diff options
| -rw-r--r-- | src/librustc_passes/liveness.rs | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/src/librustc_passes/liveness.rs b/src/librustc_passes/liveness.rs index 7718139f6e9..b355a47c394 100644 --- a/src/librustc_passes/liveness.rs +++ b/src/librustc_passes/liveness.rs @@ -822,8 +822,15 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> { return false; } - let mut changed = false; + let mut any_changed = false; self.indices2(ln, succ_ln, |this, idx, succ_idx| { + // This is a special case, pulled out from the code below, where we + // don't have to do anything. It occurs about 60-70% of the time. + if this.rwu_table.packed_rwus[succ_idx] == INV_INV_FALSE { + return; + } + + let mut changed = false; let mut rwu = this.rwu_table.get(idx); let succ_rwu = this.rwu_table.get(succ_idx); if succ_rwu.reader.is_valid() && !rwu.reader.is_valid() { @@ -843,6 +850,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> { if changed { this.rwu_table.assign_unpacked(idx, rwu); + any_changed = true; } }); @@ -851,9 +859,9 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> { ln, self.ln_str(succ_ln), first_merge, - changed + any_changed ); - return changed; + return any_changed; } // Indicates that a local variable was *defined*; we know that no |