Prepare for radical source tree reorganization. zack/build-layout-experiment

All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).

1 files changed, 257 insertions, 0 deletions

diff --git a/REORG.TODO/sysdeps/ieee754/ldbl-128ibm/s_fmal.c b/REORG.TODO/sysdeps/ieee754/ldbl-128ibm/s_fmal.c
new file mode 100644
index 0000000000..9098e79df9
--- /dev/null
+++ b/REORG.TODO/sysdeps/ieee754/ldbl-128ibm/s_fmal.c
@@ -0,0 +1,257 @@
+/* Compute x * y + z as ternary operation.
+   Copyright (C) 2011-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by David Flaherty <flaherty@linux.vnet.ibm.com>.
+
+   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 <fenv.h>
+#include <float.h>
+#include <math.h>
+#include <math_private.h>
+#include <math_ldbl_opt.h>
+#include <mul_split.h>
+#include <stdlib.h>
+
+/* Calculate X + Y exactly and store the result in *HI + *LO.  It is
+   given that |X| >= |Y| and the values are small enough that no
+   overflow occurs.  */
+
+static void
+add_split (double *hi, double *lo, double x, double y)
+{
+  /* Apply Dekker's algorithm.  */
+  *hi = x + y;
+  *lo = (x - *hi) + y;
+}
+
+/* Value with extended range, used in intermediate computations.  */
+typedef struct
+{
+  /* Value in [0.5, 1), as from frexp, or 0.  */
+  double val;
+  /* Exponent of power of 2 it is multiplied by, or 0 for zero.  */
+  int exp;
+} ext_val;
+
+/* Store D as an ext_val value.  */
+
+static void
+store_ext_val (ext_val *v, double d)
+{
+  v->val = __frexp (d, &v->exp);
+}
+
+/* Store X * Y as ext_val values *V0 and *V1.  */
+
+static void
+mul_ext_val (ext_val *v0, ext_val *v1, double x, double y)
+{
+  int xexp, yexp;
+  x = __frexp (x, &xexp);
+  y = __frexp (y, &yexp);
+  double hi, lo;
+  mul_split (&hi, &lo, x, y);
+  store_ext_val (v0, hi);
+  if (hi != 0)
+    v0->exp += xexp + yexp;
+  store_ext_val (v1, lo);
+  if (lo != 0)
+    v1->exp += xexp + yexp;
+}
+
+/* Compare absolute values of ext_val values pointed to by P and Q for
+   qsort.  */
+
+static int
+compare (const void *p, const void *q)
+{
+  const ext_val *pe = p;
+  const ext_val *qe = q;
+  if (pe->val == 0)
+    return qe->val == 0 ? 0 : -1;
+  else if (qe->val == 0)
+    return 1;
+  else if (pe->exp < qe->exp)
+    return -1;
+  else if (pe->exp > qe->exp)
+    return 1;
+  else
+    {
+      double pd = fabs (pe->val);
+      double qd = fabs (qe->val);
+      if (pd < qd)
+	return -1;
+      else if (pd == qd)
+	return 0;
+      else
+	return 1;
+    }
+}
+
+/* Calculate *X + *Y exactly, storing the high part in *X (rounded to
+   nearest) and the low part in *Y.  It is given that |X| >= |Y|.  */
+
+static void
+add_split_ext (ext_val *x, ext_val *y)
+{
+  int xexp = x->exp, yexp = y->exp;
+  if (y->val == 0 || xexp - yexp > 53)
+    return;
+  double hi = x->val;
+  double lo = __scalbn (y->val, yexp - xexp);
+  add_split (&hi, &lo, hi, lo);
+  store_ext_val (x, hi);
+  if (hi != 0)
+    x->exp += xexp;
+  store_ext_val (y, lo);
+  if (lo != 0)
+    y->exp += xexp;
+}
+
+long double
+__fmal (long double x, long double y, long double z)
+{
+  double xhi, xlo, yhi, ylo, zhi, zlo;
+  int64_t hx, hy, hz;
+  int xexp, yexp, zexp;
+  double scale_val;
+  int scale_exp;
+  ldbl_unpack (x, &xhi, &xlo);
+  EXTRACT_WORDS64 (hx, xhi);
+  xexp = (hx & 0x7ff0000000000000LL) >> 52;
+  ldbl_unpack (y, &yhi, &ylo);
+  EXTRACT_WORDS64 (hy, yhi);
+  yexp = (hy & 0x7ff0000000000000LL) >> 52;
+  ldbl_unpack (z, &zhi, &zlo);
+  EXTRACT_WORDS64 (hz, zhi);
+  zexp = (hz & 0x7ff0000000000000LL) >> 52;
+
+  /* If z is Inf or NaN, but x and y are finite, avoid any exceptions
