3 files changed, 27 insertions, 19 deletions

diff --git a/sysdeps/powerpc/power7/fpu/s_logb.c b/sysdeps/powerpc/power7/fpu/s_logb.c
index 24f7fad4d5..f7eec8ff06 100644
--- a/sysdeps/powerpc/power7/fpu/s_logb.c
+++ b/sysdeps/powerpc/power7/fpu/s_logb.c
@@ -1,5 +1,5 @@
 /* logb(). PowerPC/POWER7 version.
-   Copyright (C) 2012-2016 Free Software Foundation, Inc.
+   Copyright (C) 2012-2018 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
@@ -16,7 +16,10 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#include <math.h>
+#include <math_private.h>
 #include <math_ldbl_opt.h>
+#include <libm-alias-double.h>
 
 /* This implementation avoids FP to INT conversions by using VSX
    bitwise instructions over FP values.  */
@@ -68,12 +71,4 @@ __logb (double x)
   /* Test to avoid logb_downward (0.0) == -0.0.  */
   return ret == -0.0 ? 0.0 : ret;
 }
-weak_alias (__logb, logb)
-#ifdef NO_LONG_DOUBLE
-strong_alias (__logb, __logbl)
-weak_alias (__logb, logbl)
-#endif
-
-#if LONG_DOUBLE_COMPAT (libm, GLIBC_2_0)
-compat_symbol (libm, logb, logbl, GLIBC_2_0);
-#endif
+libm_alias_double (__logb, logb)
diff --git a/sysdeps/powerpc/power7/fpu/s_logbf.c b/sysdeps/powerpc/power7/fpu/s_logbf.c
index a3873b842b..0832ad7022 100644
--- a/sysdeps/powerpc/power7/fpu/s_logbf.c
+++ b/sysdeps/powerpc/power7/fpu/s_logbf.c
@@ -1,5 +1,5 @@
 /* logbf(). PowerPC/POWER7 version.
-   Copyright (C) 2012-2016 Free Software Foundation, Inc.
+   Copyright (C) 2012-2018 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
@@ -17,6 +17,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include "math_private.h"
+#include <libm-alias-float.h>
 
 /* This implementation avoids FP to INT conversions by using VSX
    bitwise instructions over FP values.  */
@@ -57,4 +58,4 @@ __logbf (float x)
      The test is to avoid logb_downward (0.0) == -0.0.  */
   return ret == -0.0 ? 0.0 : ret;
 }
-weak_alias (__logbf, logbf)
+libm_alias_float (__logb, logb)
diff --git a/sysdeps/powerpc/power7/fpu/s_logbl.c b/sysdeps/powerpc/power7/fpu/s_logbl.c
index ec6907efc5..192145a7a1 100644
--- a/sysdeps/powerpc/power7/fpu/s_logbl.c
+++ b/sysdeps/powerpc/power7/fpu/s_logbl.c
@@ -1,5 +1,5 @@
 /* logbl(). PowerPC/POWER7 version.
-   Copyright (C) 2012-2016 Free Software Foundation, Inc.
+   Copyright (C) 2012-2018 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
@@ -35,14 +35,16 @@ static const union {
 long double
 __logbl (long double x)
 {
-  double xh;
+  double xh, xl;
   double ret;
+  int64_t hx;
 
   if (__builtin_expect (x == 0.0L, 0))
     /* Raise FE_DIVBYZERO and return -HUGE_VAL[LF].  */
     return -1.0L / __builtin_fabsl (x);
 
-  xh = ldbl_high (x);
+  ldbl_unpack (x, &xh, &xl);
+  EXTRACT_WORDS64 (hx, xh);
   /* ret = x & 0x7ff0000000000000;  */
   asm (
     "xxland %x0,%x1,%x2\n"
@@ -58,10 +60,20 @@ __logbl (long double x)
     {
       /* POSIX specifies that denormal number is treated as
          though it were normalized.  */
-      int64_t hx;
-
-      EXTRACT_WORDS64 (hx, xh);
-      return (long double) (-1023 - (__builtin_clzll (hx) - 12));
+      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;