp-2450L, -0x8.01ecp-2440L);
+  TEST_fff_f (fma, 0x9.fcp+2033L, -0x8.000e1f000ff800fp-3613L, -0xf.fffffffffffc0ffp-1579L, -0xd.fc119fb093ed092p-1577L);
+  TEST_fff_f (fma, 0xc.7fc000003ffffffp-1194L, 0x8.1e0003fffffffffp+15327L, -0x8.fffep+14072L, 0xc.ae9f164020effffp+14136L);
+  TEST_fff_f (fma, -0x8.0001fc000000003p+1798L, 0xcp-2230L, 0x8.f7e000000000007p-468L, -0xc.0002f9ffee10404p-429L);
+  TEST_fff_f (fma, 0xc.0000000000007ffp+10130L, -0x8.000000000000001p+4430L, 0xc.07000000001ffffp+14513L, -0xb.fffffffffffd7e4p+14563L);
+  TEST_fff_f (fma, 0xb.ffffp-4777L, 0x8.000000fffffffffp-11612L, -0x0.3800fff8p-16385L, 0x5.c7fe80c7ffeffffp-16385L);
 #endif
 
   END (fma);
diff --git a/sysdeps/i386/fpu/s_fma.S b/sysdeps/i386/fpu/s_fma.S
deleted file mode 100644
index db4959c..0000000
--- a/sysdeps/i386/fpu/s_fma.S
+++ /dev/null
@@ -1,31 +0,0 @@
-/* Compute (X * Y) + Z as ternary operation.
-   Copyright (C) 1997, 1998 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
-
-   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, write to the Free
-   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
-   02111-1307 USA.  */
-
-#include <sysdep.h>
-
-	.text
-ENTRY(__fma)
-	fldl	4(%esp)		// x
-	fmull	12(%esp)	// x * y
-	fldl	20(%esp)	// z : x * y
-	faddp			// (x * y) + z
-	ret
-END(__fma)
-weak_alias (__fma, fma)
diff --git a/sysdeps/i386/fpu/s_fmaf.S b/sysdeps/i386/fpu/s_fmaf.S
deleted file mode 100644
index 5f87553..0000000
--- a/sysdeps/i386/fpu/s_fmaf.S
+++ /dev/null
@@ -1,31 +0,0 @@
-/* Compute (X * Y) + Z as ternary operation.
-   Copyright (C) 1997 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
-
-   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, write to the Free
-   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
-   02111-1307 USA.  */
-
-#include <sysdep.h>
-
-	.text
-ENTRY(__fmaf)
-	flds	4(%esp)		// x
-	fmuls	8(%esp)		// x * y
-	flds	12(%esp)	// z : x * y
-	faddp			// (x * y) + z
-	ret
-END(__fmaf)
-weak_alias (__fmaf, fmaf)
diff --git a/sysdeps/i386/fpu/s_fmal.S b/sysdeps/i386/fpu/s_fmal.S
deleted file mode 100644
index 1837f84..0000000
--- a/sysdeps/i386/fpu/s_fmal.S
+++ /dev/null
@@ -1,32 +0,0 @@
-/* Compute (X * Y) + Z as ternary operation.
-   Copyright (C) 1997 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
-
-   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, write to the Free
-   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
-   02111-1307 USA.  */
-
-#include <sysdep.h>
-
-	.text
-ENTRY(__fmal)
-	fldt	4(%esp)		// x
-	fldt	16(%esp)	// x : y
-	fmulp			// x * y
-	fldt	28(%esp)	// z : x * y
-	faddp			// (x * y) + z
-	ret
-END(__fmal)
-weak_alias (__fmal, fmal)
diff --git a/sysdeps/ieee754/dbl-64/s_fma.c b/sysdeps/ieee754/dbl-64/s_fma.c
index 911682e..3b0bfd5 100644
--- a/sysdeps/ieee754/dbl-64/s_fma.c
+++ b/sysdeps/ieee754/dbl-64/s_fma.c
@@ -43,6 +43,12 @@ __fma (double x, double y, double z)
       || __builtin_expect (u.ieee.exponent + v.ieee.exponent
 			   <= IEEE754_DOUBLE_BIAS + DBL_MANT_DIG, 0))
     {
+      /* If z is Inf, but x and y are finite, the result should be
+	 z rather than NaN.  */
+      if (w.ieee.exponent == 0x7ff
+	  && u.ieee.exponent != 0x7ff
+          && v.ieee.exponent != 0x7ff)
+	return (z + x) + y;
       /* If x or y or z is Inf/NaN, or if fma will certainly overflow,
 	 or if x * y is less than half of DBL_DENORM_MIN,
 	 compute as x * y + z.  */
@@ -165,6 +171,8 @@ __fma (double x, double y, double z)
     }
   else
     {
+      if ((u.ieee.mantissa1 & 1) == 0)
+	u.ieee.mantissa1 |= fetestexcept (FE_INEXACT) != 0;
       v.d = a1 + u.d;
       int j = fetestexcept (FE_INEXACT) != 0;
       feupdateenv (&env);
diff --git a/sysdeps/ieee754/dbl-64/s_fma.c b/sysdeps/ieee754/ldbl-128/s_fmal.c
similarity index 53%
copy from sysdeps/ieee754/dbl-64/s_fma.c
copy to sysdeps/ieee754/ldbl-128/s_fmal.c
index 911682e..9ec5ba9 100644
--- a/sysdeps/ieee754/dbl-64/s_fma.c
+++ b/sysdeps/ieee754/ldbl-128/s_fmal.c
@@ -27,92 +27,99 @@
    double rounding.  See a paper by Boldo and Melquiond:
    http://www.lri.fr/~melquion/doc/08-tc.pdf  */
 
