diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src')
10 files changed, 72 insertions, 1 deletions
diff --git a/compiler/rustc_mir_transform/src/check_unsafety.rs b/compiler/rustc_mir_transform/src/check_unsafety.rs index 9f006a76162..8afa53313fc 100644 --- a/compiler/rustc_mir_transform/src/check_unsafety.rs +++ b/compiler/rustc_mir_transform/src/check_unsafety.rs @@ -104,6 +104,7 @@ impl<'tcx> Visitor<'tcx> for UnsafetyChecker<'_, 'tcx> { | StatementKind::AscribeUserType(..) | StatementKind::Coverage(..) | StatementKind::Intrinsic(..) + | StatementKind::ConstEvalCounter | StatementKind::Nop => { // safe (at least as emitted during MIR construction) } diff --git a/compiler/rustc_mir_transform/src/coverage/spans.rs b/compiler/rustc_mir_transform/src/coverage/spans.rs index 31d5541a31b..f973c1ed28f 100644 --- a/compiler/rustc_mir_transform/src/coverage/spans.rs +++ b/compiler/rustc_mir_transform/src/coverage/spans.rs @@ -802,6 +802,8 @@ pub(super) fn filtered_statement_span(statement: &Statement<'_>) -> Option<Span> | StatementKind::StorageDead(_) // Coverage should not be encountered, but don't inject coverage coverage | StatementKind::Coverage(_) + // Ignore `ConstEvalCounter`s + | StatementKind::ConstEvalCounter // Ignore `Nop`s | StatementKind::Nop => None, diff --git a/compiler/rustc_mir_transform/src/ctfe_limit.rs b/compiler/rustc_mir_transform/src/ctfe_limit.rs new file mode 100644 index 00000000000..7d127032179 --- /dev/null +++ b/compiler/rustc_mir_transform/src/ctfe_limit.rs @@ -0,0 +1,59 @@ +//! A pass that inserts the `ConstEvalCounter` instruction into any blocks that have a back edge +//! (thus indicating there is a loop in the CFG), or whose terminator is a function call. +use crate::MirPass; + +use rustc_data_structures::graph::dominators::Dominators; +use rustc_middle::mir::{ + BasicBlock, BasicBlockData, Body, Statement, StatementKind, TerminatorKind, +}; +use rustc_middle::ty::TyCtxt; + +pub struct CtfeLimit; + +impl<'tcx> MirPass<'tcx> for CtfeLimit { + #[instrument(skip(self, _tcx, body))] + fn run_pass(&self, _tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { + let doms = body.basic_blocks.dominators(); + let indices: Vec<BasicBlock> = body + .basic_blocks + .iter_enumerated() + .filter_map(|(node, node_data)| { + if matches!(node_data.terminator().kind, TerminatorKind::Call { .. }) + // Back edges in a CFG indicate loops + || has_back_edge(&doms, node, &node_data) + { + Some(node) + } else { + None + } + }) + .collect(); + for index in indices { + insert_counter( + body.basic_blocks_mut() + .get_mut(index) + .expect("basic_blocks index {index} should exist"), + ); + } + } +} + +fn has_back_edge( + doms: &Dominators<BasicBlock>, + node: BasicBlock, + node_data: &BasicBlockData<'_>, +) -> bool { + if !doms.is_reachable(node) { + return false; + } + // Check if any of the dominators of the node are also the node's successor. + doms.dominators(node) + .any(|dom| node_data.terminator().successors().into_iter().any(|succ| succ == dom)) +} + +fn insert_counter(basic_block_data: &mut BasicBlockData<'_>) { + basic_block_data.statements.push(Statement { + source_info: basic_block_data.terminator().source_info, + kind: StatementKind::ConstEvalCounter, + }); +} diff --git a/compiler/rustc_mir_transform/src/dead_store_elimination.rs b/compiler/rustc_mir_transform/src/dead_store_elimination.rs index 09546330cec..9dbfb089dc6 100644 --- a/compiler/rustc_mir_transform/src/dead_store_elimination.rs +++ b/compiler/rustc_mir_transform/src/dead_store_elimination.rs @@ -53,6 +53,7 @@ pub fn eliminate<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>, borrowed: &BitS | StatementKind::StorageDead(_) | StatementKind::Coverage(_) | StatementKind::Intrinsic(_) + | StatementKind::ConstEvalCounter | StatementKind::Nop => (), StatementKind::FakeRead(_) | StatementKind::AscribeUserType(_, _) => { diff --git a/compiler/rustc_mir_transform/src/dest_prop.rs b/compiler/rustc_mir_transform/src/dest_prop.rs index 08e296a8371..20ffb0ab334 100644 --- a/compiler/rustc_mir_transform/src/dest_prop.rs +++ b/compiler/rustc_mir_transform/src/dest_prop.rs @@ -577,6 +577,7 @@ impl WriteInfo { self.add_place(**place); } StatementKind::Intrinsic(_) + | StatementKind::ConstEvalCounter | StatementKind::Nop | StatementKind::Coverage(_) | StatementKind::StorageLive(_) diff --git a/compiler/rustc_mir_transform/src/generator.rs b/compiler/rustc_mir_transform/src/generator.rs index a9fd95f4541..5624e312da1 100644 --- a/compiler/rustc_mir_transform/src/generator.rs +++ b/compiler/rustc_mir_transform/src/generator.rs @@ -1657,6 +1657,7 @@ impl<'tcx> Visitor<'tcx> for EnsureGeneratorFieldAssignmentsNeverAlias<'_> { | StatementKind::AscribeUserType(..) | StatementKind::Coverage(..) | StatementKind::Intrinsic(..) + | StatementKind::ConstEvalCounter | StatementKind::Nop => {} } } diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs index fcb09fa02dd..6858fa8e524 100644 --- a/compiler/rustc_mir_transform/src/lib.rs +++ b/compiler/rustc_mir_transform/src/lib.rs @@ -55,6 +55,7 @@ mod const_goto; mod const_prop; mod const_prop_lint; mod coverage; +mod ctfe_limit; mod dataflow_const_prop; mod dead_store_elimination; mod deaggregator; @@ -410,6 +411,8 @@ fn inner_mir_for_ctfe(tcx: TyCtxt<'_>, def: ty::WithOptConstParam<LocalDefId>) - } } + pm::run_passes(tcx, &mut body, &[&ctfe_limit::CtfeLimit], None); + debug_assert!(!body.has_free_regions(), "Free regions in MIR for CTFE"); body diff --git a/compiler/rustc_mir_transform/src/remove_noop_landing_pads.rs b/compiler/rustc_mir_transform/src/remove_noop_landing_pads.rs index f1bbf2ea7e8..e3a03aa08af 100644 --- a/compiler/rustc_mir_transform/src/remove_noop_landing_pads.rs +++ b/compiler/rustc_mir_transform/src/remove_noop_landing_pads.rs @@ -35,6 +35,7 @@ impl RemoveNoopLandingPads { | StatementKind::StorageDead(_) | StatementKind::AscribeUserType(..) | StatementKind::Coverage(..) + | StatementKind::ConstEvalCounter | StatementKind::Nop => { // These are all noops in a landing pad } diff --git a/compiler/rustc_mir_transform/src/separate_const_switch.rs b/compiler/rustc_mir_transform/src/separate_const_switch.rs index 2f116aaa958..a24d2d34d79 100644 --- a/compiler/rustc_mir_transform/src/separate_const_switch.rs +++ b/compiler/rustc_mir_transform/src/separate_const_switch.rs @@ -250,6 +250,7 @@ fn is_likely_const<'tcx>(mut tracked_place: Place<'tcx>, block: &BasicBlockData< | StatementKind::Coverage(_) | StatementKind::StorageDead(_) | StatementKind::Intrinsic(_) + | StatementKind::ConstEvalCounter | StatementKind::Nop => {} } } @@ -318,6 +319,7 @@ fn find_determining_place<'tcx>( | StatementKind::AscribeUserType(_, _) | StatementKind::Coverage(_) | StatementKind::Intrinsic(_) + | StatementKind::ConstEvalCounter | StatementKind::Nop => {} // If the discriminant is set, it is always set diff --git a/compiler/rustc_mir_transform/src/simplify.rs b/compiler/rustc_mir_transform/src/simplify.rs index 8f6abe7a912..7b6fa2baf2f 100644 --- a/compiler/rustc_mir_transform/src/simplify.rs +++ b/compiler/rustc_mir_transform/src/simplify.rs @@ -517,7 +517,7 @@ impl<'tcx> Visitor<'tcx> for UsedLocals { self.super_statement(statement, location); } - StatementKind::Nop => {} + StatementKind::ConstEvalCounter | StatementKind::Nop => {} StatementKind::StorageLive(_local) | StatementKind::StorageDead(_local) => {} |