Constructor Optimization

[Benjamin Meyer]

I was curius if GCC/G++ would optimize foo =3D x down to foo(x) if the=20
constructor existed so I wrote a small program to time the two.  Now of=20
course the time savings couldn't be much, but a wide scale fix/change cou=
ld=20
probably help, especially in applications that constently generate/remove=
 new=20
variables.

Here was my result:
v("x") is faster then v =3D "x": 24microseconds

This was compiled with:=20
g++ -c -pipe -DQWS -fno-exceptions -fno-rtti -Wall -W -O2 -fno-default-in=
line=20
-DNO_DEBUG

Is this wrong?

-Benjamin Meyer

---
#include <qstring.h>
#include <sys/time.h>
#include <time.h>

int main( int argc, char **argv ){
  int j =3D 1000;
  timeval t1, t2, t3;
  gettimeofday(&t1, NULL);
  for(int i =3D 0; i < j; i++)
    QString v =3D "Hello World!";
  gettimeofday(&t2, NULL);
  for(int i =3D 0; i < j; i++)
    QString v("Hello World!");
  gettimeofday(&t3, NULL);
 =20
  long firstLoop =3D (t2.tv_usec - t1.tv_usec);
  long secondLoop =3D (t3.tv_usec - t2.tv_usec);
  if(firstLoop < secondLoop)
    qDebug("v =3D \"x\" is faster then v(\"x\"): %dmicroseconds", (second=
Loop -=20
firstLoop));=20
  else
    qDebug("v(\"x\") is faster then v =3D \"x\": %dmicroseconds", (firstL=
oop -=20
secondLoop));
 =20
  return 0;
}