[Bug target/31394] cos() returns wrong value unless -O0 is used

[Bug target/31394] cos() returns wrong value unless -O0 is used

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31394

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-01-19 05:01:17 UTC ---
This is a bug in Solaris's libc where sincos does not produce the same results
as sin() and cos() separately would.

[Bug target/31394] cos() returns wrong value unless -O0 is used

[dominiq at lps dot ens dot fr]

------- Comment #4 from dominiq at lps dot ens dot fr  2007-03-30 21:56 -------
> I suppose that makes it a duplicate of PR30980.

It would have been better to check it directly before updating.  PR30980 was
related to g++ and gfortran and not gcc, so it seems that your platform
(i386-pc-solaris2.10?) differs from Darwin at least.

Now, could you please time the C test of PR31249, with and without -O and
report what you get:

#include <math.h>
#include <stdio.h>

int main()
{

  long    n = 1000000;
  long    i;
  double mo = -1.0;
  double pi = acos(mo);
  double sc = 0.0;
  double ss = 0.0;
  double  t = 0.0;
  double dt = pi/n;

  printf("%.17g \n", pi);
  printf("%.17g \n", dt);
  for (i=0; i< 40*n; i++) {
    sc += cos(t);
    ss += sin(t);
    t += dt;
  }
  printf("%.17g %.17g \n", sc, ss);
}

It will take less than a couple of minutes and see if -O is a real optimization
or not on your platform.
TIA


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31394

[Bug target/31394] cos() returns wrong value unless -O0 is used

[sdirkse at gams dot com]

------- Comment #3 from sdirkse at gams dot com  2007-03-30 21:36 -------
I installed gcc 20070329 and the problem I was having is solved.  I suppose
that makes it a duplicate of PR30980.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31394

[Bug target/31394] cos() returns wrong value unless -O0 is used

[dominiq at lps dot ens dot fr]

------- Comment #2 from dominiq at lps dot ens dot fr  2007-03-29 18:50 -------
This bug reminds me PR30980 and PR31161, though they were reported only for g++
and gfortran (they were fixed on 2007-03-16). Could you look at them to see if
the bug you have reported is not a duplicate? If yes, you should update your
build.

Could you be also kind enough to look at the related optimization problem
PR31249 and see it affects also your platform?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31394