Optimizations for 'lua_rawgeti' and 'lua_rawseti'

'lua_rawgeti' now uses "fast track"; 'lua_rawseti' still calls
'luaH_setint', but the latter was recoded to avoid extra overhead
when writing to the array part after 'alimit'.

lapi.c

@@ -102,7 +102,7 @@ static TValue *index2value (lua_State *L, int idx) {
 /*
 ** Convert a valid actual index (not a pseudo-index) to its address.
 */
-l_sinline StkId index2stack (lua_State *L, int idx) {
+static StkId index2stack (lua_State *L, int idx) {
   CallInfo *ci = L->ci;
   if (idx > 0) {
     StkId o = ci->func.p + idx;
@@ -234,7 +234,7 @@ LUA_API void lua_closeslot (lua_State *L, int idx) {
 ** Note that we move(copy) only the value inside the stack.
 ** (We do not move additional fields that may exist.)
 */
-l_sinline void reverse (lua_State *L, StkId from, StkId to) {
+static void reverse (lua_State *L, StkId from, StkId to) {
   for (; from < to; from++, to--) {
     TValue temp;
     setobj(L, &temp, s2v(from));
@@ -664,7 +664,7 @@ LUA_API int lua_pushthread (lua_State *L) {
 */
 
 
-l_sinline int auxgetstr (lua_State *L, const TValue *t, const char *k) {
+static int auxgetstr (lua_State *L, const TValue *t, const char *k) {
   int hres;
   TString *str = luaS_new(L, k);
   luaV_fastget(t, str, s2v(L->top.p), luaH_getstr, hres);
@@ -683,7 +683,9 @@ l_sinline int auxgetstr (lua_State *L, const TValue *t, const char *k) {
 
 static void getGlobalTable (lua_State *L, TValue *gt) {
   Table *registry = hvalue(&G(L)->l_registry);
-  luaH_getint(registry, LUA_RIDX_GLOBALS, gt);
+  int hres = luaH_getint(registry, LUA_RIDX_GLOBALS, gt);
+  (void)hres;  /* avoid warnings (not used) when checks are off */
+  api_check(L, hres == HOK, "global table must exist");
 }
 
 
@@ -740,7 +742,7 @@ l_sinline int finishrawget (lua_State *L, int hres) {
 }
 
 
-static Table *gettable (lua_State *L, int idx) {
+l_sinline Table *gettable (lua_State *L, int idx) {
   TValue *t = index2value(L, idx);
   api_check(L, ttistable(t), "table expected");
   return hvalue(t);
@@ -761,9 +763,11 @@ LUA_API int lua_rawget (lua_State *L, int idx) {
 
 LUA_API int lua_rawgeti (lua_State *L, int idx, lua_Integer n) {
   Table *t;
+  int hres;
   lua_lock(L);
   t = gettable(L, idx);
-  return finishrawget(L, luaH_getint(t, n, s2v(L->top.p)));
+  luaH_fastgeti(t, n, s2v(L->top.p), hres);
+  return finishrawget(L, hres);
 }
 
 
@@ -901,9 +905,8 @@ LUA_API void lua_seti (lua_State *L, int idx, lua_Integer n) {
   api_checknelems(L, 1);
   t = index2value(L, idx);
   luaV_fastseti(t, n, s2v(L->top.p - 1), hres);
-  if (hres == HOK) {
+  if (hres == HOK)
     luaV_finishfastset(L, t, s2v(L->top.p - 1));
-  }
   else {
     TValue temp;
     setivalue(&temp, n);

ltable.c

@@ -408,21 +408,22 @@ static void freehash (lua_State *L, Table *t) {
 ** 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
+** The trick works as follow: let 'p' be the integer such that
-** '2^(p+1) >= alimit > 2^p', or  '2^(p+1) > alimit-1 >= 2^p'.
+** '2^(p+1) >= alimit > 2^p', or '2^(p+1) > alimit-1 >= 2^p'.  That is,
-** That is, 2^(p+1) is the real size of the array, and 'p' is the highest
+** 'p' is the highest 1-bit in 'alimit-1', and 2^(p+1) is the real size
-** bit on in 'alimit-1'. What we have to check becomes 'key-1 < 2^(p+1)'.
+** of the array. What we have to check becomes 'key-1 < 2^(p+1)'.  We
-** We compute '(key-1) & ~(alimit-1)', which we call 'res'; it will
+** compute '(key-1) & ~(alimit-1)', which we call 'res'; it will have
-** have the 'p' bit cleared. If the key is outside the array, that is,
+** the 'p' bit cleared. (It may also clear other bits smaller than 'p',
-** 'key-1 >= 2^(p+1)', then 'res' will have some 1-bit higher than 'p',
+** but no bit higher than 'p'.) If the key is outside the array, that
-** therefore it will be larger or equal to 'alimit', and the check
+** 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.
+** it cannot be smaller than 'alimit'.
 */
 static int keyinarray (Table *t, lua_Integer key) {
   lua_Unsigned alimit = t->alimit;
@@ -788,11 +789,11 @@ static Node *getfreepos (Table *t) {
 
