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Enforce unwind invariants #73133

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merged 4 commits into from
Jun 10, 2020
Merged

Enforce unwind invariants #73133

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3aedfbe
Enforce unwind invariants
doctorn Jun 8, 2020
4158bb0
Relax cleanup to cleanup check
doctorn Jun 8, 2020
1c4fd22
Strengthen cleanup to cleanup check
doctorn Jun 8, 2020
9495ee2
Address comments
doctorn Jun 9, 2020
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67 changes: 48 additions & 19 deletions src/librustc_mir/transform/validate.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,12 @@ use rustc_middle::{
};
use rustc_span::def_id::DefId;

#[derive(Copy, Clone, Debug)]
enum EdgeKind {
Unwind,
Normal,
}

pub struct Validator {
/// Describes at which point in the pipeline this validation is happening.
pub when: String,
Expand Down Expand Up @@ -49,8 +55,31 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
);
}

fn check_bb(&self, location: Location, bb: BasicBlock) {
if self.body.basic_blocks().get(bb).is_none() {
fn check_edge(&self, location: Location, bb: BasicBlock, edge_kind: EdgeKind) {
if let Some(bb) = self.body.basic_blocks().get(bb) {
let src = self.body.basic_blocks().get(location.block).unwrap();
match (src.is_cleanup, bb.is_cleanup, edge_kind) {
// Non-cleanup blocks can jump to non-cleanup blocks along non-unwind edges
(false, false, EdgeKind::Normal)
// Non-cleanup blocks can jump to cleanup blocks along unwind edges
| (false, true, EdgeKind::Unwind)
// Cleanup blocks can jump to cleanup blocks along non-unwind edges
| (true, true, EdgeKind::Normal) => {}
// All other jumps are invalid
_ => {
self.fail(
location,
format!(
"{:?} edge to {:?} violates unwind invariants (cleanup {:?} -> {:?})",
edge_kind,
bb,
src.is_cleanup,
bb.is_cleanup,
)
)
}
}
} else {
self.fail(location, format!("encountered jump to invalid basic block {:?}", bb))
}
}
Expand Down Expand Up @@ -92,7 +121,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
match &terminator.kind {
TerminatorKind::Goto { target } => {
self.check_bb(location, *target);
self.check_edge(location, *target, EdgeKind::Normal);
}
TerminatorKind::SwitchInt { targets, values, .. } => {
if targets.len() != values.len() + 1 {
Expand All @@ -106,19 +135,19 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
);
}
for target in targets {
self.check_bb(location, *target);
self.check_edge(location, *target, EdgeKind::Normal);
}
}
TerminatorKind::Drop { target, unwind, .. } => {
self.check_bb(location, *target);
self.check_edge(location, *target, EdgeKind::Normal);
if let Some(unwind) = unwind {
self.check_bb(location, *unwind);
self.check_edge(location, *unwind, EdgeKind::Unwind);
}
}
TerminatorKind::DropAndReplace { target, unwind, .. } => {
self.check_bb(location, *target);
self.check_edge(location, *target, EdgeKind::Normal);
if let Some(unwind) = unwind {
self.check_bb(location, *unwind);
self.check_edge(location, *unwind, EdgeKind::Unwind);
}
}
TerminatorKind::Call { func, destination, cleanup, .. } => {
Expand All @@ -131,10 +160,10 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
),
}
if let Some((_, target)) = destination {
self.check_bb(location, *target);
self.check_edge(location, *target, EdgeKind::Normal);
}
if let Some(cleanup) = cleanup {
self.check_bb(location, *cleanup);
self.check_edge(location, *cleanup, EdgeKind::Unwind);
}
}
TerminatorKind::Assert { cond, target, cleanup, .. } => {
Expand All @@ -148,30 +177,30 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
),
);
}
self.check_bb(location, *target);
self.check_edge(location, *target, EdgeKind::Normal);
if let Some(cleanup) = cleanup {
self.check_bb(location, *cleanup);
self.check_edge(location, *cleanup, EdgeKind::Unwind);
}
}
TerminatorKind::Yield { resume, drop, .. } => {
self.check_bb(location, *resume);
self.check_edge(location, *resume, EdgeKind::Normal);
if let Some(drop) = drop {
self.check_bb(location, *drop);
self.check_edge(location, *drop, EdgeKind::Normal);
}
}
TerminatorKind::FalseEdge { real_target, imaginary_target } => {
self.check_bb(location, *real_target);
self.check_bb(location, *imaginary_target);
self.check_edge(location, *real_target, EdgeKind::Normal);
self.check_edge(location, *imaginary_target, EdgeKind::Normal);
}
TerminatorKind::FalseUnwind { real_target, unwind } => {
self.check_bb(location, *real_target);
self.check_edge(location, *real_target, EdgeKind::Normal);
if let Some(unwind) = unwind {
self.check_bb(location, *unwind);
self.check_edge(location, *unwind, EdgeKind::Unwind);
}
}
TerminatorKind::InlineAsm { destination, .. } => {
if let Some(destination) = destination {
self.check_bb(location, *destination);
self.check_edge(location, *destination, EdgeKind::Normal);
}
}
// Nothing to validate for these.
Expand Down