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Big revamp in the implmentation of labels/gotos

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Added restriction that, when a label is created, there cannot be
another label with the same name visible. That allows backward goto's
to be resolved when they are read. Backward goto's get a close if
they jump out of the scope of some variable; labels get a close only
if previous goto to it jumps out of the scope of some upvalue.
This commit is contained in:
Roberto Ierusalimschy
2018-10-29 14:26:48 -03:00
parent 6e9b719694
commit a006514ea1
8 changed files with 131 additions and 182 deletions
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34
lcode.c
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@@ -275,40 +275,6 @@ void luaK_patchtohere (FuncState *fs, int list) {
}
/*
** Correct a jump list to jump to 'target'. If 'hasclose' is true,
** 'target' contains an OP_CLOSE instruction (see first assert).
** Only the jumps with ('m' == true) need that close; other jumps
** avoid it jumping to the next instruction.
*/
void luaK_patchgoto (FuncState *fs, int list, int target, int hasclose) {
lua_assert(!hasclose || GET_OPCODE(fs->f->code[target]) == OP_CLOSE);
while (list != NO_JUMP) {
int next = getjump(fs, list);
lua_assert(!GETARG_m(fs->f->code[list]) || hasclose);
patchtestreg(fs, list, NO_REG); /* do not generate values */
if (!hasclose || GETARG_m(fs->f->code[list]))
fixjump(fs, list, target);
else /* there is a CLOSE instruction but jump does not need it */
fixjump(fs, list, target + 1); /* avoid CLOSE instruction */
list = next;
}
}
/*
** Mark (using the 'm' arg) all jumps in 'list' to close upvalues. Mark
** will instruct 'luaK_patchgoto' to make these jumps go to OP_CLOSE
** instructions.
*/
void luaK_patchclose (FuncState *fs, int list) {
for (; list != NO_JUMP; list = getjump(fs, list)) {
lua_assert(GET_OPCODE(fs->f->code[list]) == OP_JMP);
SETARG_m(fs->f->code[list], 1);
}
}
/*
** MAXimum number of successive Instructions WiTHout ABSolute line
** information.