-double
-__fma (double x, double y, double z)
+long double
+__fmal (long double x, long double y, long double z)
 {
-  union ieee754_double u, v, w;
+  union ieee854_long_double u, v, w;
   int adjust = 0;
   u.d = x;
   v.d = y;
   w.d = z;
   if (__builtin_expect (u.ieee.exponent + v.ieee.exponent
-			>= 0x7ff + IEEE754_DOUBLE_BIAS - DBL_MANT_DIG, 0)
-      || __builtin_expect (u.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0)
-      || __builtin_expect (v.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0)
-      || __builtin_expect (w.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0)
+			>= 0x7fff + IEEE854_LONG_DOUBLE_BIAS
+			   - LDBL_MANT_DIG, 0)
+      || __builtin_expect (u.ieee.exponent >= 0x7fff - LDBL_MANT_DIG, 0)
+      || __builtin_expect (v.ieee.exponent >= 0x7fff - LDBL_MANT_DIG, 0)
+      || __builtin_expect (w.ieee.exponent >= 0x7fff - LDBL_MANT_DIG, 0)
       || __builtin_expect (u.ieee.exponent + v.ieee.exponent
-			   <= IEEE754_DOUBLE_BIAS + DBL_MANT_DIG, 0))
+			   <= IEEE854_LONG_DOUBLE_BIAS + LDBL_MANT_DIG, 0))
     {
+      /* If z is Inf, but x and y are finite, the result should be
+	 z rather than NaN.  */
+      if (w.ieee.exponent == 0x7fff
+	  && u.ieee.exponent != 0x7fff
+          && v.ieee.exponent != 0x7fff)
+	return (z + x) + y;
       /* If x or y or z is Inf/NaN, or if fma will certainly overflow,
-	 or if x * y is less than half of DBL_DENORM_MIN,
+	 or if x * y is less than half of LDBL_DENORM_MIN,
 	 compute as x * y + z.  */
-      if (u.ieee.exponent == 0x7ff
-	  || v.ieee.exponent == 0x7ff
-	  || w.ieee.exponent == 0x7ff
+      if (u.ieee.exponent == 0x7fff
+	  || v.ieee.exponent == 0x7fff
+	  || w.ieee.exponent == 0x7fff
 	  || u.ieee.exponent + v.ieee.exponent
-	     > 0x7ff + IEEE754_DOUBLE_BIAS
+	     > 0x7fff + IEEE854_LONG_DOUBLE_BIAS
 	  || u.ieee.exponent + v.ieee.exponent
-	     < IEEE754_DOUBLE_BIAS - DBL_MANT_DIG - 2)
+	     < IEEE854_LONG_DOUBLE_BIAS - LDBL_MANT_DIG - 2)
 	return x * y + z;
       if (u.ieee.exponent + v.ieee.exponent
-	  >= 0x7ff + IEEE754_DOUBLE_BIAS - DBL_MANT_DIG)
+	  >= 0x7fff + IEEE854_LONG_DOUBLE_BIAS - LDBL_MANT_DIG)
 	{
-	  /* Compute 1p-53 times smaller result and multiply
+	  /* Compute 1p-113 times smaller result and multiply
 	     at the end.  */
 	  if (u.ieee.exponent > v.ieee.exponent)
-	    u.ieee.exponent -= DBL_MANT_DIG;
+	    u.ieee.exponent -= LDBL_MANT_DIG;
 	  else
-	    v.ieee.exponent -= DBL_MANT_DIG;
+	    v.ieee.exponent -= LDBL_MANT_DIG;
 	  /* If x + y exponent is very large and z exponent is very small,
 	     it doesn't matter if we don't adjust it.  */
-	  if (w.ieee.exponent > DBL_MANT_DIG)
-	    w.ieee.exponent -= DBL_MANT_DIG;
+	  if (w.ieee.exponent > LDBL_MANT_DIG)
+	    w.ieee.exponent -= LDBL_MANT_DIG;
 	  adjust = 1;
 	}
-      else if (w.ieee.exponent >= 0x7ff - DBL_MANT_DIG)
