Below Java code patterns

int c = a * (-b);
int d = (-a) * b;
long p = m * (-n);
long q = (-m) * n;

generates code like

0x0000ffff88ae66d4: neg w10, w2
0x0000ffff88ae66d8: mul w0, w1, w10

OR

0x0000ffff88ae66d4: neg x10, x2
0x0000ffff88ae66d8: mul x0, x1, x10

The neg & mul instructions can be combined into one single mneg instruction like

mneg w0, w1, w2

OR

mneg x0, x1, x2