diff options
Diffstat (limited to 'lparser.c')
-rw-r--r-- | lparser.c | 50 |
1 files changed, 6 insertions, 44 deletions
@@ -1623,59 +1623,21 @@ static void forstat (LexState *ls, int line) { | |||
1623 | } | 1623 | } |
1624 | 1624 | ||
1625 | 1625 | ||
1626 | /* | ||
1627 | ** Check whether next instruction is a single jump (a 'break', a 'goto' | ||
1628 | ** to a forward label, or a 'goto' to a backward label with no variable | ||
1629 | ** to close). If so, set the name of the 'label' it is jumping to | ||
1630 | ** ("break" for a 'break') or to where it is jumping to ('target') and | ||
1631 | ** return true. If not a single jump, leave input unchanged, to be | ||
1632 | ** handled as a regular statement. | ||
1633 | */ | ||
1634 | static int issinglejump (LexState *ls, TString **label, int *target) { | ||
1635 | if (testnext(ls, TK_BREAK)) { /* a break? */ | ||
1636 | *label = luaS_newliteral(ls->L, "break"); | ||
1637 | return 1; | ||
1638 | } | ||
1639 | else if (ls->t.token != TK_GOTO || luaX_lookahead(ls) != TK_NAME) | ||
1640 | return 0; /* not a valid goto */ | ||
1641 | else { | ||
1642 | TString *lname = ls->lookahead.seminfo.ts; /* label's id */ | ||
1643 | Labeldesc *lb = findlabel(ls, lname); | ||
1644 | if (lb) { /* a backward jump? */ | ||
1645 | /* does it need to close variables? */ | ||
1646 | if (luaY_nvarstack(ls->fs) > stacklevel(ls->fs, lb->nactvar)) | ||
1647 | return 0; /* not a single jump; cannot optimize */ | ||
1648 | *target = lb->pc; | ||
1649 | } | ||
1650 | else /* jump forward */ | ||
1651 | *label = lname; | ||
1652 | luaX_next(ls); /* skip goto */ | ||
1653 | luaX_next(ls); /* skip name */ | ||
1654 | return 1; | ||
1655 | } | ||
1656 | } | ||
1657 | |||
1658 | |||
1659 | static void test_then_block (LexState *ls, int *escapelist) { | 1626 | static void test_then_block (LexState *ls, int *escapelist) { |
1660 | /* test_then_block -> [IF | ELSEIF] cond THEN block */ | 1627 | /* test_then_block -> [IF | ELSEIF] cond THEN block */ |
1661 | BlockCnt bl; | 1628 | BlockCnt bl; |
1662 | int line; | ||
1663 | FuncState *fs = ls->fs; | 1629 | FuncState *fs = ls->fs; |
1664 | TString *jlb = NULL; | ||
1665 | int target = NO_JUMP; | ||
1666 | expdesc v; | 1630 | expdesc v; |
1667 | int jf; /* instruction to skip 'then' code (if condition is false) */ | 1631 | int jf; /* instruction to skip 'then' code (if condition is false) */ |
1668 | luaX_next(ls); /* skip IF or ELSEIF */ | 1632 | luaX_next(ls); /* skip IF or ELSEIF */ |
1669 | expr(ls, &v); /* read condition */ | 1633 | expr(ls, &v); /* read condition */ |
1670 | checknext(ls, TK_THEN); | 1634 | checknext(ls, TK_THEN); |
1671 | line = ls->linenumber; | 1635 | if (ls->t.token == TK_BREAK) { /* 'if x then break' ? */ |
1672 | if (issinglejump(ls, &jlb, &target)) { /* 'if x then goto' ? */ | 1636 | int line = ls->linenumber; |
1673 | luaK_goiffalse(ls->fs, &v); /* will jump to label if condition is true */ | 1637 | luaK_goiffalse(ls->fs, &v); /* will jump if condition is true */ |
1638 | luaX_next(ls); /* skip 'break' */ | ||
1674 | enterblock(fs, &bl, 0); /* must enter block before 'goto' */ | 1639 | enterblock(fs, &bl, 0); /* must enter block before 'goto' */ |
1675 | if (jlb != NULL) /* forward jump? */ | 1640 | newgotoentry(ls, luaS_newliteral(ls->L, "break"), line, v.t); |
1676 | newgotoentry(ls, jlb, line, v.t); /* will be resolved later */ | ||
1677 | else /* backward jump */ | ||
1678 | luaK_patchlist(fs, v.t, target); /* jump directly to 'target' */ | ||
1679 | while (testnext(ls, ';')) {} /* skip semicolons */ | 1641 | while (testnext(ls, ';')) {} /* skip semicolons */ |
1680 | if (block_follow(ls, 0)) { /* jump is the entire block? */ | 1642 | if (block_follow(ls, 0)) { /* jump is the entire block? */ |
1681 | leaveblock(fs); | 1643 | leaveblock(fs); |
@@ -1684,7 +1646,7 @@ static void test_then_block (LexState *ls, int *escapelist) { | |||
1684 | else /* must skip over 'then' part if condition is false */ | 1646 | else /* must skip over 'then' part if condition is false */ |
1685 | jf = luaK_jump(fs); | 1647 | jf = luaK_jump(fs); |
1686 | } | 1648 | } |
1687 | else { /* regular case (not a jump) */ | 1649 | else { /* regular case (not a break) */ |
1688 | luaK_goiftrue(ls->fs, &v); /* skip over block if condition is false */ | 1650 | luaK_goiftrue(ls->fs, &v); /* skip over block if condition is false */ |
1689 | enterblock(fs, &bl, 0); | 1651 | enterblock(fs, &bl, 0); |
1690 | jf = v.f; | 1652 | jf = v.f; |