[fpc-pascal] FreePascal/Lazarus plug-in's for Delphi.

Jonas Maebe jonas.maebe at elis.ugent.be
Thu Dec 18 14:34:53 CET 2008


On 18 Dec 2008, at 14:07, Frank de Groot (Rent-a-Geek) wrote:

>>> Free Pascal compiler can do 64 bit but no performance benefits so  
>>> far ?!
>>
>> There were never supposed to be any.
>
> 64-bit code can, in some specialist cases, be made to execute in  
> about double the speed of 32-bit code due to the wider registers.

These are indeed really specialist cases, as it requires to consist of  
almost nothing but 64 bit math and almost no pointers (since every  
pointer is twice as wide, reducing cache effectivity by half).

> The availability of more registers is another speed-boon to 64-bit  
> code.

On x86_64, to be precise (on other architectures, 32 bit mode already  
has plentiful registers). However, register variables are not enabled  
in FPC 2.2.x for x86_64, but only in in 2.3.x (and this will not be  
merged).


Jonas



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