Am 04.03.2013 13:38, schrieb Daniël Mantione:
1. Operator overloading
Operators are some of the most common tokens in source code. Without
operator overloading, if you parse an operator, you simply generate a
tree node.
With operator overloading, for each operator that you parse, you have
to traverse all loaded units to check if the operator is overloaded.
If there are 50 units loaded, this means 50 symtable lookups, simply
because the operator might be overloaded.
For each operator overload candidate that is found, the compiler has
need to check for many possible type conversions to see if the
candidate can actually be used.
The situation with Pascal type conversion has grown increasingly
complex over the years. For example almost any type can be converted
into a variant, and a variant can be converted into almost any type.
This requires all kinds of special handling, not only to do the right
thing, but also not to do ineffcient type conversions.
So even if you don't use operator overloading or variants at all, they
do affect the compiler speed.
Maybe we can improve this situation. For class helpers I added the
possibility to add flags to symtables (so that only units are checked
that really contain class helpers). Maybe we can add an additional
"has_operators" flag and ignore all units when searching for overloads
that don't have this flag set (the flag would propagate from the
symtable of e.g. advanced records up to the unit symtable when parsing
the record's declaration). As most units don't declare operators this
could result in a little speedup especially considering that the lookup
is done on each operator... and then we might add some caching
structures to improve this further.
Regards,
Sven
_______________________________________________
fpc-devel maillist - fpc-devel@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-devel
