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Prevent query cycles during inlining
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,157 @@ | ||
| use rustc_data_structures::fx::{FxHashMap, FxHashSet}; | ||
| use rustc_data_structures::stack::ensure_sufficient_stack; | ||
| use rustc_hir::def_id::{DefId, LocalDefId}; | ||
| use rustc_middle::mir::TerminatorKind; | ||
| use rustc_middle::ty::TypeFoldable; | ||
| use rustc_middle::ty::{self, subst::SubstsRef, InstanceDef, TyCtxt}; | ||
|
|
||
| // FIXME: check whether it is cheaper to precompute the entire call graph instead of invoking | ||
| // this query riddiculously often. | ||
| #[instrument(skip(tcx, root, target))] | ||
| crate fn mir_callgraph_reachable( | ||
| tcx: TyCtxt<'tcx>, | ||
| (root, target): (ty::Instance<'tcx>, LocalDefId), | ||
| ) -> bool { | ||
| trace!(%root, target = %tcx.def_path_str(target.to_def_id())); | ||
| let param_env = tcx.param_env_reveal_all_normalized(target); | ||
| assert_ne!( | ||
| root.def_id().expect_local(), | ||
| target, | ||
| "you should not call `mir_callgraph_reachable` on immediate self recursion" | ||
| ); | ||
| assert!( | ||
| matches!(root.def, InstanceDef::Item(_)), | ||
| "you should not call `mir_callgraph_reachable` on shims" | ||
| ); | ||
| assert!( | ||
| !tcx.is_constructor(root.def_id()), | ||
| "you should not call `mir_callgraph_reachable` on enum/struct constructor functions" | ||
| ); | ||
| #[instrument(skip(tcx, param_env, target, stack, seen, recursion_limiter, caller))] | ||
| fn process( | ||
| tcx: TyCtxt<'tcx>, | ||
| param_env: ty::ParamEnv<'tcx>, | ||
| caller: ty::Instance<'tcx>, | ||
| target: LocalDefId, | ||
| stack: &mut Vec<ty::Instance<'tcx>>, | ||
| seen: &mut FxHashSet<ty::Instance<'tcx>>, | ||
| recursion_limiter: &mut FxHashMap<DefId, usize>, | ||
| ) -> bool { | ||
| trace!(%caller); | ||
| for &(callee, substs) in tcx.mir_inliner_callees(caller.def) { | ||
| let substs = caller.subst_mir_and_normalize_erasing_regions(tcx, param_env, substs); | ||
| let callee = match ty::Instance::resolve(tcx, param_env, callee, substs).unwrap() { | ||
| Some(callee) => callee, | ||
| None => { | ||
| trace!(?callee, "cannot resolve, skipping"); | ||
| continue; | ||
| } | ||
| }; | ||
|
|
||
| // Found a path. | ||
| if callee.def_id() == target.to_def_id() { | ||
| return true; | ||
| } | ||
|
|
||
| if tcx.is_constructor(callee.def_id()) { | ||
| trace!("constructors always have MIR"); | ||
| // Constructor functions cannot cause a query cycle. | ||
| continue; | ||
| } | ||
|
|
||
| match callee.def { | ||
| InstanceDef::Item(_) => { | ||
| // If there is no MIR available (either because it was not in metadata or | ||
| // because it has no MIR because it's an extern function), then the inliner | ||
| // won't cause cycles on this. | ||
| if !tcx.is_mir_available(callee.def_id()) { | ||
| trace!(?callee, "no mir available, skipping"); | ||
| continue; | ||
| } | ||
| } | ||
| // These have no own callable MIR. | ||
| InstanceDef::Intrinsic(_) | InstanceDef::Virtual(..) => continue, | ||
| // These have MIR and if that MIR is inlined, substituted and then inlining is run | ||
| // again, a function item can end up getting inlined. Thus we'll be able to cause | ||
| // a cycle that way | ||
| InstanceDef::VtableShim(_) | ||
| | InstanceDef::ReifyShim(_) | ||
| | InstanceDef::FnPtrShim(..) | ||
| | InstanceDef::ClosureOnceShim { .. } | ||
| | InstanceDef::CloneShim(..) => {} | ||
| InstanceDef::DropGlue(..) => { | ||
| // FIXME: A not fully substituted drop shim can cause ICEs if one attempts to | ||
| // have its MIR built. Likely oli-obk just screwed up the `ParamEnv`s, so this | ||
| // needs some more analysis. | ||
| if callee.needs_subst() { | ||
| continue; | ||
| } | ||
| } | ||
| } | ||
|
|
||
| if seen.insert(callee) { | ||
| let recursion = recursion_limiter.entry(callee.def_id()).or_default(); | ||
| trace!(?callee, recursion = *recursion); | ||
| if tcx.sess.recursion_limit().value_within_limit(*recursion) { | ||
| *recursion += 1; | ||
| stack.push(callee); | ||
| let found_recursion = ensure_sufficient_stack(|| { | ||
| process(tcx, param_env, callee, target, stack, seen, recursion_limiter) | ||
| }); | ||
| if found_recursion { | ||
| return true; | ||
| } | ||
| stack.pop(); | ||
| } else { | ||
| // Pessimistically assume that there could be recursion. | ||
| return true; | ||
| } | ||
| } | ||
| } | ||
| false | ||
| } | ||
| process( | ||
| tcx, | ||
| param_env, | ||
| root, | ||
| target, | ||
| &mut Vec::new(), | ||
| &mut FxHashSet::default(), | ||
| &mut FxHashMap::default(), | ||
| ) | ||
| } | ||
|
|
||
| crate fn mir_inliner_callees<'tcx>( | ||
| tcx: TyCtxt<'tcx>, | ||
| instance: ty::InstanceDef<'tcx>, | ||
| ) -> &'tcx [(DefId, SubstsRef<'tcx>)] { | ||
| let steal; | ||
| let guard; | ||
| let body = match (instance, instance.def_id().as_local()) { | ||
| (InstanceDef::Item(_), Some(def_id)) => { | ||
| let def = ty::WithOptConstParam::unknown(def_id); | ||
| steal = tcx.mir_promoted(def).0; | ||
| guard = steal.borrow(); | ||
| &*guard | ||
| } | ||
| // Functions from other crates and MIR shims | ||
| _ => tcx.instance_mir(instance), | ||
| }; | ||
| let mut calls = Vec::new(); | ||
| for bb_data in body.basic_blocks() { | ||
| let terminator = bb_data.terminator(); | ||
| if let TerminatorKind::Call { func, .. } = &terminator.kind { | ||
| let ty = func.ty(&body.local_decls, tcx); | ||
| let call = match ty.kind() { | ||
| ty::FnDef(def_id, substs) => (*def_id, *substs), | ||
| _ => continue, | ||
| }; | ||
| // We've seen this before | ||
| if calls.contains(&call) { | ||
| continue; | ||
| } | ||
| calls.push(call); | ||
| } | ||
| } | ||
| tcx.arena.alloc_slice(&calls) | ||
| } |
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