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More uniformity in code generation for 'for' loops

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Added new instruction 'OP_TFORPREP' to prepare a generic for loop.
Currently it is equivalent to a jump (but with a format 'iABx',
similar to other for-loop preparing instructions), but soon it will
be the place to create upvalues for closing loop states.
This commit is contained in:
Roberto Ierusalimschy
2018-10-26 10:38:50 -03:00
parent 34840301b5
commit 6e9b719694
6 changed files with 14 additions and 10 deletions
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16
lparser.c
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@@ -1350,30 +1350,26 @@ static void fixforjump (FuncState *fs, int pc, int dest, int back) {
*/
static void forbody (LexState *ls, int base, int line, int nvars, int kind) {
/* forbody -> DO block */
static OpCode forprep[3] = {OP_FORPREP, OP_FORPREP1, OP_TFORPREP};
static OpCode forloop[3] = {OP_FORLOOP, OP_FORLOOP1, OP_TFORLOOP};
BlockCnt bl;
FuncState *fs = ls->fs;
int prep, endfor;
adjustlocalvars(ls, 3); /* control variables */
checknext(ls, TK_DO);
prep = (kind == 0) ? luaK_codeABx(fs, OP_FORPREP, base, 0)
: (kind == 1) ? luaK_codeABx(fs, OP_FORPREP1, base, 0)
: luaK_jump(fs);
prep = luaK_codeABx(fs, forprep[kind], base, 0);
enterblock(fs, &bl, 0); /* scope for declared variables */
adjustlocalvars(ls, nvars);
luaK_reserveregs(fs, nvars);
block(ls);
leaveblock(fs); /* end of scope for declared variables */
fixforjump(fs, prep, luaK_getlabel(fs), 0);
if (kind == 2) { /* generic for? */
luaK_patchtohere(fs, prep);
luaK_codeABC(fs, OP_TFORCALL, base, 0, nvars);
luaK_fixline(fs, line);
endfor = luaK_codeABx(fs, OP_TFORLOOP, base + 2, 0);
}
else {
fixforjump(fs, prep, luaK_getlabel(fs), 0);
endfor = (kind == 0) ? luaK_codeABx(fs, OP_FORLOOP, base, 0)
: luaK_codeABx(fs, OP_FORLOOP1, base, 0);
base += 2; /* base for 'OP_TFORLOOP' (skips function and state) */
}
endfor = luaK_codeABx(fs, forloop[kind], base, 0);
fixforjump(fs, endfor, prep + 1, 1);
luaK_fixline(fs, line);
}