2009-12-08 18:46:35 +00:00
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
< html >
< head >
< title > Frequently Asked Questions (FAQ)< / title >
< meta http-equiv = "Content-Type" content = "text/html; charset=iso-8859-1" >
< meta name = "Author" content = "Mike Pall" >
2013-02-11 11:54:48 +00:00
< meta name = "Copyright" content = "Copyright (C) 2005-2013, Mike Pall" >
2009-12-08 18:46:35 +00:00
< meta name = "Language" content = "en" >
< link rel = "stylesheet" type = "text/css" href = "bluequad.css" media = "screen" >
< link rel = "stylesheet" type = "text/css" href = "bluequad-print.css" media = "print" >
< style type = "text/css" >
dd { margin-left: 1.5em; }
< / style >
< / head >
< body >
< div id = "site" >
< a href = "http://luajit.org" > < span > Lua< span id = "logo" > JIT< / span > < / span > < / a >
< / div >
< div id = "head" >
< h1 > Frequently Asked Questions (FAQ)< / h1 >
< / div >
< div id = "nav" >
< ul > < li >
< a href = "luajit.html" > LuaJIT< / a >
< ul > < li >
2012-10-14 19:48:04 +00:00
< a href = "http://luajit.org/download.html" > Download < span class = "ext" > » < / span > < / a >
< / li > < li >
2009-12-08 18:46:35 +00:00
< a href = "install.html" > Installation< / a >
< / li > < li >
< a href = "running.html" > Running< / a >
2010-11-09 17:11:35 +00:00
< / li > < / ul >
< / li > < li >
< a href = "extensions.html" > Extensions< / a >
< ul > < li >
2011-01-20 21:14:17 +00:00
< a href = "ext_ffi.html" > FFI Library< / a >
< ul > < li >
< a href = "ext_ffi_tutorial.html" > FFI Tutorial< / a >
< / li > < li >
< a href = "ext_ffi_api.html" > ffi.* API< / a >
< / li > < li >
< a href = "ext_ffi_semantics.html" > FFI Semantics< / a >
< / li > < / ul >
< / li > < li >
2010-11-09 17:11:35 +00:00
< a href = "ext_jit.html" > jit.* Library< / a >
2009-12-08 18:46:35 +00:00
< / li > < li >
2010-11-09 17:11:35 +00:00
< a href = "ext_c_api.html" > Lua/C API< / a >
2013-09-09 22:06:17 +00:00
< / li > < li >
< a href = "ext_profiler.html" > Profiler< / a >
2009-12-08 18:46:35 +00:00
< / li > < / ul >
< / li > < li >
< a href = "status.html" > Status< / a >
< ul > < li >
< a href = "changes.html" > Changes< / a >
< / li > < / ul >
< / li > < li >
< a class = "current" href = "faq.html" > FAQ< / a >
< / li > < li >
2010-03-19 20:01:14 +00:00
< a href = "http://luajit.org/performance.html" > Performance < span class = "ext" > » < / span > < / a >
< / li > < li >
2012-05-31 21:54:44 +00:00
< a href = "http://wiki.luajit.org/" > Wiki < span class = "ext" > » < / span > < / a >
< / li > < li >
2012-05-04 19:58:52 +00:00
< a href = "http://luajit.org/list.html" > Mailing List < span class = "ext" > » < / span > < / a >
2009-12-08 18:46:35 +00:00
< / li > < / ul >
< / div >
< div id = "main" >
< dl >
2012-05-04 19:58:52 +00:00
< dt > Q: Where can I learn more about LuaJIT and Lua?< / dt >
2009-12-08 18:46:35 +00:00
< dd >
< ul style = "padding: 0;" >
2012-05-04 19:58:52 +00:00
< li > The < a href = "http://luajit.org/list.html" > < span class = "ext" > » < / span > LuaJIT mailing list< / a > focuses on topics
related to LuaJIT.< / li >
2012-05-31 21:54:44 +00:00
< li > The < a href = "http://wiki.luajit.org/" > < span class = "ext" > » < / span > LuaJIT wiki< / a > gathers community
resources about LuaJIT.< / li >
2012-05-04 19:58:52 +00:00
< li > News about Lua itself can be found at the
< a href = "http://www.lua.org/lua-l.html" > < span class = "ext" > » < / span > Lua mailing list< / a > .
The mailing list archives are worth checking out for older postings
about LuaJIT.< / li >
2009-12-08 18:46:35 +00:00
< li > The < a href = "http://lua.org" > < span class = "ext" > » < / span > main Lua.org site< / a > has complete
< a href = "http://www.lua.org/docs.html" > < span class = "ext" > » < / span > documentation< / a > of the language
and links to books and papers about Lua.< / li >
< li > The community-managed < a href = "http://lua-users.org/wiki/" > < span class = "ext" > » < / span > Lua Wiki< / a >
has information about diverse topics.< / li >
< / ul >
< / dl >
< dl >
< dt > Q: Where can I learn more about the compiler technology used by LuaJIT?< / dt >
< dd >
I'm planning to write more documentation about the internals of LuaJIT.