+      else if (w.ieee.exponent >= 0x7fff - LDBL_MANT_DIG)
 	{
 	  /* Similarly.
 	     If z exponent is very large and x and y exponents are
 	     very small, it doesn't matter if we don't adjust it.  */
 	  if (u.ieee.exponent > v.ieee.exponent)
 	    {
-	      if (u.ieee.exponent > DBL_MANT_DIG)
-		u.ieee.exponent -= DBL_MANT_DIG;
+	      if (u.ieee.exponent > LDBL_MANT_DIG)
+		u.ieee.exponent -= LDBL_MANT_DIG;
 	    }
-	  else if (v.ieee.exponent > DBL_MANT_DIG)
-	    v.ieee.exponent -= DBL_MANT_DIG;
-	  w.ieee.exponent -= DBL_MANT_DIG;
+	  else if (v.ieee.exponent > LDBL_MANT_DIG)
+	    v.ieee.exponent -= LDBL_MANT_DIG;
+	  w.ieee.exponent -= LDBL_MANT_DIG;
 	  adjust = 1;
 	}
-      else if (u.ieee.exponent >= 0x7ff - DBL_MANT_DIG)
+      else if (u.ieee.exponent >= 0x7fff - LDBL_MANT_DIG)
 	{
-	  u.ieee.exponent -= DBL_MANT_DIG;
+	  u.ieee.exponent -= LDBL_MANT_DIG;
 	  if (v.ieee.exponent)
-	    v.ieee.exponent += DBL_MANT_DIG;
+	    v.ieee.exponent += LDBL_MANT_DIG;
 	  else
-	    v.d *= 0x1p53;
+	    v.d *= 0x1p113L;
 	}
-      else if (v.ieee.exponent >= 0x7ff - DBL_MANT_DIG)
+      else if (v.ieee.exponent >= 0x7fff - LDBL_MANT_DIG)
 	{
-	  v.ieee.exponent -= DBL_MANT_DIG;
+	  v.ieee.exponent -= LDBL_MANT_DIG;
 	  if (u.ieee.exponent)
-	    u.ieee.exponent += DBL_MANT_DIG;
+	    u.ieee.exponent += LDBL_MANT_DIG;
 	  else
-	    u.d *= 0x1p53;
+	    u.d *= 0x1p113L;
 	}
       else /* if (u.ieee.exponent + v.ieee.exponent
-		  <= IEEE754_DOUBLE_BIAS + DBL_MANT_DIG) */
+		  <= IEEE854_LONG_DOUBLE_BIAS + LDBL_MANT_DIG) */
 	{
 	  if (u.ieee.exponent > v.ieee.exponent)
-	    u.ieee.exponent += 2 * DBL_MANT_DIG;
+	    u.ieee.exponent += 2 * LDBL_MANT_DIG;
 	  else
-	    v.ieee.exponent += 2 * DBL_MANT_DIG;
-	  if (w.ieee.exponent <= 4 * DBL_MANT_DIG + 4)
+	    v.ieee.exponent += 2 * LDBL_MANT_DIG;
+	  if (w.ieee.exponent <= 4 * LDBL_MANT_DIG + 4)
 	    {
 	      if (w.ieee.exponent)
-		w.ieee.exponent += 2 * DBL_MANT_DIG;
+		w.ieee.exponent += 2 * LDBL_MANT_DIG;
 	      else
-		w.d *= 0x1p106;
+		w.d *= 0x1p226L;
 	      adjust = -1;
 	    }
 	  /* Otherwise x * y should just affect inexact
@@ -123,23 +130,23 @@ __fma (double x, double y, double z)
       z = w.d;
     }
   /* Multiplication m1 + m2 = x * y using Dekker's algorithm.  */
-#define C ((1 << (DBL_MANT_DIG + 1) / 2) + 1)
-  double x1 = x * C;
-  double y1 = y * C;
-  double m1 = x * y;
+#define C ((1LL << (LDBL_MANT_DIG + 1) / 2) + 1)
+  long double x1 = x * C;
+  long double y1 = y * C;
+  long double m1 = x * y;
   x1 = (x - x1) + x1;
   y1 = (y - y1) + y1;
-  double x2 = x - x1;
-  double y2 = y - y1;
-  double m2 = (((x1 * y1 - m1) + x1 * y2) + x2 * y1) + x2 * y2;
+  long double x2 = x - x1;
+  long double y2 = y - y1;
+  long double m2 = (((x1 * y1 - m1) + x1 * y2) + x2 * y1) + x2 * y2;
 
