How to detect in runtime if some Compiler Option (like Optimization) is on?

Question

I would like to show in the Caption of the program how was the program complied. Most important, I would like to show if the Compiler Optimization is on/off.

(Range Checking and other stuff like this would be interesting to show also, but mainly I am interested in Compiler Optimization).

Any idea how to do it?

---

Ready to use function based on Arioch answer:

function CompilerOptimization: Boolean;  { Importan note: $O+ has a local scope, therefore, the result of the function reflects only the optimization state at that specific source code location. }
begin
 {$IfOpt O+}
 Result:= TRUE;
 {$Else}
 Result:= FALSE;
 {$EndIf}
end;

function CompilerOptimizationS: String;
begin
 Result:= 'Compiler optimization is ' +
 {$IfOpt O+}
 'enabled'
 {$Else}
 'disabled'
 {$EndIf}
end;

---

IMPORTANT: If you are using the {$O} switch to optimize pieces of code then it MUST be used as a subfunction like this, otherwise, if you use the global switch only (in Project Options) it can be used as a normal (declared) function.

// {$O+} or {$O-}
procedure TFrmTest.FormCreate(Sender: TObject);

 function CompilerOptimizationS: String;
 begin
  Result:= 'Compiler optimization is ' +
  {$IfOpt O+}
  'enabled'
  {$Else}
  'disabled'
  {$EndIf}
 end;

begin
 ///...more code here
 Caption:= 'Version: '+ GerVerStr+ ' '+ CompilerOptimizationS+ etc+ etc;
end;

Answer 1

ShowMessage(' Optimization is ' +
{$IfOpt O+}
'enabled'
{$Else}
'disabled'
{$EndIf}
);

PS. Documentation... Going Google for "Delphi IfOpt" will bring you a lot of links, including

• http://www.delphibasics.co.uk/RTL.asp?Name=$IfOpt
• http://docwiki.embarcadero.com/RADStudio/en/IFOPT_directive_(Delphi)

PPS. gammatester is absolutely correct that "Since {$O+} has a local scope, your message/caption reflects only the optimization state at that specific source code location"