'luaH_get' functions return tag of the result

Undoing previous commit. Returning TValue increases code size without
any visible gains. Returning the tag is a little simpler than returning
a special code (HOK/HNOTFOUND) and the tag is useful by itself in
some cases.

lapi.c

@@ -353,7 +353,7 @@ LUA_API void lua_arith (lua_State *L, int op) {
   }
   /* first operand at top - 2, second at top - 1; result go to top - 2 */
   luaO_arith(L, op, s2v(L->top.p - 2), s2v(L->top.p - 1), L->top.p - 2);
-  L->top.p--;  /* remove second operand */
+  L->top.p--;  /* pop second operand */
   lua_unlock(L);
 }
 
@@ -666,47 +666,49 @@ LUA_API int lua_pushthread (lua_State *L) {
 
 
 static int auxgetstr (lua_State *L, const TValue *t, const char *k) {
-  TValue aux;
+  int tag;
   TString *str = luaS_new(L, k);
-  luaV_fastget(t, str, s2v(L->top.p), luaH_getstr, aux);
-  if (!isemptyV(aux)) {
+  luaV_fastget(t, str, s2v(L->top.p), luaH_getstr, tag);
+  if (!tagisempty(tag)) {
     api_incr_top(L);
   }
   else {
     setsvalue2s(L, L->top.p, str);
     api_incr_top(L);
-    luaV_finishget(L, t, s2v(L->top.p - 1), L->top.p - 1, aux);
+    tag = luaV_finishget(L, t, s2v(L->top.p - 1), L->top.p - 1, tag);
   }
   lua_unlock(L);
-  return ttype(s2v(L->top.p - 1));
+  return novariant(tag);
 }
 
 
-static TValue getGlobalTable (lua_State *L) {
+static void getGlobalTable (lua_State *L, TValue *gt) {
   Table *registry = hvalue(&G(L)->l_registry);
-  return luaH_getint(registry, LUA_RIDX_GLOBALS);
+  int tag = luaH_getint(registry, LUA_RIDX_GLOBALS, gt);
+  (void)tag;  /* avoid not-used warnings when checks are off */
+  api_check(L, novariant(tag) == LUA_TTABLE, "global table must exist");
 }
 
 
 LUA_API int lua_getglobal (lua_State *L, const char *name) {
   TValue gt;
   lua_lock(L);
-  gt = getGlobalTable(L);
+  getGlobalTable(L, &gt);
   return auxgetstr(L, &gt, name);
 }
 
 
 LUA_API int lua_gettable (lua_State *L, int idx) {
-  TValue aux;
+  int tag;
   TValue *t;
   lua_lock(L);
   api_checkpop(L, 1);
   t = index2value(L, idx);
-  luaV_fastget(t, s2v(L->top.p - 1), s2v(L->top.p - 1), luaH_get, aux);
-  if (isemptyV(aux))
-    luaV_finishget(L, t, s2v(L->top.p - 1), L->top.p - 1, aux);
+  luaV_fastget(t, s2v(L->top.p - 1), s2v(L->top.p - 1), luaH_get, tag);
+  if (tagisempty(tag))
+    tag = luaV_finishget(L, t, s2v(L->top.p - 1), L->top.p - 1, tag);
   lua_unlock(L);
-  return ttype(s2v(L->top.p - 1));
+  return novariant(tag);
 }
 
 
@@ -718,29 +720,27 @@ LUA_API int lua_getfield (lua_State *L, int idx, const char *k) {
 
 LUA_API int lua_geti (lua_State *L, int idx, lua_Integer n) {
   TValue *t;
-  TValue aux;
+  int tag;
   lua_lock(L);
   t = index2value(L, idx);
-  luaV_fastgeti(t, n, s2v(L->top.p), aux);
-  if (isemptyV(aux)) {
+  luaV_fastgeti(t, n, s2v(L->top.p), tag);
+  if (tagisempty(tag)) {
     TValue key;
     setivalue(&key, n);
-    luaV_finishget(L, t, &key, L->top.p, aux);
+    tag = luaV_finishget(L, t, &key, L->top.p, tag);
   }
   api_incr_top(L);
   lua_unlock(L);
-  return ttype(s2v(L->top.p - 1));
+  return novariant(tag);
 }
 
 
-l_sinline int finishrawget (lua_State *L, TValue res) {
-  if (isemptyV(res))  /* avoid copying empty items to the stack */
+static int finishrawget (lua_State *L, int tag) {
+  if (tagisempty(tag))  /* avoid copying empty items to the stack */
     setnilvalue(s2v(L->top.p));
-  else
-    setobjV(L, s2v(L->top.p), res);
   api_incr_top(L);
   lua_unlock(L);
-  return ttypeV(res);
+  return novariant(tag);
 }
 
 
@@ -753,23 +753,23 @@ l_sinline Table *gettable (lua_State *L, int idx) {
 
 LUA_API int lua_rawget (lua_State *L, int idx) {
   Table *t;
-  TValue res;
+  int tag;
   lua_lock(L);
   api_checkpop(L, 1);
   t = gettable(L, idx);
-  res = luaH_get(t, s2v(L->top.p - 1));
+  tag = luaH_get(t, s2v(L->top.p - 1), s2v(L->top.p - 1));
   L->top.p--;  /* pop key */
-  return finishrawget(L, res);
+  return finishrawget(L, tag);
 }
 
 
 LUA_API int lua_rawgeti (lua_State *L, int idx, lua_Integer n) {
   Table *t;
-  TValue aux;
+  int tag;
   lua_lock(L);
   t = gettable(L, idx);
-  luaH_fastgeti(t, n, s2v(L->top.p), aux);
-  return finishrawget(L, aux);
+  luaH_fastgeti(t, n, s2v(L->top.p), tag);
+  return finishrawget(L, tag);
 }
 
 
@@ -779,7 +779,7 @@ LUA_API int lua_rawgetp (lua_State *L, int idx, const void *p) {
   lua_lock(L);
   t = gettable(L, idx);
   setpvalue(&k, cast_voidp(p));
-  return finishrawget(L, luaH_get(t, &k));
+  return finishrawget(L, luaH_get(t, &k, s2v(L->top.p)));
 }
 
 
@@ -872,7 +872,7 @@ static void auxsetstr (lua_State *L, const TValue *t, const char *k) {
 LUA_API void lua_setglobal (lua_State *L, const char *name) {
   TValue gt;
   lua_lock(L);  /* unlock done in 'auxsetstr' */
-  gt = getGlobalTable(L);
+  getGlobalTable(L, &gt);
   auxsetstr(L, &gt, name);
 }
 
@@ -1122,7 +1122,8 @@ 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 */
-      TValue gt = getGlobalTable(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);
@@ -1266,7 +1267,7 @@ LUA_API int lua_next (lua_State *L, int idx) {
   if (more)
     api_incr_top(L);
   else  /* no more elements */
-    L->top.p -= 1;  /* remove key */
+    L->top.p--;  /* pop key */
   lua_unlock(L);
   return more;
 }