Seems like [1] could benefit from use of the X macro [2], should make adding new instructions much easier and you can avoid the hassle of having to keep two separate tables in sync. There's probably quite a few places where the code could be made clearer by using it. Also in the implementation of your functions, there's a hell of a lot of repetition in all the binary operations, another macro which you pass in the operation and the function name would make life earier:

    #define binop(NAME, OP) definstr (NAME) { \
        long long b, a; \
        if (carp_stack_pop(&m->stack, &b) == -1)\
            carp_vm_err(m, CARP_STACK_EMPTY);\
        if (carp_stack_pop(&m->stack, &a) == -1)\
            carp_vm_err(m, CARP_STACK_EMPTY);\
        carp_stack_push(&m->stack, a OP b);}
    
    binop(ADD,+)
    binop(MUL,*)
    ...

The repetition of

    if (carp_stack_pop(&m->stack, &a) == -1)
        carp_vm_err(m, CARP_STACK_EMPTY);

seems like a good place to just use a function to encapsulate all the error checking and handling.

[1] https://github.com/tekknolagi/carp/blob/master/src/carp_inst...

[2] http://www.embedded.com/design/programming-languages-and-too... and the following parts