On 07/24/2010 06:52 PM, Nikolai Zhubr wrote:
IMHO the question is not how to avoid using FS trick altogether (which
is of course possible, right), but on the contrary, how to reliably
employ it in order to avoid wasting some more usefull registers and
excessive OS calls.
It's only possible to dedicate another register to that purpose.
With X86/32 it does not seem to make much sense, as this arch has so few
registers and dedicating one would slow down all programs - and the
Win32 FS-"trick" documented in the unofficial aper mentioned above and
used in Delphi (and supposedly gnuC and M$ C) is believed to work fine
(AFAIK, in Linux GS is different with different threads and directly
points to the TLS, but I'm not sure, yet).
With X86/64 and other archs (such as ARM) that provide many general
purpose registers, I suppose it's a usual way to dedicate one of them as
a Thread Local Storage area pointer.
Maybe Win64 uses some "Selector" mechanism (similar as ) so that there
are no different Selector-Register values in different threads.
-Michael
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