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Validate there are no critical call edges in optimized MIR

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This commit is contained in:
Tomasz Miąsko 2023-11-19 00:00:00 +00:00
parent 0ff8610964
commit cef892ebab
2 changed files with 53 additions and 0 deletions
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22
compiler/rustc_const_eval/src/transform/validate.rs
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@ -285,6 +285,12 @@ impl<'a, 'tcx> CfgChecker<'a, 'tcx> {
UnwindAction::Unreachable | UnwindAction::Terminate(UnwindTerminateReason::Abi) => (),
}
}
fn is_critical_call_edge(&self, target: Option<BasicBlock>, unwind: UnwindAction) -> bool {
let Some(target) = target else { return false };
matches!(unwind, UnwindAction::Cleanup(_) | UnwindAction::Terminate(_))
&& self.body.basic_blocks.predecessors()[target].len() > 1
}
}
impl<'a, 'tcx> Visitor<'tcx> for CfgChecker<'a, 'tcx> {
@ -425,6 +431,22 @@ impl<'a, 'tcx> Visitor<'tcx> for CfgChecker<'a, 'tcx> {
}
self.check_unwind_edge(location, *unwind);
// The code generation assumes that there are no critical call edges. The assumption
// is used to simplify inserting code that should be executed along the return edge
// from the call. FIXME(tmiasko): Since this is a strictly code generation concern,
// the code generation should be responsible for handling it.
if self.mir_phase >= MirPhase::Runtime(RuntimePhase::Optimized)
&& self.is_critical_call_edge(*target, *unwind)
{
self.fail(
location,
format!(
"encountered critical edge in `Call` terminator {:?}",
terminator.kind,
),
);
}
// The call destination place and Operand::Move place used as an argument might be
// passed by a reference to the callee. Consequently they must be non-overlapping
// and cannot be packed. Currently this simply checks for duplicate places.