   /* Addition a1 + a2 = z + m1 using Knuth's algorithm.  */
-  double a1 = z + m1;
-  double t1 = a1 - z;
-  double t2 = a1 - t1;
+  long double a1 = z + m1;
+  long double t1 = a1 - z;
+  long double t2 = a1 - t1;
   t1 = m1 - t1;
   t2 = z - t2;
-  double a2 = t1 + t2;
+  long double a2 = t1 + t2;
 
   fenv_t env;
   feholdexcept (&env);
@@ -149,22 +156,24 @@ __fma (double x, double y, double z)
 
   if (__builtin_expect (adjust == 0, 1))
     {
-      if ((u.ieee.mantissa1 & 1) == 0 && u.ieee.exponent != 0x7ff)
-	u.ieee.mantissa1 |= fetestexcept (FE_INEXACT) != 0;
+      if ((u.ieee.mantissa3 & 1) == 0 && u.ieee.exponent != 0x7fff)
+	u.ieee.mantissa3 |= fetestexcept (FE_INEXACT) != 0;
       feupdateenv (&env);
       /* Result is a1 + u.d.  */
       return a1 + u.d;
     }
   else if (__builtin_expect (adjust > 0, 1))
     {
-      if ((u.ieee.mantissa1 & 1) == 0 && u.ieee.exponent != 0x7ff)
-	u.ieee.mantissa1 |= fetestexcept (FE_INEXACT) != 0;
+      if ((u.ieee.mantissa3 & 1) == 0 && u.ieee.exponent != 0x7fff)
+	u.ieee.mantissa3 |= fetestexcept (FE_INEXACT) != 0;
       feupdateenv (&env);
       /* Result is a1 + u.d, scaled up.  */
-      return (a1 + u.d) * 0x1p53;
+      return (a1 + u.d) * 0x1p113L;
     }
   else
     {
+      if ((u.ieee.mantissa3 & 1) == 0)
+	u.ieee.mantissa3 |= fetestexcept (FE_INEXACT) != 0;
       v.d = a1 + u.d;
       int j = fetestexcept (FE_INEXACT) != 0;
       feupdateenv (&env);
@@ -174,46 +183,39 @@ __fma (double x, double y, double z)
       /* If a1 + u.d is exact, the only rounding happens during
 	 scaling down.  */
       if (j == 0)
-	return v.d * 0x1p-106;
+	return v.d * 0x1p-226L;
       /* If result rounded to zero is not subnormal, no double
 	 rounding will occur.  */
-      if (v.ieee.exponent > 106)
-	return (a1 + u.d) * 0x1p-106;
-      /* If v.d * 0x1p-106 with round to zero is a subnormal above
-	 or equal to DBL_MIN / 2, then v.d * 0x1p-106 shifts mantissa
-	 down just by 1 bit, which means v.ieee.mantissa1 |= j would
+      if (v.ieee.exponent > 226)
+	return (a1 + u.d) * 0x1p-226L;
+      /* If v.d * 0x1p-226L with round to zero is a subnormal above
+	 or equal to LDBL_MIN / 2, then v.d * 0x1p-226L shifts mantissa
+	 down just by 1 bit, which means v.ieee.mantissa3 |= j would
 	 change the round bit, not sticky or guard bit.
-	 v.d * 0x1p-106 never normalizes by shifting up,
+	 v.d * 0x1p-226L never normalizes by shifting up,
 	 so round bit plus sticky bit should be already enough
 	 for proper rounding.  */
-      if (v.ieee.exponent == 106)
+      if (v.ieee.exponent == 226)
 	{
-	  /* v.ieee.mantissa1 & 2 is LSB bit of the result before rounding,
-	     v.ieee.mantissa1 & 1 is the round bit and j is our sticky
+	  /* v.ieee.mantissa3 & 2 is LSB bit of the result before rounding,
+	     v.ieee.mantissa3 & 1 is the round bit and j is our sticky
 	     bit.  In round-to-nearest 001 rounds down like 00,
 	     011 rounds up, even though 01 rounds down (thus we need
 	     to adjust), 101 rounds down like 10 and 111 rounds up
 	     like 11.  */
-	  if ((v.ieee.mantissa1 & 3) == 1)
+	  if ((v.ieee.mantissa3 & 3) == 1)
 	    {
-	      v.d *= 0x1p-106;
+	      v.d *= 0x1p-226L;
 	      if (v.ieee.negative)
-		return v.d - 0x1p-1074 /* __DBL_DENORM_MIN__ */;
+		return v.d - 0x1p-16493L /* __LDBL_DENORM_MIN__ */;
 	      else
-		return v.d + 0x1p-1074 /* __DBL_DENORM_MIN__ */;
+		return v.d + 0x1p-16493L /* __LDBL_DENORM_MIN__ */;
 	    }
 	  else
-	    return v.d * 0x1p-106;
+	    return v.d * 0x1p-226L;
 	}
-      v.ieee.mantissa1 |= j;
-      return v.d * 0x1p-106;
+      v.ieee.mantissa3 |= j;
+      return v.d * 0x1p-226L;
     }
 }
-#ifndef __fma
-weak_alias (__fma, fma)
-#endif
-
-#ifdef NO_LONG_DOUBLE
-strong_alias (__fma, __fmal)
 weak_alias (__fmal, fmal)
-#endif
diff --git a/sysdeps/ieee754/ldbl-64-128/s_fmal.c b/sysdeps/ieee754/ldbl-64-128/s_fmal.c
new file mode 100644
index 0000000..218aa52
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-64-128/s_fmal.c
@@ -0,0 +1,5 @@
+#include <math_ldbl_opt.h>
+#undef weak_alias
+#define weak_alias(n,a)
+#include <sysdeps/ieee754/ldbl-128/s_fmal.c>
+long_double_symbol (libm, __fmal, fmal);
diff --git a/sysdeps/ieee754/ldbl-96/s_fma.c b/sysdeps/ieee754/ldbl-96/s_fma.c
index 90c6d1f..6c7e9d0 100644
--- a/sysdeps/ieee754/ldbl-96/s_fma.c
+++ b/sysdeps/ieee754/ldbl-96/s_fma.c
@@ -30,11 +30,20 @@
 double
 __fma (double x, double y, double z)
 {
+  if (__builtin_expect (isinf (z), 0))
+    {
+      /* If z is Inf, but x and y are finite, the result should be
+	 z rather than NaN.  */
+      if (finite (x) && finite (y))
+	return (z + x) + y;
+      return (x * y) + z;
+    }
+
   /* Multiplication m1 + m2 = x * y using Dekker's algorithm.  */
 #define C ((1ULL << (LDBL_MANT_DIG + 1) / 2) + 1)
-  long double x1 = x * C;
-  long double y1 = y * C;
-  long double m1 = x * y;
+  long double x1 = (long double) x * C;
+  long double y1 = (long double) y * C;
+  long double m1 = (long double) x * y;
   x1 = (x - x1) + x1;
   y1 = (y - y1) + y1;
   long double x2 = x - x1;
diff --git a/sysdeps/ieee754/dbl-64/s_fma.c b/sysdeps/ieee754/ldbl-96/s_fmal.c
similarity index 59%
copy from sysdeps/ieee754/dbl-64/s_fma.c
copy to sysdeps/ieee754/ldbl-96/s_fmal.c
index 911682e..340f025 100644
--- a/sysdeps/ieee754/dbl-64/s_fma.c
+++ b/sysdeps/ieee754/ldbl-96/s_fmal.c
@@ -27,92 +27,99 @@
    double rounding.  See a paper by Boldo and Melquiond:
    http://www.lri.fr/~melquion/doc/08-tc.pdf  */
 
