[fpc-devel] Generated code of constant parameters of double type
florian at freepascal.org
Sun Nov 16 17:54:09 CET 2008
Luiz Americo Pereira Camara schrieb:
> Jonas Maebe escreveu:
>> On 16 Nov 2008, at 14:52, Florian Klaempfl wrote:
>>> Luiz Americo Pereira Camara schrieb:
>>>> Maybe the documentation
>>>> can be modified to clarify this since the statement:
>>>> "A constant argument is passed by reference if its size is larger
>>>> than a pointer."
>>>> leads to the conclusion that double types (8 bytes) would be passed
>>>> as reference in 32bit code.
>>> Well, the bigger problem is that this is target dependent.
>> And calling convention dependent. In most cases, how exactly constant
>> and value parameters are handled by the compiler is a private
>> implementation detail. You cannot count on how it is exactly implemented.
> Ok. I was not counting in implementation details.
> My point was that this could be a missing optimization opportunity: pass
> by reference a 8 bytes parameter when the pointer size is 4.
Don't forget that this makes an extra memory access.
More information about the fpc-devel