gpc issue with some record structure - Gpc

22 Sep 2007


      I did some further investigations on the gpc issue I recently discovered 
on Mac OS X 10.4.10 PowerPC (gpc 20070904, based on gcc-4.1.2). The 
following program exhibits the problem:
program schorn3;
type abc = record
     a, b, c: Extended;
   end;
const d = 22092007.192016;
procedure outer;
   var x: abc;
procedure inner(p: abc);
     begin
       if x.a = d then
         writeln('OK')
       else
         writeln('Fail. Got x.a = ', x.a, '. Expected x.a =', d);
     end;
begin { outer }
     x.a := d;
     inner(x);
   end;
begin
outer;
end.
The following behavior is observed:
peter% /Developer/Pascal/gpc412/bin/gpc -o schorn3 schorn3.pas
peter% schorn3
Fail. Got x.a = -3.066700750256657e-231. Expected x.a = 
2.209200719201600e+07
Now with --pack-struct (although it seems there is nothing to pack)
peter% /Developer/Pascal/gpc412/bin/gpc --pack-struct -o schorn3 schorn3.pas
peter% schorn3
OK
The previous test program for this issue caused bus errors or 
segmentation faults on Macintoshes but also had a chance to succeed by 
chance (only a boolean at a possibly wrong address was tested). Maybe 
the issue now shows up on other platforms as well.
Peter
-----
peter.schorn at acm.org