diff --git a/compiler/rustc_const_eval/src/transform/validate.rs b/compiler/rustc_const_eval/src/transform/validate.rs index 5922922d47b66..3e8a0a2b7df08 100644 --- a/compiler/rustc_const_eval/src/transform/validate.rs +++ b/compiler/rustc_const_eval/src/transform/validate.rs @@ -285,6 +285,12 @@ impl<'a, 'tcx> CfgChecker<'a, 'tcx> { UnwindAction::Unreachable | UnwindAction::Terminate(UnwindTerminateReason::Abi) => (), } } + + fn is_critical_call_edge(&self, target: Option, 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. diff --git a/compiler/rustc_mir_transform/src/coroutine.rs b/compiler/rustc_mir_transform/src/coroutine.rs index df9c84c35ac90..1cb1a9886a09d 100644 --- a/compiler/rustc_mir_transform/src/coroutine.rs +++ b/compiler/rustc_mir_transform/src/coroutine.rs @@ -51,6 +51,7 @@ //! Otherwise it drops all the values in scope at the last suspension point. use crate::abort_unwinding_calls; +use crate::add_call_guards; use crate::deref_separator::deref_finder; use crate::errors; use crate::pass_manager as pm; @@ -1176,7 +1177,7 @@ fn create_coroutine_drop_shim<'tcx>( pm::run_passes_no_validate( tcx, &mut body, - &[&abort_unwinding_calls::AbortUnwindingCalls], + &[&abort_unwinding_calls::AbortUnwindingCalls, &add_call_guards::CriticalCallEdges], None, ); diff --git a/compiler/rustc_mir_transform/src/shim.rs b/compiler/rustc_mir_transform/src/shim.rs index a9640146a5274..f24a2d07e4949 100644 --- a/compiler/rustc_mir_transform/src/shim.rs +++ b/compiler/rustc_mir_transform/src/shim.rs @@ -111,8 +111,8 @@ fn make_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceDef<'tcx>) -> Body<' &deref_separator::Derefer, &remove_noop_landing_pads::RemoveNoopLandingPads, &simplify::SimplifyCfg::MakeShim, - &add_call_guards::CriticalCallEdges, &abort_unwinding_calls::AbortUnwindingCalls, + &add_call_guards::CriticalCallEdges, ], Some(MirPhase::Runtime(RuntimePhase::Optimized)), ); diff --git a/tests/ui/mir/validate/critical-edge.rs b/tests/ui/mir/validate/critical-edge.rs new file mode 100644 index 0000000000000..9ef655cd1bb4a --- /dev/null +++ b/tests/ui/mir/validate/critical-edge.rs @@ -0,0 +1,31 @@ +// Optimized MIR shouldn't have critical call edges +// +// build-fail +// edition: 2021 +// compile-flags: --crate-type=lib +// failure-status: 101 +// dont-check-compiler-stderr +// error-pattern: encountered critical edge in `Call` terminator +#![feature(custom_mir, core_intrinsics)] +use core::intrinsics::mir::*; + +#[custom_mir(dialect = "runtime", phase = "optimized")] +#[inline(always)] +pub fn f(a: u32) -> u32 { + mir!( + { + match a { + 0 => bb1, + _ => bb2, + } + } + bb1 = { + Call(RET = f(1), bb2, UnwindTerminate(ReasonAbi)) + } + + bb2 = { + RET = 2; + Return() + } + ) +}