[fpc-devel] Merging identical procedure proposals

J. Gareth Moreton gareth at moreton-family.com
Sat Oct 16 20:45:26 CEST 2021

I figured that virtual methods would be no-go and that this would only 
apply to static methods.  It seems a shame to dismiss it completely 
though because there's a huge number of procedures that compile to the 
same code, especially when generics come into play, and I have 
identified a fair number in the compiler itself (at least when compiled 
under x86_64-win64).

I guess it would be something that would have to be showcased and 
thoroughly tested.  I can only try!

Gareth aka. Kit

On 16/10/2021 19:21, Jonas Maebe via fpc-devel wrote:
> On 16/10/2021 19:59, J. Gareth Moreton via fpc-devel wrote:
>> Sounds like "procvar = @myproc" would be -O4 at best due to the 
>> side-effects,
> That's not a kind of side-effect that would be acceptable at any 
> optimisation level. That is an explicit, valid comparison in code that 
> would suddenly behave wrongly.
>> otherwise I would wonder if it's possible to track such references, 
>> especially with units that are pre-compiled.
> It is possible to track whether the address gets taken of a procedure 
> and store that if the ppu file if you would be so inclined. This means 
> it will be impossible to apply the optimisation for any virtual method 
> though, since all of their addresses get implicitly taken.
> For the reason mentioned in my previous message, I don't think it's a 
> good optimisation to implement in a compiler though.
> Jonas
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