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Full abstraction for representation of array values

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This commit is contained in:
Roberto Ierusalimschy
2023-10-30 14:25:59 -03:00
parent b8b709b6d4
commit 43c8e5bded
9 changed files with 128 additions and 93 deletions
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31
lapi.c
View File

@@ -653,21 +653,17 @@ l_sinline int auxgetstr (lua_State *L, const TValue *t, const char *k) {
}
/*
** Get the global table in the registry. Since all predefined
** indices in the registry were inserted right when the registry
** was created and never removed, they must always be in the array
** part of the registry.
*/
#define getGtable(L) \
(&hvalue(&G(L)->l_registry)->array[LUA_RIDX_GLOBALS - 1])
static void getGlobalTable (lua_State *L, TValue *gt) {
Table *registry = hvalue(&G(L)->l_registry);
luaH_getint(registry, LUA_RIDX_GLOBALS, gt);
}
LUA_API int lua_getglobal (lua_State *L, const char *name) {
const TValue *G;
TValue gt;
lua_lock(L);
G = getGtable(L);
return auxgetstr(L, G, name);
getGlobalTable(L, &gt);
return auxgetstr(L, &gt, name);
}
@@ -840,10 +836,10 @@ static void auxsetstr (lua_State *L, const TValue *t, const char *k) {
LUA_API void lua_setglobal (lua_State *L, const char *name) {
const TValue *G;
TValue gt;
lua_lock(L); /* unlock done in 'auxsetstr' */
G = getGtable(L);
auxsetstr(L, G, name);
getGlobalTable(L, &gt);
auxsetstr(L, &gt, name);
}
@@ -1093,10 +1089,11 @@ LUA_API int lua_load (lua_State *L, lua_Reader reader, void *data,
LClosure *f = clLvalue(s2v(L->top.p - 1)); /* get new function */
if (f->nupvalues >= 1) { /* does it have an upvalue? */
/* get global table from registry */
const TValue *gt = getGtable(L);
TValue gt;
getGlobalTable(L, &gt);
/* set global table as 1st upvalue of 'f' (may be LUA_ENV) */
setobj(L, f->upvals[0]->v.p, gt);
luaC_barrier(L, f->upvals[0], gt);
setobj(L, f->upvals[0]->v.p, &gt);
luaC_barrier(L, f->upvals[0], &gt);
}
}
lua_unlock(L);

25
lgc.c
View File

@@ -91,6 +91,13 @@
#define gcvalueN(o) (iscollectable(o) ? gcvalue(o) : NULL)
/*
** Access to collectable objects in array part of tables
*/
#define gcvalarr(t,i) \
((*getArrTag(t,i) & BIT_ISCOLLECTABLE) ? getArrVal(t,i)->gc : NULL)
#define markvalue(g,o) { checkliveness(g->mainthread,o); \
if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); }
@@ -486,9 +493,10 @@ static int traverseephemeron (global_State *g, Table *h, int inv) {
unsigned int nsize = sizenode(h);
/* traverse array part */
for (i = 0; i < asize; i++) {
if (valiswhite(&h->array[i])) {
GCObject *o = gcvalarr(h, i + 1);
if (o != NULL && iswhite(o)) {
marked = 1;
reallymarkobject(g, gcvalue(&h->array[i]));
reallymarkobject(g, o);
}
}
/* traverse hash part; if 'inv', traverse descending
@@ -524,8 +532,11 @@ static void traversestrongtable (global_State *g, Table *h) {
Node *n, *limit = gnodelast(h);
unsigned int i;
unsigned int asize = luaH_realasize(h);
for (i = 0; i < asize; i++) /* traverse array part */
markvalue(g, &h->array[i]);
for (i = 0; i < asize; i++) { /* traverse array part */
GCObject *o = gcvalarr(h, i + 1);
if (o != NULL && iswhite(o))
reallymarkobject(g, o);
}
for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */
if (isempty(gval(n))) /* entry is empty? */
clearkey(n); /* clear its key */
@@ -746,9 +757,9 @@ static void clearbyvalues (global_State *g, GCObject *l, GCObject *f) {
unsigned int i;
unsigned int asize = luaH_realasize(h);
for (i = 0; i < asize; i++) {
TValue *o = &h->array[i];
if (iscleared(g, gcvalueN(o))) /* value was collected? */
setempty(o); /* remove entry */
GCObject *o = gcvalarr(h, i + 1);
if (iscleared(g, o)) /* value was collected? */
*getArrTag(h, i + 1) = LUA_VEMPTY; /* remove entry */
}
for (n = gnode(h, 0); n < limit; n++) {
if (iscleared(g, gcvalueN(gval(n)))) /* unmarked value? */

