Replace table.remove with bytecode builtin.

src/host/buildvm_libbc.h

@@ -9,7 +9,11 @@ static const uint8_t libbc_code[] = {
 59,8,5,0,66,6,3,2,10,6,0,0,88,7,1,128,76,6,2,0,79,2,248,127,75,0,1,0,0,2,10,
 0,0,0,16,16,0,12,0,16,1,9,0,43,2,0,0,18,3,0,0,41,4,0,0,88,5,7,128,18,7,1,0,
 18,8,5,0,18,9,6,0,66,7,3,2,10,7,0,0,88,8,1,128,76,7,2,0,70,5,3,3,82,5,247,127,
-75,0,1,0,0,1,2,0,0,0,3,16,0,12,0,21,1,0,0,76,1,2,0,0
+75,0,1,0,0,1,2,0,0,0,3,16,0,12,0,21,1,0,0,76,1,2,0,0,2,10,0,0,2,30,16,0,12,
+0,21,2,0,0,11,1,0,0,88,3,7,128,8,2,0,0,88,3,23,128,59,3,2,0,43,4,0,0,64,4,2,
+0,76,3,2,0,88,3,18,128,16,1,14,0,41,3,1,0,3,3,1,0,88,3,14,128,3,1,2,0,88,3,
+12,128,59,3,1,0,22,4,1,1,18,5,2,0,41,6,1,0,77,4,4,128,23,8,1,7,59,9,7,0,64,
+9,8,0,79,4,252,127,43,4,0,0,64,4,2,0,76,3,2,0,75,0,1,0,0,2,0
 };
 
 static const struct { const char *name; int ofs; } libbc_map[] = {
@@ -18,6 +22,7 @@ static const struct { const char *name; int ofs; } libbc_map[] = {
 {"table_foreachi",50},
 {"table_foreach",117},
 {"table_getn",188},
-{NULL,207}
+{"table_remove",207},
+{NULL,336}
 };
 

src/lib_table.c

@@ -103,27 +103,29 @@ LJLIB_CF(table_insert)		LJLIB_REC(.)
   return 0;
 }
 
-LJLIB_CF(table_remove)		LJLIB_REC(.)
-{
-  GCtab *t = lj_lib_checktab(L, 1);
-  int32_t e = (int32_t)lj_tab_len(t);
-  int32_t pos = lj_lib_optint(L, 2, e);
-  if (!(1 <= pos && pos <= e))  /* Nothing to remove? */
-    return 0;
-  lua_rawgeti(L, 1, pos);  /* Get previous value. */
-  /* NOBARRIER: This just moves existing elements around. */
-  for (; pos < e; pos++) {
-    cTValue *src = lj_tab_getint(t, pos+1);
-    TValue *dst = lj_tab_setint(L, t, pos);
-    if (src) {
-      copyTV(L, dst, src);
-    } else {
-      setnilV(dst);
-    }
-  }
-  setnilV(lj_tab_setint(L, t, e));  /* Remove (last) value. */
-  return 1;  /* Return previous value. */
-}
+LJLIB_LUA(table_remove) /*
+  function(t, pos)
+    CHECK_tab(t)
+    local len = #t
+    if pos == nil then
+      if len ~= 0 then
+	local old = t[len]
+	t[len] = nil
+	return old
+      end
+    else
+      CHECK_int(pos)
+      if pos >= 1 and pos <= len then
+	local old = t[pos]
+	for i=pos+1,len do
+	  t[i-1] = t[i]
+	end
+	t[len] = nil
+	return old
+      end
+    end
+  end
+*/
 
 LJLIB_CF(table_concat)
 {

src/lj_ffrecord.c

@@ -729,38 +729,6 @@ static void LJ_FASTCALL recff_string_range(jit_State *J, RecordFFData *rd)
 
 /* -- Table library fast functions ---------------------------------------- */
 
-static void LJ_FASTCALL recff_table_remove(jit_State *J, RecordFFData *rd)
-{
-  TRef tab = J->base[0];
-  rd->nres = 0;
-  if (tref_istab(tab)) {
-    if (!J->base[1] || tref_isnil(J->base[1])) {  /* Simple pop: t[#t] = nil */
-      TRef trlen = lj_ir_call(J, IRCALL_lj_tab_len, tab);
-      GCtab *t = tabV(&rd->argv[0]);
-      MSize len = lj_tab_len(t);
-      emitir(IRTGI(len ? IR_NE : IR_EQ), trlen, lj_ir_kint(J, 0));
-      if (len) {
-	RecordIndex ix;
-	ix.tab = tab;
-	ix.key = trlen;
-	settabV(J->L, &ix.tabv, t);
-	setintV(&ix.keyv, len);
-	ix.idxchain = 0;
-	if (results_wanted(J) != 0) {  /* Specialize load only if needed. */
-	  ix.val = 0;
-	  J->base[0] = lj_record_idx(J, &ix);  /* Load previous value. */
-	  rd->nres = 1;
-	  /* Assumes ix.key/ix.tab is not modified for raw lj_record_idx(). */
-	}
-	ix.val = TREF_NIL;
-	lj_record_idx(J, &ix);  /* Remove value. */
-      }
-    } else {  /* Complex case: remove in the middle. */
-      recff_nyiu(J);
-    }
-  }  /* else: Interpreter will throw. */
-}
-
 static void LJ_FASTCALL recff_table_insert(jit_State *J, RecordFFData *rd)
 {
   RecordIndex ix;