diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src')
| -rw-r--r-- | compiler/rustc_mir_transform/src/lib.rs | 24 |
1 files changed, 13 insertions, 11 deletions
diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs index 3def30b51b7..50b7dda2bc2 100644 --- a/compiler/rustc_mir_transform/src/lib.rs +++ b/compiler/rustc_mir_transform/src/lib.rs @@ -30,7 +30,7 @@ use rustc_middle::mir::visit::Visitor as _; use rustc_middle::mir::{ traversal, AnalysisPhase, Body, ClearCrossCrate, ConstQualifs, Constant, LocalDecl, MirPass, MirPhase, Operand, Place, ProjectionElem, Promoted, RuntimePhase, Rvalue, SourceInfo, - Statement, StatementKind, TerminatorKind, + Statement, StatementKind, TerminatorKind, START_BLOCK, }; use rustc_middle::ty::query::Providers; use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt}; @@ -491,9 +491,10 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { // // We don't usually need to worry about this kind of case, // since we would get a compilation error if the user tried - // to call it. However, since we can do const propagation - // even without any calls to the function, we need to make - // sure that it even makes sense to try to evaluate the body. + // to call it. However, since we optimize even without any + // calls to the function, we need to make sure that it even + // makes sense to try to evaluate the body. + // // If there are unsatisfiable where clauses, then all bets are // off, and we just give up. // @@ -515,16 +516,17 @@ fn run_optimization_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { .filter_map(|(p, _)| if p.is_global() { Some(*p) } else { None }); if traits::impossible_predicates(tcx, traits::elaborate(tcx, predicates).collect()) { trace!("optimizations skipped for {:?}: found unsatisfiable predicates", body.source); + // Clear the body to only contain a single `unreachable` statement. + let bbs = body.basic_blocks.as_mut(); + bbs.raw.truncate(1); + bbs[START_BLOCK].statements.clear(); + bbs[START_BLOCK].terminator_mut().kind = TerminatorKind::Unreachable; + body.var_debug_info.clear(); + body.local_decls.raw.truncate(body.arg_count + 1); pm::run_passes( tcx, body, - &[ - &reveal_all::RevealAll, - &simplify::SimplifyCfg::Final, - &simplify::SimplifyLocals::Final, - // Dump the end result for testing and debugging purposes. - &dump_mir::Marker("PreCodegen"), - ], + &[&reveal_all::RevealAll, &dump_mir::Marker("PreCodegen")], Some(MirPhase::Runtime(RuntimePhase::Optimized)), ); return; |