Question

Do ‘What’s wrong with using inline functions‘ and ‘Can a recursive function be inline‘ apply to Delphi inline functions? Furthermore, does anyone know how recursive inline functions are handled in Delphi?

Answer 1

My guess is probably not since inline is only a suggestion, but lets find out.

A simple recursive factorial routine:

function Factorial(const aNum: cardinal): cardinal; begin   if aNum > 1 then     Result := Factorial(aNum - 1) * aNum   else     Result := 1; end; 

Here is the disassembly of the call to it:

// fact := Factorial(5); mov eax,$00000005 call Factorial mov ebx,eax 

And the disassembly of the routine itself:

// 9: begin push ebx mov ebx,eax // 10: if aNum > 1 then cmp ebx,$01 jbe $0040ab30 // 11: Result := Factorial(aNum - 1) * aNum mov eax,ebx dec eax call Factorial imul ebx pop ebx ret  // 13: Result := 1; 0040ab30: mov eax,$00000001 // 14: end; pop ebx ret  

Now we make it inline and see what is different in the call:

// 21: fact := Factorial(5); mov eax,$00000005 call Factorial mov ebx,eax 

And the routine itself:

// 9: begin push ebx mov ebx,eax // 10: if aNum > 1 then cmp ebx,$01 jbe $0040ab30 // 11: Result := Factorial(aNum - 1) * aNum mov eax,ebx dec eax call Factorial imul ebx pop ebx ret      // 13: Result := 1; 0040ab30: mov eax,$00000001 // 14: end; pop ebx ret  

And they both appear the same to me, so I am going to stick with my original hypothesis and say they are not supported.

BTW: this is in Delphi 2009.