Fixed some DBUGing, and optimized SET slightly.

sql/sp.cc:
  Added DBUG statements.
sql/sp_head.cc:
  Added DBUG statements.
sql/sql_parse.cc:
  Changed returns into DBUG_RETURNs in mysql_execute_command().
sql/sql_yacc.yy:
  Small optimization: Don't generate sp_instr_stmt instructions for empty
  SET_OPTIONs. (Which happened if there were only local variables in the SET
  statement.)

sql/sp.cc

@@ -26,6 +26,7 @@
 sp_head *
 sp_find_procedure(THD *thd, Item_string *iname)
 {
+  DBUG_ENTER("sp_find_procedure");
   extern int yyparse(void *thd);
   LEX *tmplex;
   TABLE *table;
@@ -35,11 +36,12 @@ sp_find_procedure(THD *thd, Item_string *iname)
   sp_head *sp = NULL;
 
   name = iname->const_string();
+  DBUG_PRINT("enter", ("name: %*s", name->length(), name->c_ptr()));
   memset(&tables, 0, sizeof(tables));
   tables.db= (char*)"mysql";
   tables.real_name= tables.alias= (char*)"proc";
   if (! (table= open_ltable(thd, &tables, TL_READ)))
-    return NULL;
+    DBUG_RETURN(NULL);
 
   if (table->file->index_read_idx(table->record[0], 0,
 				  (byte*)name->c_ptr(), name->length(),
@@ -59,12 +61,14 @@ sp_find_procedure(THD *thd, Item_string *iname)
  done:
   if (table)
     close_thread_tables(thd);
-  return sp;
+  DBUG_RETURN(sp);
 }
 
 int
 sp_create_procedure(THD *thd, char *name, uint namelen, char *def, uint deflen)
 {
+  DBUG_ENTER("sp_create_procedure");
+  DBUG_PRINT("enter", ("name: %*s def: %*s", namelen, name, deflen, def));
   int ret= 0;
   TABLE *table;
   TABLE_LIST tables;
@@ -88,12 +92,14 @@ sp_create_procedure(THD *thd, char *name, uint namelen, char *def, uint deflen)
 
  done:
   close_thread_tables(thd);
-  return ret;
+  DBUG_RETURN(ret);
 }
 
 int
 sp_drop_procedure(THD *thd, char *name, uint namelen)
 {
+  DBUG_ENTER("sp_drop_procedure");
+  DBUG_PRINT("enter", ("name: %*s", namelen, name));
   TABLE *table;
   TABLE_LIST tables;
 
@@ -111,9 +117,9 @@ sp_drop_procedure(THD *thd, char *name, uint namelen)
       table->file->print_error(error, MYF(0));
   }
   close_thread_tables(thd);
-  return 0;
+  DBUG_RETURN(0);
 
  err:
   close_thread_tables(thd);
-  return -1;
+  DBUG_RETURN(-1);
 }

sql/sp_head.cc

@@ -99,17 +99,21 @@ sp_head::sp_head(LEX_STRING *name, LEX *lex)
 int
 sp_head::create(THD *thd)
 {
+  DBUG_ENTER("sp_head::create");
   String *name= m_name->const_string();
   String *def= m_defstr->const_string();
 
-  return sp_create_procedure(thd,
-			     name->c_ptr(), name->length(),
-			     def->c_ptr(), def->length());
+  DBUG_PRINT("info", ("name: %s def: %s", name->c_ptr(), def->c_ptr()));
+  DBUG_RETURN(sp_create_procedure(thd,
+				  name->c_ptr(), name->length(),
+				  def->c_ptr(), def->length()));
 }
 
 int
 sp_head::execute(THD *thd)
 {
+  DBUG_ENTER("sp_head::execute");
+  DBUG_PRINT("executing", ("procedure %s", ((String *)m_name->const_string())->c_ptr()));
   int ret= 0;
   sp_instr *p;
   sp_pcontext *pctx = m_call_lex->spcont;
@@ -171,6 +175,7 @@ sp_head::execute(THD *thd)
       i = get_instr(ip);	// Returns NULL when we're done.
       if (i == NULL)
 	break;
+      DBUG_PRINT("execute", ("Instruction %u", ip));
       ret= i->execute(thd, &ip);
     }
   }
@@ -218,7 +223,7 @@ sp_head::execute(THD *thd)
       thd->spcont= octx;
   }
 
-  return ret;
+  DBUG_RETURN(ret);
 }
 
 
@@ -351,6 +356,8 @@ sp_head::backpatch(sp_label_t *lab)
 int
 sp_instr_stmt::execute(THD *thd, uint *nextp)
 {
+  DBUG_ENTER("sp_instr_stmt::execute");
+  DBUG_PRINT("info", ("command: %d", m_lex.sql_command));
   LEX olex;			// The other lex
   int res;
 
