1 files changed, 78 insertions, 0 deletions
diff --git a/sysdeps/powerpc/fpu/s_logbl.c b/sysdeps/powerpc/fpu/s_logbl.c
new file mode 100644
index 0000000000..543cd4a188
--- /dev/null
+++ b/sysdeps/powerpc/fpu/s_logbl.c
@@ -0,0 +1,78 @@
+/* Get exponent of a floating-point value.  PowerPC version.
+   Copyright (C) 2012-2019 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/>.  */
+
+/* ISA 2.07 provides fast GPR to FP instruction (mfvsr{d,wz}) which make
+   generic implementation faster.  */
+#if defined(_ARCH_PWR8) || !defined(_ARCH_PWR7)
+# include <./sysdeps/ieee754/ldbl-128ibm/s_logbl.c>
+#else
+# include <math.h>
+# include <math_private.h>
+# include <math_ldbl_opt.h>
+
+/* This implementation avoids FP to INT conversions by using VSX
+   bitwise instructions over FP values.  */
+long double
+__logbl (long double x)
+{
+  double xh, xl;
+  double ret;
+  int64_t hx;
+
+  if (__glibc_unlikely (x == 0.0))
+    /* Raise FE_DIVBYZERO and return -HUGE_VAL[LF].  */
+    return -1.0L / __builtin_fabsl (x);
+
+  ldbl_unpack (x, &xh, &xl);
+  EXTRACT_WORDS64 (hx, xh);
+
+  /* Mask to extract the exponent.  */
+  asm ("xxland %x0,%x1,%x2\n"
+       "fcfid  %0,%0"
+       : "=d" (ret)
+       : "d" (xh), "d" (0x7ff0000000000000ULL));
+  ret = (ret * 0x1p-52) - 1023.0;
+  if (ret > 1023.0)
+    /* Multiplication is used to set logb (+-INF) = INF.  */
+    return (xh * xh);
+  else if (ret == -1023.0)
+    {
+      /* POSIX specifies that denormal number is treated as
+         though it were normalized.  */
+      return (long double) (- (__builtin_clzll (hx & 0x7fffffffffffffffLL) \
+			       - 12) - 1023);
+    }
+  else if ((hx & 0x000fffffffffffffLL) == 0)
+    {
+      /* If the high part is a power of 2, and the low part is nonzero
+	 with the opposite sign, the low part affects the
+	 exponent.  */
+      int64_t lx, rhx;
+      EXTRACT_WORDS64 (lx, xl);
+      rhx = (hx & 0x7ff0000000000000LL) >> 52;
+      if ((hx ^ lx) < 0 && (lx & 0x7fffffffffffffffLL) != 0)
+	rhx--;
+      return (long double) (rhx - 1023);
+    }
+  /* Test to avoid logb_downward (0.0) == -0.0.  */
+  return ret == -0.0 ? 0.0 : ret;
+}
+# ifndef __logbl
+long_double_symbol (libm, __logbl, logbl);
+# endif
+#endif