Auto merge of rust-lang#119084 - aliemjay:perf-env-bounds, r=<try>

fast path for declared_generic_bounds_from_env ~2% perf gain for diesel
rust-lang-ci · Dec 18, 2023 · e0a7b59 · e0a7b59
2 parents a7690a3 + 20e222a
commit e0a7b59
Showing 1 changed file with 11 additions and 2 deletions.
diff --git a/compiler/rustc_infer/src/infer/outlives/verify.rs b/compiler/rustc_infer/src/infer/outlives/verify.rs
@@ -1,7 +1,7 @@
 use crate::infer::outlives::components::{compute_alias_components_recursive, Component};
 use crate::infer::outlives::env::RegionBoundPairs;
 use crate::infer::region_constraints::VerifyIfEq;
-use crate::infer::VerifyBound;
+use crate::infer::{GenericKind, VerifyBound};
 use rustc_data_structures::sso::SsoHashSet;
 use rustc_middle::ty::GenericArg;
 use rustc_middle::ty::{self, OutlivesPredicate, Ty, TyCtxt};
@@ -240,10 +240,19 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
                     "declared_generic_bounds_from_env_for_erased_ty: region_bound_pair = {:?}",
                     (r, p)
                 );
+                // Fast path for the common case.
+                match (erased_ty.kind(), &p) {
+                    (ty::Alias(_, a1), GenericKind::Alias(a2)) if a1.def_id != a2.def_id => {
+                        return None;
+                    }
+                    (ty::Param(p1), GenericKind::Param(p2)) if p1 != p2 => return None,
+                    _ => {}
+                }
+
                 let p_ty = p.to_ty(tcx);
                 let erased_p_ty = self.tcx.erase_regions(p_ty);
                 (erased_p_ty == erased_ty)
-                    .then_some(ty::Binder::dummy(ty::OutlivesPredicate(p.to_ty(tcx), r)))
+                    .then_some(ty::Binder::dummy(ty::OutlivesPredicate(p_ty, r)))
             });
 
         param_bounds