Re: how to find unused local variables?

[Luiz Henrique de Figueiredo <lhf@...>]

> I seem to remember that once upon a time LHF posted a script
> that could be run over the output of luac to find unused local variables,
> but I am not having any luck finding something in the archives.

Neither am I. But I did find a script that does that though I'm not sure it
does actually work... It's attached. Please let me know how it does :-)
--lhf

-- find unused local vars
-- typical usage: luac -p -l *.lua | lua locals.lua

local R,W
local where
local OP={}

local function set(x)
	x=tonumber(x)
	W[x]=true
end

local function get(x)
	x=tonumber(x)
	if x>=0 and not W[x] then
		print("local",x,"undefined",where)
	end
	R[x]=true
end

function OP.MOVE(a,b,c)
	get(b)
	set(a)
end

function OP.LOADK(a,b,c)
	set(a)
end

function OP.LOADBOOL(a,b,c)
	set(a)
end

function OP.LOADNIL(a,b,c)
	do return end
	for i=a,b do
		set(i)
	end
end

function OP.GETUPVAL(a,b,c)
	set(a)
end

function OP.GETGLOBAL(a,b,c)
	set(a)
end

function OP.GETTABLE(a,b,c)
	get(b)
	set(a)
end

function OP.SETGLOBAL(a,b,c)
	get(a)
end

function OP.SETUPVAL(a,b,c)
	get(a)
end

function OP.SETTABLE(a,b,c)
	get(a)
	get(b)
	get(c)
end

function OP.NEWTABLE(a,b,c)
	set(a)
end

function OP.SELF(a,b,c)
	get(b)
	set(a+1)
	get(c)
	set(a)
end

function OP.ADD(a,b,c)
	get(b)
	get(c)
	set(a)
end

function OP.SUB(a,b,c)
	get(b)
	get(c)
	set(a)
end

function OP.MUL(a,b,c)
	get(b)
	get(c)
	set(a)
end

function OP.DIV(a,b,c)
	get(b)
	get(c)
	set(a)
end

function OP.MOD(a,b,c)
	get(b)
	get(c)
	set(a)
end

function OP.POW(a,b,c)
	get(b)
	get(c)
	set(a)
end

function OP.UNM(a,b,c)
	get(b)
	set(a)
end

function OP.NOT(a,b,c)
	get(b)
	set(a)
end

function OP.LEN(a,b,c)
	get(b)
	set(a)
end

function OP.CONCAT(a,b,c)
	for i=b,c do
		get(i)
	end
	set(a)
end

function OP.JMP(a,b,c)
end

function OP.EQ(a,b,c)
	get(b)
	get(c)
end

function OP.LT(a,b,c)
	get(b)
	get(c)
end

function OP.LE(a,b,c)
	get(b)
	get(c)
end

function OP.TEST(a,b,c)
	get(a)
end

function OP.TESTSET(a,b,c)
	get(b)
	set(a)
end

function OP.CALL(a,b,c)
	for i=a,a+b-1 do
		get(i)
	end
	for i=a,a+c-2 do
		set(i)
	end
end

function OP.TAILCALL(a,b,c)
	for i=a,a+b-1 do
		get(i)
	end
end

function OP.RETURN(a,b,c)
	for i=a,a+b-2 do
		get(i)
	end
end

function OP.FORLOOP(a,b,c)
	get(a)
	get(a+2)
	set(a)
	get(a+1)
	get(a)
	set(a+3)
end

function OP.FORPREP(a,b,c)
	get(a)
	get(a+2)
	set(a)
end

function OP.TFORLOOP(a,b,c)
	for i=a,a+2 do
		get(i)
	end
	for i=a+3,a+c+2 do
		set(i)
	end
end

function OP.SETLIST(a,b,c)
	get(a)
	for i=a+1,a+b do
		get(i)
	end
end

function OP.CLOSE(a,b,c)
end

function OP.CLOSURE(a,b,c)
	set(a)
end

function OP.VARARG(a,b,c)
	for i=a,a+b-1 do
		set(i)
	end
end

local function report()
 	if R~=nil then
		for i=0,table.maxn(R) do
		--for i in pairs(R) do
			if R[i]==nil then
				print("local",i,"unused",where)
			end
		end
	end
end

local S={}
local G={}
local F

while true do
 local s=io.read()
 if s==nil then break end
--print(s)
 local ok,_,f=string.find(s,"^[mf].-<(.-):[%d,]+>")
 if ok then F=f
 	report()
	R={}
	W={}
 end
 s=s.." -1"
 local ok,_,l,op,a,b,c=string.find(s,"%[%-?(%d*)%]%s*(%S+)%s+(%S+)%s+(%S+)%s+(%S+)")
--print(ok,_,l,op,a,b,c)
 if ok then
  where=F..":"..l
  OP[op](a,b,c)
 end
end

report()