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new opcodes 'FORLOOP1'/'FORPREP1' for "basic for" (integer variable

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with increment of 1)
This commit is contained in:
Roberto Ierusalimschy
2017-12-18 15:53:50 -02:00
parent ab07005568
commit d388c165ef
4 changed files with 73 additions and 18 deletions
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51
lparser.c
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@@ -1,5 +1,5 @@
/*
** $Id: lparser.c,v 2.172 2017/12/15 13:07:10 roberto Exp roberto $
** $Id: lparser.c,v 2.173 2017/12/18 12:33:54 roberto Exp roberto $
** Lua Parser
** See Copyright Notice in lua.h
*/
@@ -1313,11 +1313,20 @@ static void repeatstat (LexState *ls, int line) {
}
static void exp1 (LexState *ls) {
/*
** Read an expression and generate code to put its results in next
** stack slot. Return true if expression is a constant integer and,
** if 'i' is not-zero, its value is equal to 'i'.
**
*/
static int exp1 (LexState *ls, int i) {
expdesc e;
int res;
expr(ls, &e);
res = luaK_isKint(&e) && (i == 0 || i == e.u.ival);
luaK_exp2nextreg(ls->fs, &e);
lua_assert(e.k == VNONRELOC);
return res;
}
@@ -1337,29 +1346,37 @@ static void fixforjump (FuncState *fs, int pc, int dest, int back) {
}
static void forbody (LexState *ls, int base, int line, int nvars, int isnum) {
/*
** Generate code for a 'for' loop. 'kind' can be zero (a common for
** loop), one (a basic for loop, with integer values and increment of
** 1), or two (a generic for loop).
*/
static void forbody (LexState *ls, int base, int line, int nvars, int kind) {
/* forbody -> DO block */
BlockCnt bl;
FuncState *fs = ls->fs;
int prep, endfor;
adjustlocalvars(ls, 3); /* control variables */
checknext(ls, TK_DO);
prep = isnum ? luaK_codeABx(fs, OP_FORPREP, base, 0) : luaK_jump(fs);
prep = (kind == 0) ? luaK_codeABx(fs, OP_FORPREP, base, 0)
: (kind == 1) ? luaK_codeABx(fs, OP_FORPREP1, base, 0)
: luaK_jump(fs);
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 */
if (isnum) { /* numeric for? */
fixforjump(fs, prep, luaK_getlabel(fs), 0);
endfor = luaK_codeABx(fs, OP_FORLOOP, base, 0);
}
else { /* generic for */
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);
}
fixforjump(fs, endfor, prep + 1, 1);
luaK_fixline(fs, line);
}
@@ -1369,21 +1386,25 @@ static void fornum (LexState *ls, TString *varname, int line) {
/* fornum -> NAME = exp,exp[,exp] forbody */
FuncState *fs = ls->fs;
int base = fs->freereg;
int basicfor = 1; /* true if it is a "basic" 'for' (integer + 1) */
new_localvarliteral(ls, "(for index)");
new_localvarliteral(ls, "(for limit)");
new_localvarliteral(ls, "(for step)");
new_localvar(ls, varname);
checknext(ls, '=');
exp1(ls); /* initial value */
if (!exp1(ls, 0)) /* initial value not an integer? */
basicfor = 0; /* not a basic 'for' */
checknext(ls, ',');
exp1(ls); /* limit */
if (testnext(ls, ','))
exp1(ls); /* optional step */
exp1(ls, 0); /* limit */
if (testnext(ls, ',')) {
if (!exp1(ls, 1)) /* optional step not 1? */
basicfor = 0; /* not a basic 'for' */
}
else { /* default step = 1 */
luaK_int(fs, fs->freereg, 1);
luaK_reserveregs(fs, 1);
}
forbody(ls, base, line, 1, 1);
forbody(ls, base, line, 1, basicfor);
}
@@ -1408,7 +1429,7 @@ static void forlist (LexState *ls, TString *indexname) {
line = ls->linenumber;
adjust_assign(ls, 3, explist(ls, &e), &e);
luaK_checkstack(fs, 3); /* extra space to call generator */
forbody(ls, base, line, nvars - 3, 0);
forbody(ls, base, line, nvars - 3, 2);
}