commit 94b503d95ef00f1e38b58b024ef45bf8973a8746
parent bdc85357aa41a9610498232c2cffe7aa191e5cf6
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Mon, 10 Jun 2024 12:09:08 -0300
Encoding of table indices (hres) must use C indices
As the encoding of array indices is (~index), 0 is encoded as -1 and
INT_MAX is encoded as INT_MIN.
Diffstat:
4 files changed, 30 insertions(+), 24 deletions(-)
diff --git a/ltable.c b/ltable.c
@@ -384,7 +384,7 @@ int luaH_next (lua_State *L, Table *t, StkId key) {
int tag = *getArrTag(t, i);
if (!tagisempty(tag)) { /* a non-empty entry? */
setivalue(s2v(key), i + 1);
- farr2val(t, i + 1, tag, s2v(key + 1));
+ farr2val(t, i, tag, s2v(key + 1));
return 1;
}
}
@@ -692,7 +692,7 @@ static void reinsertOldSlice (lua_State *L, Table *t, unsigned oldasize,
int tag = *getArrTag(t, i);
if (!tagisempty(tag)) { /* a non-empty entry? */
TValue aux;
- farr2val(t, i + 1, tag, &aux); /* copy entry into 'aux' */
+ farr2val(t, i, tag, &aux); /* copy entry into 'aux' */
luaH_setint(L, t, i + 1, &aux); /* re-insert it into the table */
}
}
@@ -937,7 +937,7 @@ int luaH_getint (Table *t, lua_Integer key, TValue *res) {
if (keyinarray(t, key)) {
int tag = *getArrTag(t, key - 1);
if (!tagisempty(tag))
- farr2val(t, key, tag, res);
+ farr2val(t, key - 1, tag, res);
return tag;
}
else
@@ -1048,11 +1048,11 @@ int luaH_psetint (Table *t, lua_Integer key, TValue *val) {
if (keyinarray(t, key)) {
lu_byte *tag = getArrTag(t, key - 1);
if (!tagisempty(*tag) || checknoTM(t->metatable, TM_NEWINDEX)) {
- fval2arr(t, key, tag, val);
+ fval2arr(t, key - 1, tag, val);
return HOK; /* success */
}
else
- return ~cast_int(key); /* empty slot in the array part */
+ return ~cast_int(key - 1); /* empty slot in the array part */
}
else
return finishnodeset(t, getintfromhash(t, key), val);
@@ -1126,7 +1126,7 @@ void luaH_set (lua_State *L, Table *t, const TValue *key, TValue *value) {
*/
void luaH_setint (lua_State *L, Table *t, lua_Integer key, TValue *value) {
if (keyinarray(t, key))
- obj2arr(t, key, value);
+ obj2arr(t, key - 1, value);
else {
int ok = rawfinishnodeset(getintfromhash(t, key), value);
