Re: continue patch (help needed)

[Asko Kauppi <asko.kauppi@...>]

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