Reuse a Vec in mir simplification

Marwes · Feb 13, 2020 · 851a701 · 851a701
1 parent 1f8df25
commit 851a701
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/src/librustc_mir/transform/simplify.rs b/src/librustc_mir/transform/simplify.rs
@@ -94,6 +94,7 @@ impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> {
         self.strip_nops();
 
         let mut start = START_BLOCK;
+        let mut new_stmts = vec![];
 
         loop {
             let mut changed = false;
@@ -114,7 +115,6 @@ impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> {
                     self.collapse_goto_chain(successor, &mut changed);
                 }
 
-                let mut new_stmts = vec![];
                 let mut inner_changed = true;
                 while inner_changed {
                     inner_changed = false;
@@ -124,7 +124,7 @@ impl<'a, 'tcx> CfgSimplifier<'a, 'tcx> {
                 }
 
                 let data = &mut self.basic_blocks[bb];
-                data.statements.extend(new_stmts);
+                data.statements.extend(new_stmts.drain(..));
                 data.terminator = Some(terminator);
 
                 changed |= inner_changed;