GNU C Library master sources branch master updated. glibc-2.23-476-g4fea2cd

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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=4fea2cda618de1c74959aaec79c020993c34c552

commit 4fea2cda618de1c74959aaec79c020993c34c552
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Tue Jun 14 14:56:42 2016 +0000

    Simplify generic fdim implementations.
    
    The generic fdim implementations have unnecessarily complicated code,
    using fpclassify to determine whether the arguments are NaNs,
    subtracting NaNs if so and otherwise subtracting the non-NaN arguments
    if not (x <= y), then using fpclassify on the result to see if it is
    infinite.
    
    This patch simplifies the code.  Instead of handling NaNs separately,
    it suffices to use an unordered comparison with islessequal (x, y) to
    determine whether to return zero, and otherwise NaNs can go through
    the same subtraction as non-NaN arguments; no explicit tests for NaN
    are needed at all.  Then, isinf instead of fpclassify can be used to
    determine whether to set errno (in the normal non-overflow case, only
    one classification will need to occur, unlike the three in the
    previous code, of which two occurred even if returning zero, because
    the result will not be infinite in the normal case).
    
    The resulting logic is essentially the same as that in the powerpc
    version, except that the powerpc version is missing errno setting and
    uses <= not islessequal, so relying on
    <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58684>, the GCC bug that
    unordered comparison instructions are wrongly used on powerpc for
    ordered comparisons.
    
    The compiled code for fdim and fdimf on x86_64 is less than half the
    size of the previous code.
    
    Tested for x86_64.
    
    	* math/s_fdim.c (__fdim): Use islessequal and isinf instead of
    	fpclassify.
    	* math/s_fdimf.c (__fdimf): Likewise.
    	* math/s_fdiml.c (__fdiml): Likewise.

diff --git a/ChangeLog b/ChangeLog
index 495f088..abd8fcb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2016-06-14  Joseph Myers  <joseph@codesourcery.com>
+
+	* math/s_fdim.c (__fdim): Use islessequal and isinf instead of
+	fpclassify.
+	* math/s_fdimf.c (__fdimf): Likewise.
+	* math/s_fdiml.c (__fdiml): Likewise.
+
 2016-06-14  Rajalakshmi Srinivasaraghavan  <raji@linux.vnet.ibm.com>
 
 	* sysdeps/powerpc/powerpc64/multiarch/Makefile:
diff --git a/math/s_fdim.c b/math/s_fdim.c
index b02ed27..8789ca4 100644
--- a/math/s_fdim.c
+++ b/math/s_fdim.c
@@ -23,19 +23,11 @@
 double
 __fdim (double x, double y)
 {
-  int clsx = fpclassify (x);
-  int clsy = fpclassify (y);
-
-  if (clsx == FP_NAN || clsy == FP_NAN)
-    /* Raise invalid flag for signaling but not quiet NaN.  */
-    return x - y;
-
-  if (x <= y)
+  if (islessequal (x, y))
     return 0.0;
 
   double r = x - y;
-  if (fpclassify (r) == FP_INFINITE
-      && clsx != FP_INFINITE && clsy != FP_INFINITE)
+  if (isinf (r) && !isinf (x) && !isinf (y))
     __set_errno (ERANGE);
 
   return r;
diff --git a/math/s_fdimf.c b/math/s_fdimf.c
index b905380..2e8eccf 100644
--- a/math/s_fdimf.c
+++ b/math/s_fdimf.c
@@ -23,19 +23,11 @@
 float
 __fdimf (float x, float y)
 {
-  int clsx = fpclassify (x);
-  int clsy = fpclassify (y);
-
-  if (clsx == FP_NAN || clsy == FP_NAN)
-    /* Raise invalid flag for signaling but not quiet NaN.  */
-    return x - y;
-
-  if (x <= y)
+  if (islessequal (x, y))
     return 0.0f;
 
   float r = x - y;
-  if (fpclassify (r) == FP_INFINITE
-      && clsx != FP_INFINITE && clsy != FP_INFINITE)
+  if (isinf (r) && !isinf (x) && !isinf (y))
     __set_errno (ERANGE);
 
   return r;
diff --git a/math/s_fdiml.c b/math/s_fdiml.c
index df3f1e5..4a1f672 100644
--- a/math/s_fdiml.c
+++ b/math/s_fdiml.c
@@ -23,19 +23,11 @@
 long double
 __fdiml (long double x, long double y)
 {
-  int clsx = fpclassify (x);
-  int clsy = fpclassify (y);
-
-  if (clsx == FP_NAN || clsy == FP_NAN)
-    /* Raise invalid flag for signaling but not quiet NaN.  */
-    return x - y;
-
-  if (x <= y)
+  if (islessequal (x, y))
     return 0.0f;
 
   long double r = x - y;
-  if (fpclassify (r) == FP_INFINITE
-      && clsx != FP_INFINITE && clsy != FP_INFINITE)
+  if (isinf (r) && !isinf (x) && !isinf (y))
     __set_errno (ERANGE);
 
   return r;

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

Summary of changes:
 ChangeLog      |    7 +++++++
 math/s_fdim.c  |   12 ++----------
 math/s_fdimf.c |   12 ++----------
 math/s_fdiml.c |   12 ++----------
 4 files changed, 13 insertions(+), 30 deletions(-)


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