[fpc-devel] large constant and qword comparison broken in fixes_2_4 rev 15403

[Jonas Maebe]

On 10 Jun 2010, at 20:06, Seth Grover wrote:

> A recent change to fixes_2_4 (I think it was rev 15403) has broken
> this example. With yesterday's code the code prints out "same" both
> times (which is correct), but after pulling today's revision it only
> works if the constant is cast as a qword (it fails in the first
> example, works in the second). It should work correctly whether I cast
> the constant or not.

I'm not sure about that. The reason it doesn't work is because
a) $AB09CD87EF653412 is interpreted as an int64 constant (this was already the case before the change)
b) int64($AB09CD87EF653412) < 0
c) hence, qwordvar = $AB09CD87EF653412 can never be true.

The code also refuses to compile with range checking enabled (and prints a warning without range checking on).

It's the same situation as this code:

var
  c: cardinal;
begin
  c:=high(cardinal);
  if c=-1 then
    writeln('c = -1')
  else
    writeln('c <> -1');
end.

This prints, also with FPC 2.4.0, "c <> -1".


Jonas