Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Improve creation of 3 IndexVecs #55755

Merged
merged 1 commit into from
Nov 9, 2018
Merged

Improve creation of 3 IndexVecs #55755

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 1 addition & 2 deletions src/librustc/ty/query/on_disk_cache.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -450,8 +450,7 @@ impl<'sess> OnDiskCache<'sess> {
.map(|&(cnum, ..)| cnum)
.max()
.unwrap_or(0) + 1;
let mut map = IndexVec::new();
map.resize(map_size as usize, None);
let mut map = IndexVec::from_elem_n(None, map_size as usize);

for &(prev_cnum, ref crate_name, crate_disambiguator) in prev_cnums {
let key = (crate_name.clone(), crate_disambiguator);
Expand Down
5 changes: 3 additions & 2 deletions src/librustc_mir/shim.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -196,7 +196,7 @@ fn build_drop_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
let source_info = SourceInfo { span, scope: OUTERMOST_SOURCE_SCOPE };

let return_block = BasicBlock::new(1);
let mut blocks = IndexVec::new();
let mut blocks = IndexVec::with_capacity(2);
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

hmm do we want/need a SmallIndexVec that is analogous to SmallVec ...?

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

or ... should we try something bonkers like changing IndexVec to use a SmallVec internally...?

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I could submit an experimental PR to check the perf implications.

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This is harder than I thought; changing the underlying structure of IndexVec to a SmallVec makes Mir a recursive type of infinite size due to the promoted component.

let block = |blocks: &mut IndexVec<_, _>, kind| {
blocks.push(BasicBlockData {
statements: vec![],
Expand Down Expand Up @@ -768,7 +768,8 @@ fn build_call_shim<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
}));
}

let mut blocks = IndexVec::new();
let n_blocks = if let Adjustment::RefMut = rcvr_adjustment { 5 } else { 2 };
let mut blocks = IndexVec::with_capacity(n_blocks);
let block = |blocks: &mut IndexVec<_, _>, statements, kind, is_cleanup| {
blocks.push(BasicBlockData {
statements,
Expand Down