@@ -364,7 +371,7 @@ sp_instr_stmt::execute(THD *thd, uint *nextp)
   memcpy(&thd->lex, &olex, sizeof(LEX)); // Restore the other lex
 
   *nextp = m_ip+1;
-  return res;
+  DBUG_RETURN(res);
 }
 
 //
@@ -373,9 +380,11 @@ sp_instr_stmt::execute(THD *thd, uint *nextp)
 int
 sp_instr_set::execute(THD *thd, uint *nextp)
 {
+  DBUG_ENTER("sp_instr_set::execute");
+  DBUG_PRINT("info", ("offset: %u", m_offset));
   thd->spcont->set_item(m_offset, eval_func_item(thd, m_value, m_type));
   *nextp = m_ip+1;
-  return 0;
+  DBUG_RETURN(0);
 }
 
 //
@@ -384,13 +393,15 @@ sp_instr_set::execute(THD *thd, uint *nextp)
 int
 sp_instr_jump_if::execute(THD *thd, uint *nextp)
 {
+  DBUG_ENTER("sp_instr_jump_if::execute");
+  DBUG_PRINT("info", ("destination: %u", m_dest));
   Item *it= eval_func_item(thd, m_expr, MYSQL_TYPE_TINY);
 
   if (it->val_int())
     *nextp = m_dest;
   else
     *nextp = m_ip+1;
-  return 0;
+  DBUG_RETURN(0);
 }
 
 //
@@ -399,11 +410,13 @@ sp_instr_jump_if::execute(THD *thd, uint *nextp)
 int
 sp_instr_jump_if_not::execute(THD *thd, uint *nextp)
 {
+  DBUG_ENTER("sp_instr_jump_if_not::execute");
+  DBUG_PRINT("info", ("destination: %u", m_dest));
   Item *it= eval_func_item(thd, m_expr, MYSQL_TYPE_TINY);
 
   if (! it->val_int())
     *nextp = m_dest;
   else
     *nextp = m_ip+1;
-  return 0;
+  DBUG_RETURN(0);
 }

sql/sql_parse.cc

@@ -1513,7 +1513,7 @@ mysql_execute_command(THD *thd)
       given and the table list says the query should not be replicated
     */
     if (table_rules_on && tables && !tables_ok(thd,tables))
-      return 0;
+      DBUG_RETURN(0);
 #ifndef TO_BE_DELETED
     /*
        This is a workaround to deal with the shortcoming in 3.23.44-3.23.46
@@ -1549,7 +1549,7 @@ mysql_execute_command(THD *thd)
 	{
 	  if (res < 0 || thd->net.report_error)
 	    send_error(thd,thd->killed ? ER_SERVER_SHUTDOWN : 0);
-	  return res;
+	  DBUG_RETURN(res);
 	}
       }
     }
@@ -1558,7 +1558,7 @@ mysql_execute_command(THD *thd)
        lex->unit.create_total_list(thd, lex, &tables)) ||
       (table_rules_on && tables && thd->slave_thread &&
        !tables_ok(thd,tables)))
-    return 0;
+    DBUG_RETURN(0);
 
   statistic_increment(com_stat[lex->sql_command],&LOCK_status);
   switch (lex->sql_command) {
@@ -1838,7 +1838,7 @@ mysql_execute_command(THD *thd)
 	  find_real_table_in_list(tables->next, tables->db, tables->real_name))
       {
 	net_printf(thd,ER_UPDATE_TABLE_USED,tables->real_name);
-	return -1;
+	DBUG_RETURN(-1);
       }
       if (tables->next)
       {
@@ -2912,11 +2912,11 @@ mysql_execute_command(THD *thd)
   // or res != 0 and no send_error() has yet been done.
   if (res < 0)
     send_error(thd,thd->killed ? ER_SERVER_SHUTDOWN : 0);
-  return res;
+  DBUG_RETURN(res);
 
 error:
   // We end up here if send_error() has already been done.
-  return -1;
+  DBUG_RETURN(-1);
 }
 
 

sql/sql_yacc.yy

@@ -1049,10 +1049,18 @@ sp_proc_stmt:
 	    }
 	    else
 	    {
-	      sp_instr_stmt *i= new sp_instr_stmt(lex->sphead->instructions());
-
-	      i->set_lex(lex);
-	      lex->sphead->add_instr(i);
+	      /* Don't add an instruction for empty SET statements.
+	      ** (This happens if the SET only contained local variables,
+	      **  which get their set instructions generated separately.)
+	      */
+	      if (lex->sql_command != SQLCOM_SET_OPTION ||
+	          !lex->var_list.is_empty())
+	      {
+	        sp_instr_stmt *i= new sp_instr_stmt(lex->sphead->instructions());
+
+	        i->set_lex(lex);
+	        lex->sphead->add_instr(i);
+              }
 	      lex->sphead->restore_lex(YYTHD);
 	    }
           }