This program used to use R9 and R10.
Now it fails to compile (out of registers).
I used to know a simpler test but can't remember it.

Learned something new: Rietveld refuses change
list descriptions bigger than 10 kB.

int sum(int x, int y, int z, int w) {
        return
        (((((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))))/
        ((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))))%
        (((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))))/
        ((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))))))*
        ((((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))))/
        ((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))))%
        (((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))))/
        ((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))))))*
        (((((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))))/
        ((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))))%
        (((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))))/
        ((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))))))*
        ((((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))))/
        ((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))))%
        (((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))))/
        ((((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))|
        (((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w))&
        ((x*y+z*w|x*y+z*w)^
        (x*y+z*w|x*y+z*w)))))))
        ;
}

R=ken2
CC=golang-dev
https://golang.org/cl/4650053