------------------------------------------------------------------------------ LuaJIT compiler tracing module.---- Copyright (C) 2005-2007 Mike Pall. All rights reserved.-- Released under the MIT/X license. See luajit.h for full copyright notice.------------------------------------------------------------------------------ Activate this module to trace the progress of the JIT compiler.---- Try: luajit -j trace -e 'print "foo"'--      luajit -j trace=foo.trace foo.lua---- Default output is to stderr. To redirect output to a file,-- pass a filename as an argument or set the environment variable-- "LUAJIT_TRACEFILE".-- Note: the file is overwritten each time you run luajit.-------------------------------------------------------------------------------- Priority for compiler pipeline. Must run after backend (negative)-- and should be odd to catch compiler errors, too.local PRIORITY = -99-- Cache some library functions and objects.local jit = require("jit")assert(jit.version_num == 10103, "LuaJIT core/library version mismatch")local jutil = require("jit.util")local type, tostring, sub, format = type, tostring, string.sub, string.formatlocal getinfo, justats = debug.getinfo, jutil.statslocal stdout, stderr = io.stdout, io.stderr-- Turn compilation off for the whole module. LuaJIT would do that anyway.jit.off(true, true)-- Active flag and output file handle.local active, out-- Generate range string from table: pc[-pc] [,...]local function rangestring(t)  local s = ""  for i,range in ipairs(t) do    if i ~= 1 then s = s.."," end    local pc = range % 65536    range = (range - pc) / 65536    s = s..pc    if range ~= 0 then s = s..(-(pc+range)) end  end  return send-- Trace handler for compiler pipeline.local function h_trace(st, status)  local o = out or stderr  local func = st.func  if type(func) ~= "function" then return end  local info = getinfo(func, "S")  local src, line = info.source, info.linedefined or 0  if src then    if sub(src, 1, 1) == "@" or sub(src, 1, 2) == "=(" then      src = sub(src, 2)    else      src = "**"..string.gsub(sub(src, 1, 40), "%c", " ").."**"    end  else    src = "?"  end  local aux = st.deopt and "  DEOPT="..rangestring(st.deopt) or ""  if status == nil then    local stats = justats(func)    if not stats then return end    o:write(format("[LuaJIT: OK %4d %6d  %s:%d%s]\n",		   stats.bytecodes, stats.mcodesize or -1, src, line, aux))    return  else    local stname = jit.util.status[status] or status    local pc, err = st.dasm_pc, st.dasm_err    if type(pc) == "number" and type(err) == "number" then      local op = jutil.bytecode(func, pc) or "END"      o:write(format("[LuaJIT: %s  %s@%d %08x  %s:%d%s]\n",		     stname, op, pc, err, src, line, aux))    else      o:write(format("[LuaJIT: %s  %s:%d%s]\n", stname, src, line, aux))    end  endend-- Detach trace handler from compiler pipeline.local function traceoff()  if active then    active = false    jit.attach(h_trace)    if out and out ~= stdout then out:close() end    out = nil  endend-- Open the output file and attach trace handler to compiler pipeline.local function traceon(filename)  if active then traceoff() end  local outfile = filename or os.getenv("LUAJIT_TRACEFILE")  out = outfile and (outfile == "-" and stdout or assert(io.open(outfile, "w")))  jit.attach(h_trace, PRIORITY)  active = trueend-- Public module functions.module(...)on = traceonoff = traceoffstart = traceon -- For -j command line option.