[Bug c/44198] New: Constant floating point values are mutable (with '-O1')

[AlekM at hotmail dot com]

The example code below, compiled on x86 with gcc versions 4.1.2 through 4.4.0,
aborts when executed.

#include <stdlib.h>
#include <assert.h>

int main(void)__attribute__ ((optimize("O1")));  // Also with '-O2'
int main(void)
{
   const float a = rand(); // Any function call that returns 1804289383 will do
   volatile float tmp=a;

   assert(tmp==a); // This one aborts
   assert(tmp==a); // This one passes (if line above is replaced with printf)
}

If you replace assert() with two consecutive printf("%f ", a), two different
values are displayed for the constant variable a.


-- 
           Summary: Constant floating point values are mutable (with '-O1')
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: AlekM at hotmail dot com
 GCC build triplet: gcc version 4.4.0 20090514 (Red Hat 4.4.0-6) (GCC)
  GCC host triplet: Linux hld-lx 2.6.18-128.7.1.el5 #1 SMP Mon Aug 24
                    08:20:55 EDT 2
GCC target triplet: same as above


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44198