Hi all,
When building a unittest case in Weka.io's codebase, I measure
that appendToModuleMember takes about 10% of the total compile
time, and about 25% of total semantic analysis time.
"appendToModuleMember" is the only function that pops up in
profiling with such a large time fraction spent in it.
The culprit is the linear search at the end of
appendToModuleMember, because the members list with Dsymbols gets
pretty large (50k+ members).
https://github.com/D-Programming-Language/dmd/blob/master/src/dtemplate.d#L8012-L8026
I've modified the code to also store the list of members as an
rbtree, and voila, much faster compiles: from 26sec to 20sec
(semantic only). The old data structure is still there and the
only change is to do a lookup into the tree instead of the linear
search.
The hack is here:
https://github.com/ldc-developers/ldc/compare/master...JohanEngelen:speed_up
I couldn't use symtab as it isn't populated with all symbols and
I wasn't sure if it would break things.
I'm thinking about removing the old array all-together.
My question is: is it essential to keep an ordered list? (I see a
`.shift(...)` call on the array, to put something in first
position. If so, could that be solved by having *two* trees,
where "in-order" iteration first iterates over the first one and
then the second. The "high priority" symbols can then be put in
the first tree, normal ones in the second tree (if that is how
order matters...).
Thanks,
Johan