-double
-__fma (double x, double y, double z)
+long double
+__fmal (long double x, long double y, long double z)
 {
-  union ieee754_double u, v, w;
+  union ieee854_long_double u, v, w;
   int adjust = 0;
   u.d = x;
   v.d = y;
   w.d = z;
   if (__builtin_expect (u.ieee.exponent + v.ieee.exponent
-			>= 0x7ff + IEEE754_DOUBLE_BIAS - DBL_MANT_DIG, 0)
-      || __builtin_expect (u.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0)
-      || __builtin_expect (v.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0)
-      || __builtin_expect (w.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0)
+			>= 0x7fff + IEEE854_LONG_DOUBLE_BIAS
+			   - LDBL_MANT_DIG, 0)
+      || __builtin_expect (u.ieee.exponent >= 0x7fff - LDBL_MANT_DIG, 0)
+      || __builtin_expect (v.ieee.exponent >= 0x7fff - LDBL_MANT_DIG, 0)
+      || __builtin_expect (w.ieee.exponent >= 0x7fff - LDBL_MANT_DIG, 0)
       || __builtin_expect (u.ieee.exponent + v.ieee.exponent
-			   <= IEEE754_DOUBLE_BIAS + DBL_MANT_DIG, 0))
+			   <= IEEE854_LONG_DOUBLE_BIAS + LDBL_MANT_DIG, 0))
     {
+      /* If z is Inf, but x and y are finite, the result should be
+	 z rather than NaN.  */
+      if (w.ieee.exponent == 0x7fff
+	  && u.ieee.exponent != 0x7fff
+          && v.ieee.exponent != 0x7fff)
+	return (z + x) + y;
       /* If x or y or z is Inf/NaN, or if fma will certainly overflow,
-	 or if x * y is less than half of DBL_DENORM_MIN,
+	 or if x * y is less than half of LDBL_DENORM_MIN,
 	 compute as x * y + z.  */
-      if (u.ieee.exponent == 0x7ff
-	  || v.ieee.exponent == 0x7ff
-	  || w.ieee.exponent == 0x7ff
+      if (u.ieee.exponent == 0x7fff
+	  || v.ieee.exponent == 0x7fff
+	  || w.ieee.exponent == 0x7fff
 	  || u.ieee.exponent + v.ieee.exponent
-	     > 0x7ff + IEEE754_DOUBLE_BIAS
+	     > 0x7fff + IEEE854_LONG_DOUBLE_BIAS
 	  || u.ieee.exponent + v.ieee.exponent
-	     < IEEE754_DOUBLE_BIAS - DBL_MANT_DIG - 2)
+	     < IEEE854_LONG_DOUBLE_BIAS - LDBL_MANT_DIG - 2)
 	return x * y + z;
       if (u.ieee.exponent + v.ieee.exponent
-	  >= 0x7ff + IEEE754_DOUBLE_BIAS - DBL_MANT_DIG)
+	  >= 0x7fff + IEEE854_LONG_DOUBLE_BIAS - LDBL_MANT_DIG)
 	{
-	  /* Compute 1p-53 times smaller result and multiply
+	  /* Compute 1p-64 times smaller result and multiply
 	     at the end.  */
 	  if (u.ieee.exponent > v.ieee.exponent)
-	    u.ieee.exponent -= DBL_MANT_DIG;
+	    u.ieee.exponent -= LDBL_MANT_DIG;
 	  else
-	    v.ieee.exponent -= DBL_MANT_DIG;
+	    v.ieee.exponent -= LDBL_MANT_DIG;
 	  /* If x + y exponent is very large and z exponent is very small,
 	     it doesn't matter if we don't adjust it.  */
-	  if (w.ieee.exponent > DBL_MANT_DIG)
-	    w.ieee.exponent -= DBL_MANT_DIG;
+	  if (w.ieee.exponent > LDBL_MANT_DIG)
+	    w.ieee.exponent -= LDBL_MANT_DIG;
 	  adjust = 1;
 	}
-      else if (w.ieee.exponent >= 0x7ff - DBL_MANT_DIG)
+      else if (w.ieee.exponent >= 0x7fff - LDBL_MANT_DIG)
 	{
 	  /* Similarly.
 	     If z exponent is very large and x and y exponents are
 	     very small, it doesn't matter if we don't adjust it.  */
 	  if (u.ieee.exponent > v.ieee.exponent)
 	    {
-	      if (u.ieee.exponent > DBL_MANT_DIG)
-		u.ieee.exponent -= DBL_MANT_DIG;
+	      if (u.ieee.exponent > LDBL_MANT_DIG)
+		u.ieee.exponent -= LDBL_MANT_DIG;
 	    }
-	  else if (v.ieee.exponent > DBL_MANT_DIG)
-	    v.ieee.exponent -= DBL_MANT_DIG;
-	  w.ieee.exponent -= DBL_MANT_DIG;
+	  else if (v.ieee.exponent > LDBL_MANT_DIG)
+	    v.ieee.exponent -= LDBL_MANT_DIG;
+	  w.ieee.exponent -= LDBL_MANT_DIG;
 	  adjust = 1;
 	}
-      else if (u.ieee.exponent >= 0x7ff - DBL_MANT_DIG)
+      else if (u.ieee.exponent >= 0x7fff - LDBL_MANT_DIG)
 	{
-	  u.ieee.exponent -= DBL_MANT_DIG;
+	  u.ieee.exponent -= LDBL_MANT_DIG;
 	  if (v.ieee.exponent)
-	    v.ieee.exponent += DBL_MANT_DIG;
+	    v.ieee.exponent += LDBL_MANT_DIG;
 	  else
-	    v.d *= 0x1p53;
+	    v.d *= 0x1p64L;
 	}
-      else if (v.ieee.exponent >= 0x7ff - DBL_MANT_DIG)
+      else if (v.ieee.exponent >= 0x7fff - LDBL_MANT_DIG)
 	{
-	  v.ieee.exponent -= DBL_MANT_DIG;
+	  v.ieee.exponent -= LDBL_MANT_DIG;
 	  if (u.ieee.exponent)
-	    u.ieee.exponent += DBL_MANT_DIG;
+	    u.ieee.exponent += LDBL_MANT_DIG;
 	  else
-	    u.d *= 0x1p53;
+	    u.d *= 0x1p64L;
 	}
       else /* if (u.ieee.exponent + v.ieee.exponent
-		  <= IEEE754_DOUBLE_BIAS + DBL_MANT_DIG) */
+		  <= IEEE854_LONG_DOUBLE_BIAS + LDBL_MANT_DIG) */
 	{
 	  if (u.ieee.exponent > v.ieee.exponent)
-	    u.ieee.exponent += 2 * DBL_MANT_DIG;
+	    u.ieee.exponent += 2 * LDBL_MANT_DIG;
 	  else
-	    v.ieee.exponent += 2 * DBL_MANT_DIG;
-	  if (w.ieee.exponent <= 4 * DBL_MANT_DIG + 4)
+	    v.ieee.exponent += 2 * LDBL_MANT_DIG;
+	  if (w.ieee.exponent <= 4 * LDBL_MANT_DIG + 4)
 	    {
 	      if (w.ieee.exponent)
-		w.ieee.exponent += 2 * DBL_MANT_DIG;
+		w.ieee.exponent += 2 * LDBL_MANT_DIG;
 	      else
-		w.d *= 0x1p106;
+		w.d *= 0x1p128L;
 	      adjust = -1;
 	    }
 	  /* Otherwise x * y should just affect inexact
@@ -123,23 +130,23 @@ __fma (double x, double y, double z)
       z = w.d;
     }
   /* Multiplication m1 + m2 = x * y using Dekker's algorithm.  */
-#define C ((1 << (DBL_MANT_DIG + 1) / 2) + 1)
-  double x1 = x * C;
-  double y1 = y * C;
-  double m1 = x * y;
+#define C ((1LL << (LDBL_MANT_DIG + 1) / 2) + 1)
+  long double x1 = x * C;
+  long double y1 = y * C;
+  long double m1 = x * y;
   x1 = (x - x1) + x1;
   y1 = (y - y1) + y1;
-  double x2 = x - x1;
-  double y2 = y - y1;
-  double m2 = (((x1 * y1 - m1) + x1 * y2) + x2 * y1) + x2 * y2;
+  long double x2 = x - x1;
+  long double y2 = y - y1;
+  long double m2 = (((x1 * y1 - m1) + x1 * y2) + x2 * y1) + x2 * y2;
 
