[Bug c/55771] New: Negation and type conversion incorrectly exchanged

["ian at airs dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55771

             Bug #: 55771
           Summary: Negation and type conversion incorrectly exchanged
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ian@airs.com


This program should print the same thing twice:

#include <stdio.h>
void
f1()
{
  unsigned long x = 3;
  float y = 1;
  printf ("%g\n", (-x) * y);
}
void
f2()
{
  unsigned long x = 3;
  float y = 1;
  unsigned long z = - x;
  printf ("%g\n", z * y);
}
int
main()
{
  f1();
  f2();
}

However, on x86_64 GNU/Linux with current mainline, it prints

-3
1.84467e+19

It is already incorrect in the first GIMPLE dump.  f1 has

  x = 3;
  y = 1.0e+0;
  D.2219 = (float) x;
  D.2220 = -D.2219;

f2 has

  x = 3;
  y = 1.0e+0;
  z = -x;
  D.2223 = (float) z;

In other words, in f1, the conversion to float happens before the negation.

The bug happens with both the C and C++ frontends.