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Major redesign of function call handling.

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Drop call gates. Use function headers, dispatched like bytecodes.
Emit BC_FUNCF/BC_FUNCV bytecode at PC 0 for all Lua functions.
C functions and ASM fast functions get extra bytecodes.
Modify internal calling convention: new base in BASE (formerly in RA).
Can now use better C function wrapper semantics (dynamic on/off).
Prerequisite for call hooks with zero-overhead if disabled.
Prerequisite for compiling recursive calls.
Prerequisite for efficient 32/64 bit prototype guards.
This commit is contained in:
Mike Pall
2010-02-13 04:51:56 +01:00
parent 4f8d7be8ea
commit c93138b59e
34 changed files with 4410 additions and 4264 deletions
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38
doc/api.html
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@@ -258,13 +258,12 @@ side traces from the cache.
<h3 id="mode_engine"><tt>luaJIT_setmode(L, idx, LUAJIT_MODE_WRAPCFUNC|flag)</tt></h3>
<p>
This mode defines a wrapper function for calls to C functions. The
first time this is called with <tt>LUAJIT_MODE_ON</tt>, the stack
index at <tt>idx</tt> must be a <tt>lightuserdata</tt> object holding
a pointer to the wrapper function. All <b>subsequently created C
functions</b> are called through the wrapper functions. After the initial
definition <tt>idx</tt> can be left at <tt>0</tt> when turning the mode
on or off.
This mode defines a wrapper function for calls to C functions. If
called with <tt>LUAJIT_MODE_ON</tt>, the stack index at <tt>idx</tt>
must be a <tt>lightuserdata</tt> object holding a pointer to the wrapper
function. From now on all C functions are called through the wrapper
function. If called with <tt>LUAJIT_MODE_OFF</tt> this mode is turned
off and all C functions are directly called.
</p>
<p>
The wrapper function can be used for debugging purposes or to catch
@@ -291,38 +290,27 @@ static int wrap_exceptions(lua_State *L, lua_CFunction f)
return lua_error(L); // Rethrow as a Lua error.
}
static int myregister(lua_State *L)
static int myinit(lua_State *L)
{
...
// Define wrapper function and enable it.
lua_pushlightuserdata(L, (void *)wrap_exceptions);
luaJIT_setmode(L, -1, LUAJIT_MODE_WRAPCFUNC|LUAJIT_MODE_ON);
lua_pop(L, 1);
luaL_register(L, "mymodule", myfuncs); // Pass luaL_Reg list.
luaJIT_setmode(L, 0, LUAJIT_MODE_WRAPCFUNC|LUAJIT_MODE_OFF);
...
// Wrap some more C++ functions which might throw an exception.
luaJIT_setmode(L, 0, LUAJIT_MODE_WRAPCFUNC|LUAJIT_MODE_ON);
lua_pushcfunction(L, mythrowingfunc1);
lua_pushcclosure(L, mythrowingfunc2, 1);
luaJIT_setmode(L, 0, LUAJIT_MODE_WRAPCFUNC|LUAJIT_MODE_OFF);
...
}
</pre>
<p>
Note that you can only define <b>a single global wrapper function</b>,
so be careful when using this mechanism from multiple C++ modules.
Also note that this mechanism is not without overhead. It should only
be enabled for definitions of C++ functions that can actually throw
exceptions. If you're embedding LuaJIT into an application, only
enable it <b>after</b> running <tt>luaL_openlibs</tt>.
Also note that this mechanism is not without overhead.
</p>
<p>
LuaJIT already intercepts exception handling for all x64 systems and
for x86 systems using DWARF2 stack unwinding (e.g. Linux, OSX). This
is a zero-cost mechanism and always enabled. You don't need to use any
wrapper functions, except when you want to get a more specific error
message than <tt>"C++&nbsp;exception"</tt>.
LuaJIT already intercepts exception handling for systems using DWARF2
stack unwinding (e.g. Linux or OSX) and for Windows/x64 (but <b>not</b>
for Windows/x86). This is a zero-cost mechanism and always enabled.
You don't need to use any wrapper functions, except when you want to get
a more specific error message than <tt>"C++&nbsp;exception"</tt>.
</p>
<br class="flush">
</div>