Optimize x86-64 signbit{,f} a bit.

git-mirror · Aug 24, 2009 · ef72d5f · ef72d5f
1 parent 4b6bf3f
commit ef72d5f
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diff --git a/ChangeLog b/ChangeLog
@@ -1,3 +1,8 @@
+2009-08-24  Ulrich Drepper  <drepper@redhat.com>
+
+	* sysdeps/x86_64/fpu/bits/mathinline.h (__signbit): Optimize.
+	(__signbitf): Likewise.
+
 2009-08-23  Ulrich Drepper  <drepper@redhat.com>
 
 	* posix/regcomp.c (parse_dup_op): Verify the expression is correctly

diff --git a/sysdeps/x86_64/fpu/bits/mathinline.h b/sysdeps/x86_64/fpu/bits/mathinline.h
@@ -1,5 +1,5 @@
 /* Inline math functions for x86-64.
-   Copyright (C) 2002, 2003, 2004, 2007 Free Software Foundation, Inc.
+   Copyright (C) 2002, 2003, 2004, 2007, 2009 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Andreas Jaeger <aj@suse.de>, 2002.
 
@@ -35,14 +35,16 @@
 __MATH_INLINE int
 __NTH (__signbitf (float __x))
 {
-  __extension__ union { float __f; int __i; } __u = { __f: __x };
-  return __u.__i < 0;
+  int __m;
+  asm ("pmovmskb %1, %0" : "=r" (__m) : "x" (__x));
+  return __m & 0x8;
 }
 __MATH_INLINE int
 __NTH (__signbit (double __x))
 {
-  __extension__ union { double __d; int __i[2]; } __u = { __d: __x };
-  return __u.__i[1] < 0;
+  int __m;
+  asm ("pmovmskb %1, %0" : "=r" (__m) : "x" (__x));
+  return __m & 0x80;
 }
 __MATH_INLINE int
 __NTH (__signbitl (long double __x))