[Bug middle-end/33989] Extra load/store for float with union

[phiren at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33989

--- Comment #15 from Scott Mansell <phiren at gmail dot com> 2010-11-12 
04:04:25 UTC ---
Weirdly, it works fine with doubles.

Testcase:
union a
{
  long int i;
  double f;
};

void d(double *a, long int *b, double e)
{
  union a c;
  c.f = *a + e;
  *b = c.i;
}

Results in:
.L.d:
    lfd 0,0(3)
    fadd 0,1,0
    stfd 0,0(4)
    blr

One thing that I noticed while looking at the assembly of my program, it that
is was allocated 8 bytes on the stack for each stfs instruction. Does gcc think
that stfs writes a 64 bit value which is preventing it writing directly into
the space of an int? 

I've checked the IBM docs, stfs does write a 32 bit value.