[fpc-devel] Progress on pure functions

[J. Gareth Moreton]

The field sharing refers to this:

"What I mean is that if a function is marked as "pure" or "inline" (or 
both), only one copy of the unoptimised node tree is stored in the 
"inlininginfo" field, and both "pass1_pure" and "pass1_inline" duplicate 
this tree and transform it as needed. Because only the unoptimised tree 
is stored, I felt there was no need to store this twice (doing so would 
also increase the size of PPU files)."

This copy of the tree is stored for inline functions before the first 
pass is executed.  Pure functions copy and analyse the same tree.  If a 
function is both pure and inline, these initial trees will always be 
identical, so it is redundant to store two copies.

Kit


On 16/12/2022 06:44, Sven Barth wrote:
> Am 16.12.2022 um 02:02 schrieb J. Gareth Moreton via fpc-devel:
>> The purity analysis process is very dependent on the node tree being 
>> as clean as possible, and so depends on a fair few merge requests 
>> that have not yet been approved.  I'm guessing Florian and Jonas and 
>> others are somewhat busy, what with being December and all.
>>
>> - https://gitlab.com/freepascal.org/fpc/source/-/merge_requests/232 - 
>> strips unnecessary typeconv nodes (this helps a lot with constant 
>> propagation).
>> - https://gitlab.com/freepascal.org/fpc/source/-/merge_requests/342 - 
>> strips excess nothing nodes.
>
> I didn't say that you shouldn't clean up the tree for your purity 
> analysis (that sounds so wrong :P ), I simply asked what you meant 
> with “share the same field” and if it is what I think it is then it's 
> a bad idea and you shouldn't “share the same field” but introduce your 
> own.
>
> Regards,
> Sven
>