+     from computing x * y.  */
+  if (zexp == 0x7ff && xexp != 0x7ff && yexp != 0x7ff)
+    return (z + x) + y;
+
+  /* If z is zero and x are y are nonzero, compute the result as x * y
+     to avoid the wrong sign of a zero result if x * y underflows to
+     0.  */
+  if (z == 0 && x != 0 && y != 0)
+    return x * y;
+
+  /* If x or y or z is Inf/NaN, or if x * y is zero, compute as x * y
+     + z.  */
+  if (xexp == 0x7ff || yexp == 0x7ff || zexp == 0x7ff
+      || x == 0 || y == 0)
+    return (x * y) + z;
+
+  {
+    SET_RESTORE_ROUND (FE_TONEAREST);
+
+    ext_val vals[10];
+    store_ext_val (&vals[0], zhi);
+    store_ext_val (&vals[1], zlo);
+    mul_ext_val (&vals[2], &vals[3], xhi, yhi);
+    mul_ext_val (&vals[4], &vals[5], xhi, ylo);
+    mul_ext_val (&vals[6], &vals[7], xlo, yhi);
+    mul_ext_val (&vals[8], &vals[9], xlo, ylo);
+    qsort (vals, 10, sizeof (ext_val), compare);
+    /* Add up the values so that each element of VALS has absolute
+       value at most equal to the last set bit of the next nonzero
+       element.  */
+    for (size_t i = 0; i <= 8; i++)
+      {
+	add_split_ext (&vals[i + 1], &vals[i]);
+	qsort (vals + i + 1, 9 - i, sizeof (ext_val), compare);
+      }
+    /* Add up the values in the other direction, so that each element
+       of VALS has absolute value less than 5ulp of the next
+       value.  */
+    size_t dstpos = 9;
+    for (size_t i = 1; i <= 9; i++)
+      {
+	if (vals[dstpos].val == 0)
+	  {
+	    vals[dstpos] = vals[9 - i];
+	    vals[9 - i].val = 0;
+	    vals[9 - i].exp = 0;
+	  }
+	else
+	  {
+	    add_split_ext (&vals[dstpos], &vals[9 - i]);
+	    if (vals[9 - i].val != 0)
+	      {
+		if (9 - i < dstpos - 1)
+		  {
+		    vals[dstpos - 1] = vals[9 - i];
+		    vals[9 - i].val = 0;
+		    vals[9 - i].exp = 0;
+		  }
+		dstpos--;
+	      }
+	  }
+      }
+    /* If the result is an exact zero, it results from adding two
+       values with opposite signs; recompute in the original rounding
+       mode.  */
+    if (vals[9].val == 0)
+      goto zero_out;
+    /* Adding the top three values will now give a result as accurate
+       as the underlying long double arithmetic.  */
+    add_split_ext (&vals[9], &vals[8]);
+    if (compare (&vals[8], &vals[7]) < 0)
+      {
+	ext_val tmp = vals[7];
+	vals[7] = vals[8];
+	vals[8] = tmp;
+      }
+    add_split_ext (&vals[8], &vals[7]);
+    add_split_ext (&vals[9], &vals[8]);
+    if (vals[9].exp > DBL_MAX_EXP || vals[9].exp < DBL_MIN_EXP)
+      {
+	/* Overflow or underflow, with the result depending on the
+	   original rounding mode, but not on the low part computed
+	   here.  */
+	scale_val = vals[9].val;
+	scale_exp = vals[9].exp;
+	goto scale_out;
+      }
+    double hi = __scalbn (vals[9].val, vals[9].exp);
+    double lo = __scalbn (vals[8].val, vals[8].exp);
+    /* It is possible that the low part became subnormal and was
+       rounded so that the result is no longer canonical.  */
+    ldbl_canonicalize (&hi, &lo);
+    long double ret = ldbl_pack (hi, lo);
+    math_check_force_underflow (ret);
+    return ret;
+  }
+
+ scale_out:
+  scale_val = math_opt_barrier (scale_val);
+  scale_val = __scalbn (scale_val, scale_exp);
+  if (fabs (scale_val) == DBL_MAX)
+    return __copysignl (LDBL_MAX, scale_val);
+  math_check_force_underflow (scale_val);
+  return scale_val;
+
+ zero_out:;
+  double zero = 0.0;
+  zero = math_opt_barrier (zero);
+  return zero - zero;
+}
+#if IS_IN (libm)
+long_double_symbol (libm, __fmal, fmal);
+#else
+long_double_symbol (libc, __fmal, fmal);
+#endif