From 27e964dbfb9907970e96bd40429563449000bfbe Mon Sep 17 00:00:00 2001
From: Ali MJ Al-Nasrawy <alimjalnasrawy@gmail.com>
Date: Mon, 18 Dec 2023 16:26:14 +0000
Subject: [PATCH] fast path for declared_generic_bounds_from_env
---
compiler/rustc_infer/src/infer/outlives/verify.rs | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/compiler/rustc_infer/src/infer/outlives/verify.rs b/compiler/rustc_infer/src/infer/outlives/verify.rs
index ce619ae8a0d8c..b0caf1efb4503 100644
--- 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};
@@ -245,10 +245,20 @@ 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 (&p, erased_ty.kind()) {
+ // In outlive routines, all types are expected to be fully normalized.
+ // And therefore we can safely use structural equality for alias types.
+ (GenericKind::Param(p1), ty::Param(p2)) if p1 == p2 => {}
+ (GenericKind::Placeholder(p1), ty::Placeholder(p2)) if p1 == p2 => {}
+ (GenericKind::Alias(a1), ty::Alias(_, a2)) if a1.def_id == a2.def_id => {}
+ _ => 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