8514: Add more profiling spans into type inference r=matklad a=SomeoneToIgnore

Fixes https://github.com/rust-analyzer/rust-analyzer/issues/8503

I've added a minimal set of spans to remove `???` and showcase the underlying issue:

<img width="1552" alt="image" src="https://user-images.githubusercontent.com/2690773/114722983-f2181900-9d42-11eb-821d-9e93ded5f81f.png">

`db.trait_solve` reliably produces the same timings for the same input in the same place for me, despite supposedly being cached by Salsa.
In my perception, this is a bit odd, so I've decided to stop at this point and discuss it with people with better knowledge on the topic.

Co-authored-by: Kirill Bulatov <mail4score@gmail.com>
This commit is contained in:
bors[bot] 2021-04-14 14:20:13 +00:00 committed by GitHub
commit 678af41065
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@ -36,6 +36,7 @@ pub(crate) fn deref(
krate: CrateId,
ty: InEnvironment<&Canonical<Ty>>,
) -> Option<Canonical<Ty>> {
let _p = profile::span("deref");
if let Some(derefed) = builtin_deref(&ty.goal.value) {
Some(Canonical { value: derefed, binders: ty.goal.binders.clone() })
} else {
@ -56,6 +57,7 @@ fn deref_by_trait(
krate: CrateId,
ty: InEnvironment<&Canonical<Ty>>,
) -> Option<Canonical<Ty>> {
let _p = profile::span("deref_by_trait");
let deref_trait = match db.lang_item(krate, "deref".into())? {
LangItemTarget::TraitId(it) => it,
_ => return None,
@ -83,7 +85,10 @@ fn deref_by_trait(
environment: ty.environment.clone(),
},
};
if db.trait_solve(krate, implements_goal).is_none() {
if {
let _p = profile::span("db.trait_solve");
db.trait_solve(krate, implements_goal).is_none()
} {
return None;
}