Accessing local variables from an asm block of a nested procedure

[Avinash]

A similar construction can be seen in outline.pas from the original Borland Turbo Vision package:

Code: Pascal  [Select][+][-]

1. {$IFDEF FPC}{$ASMMODE INTEL}{$ENDIF}
2.   procedure Test;
3.   var I: Integer;
4.  
5.     procedure Nested;
6.     {var J: Integer;}
7.     begin
8.       asm
9.        {$IFDEF VER70}
10.          mov bx, word ptr [bp]  {get parent BP}
11.          mov word ptr ss:[bx + OFFSET I], 12345
12.        {$ELSE}
13.          mov eax, dword ptr [ebp]  {get parent EBP}
14.          mov dword ptr [eax + OFFSET I], 12345
15.          //mov dword ptr [eax - 4], 12345
16.        {$ENDIF}
17.       end;
18.     end;
19.  
20.   begin
21.     I := 0;
22.     Nested;
23.     WriteLn(I);  { outputs '12345' }
24.   end;
25.  
26. begin
27.   Test;
28. end.

This way it compiles and works with both TP and FPC 3.2.2. However, if you uncomment the declaration of the J variable, then FPC refuses to compile it (Error: You cannot reach I from that code). At the same time, the declaration of the J variable does not affect the offsets at all — if you use a line with [eax - 4] instead of OFFSET, it will work in both cases.

[Thaddy]

May be that OFFSET is now supported, but not that I know of. There are some very old bug reports from many moons ago (at least 4 years, probably more) wherein I asked for OFFSET support. Forgot if it is actually implemented or not.
I usually fix it in the way you describe.

[marcov]

Probably the stackframe from nested gets eliminated, since there are no local variables, and I is not acceded from nested(assembler doesn't count)

 Maybe forcedly enabling stackframes will help:

https://www.freepascal.org/docs-html/prog/progsu78.html