Re: Tracking down gcc-4.0 performance regressions

[Georg Bauhaus]

Daniel Kegel wrote:

So, I'm looking around for other reports of performance
regressions in gcc-4.0. 

I came across this one:

int foo(int a, int b)
{
         return a + b;
}

int bar()
{
       int x = 0, y = 10;
       int c;

       for (c=0; c < 123123123 && x > -1; ++c, --y)
               x = foo(c, y);
       return x;
}

int main()
{
       return bar();
}

The for loop is translated rather differently
by GCC 3.4.4 and GCC 4.0.1(pre) on i686 GNU/Linux.
Speed ratio around 85%.

Georg