[Bug rtl-optimization/323] optimized code gives strange floating point results

[bruno at clisp dot org]

------- Comment #87 from bruno at clisp dot org  2006-12-21 15:08 -------
The option -ffloat-store, recommended by Richard Henderson, has the effect of
decreasing the performance of floating-point operations for the entire
compilation unit. If you want a minimal fix that does not affect other
functions in the same compilation unit, you can use 'volatile double'
instead of 'double'. It's like a one-shot -ffloat-store. Example:

#include <stdio.h>

void test(double x, double y)
{
  const volatile double y2 = x + 1.0;
  if (y != y2) printf("error\n");
}

void main()
{
  const double x = .012;
  const double y = x + 1.0;

  test(x, y);
}


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323