Re: continue patch (help needed)
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- Subject: Re: continue patch (help needed)
- From: Asko Kauppi <asko.kauppi@...>
- Date: 2005年4月10日 02:20:12 +0300
This works on 5.1w4, but.. could some Lua Guru :) please check. I'm
not sure that the stabbing is in the right place. Thanks.
static void forbody (LexState *ls, int base, int line, int nvars, int
isnum) {
/* forbody -> DO block */
BlockCnt bl;
FuncState *fs = ls->fs;
int prep, endfor;
adjustlocalvars(ls, 3); /* control variables */
checknext(ls, TK_DO);
prep = luaK_codeAsBx(fs, (isnum ? OP_FORPREP : OP_TFORPREP), base,
NO_JUMP);
enterblock(fs, &bl, 0); /* scope for declared variables */
adjustlocalvars(ls, nvars);
luaK_reserveregs(fs, nvars);
block(ls);
#ifdef CONTINUE_PATCH
// TBD: NOT SURE IF THIS IS QUITE RIGHT (someone Lua Guru should
check?)
// Lua code for for loops has changed since the original patch..
//
//fprintf( stderr, "forbody() patchtohere %p %d %p %d\n",
// &bl, bl.continuelist, &bl, bl.previous,
bl.previous->continuelist );
luaK_patchtohere(fs, bl.previous->continuelist); // this works
#endif
leaveblock(fs); /* end of scope for declared variables */
luaK_patchtohere(fs, prep);
endfor = (isnum) ? luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP) :
luaK_codeABC(fs, OP_TFORLOOP, base, 0, nvars);
luaK_fixline(fs, line); /* pretend that `OP_FOR' starts the loop */
luaK_patchlist(fs, (isnum ? endfor : luaK_jump(fs)), prep + 1);
}
As a second issue with the original patch, 'continuestat' does not take
into account upvalue cleaning. Is it rightfully so, or should it now
do that?
9.4.2005 kello 21:52, Asko Kauppi kirjoitti:
The old "continue patch" is for Lua 5.0 code. It covers three files,
llex.h, llex.c, and lparser.c (where most of the fun is).
The change of for counter scope in >5.0 Lua makes me unaware, where
exactly to place the patched line. Let's see:
This is the original Lua 5.0.2 portion (with patch addition marked):
static void forbody (LexState *ls, int base, int line, int nvars, int
isnum) {
BlockCnt bl;
FuncState *fs = ls->fs;
int prep, endfor;
adjustlocalvars(ls, nvars); /* scope for all variables */
check(ls, TK_DO);
enterblock(fs, &bl, 1); /* loop block */
prep = luaK_getlabel(fs);
block(ls);
>>> luaK_patchtohere(fs, bl.continuelist);
luaK_patchtohere(fs, prep-1);
endfor = (isnum) ? luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP) :
luaK_codeABC(fs, OP_TFORLOOP, base, 0, nvars - 3);
luaK_fixline(fs, line); /* pretend that `OP_FOR' starts the loop */
luaK_patchlist(fs, (isnum) ? endfor : luaK_jump(fs), prep);
leaveblock(fs);
}
This is 5.1w4 'modern' portion with both A and B tried (but neither
worked):
static void forbody (LexState *ls, int base, int line, int nvars, int
isnum) {
/* forbody -> DO block */
BlockCnt bl;
FuncState *fs = ls->fs;
int prep, endfor;
adjustlocalvars(ls, 3); /* control variables */
checknext(ls, TK_DO);
prep = luaK_codeAsBx(fs, (isnum ? OP_FORPREP : OP_TFORPREP), base,
NO_JUMP);
enterblock(fs, &bl, 0); /* scope for declared variables */
adjustlocalvars(ls, nvars);
luaK_reserveregs(fs, nvars);
block(ls);
>>> A: luaK_patchtohere(fs, bl.continuelist);
leaveblock(fs); /* end of scope for declared variables */
>>> B: luaK_patchtohere(fs, bl.continuelist);
luaK_patchtohere(fs, prep);
endfor = (isnum) ? luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP) :
luaK_codeABC(fs, OP_TFORLOOP, base, 0, nvars);
luaK_fixline(fs, line); /* pretend that `OP_FOR' starts the loop */
luaK_patchlist(fs, (isnum ? endfor : luaK_jump(fs)), prep + 1);
}
When 'continue' within a for loop is met, the execution goes into
eternal loop (or so it seems..)
-ak