Auto merge of #91672 - b-naber:merge-normalize-erasing-regions-queries, r=jackh726

Implement normalize_erasing_regions queries in terms of 'try' version

Attempt to lessen performance regression caused by https://github.com/rust-lang/rust/pull/91255

r? `@jackh726`

compiler/rustc_middle/src/query/mod.rs

@@ -1658,27 +1658,6 @@
         remap_env_constness
     }
 
-    // FIXME: Implement `normalize_generic_arg_after_erasing_regions` and
-    // `normalize_mir_const_after_erasing_regions` in terms of
-    // `try_normalize_generic_arg_after_erasing_regions` and
-    // `try_normalize_mir_const_after_erasing_regions`, respectively.
-
-    /// Do not call this query directly: invoke `normalize_erasing_regions` instead.
-    query normalize_generic_arg_after_erasing_regions(
-        goal: ParamEnvAnd<'tcx, GenericArg<'tcx>>
-    ) -> GenericArg<'tcx> {
-        desc { "normalizing `{}`", goal.value }
-        remap_env_constness
-    }
-
-    /// Do not call this query directly: invoke `normalize_erasing_regions` instead.
-    query normalize_mir_const_after_erasing_regions(
-        goal: ParamEnvAnd<'tcx, mir::ConstantKind<'tcx>>
-    ) -> mir::ConstantKind<'tcx> {
-        desc { "normalizing `{}`", goal.value }
-        remap_env_constness
-    }
-
     /// Do not call this query directly: invoke `try_normalize_erasing_regions` instead.
     query try_normalize_generic_arg_after_erasing_regions(
         goal: ParamEnvAnd<'tcx, GenericArg<'tcx>>

compiler/rustc_middle/src/ty/normalize_erasing_regions.rs

@@ -176,7 +176,10 @@ fn normalize_generic_arg_after_erasing_regions(
         let arg = self.param_env.and(arg);
         debug!(?arg);
 
-        self.tcx.normalize_generic_arg_after_erasing_regions(arg)
+        self.tcx.try_normalize_generic_arg_after_erasing_regions(arg).unwrap_or_else(|_| bug!(
+                "Failed to normalize {:?}, maybe try to call `try_normalize_erasing_regions` instead",
+                arg.value
+            ))
     }
 }
 
@@ -197,7 +200,9 @@ fn fold_const(&mut self, c: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
     fn fold_mir_const(&mut self, c: mir::ConstantKind<'tcx>) -> mir::ConstantKind<'tcx> {
         // FIXME: This *probably* needs canonicalization too!
         let arg = self.param_env.and(c);
-        self.tcx.normalize_mir_const_after_erasing_regions(arg)
+        self.tcx
+            .try_normalize_mir_const_after_erasing_regions(arg)
+            .unwrap_or_else(|_| bug!("failed to normalize {:?}", c))
     }
 }
 

compiler/rustc_traits/src/normalize_erasing_regions.rs

@@ -8,20 +8,13 @@
 
 crate fn provide(p: &mut Providers) {
     *p = Providers {
-        normalize_generic_arg_after_erasing_regions: |tcx, goal| {
+        try_normalize_generic_arg_after_erasing_regions: |tcx, goal| {
-            debug!("normalize_generic_arg_after_erasing_regions(goal={:#?})", goal);
+            debug!("try_normalize_generic_arg_after_erasing_regions(goal={:#?}", goal);
 
             tcx.sess
                 .perf_stats
                 .normalize_generic_arg_after_erasing_regions
                 .fetch_add(1, Ordering::Relaxed);
-            normalize_after_erasing_regions(tcx, goal)
-        },
-        normalize_mir_const_after_erasing_regions: |tcx, goal| {
-            normalize_after_erasing_regions(tcx, goal)
-        },
-        try_normalize_generic_arg_after_erasing_regions: |tcx, goal| {
-            debug!("try_normalize_generic_arg_after_erasing_regions(goal={:#?}", goal);
 
             try_normalize_after_erasing_regions(tcx, goal)
         },
@@ -32,38 +25,6 @@
     };
 }
 
-#[instrument(level = "debug", skip(tcx))]
-fn normalize_after_erasing_regions<'tcx, T: TypeFoldable<'tcx> + PartialEq + Copy>(
-    tcx: TyCtxt<'tcx>,
-    goal: ParamEnvAnd<'tcx, T>,
-) -> T {
-    let ParamEnvAnd { param_env, value } = goal;
-    tcx.infer_ctxt().enter(|infcx| {
-        let cause = ObligationCause::dummy();
-        match infcx.at(&cause, param_env).normalize(value) {
-            Ok(Normalized { value: normalized_value, obligations: normalized_obligations }) => {
-                // We don't care about the `obligations`; they are
-                // always only region relations, and we are about to
-                // erase those anyway:
-                debug_assert_eq!(
-                    normalized_obligations.iter().find(|p| not_outlives_predicate(&p.predicate)),
-                    None,
-                );
-
-                let resolved_value = infcx.resolve_vars_if_possible(normalized_value);
-                // It's unclear when `resolve_vars` would have an effect in a
-                // fresh `InferCtxt`. If this assert does trigger, it will give
-                // us a test case.
-                debug_assert_eq!(normalized_value, resolved_value);
-                let erased = infcx.tcx.erase_regions(resolved_value);
-                debug_assert!(!erased.needs_infer(), "{:?}", erased);
-                erased
-            }
-            Err(NoSolution) => bug!("could not fully normalize `{:?}`", value),
-        }
-    })
-}
-
 #[instrument(level = "debug", skip(tcx))]
 fn try_normalize_after_erasing_regions<'tcx, T: TypeFoldable<'tcx> + PartialEq + Copy>(
     tcx: TyCtxt<'tcx>,