5
lobject.h
View File

@@ -736,12 +736,15 @@ typedef union Node {
#define setnorealasize(t) ((t)->flags |= BITRAS)
typedef struct ArrayCell ArrayCell;
typedef struct Table {
CommonHeader;
lu_byte flags; /* 1<<p means tagmethod(p) is not present */
lu_byte lsizenode; /* log2 of size of 'node' array */
unsigned int alimit; /* "limit" of 'array' array */
TValue *array; /* array part */
ArrayCell *array; /* array part */
Node *node;
Node *lastfree; /* any free position is before this position */
struct Table *metatable;

7
lstate.c
View File

@@ -215,13 +215,16 @@ static void freestack (lua_State *L) {
*/
static void init_registry (lua_State *L, global_State *g) {
/* create registry */
TValue aux;
Table *registry = luaH_new(L);
sethvalue(L, &g->l_registry, registry);
luaH_resize(L, registry, LUA_RIDX_LAST, 0);
/* registry[LUA_RIDX_MAINTHREAD] = L */
setthvalue(L, &registry->array[LUA_RIDX_MAINTHREAD - 1], L);
setthvalue(L, &aux, L);
luaH_setint(L, registry, LUA_RIDX_MAINTHREAD, &aux);
/* registry[LUA_RIDX_GLOBALS] = new table (table of globals) */
sethvalue(L, &registry->array[LUA_RIDX_GLOBALS - 1], luaH_new(L));
sethvalue(L, &aux, luaH_new(L));
luaH_setint(L, registry, LUA_RIDX_GLOBALS, &aux);
}

