[Cairo] Use __builtin_popcount when available

[Richard Henderson]

Ok?


r~


	* iccolor.c (Ones): Define as __builtin_popcount when available.

Index: iccolor.c
===================================================================
RCS file: /local/src/CVS/libic/src/iccolor.c,v
retrieving revision 1.2
diff -c -p -d -r1.2 iccolor.c
*** iccolor.c	31 Jul 2003 17:00:09 -0000	1.2
--- iccolor.c	31 Jul 2003 17:31:16 -0000
***************
*** 25,35 ****
  
  #include "icint.h"
  
  static int
! Ones(unsigned long mask);
! 
! static int
! Ones(unsigned long mask)                /* HACKMEM 169 */
  {
      register unsigned long y;
  
--- 25,44 ----
  
  #include "icint.h"
  
+ /* GCC 3.4 supports a "population count" builtin, which on many targets is
+    implemented with a single instruction.  There is a fallback definition
+    in libgcc in case a target does not have one, which should be just as
+    good as the static function below.  */
+ #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
+ # if __INT_MIN__ == 0x7fffffff
+ #  define Ones(mask)		__builtin_popcount(mask)
+ # else
+ #  define Ones(mask)		__builtin_popcountl((mask) & 0xffffffff)
+ # endif
+ #else
+ /* Otherwise fall back on HACKMEM 169.  */
  static int
! Ones(unsigned long mask)
  {
      register unsigned long y;
  
*************** Ones(unsigned long mask)                
*** 37,42 ****
--- 46,52 ----
      y = mask - y - ((y >>1) & 033333333333);
      return (((y + (y >> 3)) & 030707070707) % 077);
  }
+ #endif
  
  void
  IcColorToPixel (const IcFormat	*format,