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some optimizations

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This commit is contained in:
Roberto Ierusalimschy
2000-03-08 21:19:22 -03:00
parent 563de491be
commit 88b306f495
6 changed files with 105 additions and 75 deletions
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20
lparser.c
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@@ -716,7 +716,7 @@ static int get_priority (int op, int *rp) {
case '+': case '-': *rp = 5; return 5;
case CONC: *rp = 4; return 4; /* left associative (?) */
case CONC: *rp = 3; return 4; /* right associative (?) */
case EQ: case NE: case '>': case '<': case LE: case GE:
*rp = 2; return 2;
@@ -941,18 +941,17 @@ static void namestat (LexState *ls) {
static void ifpart (LexState *ls, int line) {
/* ifpart -> cond THEN block [ELSE block | ELSEIF ifpart] */
/* ifpart -> cond THEN block (ELSEIF ifpart | [ELSE block] END) */
FuncState *fs = ls->fs;
int c; /* address of the conditional jump */
int je; /* address of the unconditional jump (to skip `else' part) */
int elseinit;
next(ls); /* skip IF or ELSEIF */
exp1(ls); /* cond */
c = luaK_S(ls, IFFJMP, 0, -1); /* jump over `then' part if `cond' is false */
c = luaK_S(ls, IFFJMP, 0, -1); /* 1st jump: over `then' part */
check(ls, THEN);
block(ls); /* `then' part */
je = luaK_S(ls, JMP, 0, 0); /* jump over `else' part after `then' */
elseinit = luaK_getlabel(ls);
luaK_S(ls, JMP, 0, 0); /* 2nd jump: over `else' part */
elseinit = luaK_getlabel(ls); /* address of 2nd jump == elseinit-1 */
if (ls->token == ELSEIF)
ifpart(ls, line);
else {
@@ -961,13 +960,12 @@ static void ifpart (LexState *ls, int line) {
check_match(ls, END, IF, line);
}
if (fs->pc > elseinit) { /* is there an `else' part? */
luaK_fixjump(ls, je, luaK_getlabel(ls)); /* last jump jumps over it */
luaK_fixjump(ls, c, elseinit); /* fix first jump to `else' part */
luaK_fixjump(ls, c, elseinit); /* fix 1st jump to `else' part */
luaK_fixjump(ls, elseinit-1, luaK_getlabel(ls)); /* fix 2nd jump */
}
else { /* no else part */
fs->pc--; /* remove last jump */
LUA_ASSERT(L, fs->pc == je, "jump out of place");
luaK_fixjump(ls, c, luaK_getlabel(ls)); /* fix first jump to `if' end */
fs->pc--; /* remove 2nd jump */
luaK_fixjump(ls, c, luaK_getlabel(ls)); /* fix 1st jump to `if' end */
}
}