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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