In the meantime, please use the following Google Scholar searches
to find relevant papers:< br >
Search for: < a href = "http://scholar.google.com/scholar?q=Trace+Compiler" > < span class = "ext" > » < / span > Trace Compiler< / a > < br >
Search for: < a href = "http://scholar.google.com/scholar?q=JIT+Compiler" > < span class = "ext" > » < / span > JIT Compiler< / a > < br >
Search for: < a href = "http://scholar.google.com/scholar?q=Dynamic+Language+Optimizations" > < span class = "ext" > » < / span > Dynamic Language Optimizations< / a > < br >
Search for: < a href = "http://scholar.google.com/scholar?q=SSA+Form" > < span class = "ext" > » < / span > SSA Form< / a > < br >
Search for: < a href = "http://scholar.google.com/scholar?q=Linear+Scan+Register+Allocation" > < span class = "ext" > » < / span > Linear Scan Register Allocation< / a > < br >
2009-12-08 18:49:20 +00:00
Here is a list of the < a href = "http://article.gmane.org/gmane.comp.lang.lua.general/58908" > < span class = "ext" > » < / span > innovative features in LuaJIT< / a > .< br >
2009-12-08 18:46:35 +00:00
And, you know, reading the source is of course the only way to enlightenment. :-)
< / dd >
< / dl >
< dl >
< dt > Q: Why do I get this error: "attempt to index global 'arg' (a nil value)"?< br >
Q: My vararg functions fail after switching to LuaJIT!< / dt >
< dd > LuaJIT is compatible to the Lua 5.1 language standard. It doesn't
support the implicit < tt > arg< / tt > parameter for old-style vararg
functions from Lua 5.0.< br > Please convert your code to the
< a href = "http://www.lua.org/manual/5.1/manual.html#2.5.9" > < span class = "ext" > » < / span > Lua 5.1
vararg syntax< / a > .< / dd >
< / dl >
2009-12-08 18:49:20 +00:00
< dl >
< dt > Q: Why do I get this error: "bad FPU precision"?< br >
< dt > Q: I get weird behavior after initializing Direct3D.< br >
< dt > Q: Some FPU operations crash after I load a Delphi DLL.< br >
< / dt >
< dd >
DirectX/Direct3D (up to version 9) sets the x87 FPU to single-precision
mode by default. This violates the Windows ABI and interferes with the
operation of many programs — LuaJIT is affected, too. Please make
sure you always use the < tt > D3DCREATE_FPU_PRESERVE< / tt > flag when
initializing Direct3D.< br >
Direct3D version 10 or higher do not show this behavior anymore.
Consider testing your application with older versions, too.< br >
Similarly, the Borland/Delphi runtime modifies the FPU control word and
enables FP exceptions. Of course this violates the Windows ABI, too.
Please check the Delphi docs for the Set8087CW method.
< / dl >
2009-12-08 18:46:35 +00:00
< dl >
< dt > Q: Sometimes Ctrl-C fails to stop my Lua program. Why?< / dt >
< dd > The interrupt signal handler sets a Lua debug hook. But this is
currently ignored by compiled code (this will eventually be fixed). If
your program is running in a tight loop and never falls back to the
interpreter, the debug hook never runs and can't throw the
"interrupted!" error.< br > In the meantime you have to press Ctrl-C
twice to get stop your program. That's similar to when it's stuck
running inside a C function under the Lua interpreter.< / dd >
< / dl >
< dl >
< dt > Q: Why doesn't my favorite power-patch for Lua apply against LuaJIT?< / dt >
< dd > Because it's a completely redesigned VM and has very little code
in common with Lua anymore. Also, if the patch introduces changes to
2010-10-04 23:36:54 +00:00
the Lua semantics, these would need to be reflected everywhere in the
2009-12-08 18:46:35 +00:00
VM, from the interpreter up to all stages of the compiler.< br > Please
use only standard Lua language constructs. For many common needs you
can use source transformations or use wrapper or proxy functions.
The compiler will happily optimize away such indirections.< / dd >
< / dl >
< dl >
< dt > Q: Lua runs everywhere. Why doesn't LuaJIT support my CPU?< / dt >
< dd > Because it's a compiler — it needs to generate native
machine code. This means the code generator must be ported to each
architecture. And the fast interpreter is written in assembler and
2011-05-04 23:15:22 +00:00
must be ported, too. This is quite an undertaking.< br >
The < a href = "install.html" > install documentation< / a > shows the supported
architectures. Other architectures will follow based on sufficient user
demand and/or sponsoring.< / dd >
2009-12-08 18:46:35 +00:00
< / dl >
< dl >
< dt > Q: When will feature X be added? When will the next version be released?< / dt >
< dd > When it's ready.< br >
C'mon, it's open source — I'm doing it on my own time and you're
getting it for free. You can either contribute a patch or sponsor
the development of certain features, if they are important to you.
< / dd >
< / dl >
< br class = "flush" >
< / div >
< div id = "foot" >
< hr class = "hide" >
2013-02-11 11:54:48 +00:00
Copyright © 2005-2013 Mike Pall
2009-12-08 18:46:35 +00:00
< span class = "noprint" >
·
< a href = "contact.html" > Contact< / a >
< / span >
< / div >
< / body >
< / html >
