[luatex] Profiling LuaTeX / difference with jit

[Patrick Gundlach]

Hi all,

I try to understand Lua's debug library and came across differences between luatex and luajittex.

See the following program:

------------
function a(cp)
    return string.format("abc %d",cp)
end


function dothings()
	a(2)
	a(2)
end


function onDebugHook( hookType )
	local funcInfo = debug.getinfo( 2 )
	if hookType == "call" then
		print("call",funcInfo.name or "?")
	elseif hookType == "return" then
		print("return",funcInfo.name or "?")
	end
end

debug.sethook( onDebugHook, 'cr')


dothings()
--------------

with "luatex --luaonly main.lua" I get a balanced call/return list:

--------------
return	sethook
call	dothings
call	a
call	format
return	format
return	a
call	a
call	format
return	format
return	a
return	dothings
return	?
--------------


with "luajittex --luaonly main.lua" I get

--------------
call	dothings
call	a
call	a
call	a
call	a
return	dothings
return	?
--------------


I guess this has to do with optimizations that Luajittex does. 

Just out of curiosity (I can of course work with regular LuaTeX) Now let's say I want to have the output from LuaTeX with the LuajitTeX program, (how) is this possible?

Patrick