c++ - Impossible Register Constraint in asm -

c++ - Impossible Register Constraint in asm -

i trying utilize code multiplication in c++ file.

ll mul(ll a, ll b, ll m) { ll q; ll r; asm( "mulq %3;" "divq %4;" : "=a"(q), "=d"(r) : "a"(a), "rm"(b), "rm"(m)); homecoming r; }

but showing impossible register constraint in asm error.

c++ assembly