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cleaner semantics for test instructions (skips)

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This commit is contained in:
Roberto Ierusalimschy
2002-01-16 20:03:57 -02:00
parent 566310fa04
commit 7ab7703b53
5 changed files with 48 additions and 72 deletions
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23
lcode.c
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@@ -71,7 +71,7 @@ int luaK_jump (FuncState *fs) {
static int luaK_condjump (FuncState *fs, OpCode op, int A, int B, int C) {
luaK_codeABC(fs, op, A, B, C);
return luaK_codeAsBc(fs, OP_CJMP, 0, NO_JUMP);
return luaK_codeAsBc(fs, OP_JMP, 0, NO_JUMP);
}
@@ -127,12 +127,11 @@ static int luaK_getjump (FuncState *fs, int pc) {
static Instruction *getjumpcontrol (FuncState *fs, int pc) {
Instruction *pi = &fs->f->code[pc];
OpCode op = GET_OPCODE(*pi);
if (op == OP_CJMP)
lua_assert(op == OP_JMP || op == OP_FORLOOP || op == OP_TFORLOOP);
if (pc >= 1 && testOpMode(GET_OPCODE(*(pi-1)), OpModeT))
return pi-1;
else {
lua_assert(op == OP_JMP || op == OP_FORLOOP || op == OP_TFORLOOP);
else
return pi;
}
}
@@ -312,18 +311,23 @@ static int code_label (FuncState *fs, int A, int b, int jump) {
static void dischargejumps (FuncState *fs, expdesc *e, int reg) {
if (hasjumps(e)) {
if (e->k == VJMP || hasjumps(e)) {
int final; /* position after whole expression */
int p_f = NO_JUMP; /* position of an eventual PUSH false */
int p_t = NO_JUMP; /* position of an eventual PUSH true */
if (need_value(fs, e->f, OP_TESTF) || need_value(fs, e->t, OP_TESTT)) {
if (e->k == VJMP || need_value(fs, e->f, OP_TESTF) ||
need_value(fs, e->t, OP_TESTT)) {
/* expression needs values */
if (e->k != VJMP) {
luaK_getlabel(fs); /* these instruction may be jump target */
luaK_codeAsBc(fs, OP_JMP, 0, 2); /* to jump over both pushes */
}
p_f = code_label(fs, reg, 0, 1);
p_t = code_label(fs, reg, 1, 0);
else { /* last expression is a conditional (test + jump) */
fs->pc--; /* remove its jump */
lua_assert(testOpMode(GET_OPCODE(fs->f->code[fs->pc - 1]), OpModeT));
}
p_t = code_label(fs, reg, 1, 1);
p_f = code_label(fs, reg, 0, 0);
}
final = luaK_getlabel(fs);
luaK_patchlistaux(fs, e->f, p_f, NO_REG, final, reg, p_f);
@@ -389,7 +393,6 @@ static void luaK_exp2reg (FuncState *fs, expdesc *e, int reg) {
break;
}
case VJMP: {
luaK_concat(fs, &e->t, e->u.i.info); /* put this jump in `t' list */
break;
}
default: {