diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src')
| -rw-r--r-- | compiler/rustc_mir_transform/src/inline.rs | 27 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/lib.rs | 5 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/mentioned_items.rs | 57 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/shim.rs | 4 |
4 files changed, 91 insertions, 2 deletions
diff --git a/compiler/rustc_mir_transform/src/inline.rs b/compiler/rustc_mir_transform/src/inline.rs index f6a0945c222..0f6a7ae982c 100644 --- a/compiler/rustc_mir_transform/src/inline.rs +++ b/compiler/rustc_mir_transform/src/inline.rs @@ -565,7 +565,8 @@ impl<'tcx> Inliner<'tcx> { mut callee_body: Body<'tcx>, ) { let terminator = caller_body[callsite.block].terminator.take().unwrap(); - let TerminatorKind::Call { args, destination, unwind, target, .. } = terminator.kind else { + let TerminatorKind::Call { func, args, destination, unwind, target, .. } = terminator.kind + else { bug!("unexpected terminator kind {:?}", terminator.kind); }; @@ -717,6 +718,30 @@ impl<'tcx> Inliner<'tcx> { Const::Val(..) | Const::Unevaluated(..) => true, }, )); + // Now that we incorporated the callee's `required_consts`, we can remove the callee from + // `mentioned_items` -- but we have to take their `mentioned_items` in return. This does + // some extra work here to save the monomorphization collector work later. It helps a lot, + // since monomorphization can avoid a lot of work when the "mentioned items" are similar to + // the actually used items. By doing this we can entirely avoid visiting the callee! + let callee_item = { + // We need to reconstruct the `required_item` for the callee so that we can find and + // remove it. + let func_ty = func.ty(caller_body, self.tcx); + match func_ty.kind() { + ty::FnDef(def_id, args) => MentionedItem::Fn(*def_id, args), + _ => bug!(), + } + }; + if let Some(idx) = + caller_body.mentioned_items.iter().position(|item| item.node == callee_item) + { + // We found the callee, so remove it and add its items instead. + caller_body.mentioned_items.remove(idx); + caller_body.mentioned_items.extend(callee_body.mentioned_items); + } else { + // If we can't find the callee, there's no point in adding its items. + // Probably it already got removed by being inlined elsewhere in the same function. + } } fn make_call_args( diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs index afe228be127..74e7d51ea96 100644 --- a/compiler/rustc_mir_transform/src/lib.rs +++ b/compiler/rustc_mir_transform/src/lib.rs @@ -89,6 +89,7 @@ mod lint; mod lower_intrinsics; mod lower_slice_len; mod match_branches; +mod mentioned_items; mod multiple_return_terminators; mod normalize_array_len; mod nrvo; @@ -566,6 +567,10 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { tcx, body, &[ + // Before doing anything, remember which items are being mentioned so that the set of items + // visited does not depend on the optimization level. + &mentioned_items::MentionedItems, + // Add some UB checks before any UB gets optimized away. &check_alignment::CheckAlignment, // Before inlining: trim down MIR with passes to reduce inlining work. diff --git a/compiler/rustc_mir_transform/src/mentioned_items.rs b/compiler/rustc_mir_transform/src/mentioned_items.rs new file mode 100644 index 00000000000..ed363b4f252 --- /dev/null +++ b/compiler/rustc_mir_transform/src/mentioned_items.rs @@ -0,0 +1,57 @@ +use rustc_middle::mir::visit::Visitor; +use rustc_middle::mir::{self, ConstOperand, Location, MentionedItem, MirPass}; +use rustc_middle::ty::{self, TyCtxt}; +use rustc_session::Session; +use rustc_span::source_map::Spanned; + +pub struct MentionedItems; + +struct MentionedItemsVisitor<'a, 'tcx> { + tcx: TyCtxt<'tcx>, + body: &'a mir::Body<'tcx>, + mentioned_items: &'a mut Vec<Spanned<MentionedItem<'tcx>>>, +} + +impl<'tcx> MirPass<'tcx> for MentionedItems { + fn is_enabled(&self, _sess: &Session) -> bool { + // If this pass is skipped the collector assume that nothing got mentioned! We could + // potentially skip it in opt-level 0 if we are sure that opt-level will never *remove* uses + // of anything, but that still seems fragile. Furthermore, even debug builds use level 1, so + // special-casing level 0 is just not worth it. + true + } + + fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut mir::Body<'tcx>) { + debug_assert!(body.mentioned_items.is_empty()); + let mut mentioned_items = Vec::new(); + MentionedItemsVisitor { tcx, body, mentioned_items: &mut mentioned_items }.visit_body(body); + body.mentioned_items = mentioned_items; + } +} + +impl<'tcx> Visitor<'tcx> for MentionedItemsVisitor<'_, 'tcx> { + fn visit_constant(&mut self, constant: &ConstOperand<'tcx>, _: Location) { + let const_ = constant.const_; + // This is how function items get referenced: via constants of `FnDef` type. This handles + // both functions that are called and those that are just turned to function pointers. + if let ty::FnDef(def_id, args) = const_.ty().kind() { + debug!("adding to required_items: {def_id:?}"); + self.mentioned_items + .push(Spanned { node: MentionedItem::Fn(*def_id, args), span: constant.span }); + } + } + + fn visit_terminator(&mut self, terminator: &mir::Terminator<'tcx>, location: Location) { + self.super_terminator(terminator, location); + match terminator.kind { + // We don't need to handle `Call` as we already handled all function type operands in + // `visit_constant`. But we do need to handle `Drop`. + mir::TerminatorKind::Drop { place, .. } => { + let ty = place.ty(self.body, self.tcx).ty; + let span = self.body.source_info(location).span; + self.mentioned_items.push(Spanned { node: MentionedItem::Drop(ty), span }); + } + _ => {} + } + } +} diff --git a/compiler/rustc_mir_transform/src/shim.rs b/compiler/rustc_mir_transform/src/shim.rs index 733e2f93b25..dd2b24ad669 100644 --- a/compiler/rustc_mir_transform/src/shim.rs +++ b/compiler/rustc_mir_transform/src/shim.rs @@ -17,7 +17,7 @@ use std::iter; use crate::{ abort_unwinding_calls, add_call_guards, add_moves_for_packed_drops, deref_separator, - pass_manager as pm, remove_noop_landing_pads, simplify, + mentioned_items, pass_manager as pm, remove_noop_landing_pads, simplify, }; use rustc_middle::mir::patch::MirPatch; use rustc_mir_dataflow::elaborate_drops::{self, DropElaborator, DropFlagMode, DropStyle}; @@ -147,6 +147,7 @@ fn make_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceDef<'tcx>) -> Body<' tcx, &mut body, &[ + &mentioned_items::MentionedItems, &abort_unwinding_calls::AbortUnwindingCalls, &add_call_guards::CriticalCallEdges, ], @@ -178,6 +179,7 @@ fn make_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceDef<'tcx>) -> Body<' tcx, &mut result, &[ + &mentioned_items::MentionedItems, &add_moves_for_packed_drops::AddMovesForPackedDrops, &deref_separator::Derefer, &remove_noop_landing_pads::RemoveNoopLandingPads, |