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articles/bytecode.md: more spacing

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tocariimaa 2025-03-14 00:15:03 -03:00
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articles/bytecode.md
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@ -48,46 +48,46 @@ lua -p -l -l fact.lua
Annotated (by me) bytecode output:
```
Toplevel function: main <fact.lua:0,0> (9 instructions at 0x58e78aa2ecc0)
0+ params, 3 slots, 1 upvalue, 0 locals, 2 constants, 1 function
Varargs, 0 fixed arguments expected 1 [1] VARARGPREP 0
Create a function 2 [8] CLOSURE 0 0 ; 0x58e78aa2ef20
Bound it to the name "fact" and add it to the _ENV 3 [1] SETTABUP 0 0 0 ; _ENV "fact"
Get `print` function reference from the _ENV, to R0 4 [8] GETTABUP 0 0 1 ; _ENV "print"
Get `fact` function reference from the _ENV, to R1 5 [9] GETTABUP 1 0 0 ; _ENV "fact"
Load 5 into R2 (first argument for `fact`) 6 [9] LOADI 2 5
Call function at R1, with 2-1 args, saving result in the `top` ^1 7 [9] CALL 1 2 0 ; 1 in all out
Call function at R2, using `top` as argument, no return value 8 [9] CALL 0 0 1 ; all in 0 out
Return from toplevel (exit program) 9 [9] RETURN 0 1 1 ; 0 out
constants (2) for 0x58e78aa2ecc0:
The function name, as a string costant 0 S "fact"
Ditto for print function 1 S "print"
locals (0) for 0x58e78aa2ecc0:
upvalues (1) for 0x58e78aa2ecc0:
_ENV is the table that contains the global enviroment 0 _ENV 1 0
Toplevel function: main <fact.lua:0,0> (9 instructions at 0x58e78aa2ecc0)
0+ params, 3 slots, 1 upvalue, 0 locals, 2 constants, 1 function
Varargs, 0 fixed arguments expected 1 [1] VARARGPREP 0
Create a function 2 [8] CLOSURE 0 0 ; 0x58e78aa2ef20
Bound it to the name "fact" and add it to the _ENV 3 [1] SETTABUP 0 0 0 ; _ENV "fact"
Get `print` function reference from the _ENV, to R0 4 [8] GETTABUP 0 0 1 ; _ENV "print"
Get `fact` function reference from the _ENV, to R1 5 [9] GETTABUP 1 0 0 ; _ENV "fact"
Load 5 into R2 (first argument for `fact`) 6 [9] LOADI 2 5
Call function at R1, with 2-1 args, saving result in the `top` ^1 7 [9] CALL 1 2 0 ; 1 in all out
Call function at R2, using `top` as argument, no return value 8 [9] CALL 0 0 1 ; all in 0 out
Return from toplevel (exit program) 9 [9] RETURN 0 1 1 ; 0 out
constants (2) for 0x58e78aa2ecc0:
The function name, as a string costant 0 S "fact"
Ditto for print function 1 S "print"
locals (0) for 0x58e78aa2ecc0:
upvalues (1) for 0x58e78aa2ecc0:
_ENV is the table that contains the global enviroment 0 _ENV 1 0
The `fact` function: function <fact.lua:1,8> (10 instructions at 0x58e78aa2ef20)
1 param, 6 slots, 0 upvalues, 6 locals, 0 constants, 0 functions
Load 1 into R1 (`res`) 1 [2] LOADI 1 1
Load 1 into R2, holding the for loop initial state 2 [3] LOADI 2 1
Move value from R0 [`n`] to the for loop max limit register 3 [3] MOVE 3 0
for loop step value, 1 by default 4 [3] LOADI 4 1
Initialize for loop ^2 .--- 5 [3] FORPREP 2 2 ; exit to 9
Multiply. R1 [`res`] = R1 * R5 [`i`] | .> 6 [5] MUL 1 1 5
Attempt to execute the metamethod `__mul` ^3 | | 7 [5] MMBIN 1 5 8 ; __mul
Do a for loop iteration | `- 8 [3] FORLOOP 2 3 ; to 6
Return from function with 1 value, R1 [`res`] `--> 9 [7] RETURN1 1
Return with no arguments (redundant bytecode) ^4 10 [8] RETURN0
constants (0) for 0x58e78aa2ef20:
Local bindings for this function, with the registers: locals (6) for 0x58e78aa2ef20:
0 n 1 11
1 res 2 11
2 (for state) 5 9
3 (for state) 5 9
4 (for state) 5 9
5 i 6 8
upvalues (0) for 0x58e78aa2ef20:
The `fact` function: function <fact.lua:1,8> (10 instructions at 0x58e78aa2ef20)
1 param, 6 slots, 0 upvalues, 6 locals, 0 constants, 0 functions
Load 1 into R1 (`res`) 1 [2] LOADI 1 1
Load 1 into R2, holding the for loop initial state 2 [3] LOADI 2 1
Move value from R0 [`n`] to the for loop max limit register 3 [3] MOVE 3 0
for loop step value, 1 by default 4 [3] LOADI 4 1
Initialize for loop ^2 .--- 5 [3] FORPREP 2 2 ; exit to 9
Multiply. R1 [`res`] = R1 * R5 [`i`] | .> 6 [5] MUL 1 1 5
Attempt to execute the metamethod `__mul` ^3 | | 7 [5] MMBIN 1 5 8 ; __mul
Do a for loop iteration | `- 8 [3] FORLOOP 2 3 ; to 6
Return from function with 1 value, R1 [`res`] `--> 9 [7] RETURN1 1
Return with no arguments (redundant bytecode) ^4 10 [8] RETURN0
constants (0) for 0x58e78aa2ef20:
Local bindings for this function, with the registers: locals (6) for 0x58e78aa2ef20:
0 n 1 11
1 res 2 11
2 (for state) 5 9
3 (for state) 5 9
4 (for state) 5 9
5 i 6 8
upvalues (0) for 0x58e78aa2ef20:
```
Notes:
1. The `top` is a special slot in the virtual machine, originally meaning the "top" of the stack (when Lua had stack-based