116
ltable.c
View File

@@ -350,9 +350,10 @@ int luaH_next (lua_State *L, Table *t, StkId key) {
unsigned int asize = luaH_realasize(t);
unsigned int i = findindex(L, t, s2v(key), asize); /* find original key */
for (; i < asize; i++) { /* try first array part */
if (!isempty(&t->array[i])) { /* a non-empty entry? */
int tag = *getArrTag(t, i + 1);
if (!tagisempty(tag)) { /* a non-empty entry? */
setivalue(s2v(key), i + 1);
setobj2s(L, key + 1, &t->array[i]);
farr2val(t, i + 1, tag, s2v(key + 1));
return 1;
}
}
@@ -374,6 +375,41 @@ static void freehash (lua_State *L, Table *t) {
}
/*
** Check whether an integer key is in the array part. If 'alimit' is
** not the real size of the array, the key still can be in the array
** part. In this case, do the "Xmilia trick" to check whether 'key-1'
** is smaller than the real size.
** The trick works as follow: let 'p' be an integer such that
** '2^(p+1) >= alimit > 2^p', or '2^(p+1) > alimit-1 >= 2^p'.
** That is, 2^(p+1) is the real size of the array, and 'p' is the highest
** bit on in 'alimit-1'. What we have to check becomes 'key-1 < 2^(p+1)'.
** We compute '(key-1) & ~(alimit-1)', which we call 'res'; it will
** have the 'p' bit cleared. If the key is outside the array, that is,
** 'key-1 >= 2^(p+1)', then 'res' will have some 1-bit higher than 'p',
** therefore it will be larger or equal to 'alimit', and the check
** will fail. If 'key-1 < 2^(p+1)', then 'res' has no 1-bit higher than
** 'p', and as the bit 'p' itself was cleared, 'res' will be smaller
** than 2^p, therefore smaller than 'alimit', and the check succeeds.
** As special cases, when 'alimit' is 0 the condition is trivially false,
** and when 'alimit' is 1 the condition simplifies to 'key-1 < alimit'.
** If key is 0 or negative, 'res' will have its higher bit on, so that
** if cannot be smaller than alimit.
*/
static int keyinarray (Table *t, lua_Integer key) {
lua_Unsigned alimit = t->alimit;
if (l_castS2U(key) - 1u < alimit) /* 'key' in [1, t->alimit]? */
return 1;
else if (!isrealasize(t) && /* key still may be in the array part? */
(((l_castS2U(key) - 1u) & ~(alimit - 1u)) < alimit)) {
t->alimit = cast_uint(key); /* probably '#t' is here now */
return 1;
}
else
return 0;
}
/*
** {=============================================================
** Rehash
@@ -421,6 +457,12 @@ static int countint (lua_Integer key, unsigned int *nums) {
}
l_sinline int arraykeyisempty (const Table *t, lua_Integer key) {
int tag = *getArrTag(t, key);
return tagisempty(tag);
}
/*
** Count keys in array part of table 't': Fill 'nums[i]' with
** number of keys that will go into corresponding slice and return
@@ -443,7 +485,7 @@ static unsigned int numusearray (const Table *t, unsigned int *nums) {
}
/* count elements in range (2^(lg - 1), 2^lg] */
for (; i <= lim; i++) {
if (!isempty(&t->array[i-1]))
if (!arraykeyisempty(t, i))
lc++;
}
nums[lg] += lc;
@@ -555,7 +597,7 @@ void luaH_resize (lua_State *L, Table *t, unsigned int newasize,
unsigned int i;
Table newt; /* to keep the new hash part */
unsigned int oldasize = setlimittosize(t);
TValue *newarray;
ArrayCell *newarray;
/* create new hash part with appropriate size into 'newt' */
setnodevector(L, &newt, nhsize);
if (newasize < oldasize) { /* will array shrink? */
@@ -563,14 +605,18 @@ void luaH_resize (lua_State *L, Table *t, unsigned int newasize,
exchangehashpart(t, &newt); /* and new hash */
/* re-insert into the new hash the elements from vanishing slice */
for (i = newasize; i < oldasize; i++) {
if (!isempty(&t->array[i]))
luaH_setint(L, t, i + 1, &t->array[i]);
int tag = *getArrTag(t, i + 1);
if (!tagisempty(tag)) { /* a non-empty entry? */
TValue aux;
farr2val(t, i + 1, tag, &aux);
luaH_setint(L, t, i + 1, &aux);
}
}
t->alimit = oldasize; /* restore current size... */
exchangehashpart(t, &newt); /* and hash (in case of errors) */
}
/* allocate new array */
newarray = luaM_reallocvector(L, t->array, oldasize, newasize, TValue);
newarray = luaM_reallocvector(L, t->array, oldasize, newasize, ArrayCell);
if (l_unlikely(newarray == NULL && newasize > 0)) { /* allocation failed? */
freehash(L, &newt); /* release new hash part */
luaM_error(L); /* raise error (with array unchanged) */
@@ -580,7 +626,7 @@ void luaH_resize (lua_State *L, Table *t, unsigned int newasize,
t->array = newarray; /* set new array part */
t->alimit = newasize;
