diff options
| -rw-r--r-- | compiler/rustc_mir_transform/src/simplify.rs | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/compiler/rustc_mir_transform/src/simplify.rs b/compiler/rustc_mir_transform/src/simplify.rs index 8f88228d9bb..a54e548ad70 100644 --- a/compiler/rustc_mir_transform/src/simplify.rs +++ b/compiler/rustc_mir_transform/src/simplify.rs @@ -74,7 +74,11 @@ impl SimplifyCfg { } pub(super) fn simplify_cfg<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { - CfgSimplifier::new(tcx, body).simplify(); + if CfgSimplifier::new(tcx, body).simplify() { + // `simplify` returns that it changed something. We must invalidate the CFG caches as they + // are not consistent with the modified CFG any more. + body.basic_blocks.invalidate_cfg_cache(); + } remove_dead_blocks(body); // FIXME: Should probably be moved into some kind of pass manager @@ -121,12 +125,16 @@ impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> { // Preserve `SwitchInt` reads on built and analysis MIR, or if `-Zmir-preserve-ub`. let preserve_switch_reads = matches!(body.phase, MirPhase::Built | MirPhase::Analysis(_)) || tcx.sess.opts.unstable_opts.mir_preserve_ub; - let basic_blocks = body.basic_blocks_mut(); + // Do not clear caches yet. The caller to `simplify` will do it if anything changed. + let basic_blocks = body.basic_blocks.as_mut_preserves_cfg(); CfgSimplifier { preserve_switch_reads, basic_blocks, pred_count } } - fn simplify(mut self) { + /// Returns whether we actually simplified anything. In that case, the caller *must* invalidate + /// the CFG caches of the MIR body. + #[must_use] + fn simplify(mut self) -> bool { self.strip_nops(); // Vec of the blocks that should be merged. We store the indices here, instead of the @@ -134,6 +142,7 @@ impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> { // We do not push the statements directly into the target block (`bb`) as that is slower // due to additional reallocations let mut merged_blocks = Vec::new(); + let mut outer_changed = false; loop { let mut changed = false; @@ -177,7 +186,11 @@ impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> { if !changed { break; } + + outer_changed = true; } + + outer_changed } /// This function will return `None` if |