   /* Addition a1 + a2 = z + m1 using Knuth's algorithm.  */
-  double a1 = z + m1;
-  double t1 = a1 - z;
-  double t2 = a1 - t1;
+  long double a1 = z + m1;
+  long double t1 = a1 - z;
+  long double t2 = a1 - t1;
   t1 = m1 - t1;
   t2 = z - t2;
-  double a2 = t1 + t2;
+  long double a2 = t1 + t2;
 
   fenv_t env;
   feholdexcept (&env);
@@ -149,7 +156,7 @@ __fma (double x, double y, double z)
 
   if (__builtin_expect (adjust == 0, 1))
     {
-      if ((u.ieee.mantissa1 & 1) == 0 && u.ieee.exponent != 0x7ff)
+      if ((u.ieee.mantissa1 & 1) == 0 && u.ieee.exponent != 0x7fff)
 	u.ieee.mantissa1 |= fetestexcept (FE_INEXACT) != 0;
       feupdateenv (&env);
       /* Result is a1 + u.d.  */
@@ -157,14 +164,16 @@ __fma (double x, double y, double z)
     }
   else if (__builtin_expect (adjust > 0, 1))
     {
-      if ((u.ieee.mantissa1 & 1) == 0 && u.ieee.exponent != 0x7ff)
+      if ((u.ieee.mantissa1 & 1) == 0 && u.ieee.exponent != 0x7fff)
 	u.ieee.mantissa1 |= fetestexcept (FE_INEXACT) != 0;
       feupdateenv (&env);
       /* Result is a1 + u.d, scaled up.  */
-      return (a1 + u.d) * 0x1p53;
+      return (a1 + u.d) * 0x1p64L;
     }
   else
     {
+      if ((u.ieee.mantissa1 & 1) == 0)
+	u.ieee.mantissa1 |= fetestexcept (FE_INEXACT) != 0;
       v.d = a1 + u.d;
       int j = fetestexcept (FE_INEXACT) != 0;
       feupdateenv (&env);
@@ -174,19 +183,19 @@ __fma (double x, double y, double z)
       /* If a1 + u.d is exact, the only rounding happens during
 	 scaling down.  */
       if (j == 0)
-	return v.d * 0x1p-106;
+	return v.d * 0x1p-128L;
       /* If result rounded to zero is not subnormal, no double
 	 rounding will occur.  */
-      if (v.ieee.exponent > 106)
-	return (a1 + u.d) * 0x1p-106;
-      /* If v.d * 0x1p-106 with round to zero is a subnormal above
-	 or equal to DBL_MIN / 2, then v.d * 0x1p-106 shifts mantissa
+      if (v.ieee.exponent > 128)
+	return (a1 + u.d) * 0x1p-128L;
+      /* If v.d * 0x1p-128L with round to zero is a subnormal above
+	 or equal to LDBL_MIN / 2, then v.d * 0x1p-128L shifts mantissa
 	 down just by 1 bit, which means v.ieee.mantissa1 |= j would
 	 change the round bit, not sticky or guard bit.
-	 v.d * 0x1p-106 never normalizes by shifting up,
+	 v.d * 0x1p-128L never normalizes by shifting up,
 	 so round bit plus sticky bit should be already enough
 	 for proper rounding.  */
-      if (v.ieee.exponent == 106)
+      if (v.ieee.exponent == 128)
 	{
 	  /* v.ieee.mantissa1 & 2 is LSB bit of the result before rounding,
 	     v.ieee.mantissa1 & 1 is the round bit and j is our sticky
@@ -196,24 +205,17 @@ __fma (double x, double y, double z)
 	     like 11.  */
 	  if ((v.ieee.mantissa1 & 3) == 1)
 	    {
-	      v.d *= 0x1p-106;
+	      v.d *= 0x1p-128L;
 	      if (v.ieee.negative)
-		return v.d - 0x1p-1074 /* __DBL_DENORM_MIN__ */;
+		return v.d - 0x1p-16445L /* __LDBL_DENORM_MIN__ */;
 	      else
-		return v.d + 0x1p-1074 /* __DBL_DENORM_MIN__ */;
+		return v.d + 0x1p-16445L /* __LDBL_DENORM_MIN__ */;
 	    }
 	  else
-	    return v.d * 0x1p-106;
+	    return v.d * 0x1p-128L;
 	}
       v.ieee.mantissa1 |= j;
-      return v.d * 0x1p-106;
+      return v.d * 0x1p-128L;
     }
 }
-#ifndef __fma
-weak_alias (__fma, fma)
-#endif
-
-#ifdef NO_LONG_DOUBLE
-strong_alias (__fma, __fmal)
 weak_alias (__fmal, fmal)
-#endif

http://sources.redhat.com/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=f3f7372de1401b99f0a318ce09caf73e42d6f022

commit f3f7372de1401b99f0a318ce09caf73e42d6f022
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Oct 15 15:25:14 2010 -0400

