[fpc-pascal]Default calling convention

[Marcel Martin]

Marco van de Voort wrote:
> Marcel Martin wrote:
> >
> > I noticed that, with FPC 1.9.4, the (default) calling convention
> > "register" depends on the fact that a routine is or is not embedded
> > in an other routine.
> >
> > With "proc(A,B,C: Longint);", if "proc" is not embedded then
> > eax = A, edx = B and ecx = C but if "proc" is embedded then edx = A,
> > ecx = B and C is on the stack.
> >
> > Is this convention definitive or temporary? I am not sure it is
> > definitive since it makes the code of assembler routines dependent
> > on their status: embedded or not.

> In general it is not wise anyway to let the assembler become to dependant
> on calling convention.

> Keep on using

> mov eax,param1
> mov ecx,param2

> etc. Clearer, and doesn't have the problem between procedure/methods/nested
> procedures. 

I agree with you but it doesn't work. For instance, take this 
procedure

  procedure nx_fill(P: PLongword; Count: Longint; Value: Longword);
  assembler;
  asm
          pushl  %edi
          movl   Value,%eax
          movl   Count,%ecx
          movl   P,%edi
          rep    
          stosl
          popl   %edi
  end;

in the .s file, FPC 1.9.4 produces this:

  .globl  NXKERNEL_NX_FILL$PLONGWORD$LONGINT$LONGWORD
          pushl  %ebp
          movl   %esp,%ebp
          pushl  %edi
          movl   %ecx,%eax  // eax is modified
          movl   %edx,%ecx
          movl   %eax,%edi  // eax is more equal to P, access violation
          rep
          stosl
          popl   %edi
          ret

With this one

  procedure nx_fill(P: PLongword; Count: Longint; Value: Longword);
  assembler;
  asm
          pushl   %edi
          movl    %eax,%edi  // edi <- P
          movl    %ecx,%eax  // eax <- Value
          movl    %edx,%ecx  // ecx <- Count
          rep
          stosl
          popl    %edi
  end;

the produced code is correct but now this proc can no more be used as a 
nested proc.

-- 
mm
http://www.ellipsa.net/