\[\left(\left(x \cdot x + y \cdot y\right) + y \cdot y\right) + y \cdot y\]
\left(\left(x \cdot x + y \cdot y\right) + y \cdot y\right) + y \cdot y
double f(double x, double y) {
        double r329728 = x;
        double r329729 = r329728 * r329728;
        double r329730 = y;
        double r329731 = r329730 * r329730;
        double r329732 = r329729 + r329731;
        double r329733 = r329732 + r329731;
        double r329734 = r329733 + r329731;
        return r329734;
}

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2019323 
(FPCore (x y)
  :name "Linear.Quaternion:$c/ from linear-1.19.1.3, E"
  :precision binary64

  :herbie-target
  (+ (* x x) (* y (+ y (+ y y))))

  (+ (+ (+ (* x x) (* y y)) (* y y)) (* y y)))

Backtrace

get-representation: Unknown representation realLC
(unnamed)/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/regimes.rkt653
filter/opt/racket-7.2/collects/racket/private/list.rkt2562
infer-splitpoints/data/pavpan/nightlies/herbie/fix-interface-bugs/src/core/regimes.rkt340
get-final-combination/data/pavpan/nightlies/herbie/fix-interface-bugs/src/mainloop.rkt3690
(unnamed)/opt/racket-7.2/collects/racket/private/more-scheme.rkt26128
run/opt/racket-7.2/share/pkgs/profile-lib/main.rkt392
profile-thunk16/opt/racket-7.2/share/pkgs/profile-lib/main.rkt90
(unnamed)/opt/racket-7.2/collects/racket/private/more-scheme.rkt26128