    Fix some more dbl-64/s_fma.c issue

diff --git a/ChangeLog b/ChangeLog
index a6af960..62ba40b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2010-10-14  Jakub Jelinek  <jakub@redhat.com>
+
+	[BZ #3268]
+	* math/libm-test.inc (fma_test): Add some more tests.
+	* sysdeps/ieee754/dbl-64/s_fma.c (__fma): Handle underflows
+	correctly.
+
 2010-10-15  Andreas Schwab  <schwab@redhat.com>
 
 	* scripts/data/localplt-s390-linux-gnu.data: New file.
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 34c4fa9..1bec476 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -2808,6 +2808,16 @@ fma_test (void)
   TEST_fff_f (fma, 0x1.fffffffffffffp+1023, 0x1.001p+0, -0x1.fffffffffffffp+1023, 0x1.fffffffffffffp+1011);
   TEST_fff_f (fma, -0x1.fffffffffffffp+1023, 0x1.fffffffffffffp+0, 0x1.fffffffffffffp+1023, -0x1.ffffffffffffdp+1023);
   TEST_fff_f (fma, 0x1.fffffffffffffp+1023, 2.0, -0x1.fffffffffffffp+1023, 0x1.fffffffffffffp+1023);
+  TEST_fff_f (fma, 0x1.6a09e667f3bccp-538, 0x1.6a09e667f3bccp-538, 0.0, 0.0);
+  TEST_fff_f (fma, 0x1.deadbeef2feedp-495, 0x1.deadbeef2feedp-495, -0x1.bf86a5786a574p-989, 0x0.0000042625a1fp-1022);
+  TEST_fff_f (fma, 0x1.deadbeef2feedp-503, 0x1.deadbeef2feedp-503, -0x1.bf86a5786a574p-1005, 0x0.0000000004262p-1022);
+  TEST_fff_f (fma, 0x1p-537, 0x1p-538, 0x1p-1074, 0x0.0000000000002p-1022);
+  TEST_fff_f (fma, 0x1.7fffff8p-968, 0x1p-106, 0x0.000001p-1022, 0x0.0000010000001p-1022);
+  TEST_fff_f (fma, 0x1.4000004p-967, 0x1p-106, 0x0.000001p-1022, 0x0.0000010000003p-1022);
+  TEST_fff_f (fma, 0x1.4p-967, -0x1p-106, -0x0.000001p-1022, -0x0.0000010000002p-1022);
+  TEST_fff_f (fma, -0x1.19cab66d73e17p-959, 0x1.c7108a8c5ff51p-107, -0x0.80b0ad65d9b64p-1022, -0x0.80b0ad65d9d59p-1022);
+  TEST_fff_f (fma, -0x1.d2eaed6e8e9d3p-979, -0x1.4e066c62ac9ddp-63, -0x0.9245e6b003454p-1022, -0x0.9245c09c5fb5dp-1022);
+  TEST_fff_f (fma, 0x1.153d650bb9f06p-907, 0x1.2d01230d48407p-125, -0x0.b278d5acfc3cp-1022, -0x0.b22757123bbe9p-1022);
 #endif
 
   END (fma);
diff --git a/sysdeps/ieee754/dbl-64/s_fma.c b/sysdeps/ieee754/dbl-64/s_fma.c
index ca7300c..911682e 100644
--- a/sysdeps/ieee754/dbl-64/s_fma.c
+++ b/sysdeps/ieee754/dbl-64/s_fma.c
@@ -39,15 +39,20 @@ __fma (double x, double y, double z)
 			>= 0x7ff + IEEE754_DOUBLE_BIAS - DBL_MANT_DIG, 0)
       || __builtin_expect (u.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0)
       || __builtin_expect (v.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0)
-      || __builtin_expect (w.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0))
+      || __builtin_expect (w.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0)
+      || __builtin_expect (u.ieee.exponent + v.ieee.exponent
+			   <= IEEE754_DOUBLE_BIAS + DBL_MANT_DIG, 0))
     {
-      /* If x or y or z is Inf/NaN or if fma will certainly overflow,
+      /* If x or y or z is Inf/NaN, or if fma will certainly overflow,
+	 or if x * y is less than half of DBL_DENORM_MIN,
 	 compute as x * y + z.  */
       if (u.ieee.exponent == 0x7ff
 	  || v.ieee.exponent == 0x7ff
 	  || w.ieee.exponent == 0x7ff
 	  || u.ieee.exponent + v.ieee.exponent
-	     > 0x7ff + IEEE754_DOUBLE_BIAS)
+	     > 0x7ff + IEEE754_DOUBLE_BIAS
+	  || u.ieee.exponent + v.ieee.exponent
+	     < IEEE754_DOUBLE_BIAS - DBL_MANT_DIG - 2)
 	return x * y + z;
       if (u.ieee.exponent + v.ieee.exponent
 	  >= 0x7ff + IEEE754_DOUBLE_BIAS - DBL_MANT_DIG)
@@ -87,7 +92,7 @@ __fma (double x, double y, double z)
 	  else
 	    v.d *= 0x1p53;
 	}
-      else
+      else if (v.ieee.exponent >= 0x7ff - DBL_MANT_DIG)
 	{
 	  v.ieee.exponent -= DBL_MANT_DIG;
 	  if (u.ieee.exponent)
@@ -95,6 +100,24 @@ __fma (double x, double y, double z)
 	  else
 	    u.d *= 0x1p53;
 	}
+      else /* if (u.ieee.exponent + v.ieee.exponent
+		  <= IEEE754_DOUBLE_BIAS + DBL_MANT_DIG) */
+	{
+	  if (u.ieee.exponent > v.ieee.exponent)
+	    u.ieee.exponent += 2 * DBL_MANT_DIG;
+	  else
+	    v.ieee.exponent += 2 * DBL_MANT_DIG;
+	  if (w.ieee.exponent <= 4 * DBL_MANT_DIG + 4)
+	    {
+	      if (w.ieee.exponent)
+		w.ieee.exponent += 2 * DBL_MANT_DIG;
+	      else
+		w.d *= 0x1p106;
+	      adjust = -1;
+	    }
+	  /* Otherwise x * y should just affect inexact
+	     and nothing else.  */
+	}
       x = u.d;
       y = v.d;
       z = w.d;
@@ -123,18 +146,68 @@ __fma (double x, double y, double z)
   fesetround (FE_TOWARDZERO);
   /* Perform m2 + a2 addition with round to odd.  */
   u.d = a2 + m2;
-  if ((u.ieee.mantissa1 & 1) == 0 && u.ieee.exponent != 0x7ff)
-    u.ieee.mantissa1 |= fetestexcept (FE_INEXACT) != 0;
-  feupdateenv (&env);
-
-  /* Add that to a1.  */
-  a1 = a1 + u.d;
 
