[fpc-devel] Comparison FPC 2.6.2 - Delphi 7

[Michael Schnell]

On 03/04/2013 12:29 PM, Tomas Hajny wrote:
> It's questionable whether it should be responsibility of a compiler to 
> provide efficient support for threadvars, 

If the target platform does not support threadvars a compiler can't do 
it at all.

If the target platform only provides library calls, a compiler needs to 
use them.

If the target platform provides dedicated pointer registers for 
threadvars a compiler can use them.

In all fpc enabled patforms I examined (X86 Windows, X86 Linux, X64-64 
Windows, X86-64 Linux, ARM Linux (32 Bits) the platform provides as well 
library calls as dedicated threadvar pointer registers. In windows the 
registers seem to be undocumented but obviously "stable", as a change 
would break a lot existing C/C++ software.

All C/C++ compilers I examined used the threadvar pointer Registers for 
speed..

-Michael