Auto merge of #57697 - dotdash:fast_lex_reg_resol_item_bodies, r=nagisa
Use a faster early exit during region expansion
Turns out that the equality check for regions is rather expensive, and
the current early exit check works in such a way, that the comparison is
even done twice. As we only really care about the case of equal scopes,
we can perform a faster, more specialized check and move it up one
level, so we can eventually skip the additional full comparison as well.
diff --git a/src/librustc/infer/lexical_region_resolve/mod.rs b/src/librustc/infer/lexical_region_resolve/mod.rs
index 545192a..c0952fe 100644
--- a/src/librustc/infer/lexical_region_resolve/mod.rs
+++ b/src/librustc/infer/lexical_region_resolve/mod.rs
@@ -241,6 +241,14 @@
match *b_data {
VarValue::Value(cur_region) => {
+ // Identical scopes can show up quite often, if the fixed point
+ // iteration converges slowly, skip them
+ if let (ReScope(a_scope), ReScope(cur_scope)) = (a_region, cur_region) {
+ if a_scope == cur_scope {
+ return false;
+ }
+ }
+
let mut lub = self.lub_concrete_regions(a_region, cur_region);
if lub == cur_region {
return false;
@@ -280,12 +288,6 @@
fn lub_concrete_regions(&self, a: Region<'tcx>, b: Region<'tcx>) -> Region<'tcx> {
let tcx = self.tcx();
- // Equal scopes can show up quite often, if the fixed point
- // iteration converges slowly, skip them
- if a == b {
- return a;
- }
-
match (a, b) {
(&ty::ReClosureBound(..), _)
| (_, &ty::ReClosureBound(..))