if (!ok) {
diff --git a/ltable.h b/ltable.h
@@ -47,20 +47,20 @@
#define luaH_fastgeti(t,k,res,tag) \
- { Table *h = t; lua_Unsigned u = l_castS2U(k); \
- if ((u - 1u < h->alimit)) { \
- tag = *getArrTag(h,(u)-1u); \
+ { Table *h = t; lua_Unsigned u = l_castS2U(k) - 1u; \
+ if ((u < h->alimit)) { \
+ tag = *getArrTag(h, u); \
if (!tagisempty(tag)) { farr2val(h, u, tag, res); }} \
- else { tag = luaH_getint(h, u, res); }}
+ else { tag = luaH_getint(h, (k), res); }}
#define luaH_fastseti(t,k,val,hres) \
- { Table *h = t; lua_Unsigned u = l_castS2U(k); \
- if ((u - 1u < h->alimit)) { \
- lu_byte *tag = getArrTag(h,(u)-1u); \
+ { Table *h = t; lua_Unsigned u = l_castS2U(k) - 1u; \
+ if ((u < h->alimit)) { \
+ lu_byte *tag = getArrTag(h, u); \
if (tagisempty(*tag)) hres = ~cast_int(u); \
else { fval2arr(h, u, tag, val); hres = HOK; }} \
- else { hres = luaH_psetint(h, u, val); }}
+ else { hres = luaH_psetint(h, k, val); }}
/* results from pset */
@@ -82,6 +82,12 @@
** in the array part, the encoding is (~array index), a negative value.
** The value HNOTATABLE is used by the fast macros to signal that the
** value being indexed is not a table.
+** (The size for the array part is limited by the maximum power of two
+** that fits in an unsigned integer; that is INT_MAX+1. So, the C-index
+** ranges from 0, which encodes to -1, to INT_MAX, which encodes to
+** INT_MIN. The size of the hash part is limited by the maximum power of
+** two that fits in a signed integer; that is (INT_MAX+1)/2. So, it is
+** safe to add HFIRSTNODE to any index there.)
*/
@@ -102,21 +108,21 @@
** and 'getArrVal'.
*/
-/* Computes the address of the tag for the abstract index 'k' */
+/* Computes the address of the tag for the abstract C-index 'k' */
#define getArrTag(t,k) (cast(lu_byte*, (t)->array) + (k))
-/* Computes the address of the value for the abstract index 'k' */
+/* Computes the address of the value for the abstract C-index 'k' */
#define getArrVal(t,k) ((t)->array - 1 - (k))
/*
-** Move TValues to/from arrays, using Lua indices
+** Move TValues to/from arrays, using C indices
*/
#define arr2obj(h,k,val) \
- ((val)->tt_ = *getArrTag(h,(k)-1u), (val)->value_ = *getArrVal(h,(k)-1u))
+ ((val)->tt_ = *getArrTag(h,(k)), (val)->value_ = *getArrVal(h,(k)))
#define obj2arr(h,k,val) \
- (*getArrTag(h,(k)-1u) = (val)->tt_, *getArrVal(h,(k)-1u) = (val)->value_)
+ (*getArrTag(h,(k)) = (val)->tt_, *getArrVal(h,(k)) = (val)->value_)
/*
@@ -125,10 +131,10 @@
** precomputed tag value or address as an extra argument.
*/
#define farr2val(h,k,tag,res) \
- ((res)->tt_ = tag, (res)->value_ = *getArrVal(h,(k)-1u))
+ ((res)->tt_ = tag, (res)->value_ = *getArrVal(h,(k)))
#define fval2arr(h,k,tag,val) \
- (*tag = (val)->tt_, *getArrVal(h,(k)-1u) = (val)->value_)
+ (*tag = (val)->tt_, *getArrVal(h,(k)) = (val)->value_)
LUAI_FUNC int luaH_get (Table *t, const TValue *key, TValue *res);
diff --git a/ltests.c b/ltests.c
@@ -365,7 +365,7 @@ static void checktable (global_State *g, Table *h) {
checkobjrefN(g, hgc, h->metatable);
for (i = 0; i < asize; i++) {
TValue aux;
- arr2obj(h, i + 1, &aux);
+ arr2obj(h, i, &aux);
checkvalref(g, hgc, &aux);
}
for (n = gnode(h, 0); n < limit; n++) {
@@ -1010,7 +1010,7 @@ static int table_query (lua_State *L) {
}
else if (cast_uint(i) < asize) {
lua_pushinteger(L, i);
- arr2obj(t, i + 1, s2v(L->top.p));
+ arr2obj(t, i, s2v(L->top.p));
api_incr_top(L);
lua_pushnil(L);
}
diff --git a/lvm.c b/lvm.c
@@ -1857,7 +1857,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
luaH_resizearray(L, h, last); /* preallocate it at once */
for (; n > 0; n--) {
TValue *val = s2v(ra + n);
- obj2arr(h, last, val);
+ obj2arr(h, last - 1, val);
last--;
luaC_barrierback(L, obj2gco(h), val);
}
