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Date: Tue, 4 Feb 1997 16:04:38 +0900 (JST)
From: Tetsuya Kimura <kimura@kaiseki.yamaha-motor.co.jp>
Message-Id: <199702040704.QAA12319@eir115.yamaha-motor.co.jp>
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Subject: [FreeBSD-users-jp 9432] gcc with -malign-double (Re: performance on numerical calculationdependsonshells?)
Errors-To: owner-FreeBSD-users-jp@jp.freebsd.org
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$B%d%^%OH/F05!$NLZB<$H?=$7$^$9!#(B

$B%@%$%8%'%9%H$G!"(Bnbody.c $B$K$h$k%Y%s%A%^!<%/$N0lO"$NOC$r(B
$B6=L#?<$/GR8+$5$;$FD:$$$F$$$^$9!#(B

$B;d$b0JA0(B int $B$rDI2C$7$?$j$7$J$+$C$?$j$G%Q%U%)!<%^%s%9$,(B
$BG\$[$I0c$&$H$$$&$3$H$,$"$C$F!"$3$&$$$&$3$H$,$"$k$s$@$m$&(B
$B$HGv!946$8$F$$$^$7$?$,!"(Bgcc-2.7.2.1 $B$K$O(B -malign-double 
$B$H$$$&%*%W%7%g%s$,$"$k$N$r=i$a$FCN$j$^$7$?!#(B

$B$G!"(Bnbody.c $B$G$9$,!"$I$J$?$+$,$*$C$7$c$i$l$?$h$&$K!"(B
$BG[Ns$r(B static $B$K<h$l$PB.$/$J$k$h$&$K$O$J$C$?$N$G$9$,!"(B
$B0JA0;d$,7P83$7$?$h$&$KM>J,$K(B int $B$NJQ?t$,I,MW$G$7$?!#(B

--- nbody.c     Tue Feb  4 14:21:05 1997
+++ nbodys.c    Tue Feb  4 15:57:50 1997
@@ -6,12 +6,14 @@
 #define n nx*ny*nz
 
 int main() {
-  double m[n];
-  double rx[n], ry[n], rz[n];
-  double ax[n], ay[n], az[n];
+  static int idmy;
+  static double m[n];
+  static double rx[n], ry[n], rz[n];
+  static double ax[n], ay[n], az[n];
   double tmp;
   int ix, iy, iz, i, j;
 
+  printf("%lx\n", m);
   /* set mass */
   for (i = 0; i < n; i++) {
     m[i] = 1.0;

% gcc -O2 -DRUN -DN=20 -o nbodys nbodys.c -lm
% /usr/bin/time ./nbodys
40e8
       61.06 real        60.72 user         0.02 sys

$B$3$N(B static int idmy $B$,7y$J$N$G!"(Bgcc -malign-double $B$G(B
$B%3%s%Q%$%k$9$k$H!"CY$/$J$kB&$K(B align $B$5$l$F$7$^$&$N$G$9$,!"(B
$B2?$+B>$K%*%W%7%g%s$,I,MW$J$N$G$7$g$&$+!#$=$l$H$b(B gcc $B$N(B
make $B$K<:GT$7$F$$$k$N$G$7$g$&$+!#(B
OS $B$O(B FreeBSD-2.1.5R $B$G$9!#(B

% gcc -O2 -malign-double -DRUN -DN=20 -o nbodys nbodys.c -lm
% /usr/bin/time ./nbodys
40ec
      110.14 real       109.49 user         0.00 sys

-----
$BLZB<(B $BE/Li(B
kimura@kaiseki.yamaha-motor.co.jp
