Fix some assembler issues: The assembler was miscompiling "add" (specifically, the "add reg/mem, imm" variations). The change that caused this seems to have been made because without it, some "add"s didn't compile at all. This patch reverts the previous change, and makes sure assembler operands are remapped correctly even though the input operands auto-generated due to updating operations aren't explicitly used.

struct Color {
    uint c;

}

struct Vertex {
    double x, y;
    Color c;
    static Vertex opCall(double x, double y, Color c) {
        Vertex ret;
        ret.x = x;
        ret.y = y;
        ret.c = c;
        return ret;
    }
}

void main() {
    Color c = {0xffffffff};

    auto v = Vertex(1, 5, c);

    assert(v.x == 1 && v.y == 5); // passes
    assert(v.c.c == 0xffffffff);  // fails in LDC
}