for (i = oldasize; i < newasize; i++) /* clear new slice of the array */
setempty(&t->array[i]);
*getArrTag(t, i + 1) = LUA_VEMPTY;
/* re-insert elements from old hash part into new parts */
reinsert(L, &newt, t); /* 'newt' now has the old hash */
freehash(L, &newt); /* free old hash part */
@@ -719,41 +765,6 @@ void luaH_newkey (lua_State *L, Table *t, const TValue *key, TValue *value) {
}
/*
** Check whether key is in the array part. If 'alimit' is not the real
** size of the array, the key still can be in the array part. In this
** case, do the "Xmilia trick" to check whether 'key-1' is smaller than
** the real size.
** The trick works as follow: let 'p' be an integer such that
** '2^(p+1) >= alimit > 2^p', or '2^(p+1) > alimit-1 >= 2^p'.
** That is, 2^(p+1) is the real size of the array, and 'p' is the highest
** bit on in 'alimit-1'. What we have to check becomes 'key-1 < 2^(p+1)'.
** We compute '(key-1) & ~(alimit-1)', which we call 'res'; it will
** have the 'p' bit cleared. If the key is outside the array, that is,
** 'key-1 >= 2^(p+1)', then 'res' will have some 1-bit higher than 'p',
** therefore it will be larger or equal to 'alimit', and the check
** will fail. If 'key-1 < 2^(p+1)', then 'res' has no 1-bit higher than
** 'p', and as the bit 'p' itself was cleared, 'res' will be smaller
** than 2^p, therefore smaller than 'alimit', and the check succeeds.
** As special cases, when 'alimit' is 0 the condition is trivially false,
** and when 'alimit' is 1 the condition simplifies to 'key-1 < alimit'.
** If key is 0 or negative, 'res' will have its higher bit on, so that
** if cannot be smaller than alimit.
*/
static int keyinarray (Table *t, lua_Integer key) {
lua_Unsigned alimit = t->alimit;
if (l_castS2U(key) - 1u < alimit) /* 'key' in [1, t->alimit]? */
return 1;
else if (!isrealasize(t) && /* key still may be in the array part? */
(((l_castS2U(key) - 1u) & ~(alimit - 1u)) < alimit)) {
t->alimit = cast_uint(key); /* probably '#t' is here now */
return 1;
}
else
return 0;
}
static const TValue *getintfromhash (Table *t, lua_Integer key) {
Node *n = hashint(t, key);
lua_assert(l_castS2U(key) - 1u >= luaH_realasize(t));
@@ -770,15 +781,8 @@ static const TValue *getintfromhash (Table *t, lua_Integer key) {
}
l_sinline int arraykeyisempty (Table *t, lua_Integer key) {
int tag = *getArrTag(t, key);
return tagisempty(tag);
}
static int hashkeyisempty (Table *t, lua_Integer key) {
const TValue *val = getintfromhash(t, key);
lua_assert(!keyinarray(t, key));
return isempty(val);
}
@@ -797,7 +801,7 @@ int luaH_getint (Table *t, lua_Integer key, TValue *res) {
if (keyinarray(t, key)) {
int tag = *getArrTag(t, key);
if (!tagisempty(tag)) {
arr2val(t, key, tag, res);
farr2val(t, key, tag, res);
return HOK; /* success */
}
else
@@ -900,7 +904,7 @@ int luaH_psetint (Table *t, lua_Integer key, TValue *val) {
if (keyinarray(t, key)) {
lu_byte *tag = getArrTag(t, key);
if (!tagisempty(*tag)) {
val2arr(t, key, tag, val);
fval2arr(t, key, tag, val);
return HOK; /* success */
}
else
@@ -956,7 +960,7 @@ void luaH_finishset (lua_State *L, Table *t, const TValue *key,
}
else { /* array entry */
hres = ~hres; /* real index */
val2arr(t, hres, getArrTag(t, hres), value);
fval2arr(t, hres, getArrTag(t, hres), value);
}
}
@@ -1087,11 +1091,11 @@ lua_Unsigned luaH_getn (Table *t) {
/* 'limit' is zero or present in table */
if (!limitequalsasize(t)) { /* (2)? */
/* 'limit' > 0 and array has more elements after 'limit' */
if (isempty(&t->array[limit])) /* 'limit + 1' is empty? */
if (arraykeyisempty(t, limit + 1)) /* 'limit + 1' is empty? */
return limit; /* this is the boundary */
/* else, try last element in the array */
limit = luaH_realasize(t);
if (isempty(&t->array[limit - 1])) { /* empty? */
if (arraykeyisempty(t, limit)) { /* empty? */
/* there must be a boundary in the array after old limit,
and it must be a valid new limit */
unsigned int boundary = binsearch(t, t->alimit, limit);
@@ -1102,7 +1106,7 @@ lua_Unsigned luaH_getn (Table *t) {
}
/* (3) 'limit' is the last element and either is zero or present in table */
lua_assert(limit == luaH_realasize(t) &&
(limit == 0 || !isempty(&t->array[limit - 1])));
(limit == 0 || !arraykeyisempty(t, limit)));
if (isdummy(t) || hashkeyisempty(t, cast(lua_Integer, limit + 1)))
return limit; /* 'limit + 1' is absent */
else /* 'limit + 1' is also present */

