user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Replace flat_map() with filter_map() in is_useful_specialized().

Browse source 
`filter_map()` is less general, but more efficient, and has the same
effect in this case.

This commit reduces the instruction count for
`unicode_normalization-check-clean` by about 2%.
This commit is contained in:
Nicholas Nethercote 2019-10-04 16:22:13 +10:00
parent 5515a97646
commit 2a3a544741
1 changed files with 5 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

8
src/librustc_mir/hair/pattern/_match.rs
View file

@ -1355,9 +1355,11 @@ fn is_useful_specialized<'p, 'a, 'tcx>(
}
}).collect();
let wild_patterns: Vec<_> = wild_patterns_owned.iter().collect();
let matrix = Matrix(m.iter().flat_map(|r| {
specialize(cx, &r, &ctor, &wild_patterns)
}).collect());
let matrix = Matrix(
m.iter()
.filter_map(|r| specialize(cx, &r, &ctor, &wild_patterns))
.collect()
);
match specialize(cx, v, &ctor, &wild_patterns) {
Some(v) => match is_useful(cx, &matrix, &v, witness) {
UsefulWithWitness(witnesses) => UsefulWithWitness(