[fpc-devel] ifdef'd ThreadVar code in win/systhrd.inc

[Sven Barth]

On 03.10.2010 13:59, Florian Klämpfl wrote:
> Am 03.10.2010 11:37, schrieb Sven Barth:
>> Hello together!
>>
>> While I looked for a solution for the bug report about external threads
>> on Windows ( http://bugs.freepascal.org/view.php?id=17300 ), I found the
>> following code in SysRelocateThreadVar in rtl/win/systhrd.inc:
>>
>> ==== begin ====
>>
>> {$ifdef dummy}
>>          { it least in the on windows 7 x64, this still doesn't not work,
>> fs:(0x2c) is
>>            self referencing on this system (FK)
>>            MVC: It also does not work on Windows Vista 32-bit, Home
>> Premium, SP 1. Results in a crash}
>>          asm
>>            movl TLSKey,%edx
>>            movl %fs:(0x2c),%eax
>>            orl  %eax,%eax
>>            jnz  .LAddressInEAX
>>            { this works on Windows 7, but I don't know if it works on
>> other OSes (FK) }
>>            movl %fs:(0x18),%eax
>>            movl 0xe10(%eax,%edx,4),%eax
>>            jmp  .LToDataIndex
>>            .LAddressInEAX:
>>             movl (%eax,%edx,4),%eax
>>            .LToDataIndex:
>>            movl %eax,dataindex
>>          end;
>>          if DataIndex=nil then
>>            begin
>>              errorsave:=GetLastError;
>>              SysAllocateThreadVars;
>>              DataIndex:=TlsGetValue(tlskey);
>>              SetLastError(errorsave);
>>            end;
>> {$else win32}
>>
>> ==== end ====
>>
>> According to http://en.wikipedia.org/wiki/X86-64#Windows 64-bit Windows
>> uses GS instead of FS for the TIB. This might be the reason that the
>> code doesn't work on 64-bit Windows.
>
> Also for 32 bit programs? The code above is only used by 32 bit programs.

No, not for 32 bit programs. -.-

Note to self: Study foreign code more intensively.

Regards,
Sven