Hi, I know when compile the project with optimize in Delphi the variable freed/allocated after the last line used.
How can i make same in FPC, O3 not worked for me.
I used FPC 2.4.4

var
  c: Currency;
begin
   c := 10;
   writeln(c);
<<now c freed
   some code here
end;

Thanks in advance.

Zaher Dirkey wrote

Hi, I know when compile the project with optimize in Delphi the variable freed/allocated after the last line used. How can i make same in FPC, O3 not worked for me.

FPC only reuses stack slots allocated for temporary expressions. It does not reuse stack slots used by variables.

Jonas

C (as a currency) is never 'freed'. It is declared throughout the whole procedure.

Michael.

What if C is string or Interface of TInterfacedObject?

Thanks

Read the following threads, it has been lengthly discussed before:

http://lists.freepascal.org/lists/fpc-devel/2010-November/022806.html http://lists.freepascal.org/lists/fpc-devel/2010-November/022867.html

there may be more threads by the same subject

It is the same logic. It's freed only at the end.

For compiler-generated temporary variables, you should not make any assumptions.

Michael.

While we are at it, is this a limitation or by design?

> What if C is string or Interface of TInterfacedObject? It is the same logic. It's freed only at the end.

I recently noticed that this is also true for ansistrings. I see this can avoid lots of errors, but also makes it very ackward to intentionally avoid copies when modifying strings in-place if they are obtained from a function...

-Flávio