21
ltable.h
View File

@@ -51,20 +51,33 @@
*/
struct ArrayCell {
lu_byte tt;
Value value;
};
/* fast access to components of array values */
#define getArrTag(t,k) (&(t)->array[k - 1].tt_)
#define getArrVal(t,k) (&(t)->array[k - 1].value_)
#define getArrTag(t,k) (&(t)->array[k - 1].tt)
#define getArrVal(t,k) (&(t)->array[k - 1].value)
#define tagisempty(tag) (novariant(tag) == LUA_TNIL)
#define arr2val(h,k,tag,res) \
#define farr2val(h,k,tag,res) \
((res)->tt_ = tag, (res)->value_ = *getArrVal(h,k))
#define val2arr(h,k,tag,val) \
#define fval2arr(h,k,tag,val) \
(*tag = (val)->tt_, *getArrVal(h,k) = (val)->value_)
#define obj2arr(h,k,val) \
(*getArrTag(h,k) = (val)->tt_, *getArrVal(h,k) = (val)->value_)
#define arr2obj(h,k,val) \
((val)->tt_ = *getArrTag(h,k), (val)->value_ = *getArrVal(h,k))
LUAI_FUNC int luaH_getshortstr (Table *t, TString *key, TValue *res);
LUAI_FUNC int luaH_getstr (Table *t, TString *key, TValue *res);
LUAI_FUNC int luaH_get (Table *t, const TValue *key, TValue *res);

10
ltests.c
View File

@@ -362,8 +362,11 @@ static void checktable (global_State *g, Table *h) {
Node *n, *limit = gnode(h, sizenode(h));
GCObject *hgc = obj2gco(h);
checkobjrefN(g, hgc, h->metatable);
for (i = 0; i < asize; i++)
checkvalref(g, hgc, &h->array[i]);
for (i = 0; i < asize; i++) {
TValue aux;
arr2obj(h, i + 1, &aux);
checkvalref(g, hgc, &aux);
}
for (n = gnode(h, 0); n < limit; n++) {
if (!isempty(gval(n))) {
TValue k;
@@ -1005,7 +1008,8 @@ static int table_query (lua_State *L) {
}
else if ((unsigned int)i < asize) {
lua_pushinteger(L, i);
pushobject(L, &t->array[i]);
arr2obj(t, i + 1, s2v(L->top.p));
api_incr_top(L);
lua_pushnil(L);
}
else if ((i -= asize) < sizenode(t)) {

2
lvm.c
View File

@@ -1845,7 +1845,7 @@ 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);
setobj2t(L, &h->array[last - 1], val);
obj2arr(h, last, val);
last--;
luaC_barrierback(L, obj2gco(h), val);
}

4
lvm.h
View File

@@ -92,7 +92,7 @@ typedef enum {
if ((u - 1u < h->alimit)) { \
int tag = *getArrTag(h,u); \
if (tagisempty(tag)) aux = HNOTFOUND; \
else { arr2val(h, u, tag, res); aux = HOK; }} \
else { farr2val(h, u, tag, res); aux = HOK; }} \
else { aux = luaH_getint(h, u, res); }}
@@ -105,7 +105,7 @@ typedef enum {
if ((u - 1u < h->alimit)) { \
lu_byte *tag = getArrTag(h,u); \
if (tagisempty(*tag)) aux = ~cast_int(u); \
else { val2arr(h, u, tag, val); aux = HOK; }} \
else { fval2arr(h, u, tag, val); aux = HOK; }} \
else { aux = luaH_psetint(h, u, val); }}