-  /* And adjust exponent if needed.  */
-  if (__builtin_expect (adjust, 0))
-    a1 *= 0x1p53;
-
-  return a1;
+  if (__builtin_expect (adjust == 0, 1))
+    {
+      if ((u.ieee.mantissa1 & 1) == 0 && u.ieee.exponent != 0x7ff)
+	u.ieee.mantissa1 |= fetestexcept (FE_INEXACT) != 0;
+      feupdateenv (&env);
+      /* Result is a1 + u.d.  */
+      return a1 + u.d;
+    }
+  else if (__builtin_expect (adjust > 0, 1))
+    {
+      if ((u.ieee.mantissa1 & 1) == 0 && u.ieee.exponent != 0x7ff)
+	u.ieee.mantissa1 |= fetestexcept (FE_INEXACT) != 0;
+      feupdateenv (&env);
+      /* Result is a1 + u.d, scaled up.  */
+      return (a1 + u.d) * 0x1p53;
+    }
+  else
+    {
+      v.d = a1 + u.d;
+      int j = fetestexcept (FE_INEXACT) != 0;
+      feupdateenv (&env);
+      /* Ensure the following computations are performed in default rounding
+	 mode instead of just reusing the round to zero computation.  */
+      asm volatile ("" : "=m" (u) : "m" (u));
+      /* If a1 + u.d is exact, the only rounding happens during
+	 scaling down.  */
+      if (j == 0)
+	return v.d * 0x1p-106;
+      /* If result rounded to zero is not subnormal, no double
+	 rounding will occur.  */
+      if (v.ieee.exponent > 106)
+	return (a1 + u.d) * 0x1p-106;
+      /* If v.d * 0x1p-106 with round to zero is a subnormal above
+	 or equal to DBL_MIN / 2, then v.d * 0x1p-106 shifts mantissa
+	 down just by 1 bit, which means v.ieee.mantissa1 |= j would
+	 change the round bit, not sticky or guard bit.
+	 v.d * 0x1p-106 never normalizes by shifting up,
+	 so round bit plus sticky bit should be already enough
+	 for proper rounding.  */
+      if (v.ieee.exponent == 106)
+	{
+	  /* v.ieee.mantissa1 & 2 is LSB bit of the result before rounding,
+	     v.ieee.mantissa1 & 1 is the round bit and j is our sticky
+	     bit.  In round-to-nearest 001 rounds down like 00,
+	     011 rounds up, even though 01 rounds down (thus we need
+	     to adjust), 101 rounds down like 10 and 111 rounds up
+	     like 11.  */
+	  if ((v.ieee.mantissa1 & 3) == 1)
+	    {
+	      v.d *= 0x1p-106;
+	      if (v.ieee.negative)
+		return v.d - 0x1p-1074 /* __DBL_DENORM_MIN__ */;
+	      else
+		return v.d + 0x1p-1074 /* __DBL_DENORM_MIN__ */;
+	    }
+	  else
+	    return v.d * 0x1p-106;
+	}
+      v.ieee.mantissa1 |= j;
+      return v.d * 0x1p-106;
+    }
 }
 #ifndef __fma
 weak_alias (__fma, fma)

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

Summary of changes:
 ChangeLog                                          |    7 +
 math/libm-test.inc                                 |   35 +++
 sysdeps/i386/fpu/s_fma.S                           |   31 ---
 sysdeps/i386/fpu/s_fmaf.S                          |   31 ---
 sysdeps/i386/fpu/s_fmal.S                          |   32 ---
 sysdeps/ieee754/dbl-64/s_fma.c                     |  111 +++++++++--
 sysdeps/ieee754/ldbl-128/s_fmal.c                  |  221 ++++++++++++++++++++
 sysdeps/ieee754/{ldbl-opt => ldbl-64-128}/s_fmal.c |    2 +-
 sysdeps/ieee754/ldbl-96/s_fma.c                    |   15 +-
 sysdeps/ieee754/ldbl-96/s_fmal.c                   |  221 ++++++++++++++++++++
 10 files changed, 593 insertions(+), 113 deletions(-)
 delete mode 100644 sysdeps/i386/fpu/s_fma.S
 delete mode 100644 sysdeps/i386/fpu/s_fmaf.S
 delete mode 100644 sysdeps/i386/fpu/s_fmal.S
 create mode 100644 sysdeps/ieee754/ldbl-128/s_fmal.c
 copy sysdeps/ieee754/{ldbl-opt => ldbl-64-128}/s_fmal.c (70%)
 create mode 100644 sysdeps/ieee754/ldbl-96/s_fmal.c


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