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Towards a new implementation of arrays

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The array part of a table wastes too much space, due to padding.
To avoid that, we need to store values in the array as something
different from a TValue. Therefore, the API for table access
should not assume that any value in a table lives in a *TValue.
This commit is the first step to remove that assumption: functions
luaH_get*, instead of returning a *TValue where the value lives,
receive a *TValue where to put the value being accessed.
(We still have to change the luaH_set* functions.)
This commit is contained in:
Roberto Ierusalimschy
2023-05-15 17:56:25 -03:00
parent 6443185167
commit 351ccd7332
5 changed files with 108 additions and 59 deletions
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67
lvm.c
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@@ -284,12 +284,12 @@ static int floatforloop (StkId ra) {
** if 'slot' is NULL, 't' is not a table; otherwise, 'slot' points to
** t[k] entry (which must be empty).
*/
void luaV_finishget (lua_State *L, const TValue *t, TValue *key, StkId val,
const TValue *slot) {
void luaV_finishget1 (lua_State *L, const TValue *t, TValue *key, StkId val,
int aux) {
int loop; /* counter to avoid infinite loops */
const TValue *tm; /* metamethod */
for (loop = 0; loop < MAXTAGLOOP; loop++) {
if (slot == NULL) { /* 't' is not a table? */
if (aux == HNOTATABLE) { /* 't' is not a table? */
lua_assert(!ttistable(t));
tm = luaT_gettmbyobj(L, t, TM_INDEX);
if (l_unlikely(notm(tm)))
@@ -297,7 +297,6 @@ void luaV_finishget (lua_State *L, const TValue *t, TValue *key, StkId val,
/* else will try the metamethod */
}
else { /* 't' is a table */
lua_assert(isempty(slot));
tm = fasttm(L, hvalue(t)->metatable, TM_INDEX); /* table's metamethod */
if (tm == NULL) { /* no metamethod? */
setnilvalue(s2v(val)); /* result is nil */
@@ -310,10 +309,9 @@ void luaV_finishget (lua_State *L, const TValue *t, TValue *key, StkId val,
return;
}
t = tm; /* else try to access 'tm[key]' */
if (luaV_fastget(L, t, key, slot, luaH_get)) { /* fast track? */
setobj2s(L, val, slot); /* done */
return;
}
luaV_fastget1(t, key, s2v(val), luaH_get1, aux);
if (aux == HOK)
return; /* done */
/* else repeat (tail call 'luaV_finishget') */
}
luaG_runerror(L, "'__index' chain too long; possible loop");
@@ -1250,58 +1248,51 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
}
vmcase(OP_GETTABUP) {
StkId ra = RA(i);
const TValue *slot;
TValue *upval = cl->upvals[GETARG_B(i)]->v.p;
TValue *rc = KC(i);
TString *key = tsvalue(rc); /* key must be a string */
if (luaV_fastget(L, upval, key, slot, luaH_getshortstr)) {
setobj2s(L, ra, slot);
}
else
Protect(luaV_finishget(L, upval, rc, ra, slot));
int aux;
luaV_fastget1(upval, key, s2v(ra), luaH_getshortstr1, aux);
if (aux != HOK)
Protect(luaV_finishget1(L, upval, rc, ra, aux));
vmbreak;
}
vmcase(OP_GETTABLE) {
StkId ra = RA(i);
const TValue *slot;
TValue *rb = vRB(i);
TValue *rc = vRC(i);
lua_Unsigned n;
if (ttisinteger(rc) /* fast track for integers? */
? (cast_void(n = ivalue(rc)), luaV_fastgeti(L, rb, n, slot))
: luaV_fastget(L, rb, rc, slot, luaH_get)) {
setobj2s(L, ra, slot);
int aux;
if (ttisinteger(rc)) { /* fast track for integers? */
luaV_fastgeti1(rb, ivalue(rc), s2v(ra), aux);
}
else
Protect(luaV_finishget(L, rb, rc, ra, slot));
luaV_fastget1(rb, rc, s2v(ra), luaH_get1, aux);
if (aux != HOK) /* fast track for integers? */
Protect(luaV_finishget1(L, rb, rc, ra, aux));
vmbreak;
}
vmcase(OP_GETI) {
StkId ra = RA(i);
const TValue *slot;
TValue *rb = vRB(i);
int c = GETARG_C(i);
if (luaV_fastgeti(L, rb, c, slot)) {
setobj2s(L, ra, slot);
}
else {
int aux;
luaV_fastgeti1(rb, c, s2v(ra), aux);
if (aux != HOK) {
TValue key;
setivalue(&key, c);
Protect(luaV_finishget(L, rb, &key, ra, slot));
Protect(luaV_finishget1(L, rb, &key, ra, aux));
}
vmbreak;
}
vmcase(OP_GETFIELD) {
StkId ra = RA(i);
const TValue *slot;
TValue *rb = vRB(i);
TValue *rc = KC(i);
TString *key = tsvalue(rc); /* key must be a string */
if (luaV_fastget(L, rb, key, slot, luaH_getshortstr)) {
setobj2s(L, ra, slot);
}
else
Protect(luaV_finishget(L, rb, rc, ra, slot));
int aux;
luaV_fastget1(rb, key, s2v(ra), luaH_getshortstr1, aux);
if (aux != HOK)
Protect(luaV_finishget1(L, rb, rc, ra, aux));
vmbreak;
}
vmcase(OP_SETTABUP) {
@@ -1381,16 +1372,14 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
}
vmcase(OP_SELF) {
StkId ra = RA(i);
const TValue *slot;
int aux;
TValue *rb = vRB(i);
TValue *rc = RKC(i);
TString *key = tsvalue(rc); /* key must be a string */
setobj2s(L, ra + 1, rb);
if (luaV_fastget(L, rb, key, slot, luaH_getstr)) {
setobj2s(L, ra, slot);
}
else
Protect(luaV_finishget(L, rb, rc, ra, slot));
luaV_fastget1(rb, key, s2v(ra), luaH_getstr1, aux);
if (aux != HOK)
Protect(luaV_finishget1(L, rb, rc, ra, aux));
vmbreak;
}
vmcase(OP_ADDI) {