 
 /*
-** inserts a new key into a hash table; first, check whether key's main
+** Inserts a new key into a hash table; first, check whether key's main
 ** position is free. If not, check whether colliding node is in its main
-** position or not: if it is not, move colliding node to an empty place and
+** position or not: if it is not, move colliding node to an empty place
-** put new key in its main position; otherwise (colliding node is in its main
+** and put new key in its main position; otherwise (colliding node is in
-** position), new key goes to an empty position.
+** its main position), new key goes to an empty position.
 */
 static void luaH_newkey (lua_State *L, Table *t, const TValue *key,
                                                  TValue *value) {
@@ -987,6 +988,16 @@ static int finishnodeset (Table *t, const TValue *slot, TValue *val) {
 }
 
 
+static int rawfinishnodeset (const TValue *slot, TValue *val) {
+  if (isabstkey(slot))
+    return 0;  /* no slot with that key */
+  else {
+    setobj(((lua_State*)NULL), cast(TValue*, slot), val);
+    return 1;  /* success */
+  }
+}
+
+
 int luaH_psetint (Table *t, lua_Integer key, TValue *val) {
   if (keyinarray(t, key)) {
     lu_byte *tag = getArrTag(t, key - 1);
@@ -1063,12 +1074,20 @@ void luaH_set (lua_State *L, Table *t, const TValue *key, TValue *value) {
 }
 
 
+/*
+** Ditto for a GC barrier. (No need to invalidate the TM cache, as
+** integers cannot be keys to metamethods.)
+*/
 void luaH_setint (lua_State *L, Table *t, lua_Integer key, TValue *value) {
-  int hres = luaH_psetint(t, key, value);
+  if (keyinarray(t, key))
-  if (hres != HOK) {
+    obj2arr(t, key, value);
-    TValue k;
+  else {
-    setivalue(&k, key);
+    int ok = rawfinishnodeset(getintfromhash(t, key), value);
-    luaH_finishset(L, t, &k, value, hres);
+    if (!ok) {
+      TValue k;
+      setivalue(&k, key);
+      luaH_newkey(L, t, &k, value);
+    }
   }
 }
 

ltable.h

@@ -45,6 +45,25 @@
 #define nodefromval(v)	cast(Node *, (v))
 
 
+
+#define luaH_fastgeti(t,k,res,hres) \
+  { Table *h = t; lua_Unsigned u = l_castS2U(k); \
+    if ((u - 1u < h->alimit)) { \
+      int tag = *getArrTag(h,(u)-1u); \
+      if (tagisempty(tag)) hres = HNOTFOUND; \
+      else { farr2val(h, u, tag, res); hres = HOK; }} \
+    else { hres = luaH_getint(h, u, 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); \
+      if (tagisempty(*tag)) hres = ~cast_int(u); \
+      else { fval2arr(h, u, tag, val); hres = HOK; }} \
+    else { hres = luaH_psetint(h, u, val); }}
+
+
 /* results from get/pset */
 #define HOK		0
 #define HNOTFOUND	1

lvm.h

@@ -78,35 +78,25 @@ typedef enum {
 /*
 ** fast track for 'gettable'
 */
-#define luaV_fastget(t,k,res,f, aux) \
+#define luaV_fastget(t,k,res,f, hres) \
-  (aux = (!ttistable(t) ? HNOTATABLE : f(hvalue(t), k, res)))
+  (hres = (!ttistable(t) ? HNOTATABLE : f(hvalue(t), k, res)))
 
 
 /*
 ** Special case of 'luaV_fastget' for integers, inlining the fast case
 ** of 'luaH_getint'.
 */
-#define luaV_fastgeti(t,k,res,aux) \
+#define luaV_fastgeti(t,k,res,hres) \
-  if (!ttistable(t)) aux = HNOTATABLE; \
+  if (!ttistable(t)) hres = HNOTATABLE; \
-  else { Table *h = hvalue(t); lua_Unsigned u = l_castS2U(k); \
+  else { luaH_fastgeti(hvalue(t), k, res, hres); }
-    if ((u - 1u < h->alimit)) { \
-      int tag = *getArrTag(h,(u)-1u); \
-      if (tagisempty(tag)) aux = HNOTFOUND; \
-      else { farr2val(h, u, tag, res); aux = HOK; }} \
-    else { aux = luaH_getint(h, u, res); }}
 
 
-#define luaV_fastset(t,k,val,aux,f) \
+#define luaV_fastset(t,k,val,hres,f) \
-  (aux = (!ttistable(t) ? HNOTATABLE : f(hvalue(t), k, val)))
+  (hres = (!ttistable(t) ? HNOTATABLE : f(hvalue(t), k, val)))
 
-#define luaV_fastseti(t,k,val,aux) \
+#define luaV_fastseti(t,k,val,hres) \
-  if (!ttistable(t)) aux = HNOTATABLE; \
+  if (!ttistable(t)) hres = HNOTATABLE; \
-  else { Table *h = hvalue(t); lua_Unsigned u = l_castS2U(k); \
+  else { luaH_fastseti(hvalue(t), k, val, hres); }
-    if ((u - 1u < h->alimit)) { \
-      lu_byte *tag = getArrTag(h,(u)-1u); \
-      if (tagisempty(*tag)) aux = ~cast_int(u); \
-      else { fval2arr(h, u, tag, val); aux = HOK; }} \
-    else { aux = luaH_psetint(h, u, val); }}
 
 
 /*