Hello, if I'm not wrong it is not allowed in goasm 64 bits for now "mov eax, 64+34" for example, i.e the precompiler doesn't do some calculus
That particular example with 32-bit integer values and register would work, but yes, there are currently some limitations with 64-bit arithmetic expressions.
Addition of 64-bit integer values does currently work, in which case you would also need to specify a 64-bit register for the result. However, 64-bit subtraction, multiplication, and division are not yet supported.