When using ChunkSpy, I find one thing makes me coufused. Let's see the following example
>a = 1
; source chunk: (interactive mode)
; x86 standard (32-bit, little endian, doubles)
; function [0] definition (level 1)
; 0 upvalues, 0 params, 2 stacks
.function 0 0 2 2
.const "a" ; 0
.const 1 ; 1
[1] loadk 0 1 ; 1
[2] setglobal 0 0 ; a
[3] return 0 1
; end of function
Since here is 0 upvalues, 0 params, 2 stacks, why there are four parameters in .function 0 0 2 2
In another example, we can see that
>local a; function b() a = 1 return a end
; source chunk: (interactive mode)
; x86 standard (32-bit, little endian, doubles)
; function [0] definition (level 1)
; 0 upvalues, 0 params, 2 stacks
.function 0 0 2 2
.local "a" ; 0
.const "b" ; 0
; function [0] definition (level 2)
; 1 upvalues, 0 params, 2 stacks
.function 1 0 0 2
.upvalue "a" ; 0
.const 1 ; 0
[1] loadk 0 0 ; 1
[2] setupval 0 0 ; a
[3] getupval 0 0 ; a
[4] return 0 2
[5] return 0 1
; end of function
[1] closure 1 0 ; 1 upvalues
[2] move 0 0
[3] setglobal 1 0 ; b
[4] return 0 1
; end of function
So I guess the first parameter is upvalues, but what is the use of the second?
I get the answer by the help of Egor Skriptunoff from comments.
The .fucntion part with four parameters are meaning like below: