rust-lang
diff --git a/‎src/librustc_mir/transform/simplify.rs
Lines changed: 12 additions & 14 deletions b/‎src/librustc_mir/transform/simplify.rs
Lines changed: 12 additions & 14 deletions
@@ -438,13 +438,16 @@ impl<'a, 'tcx> Visitor<'tcx> for DeclMarker<'a, 'tcx> {
 }
 
 struct StatementDeclMarker<'a, 'tcx> {
-    used_locals: IndexVec<Local, usize>,
+    used_locals: &'a mut IndexVec<Local, usize>,
     statement: &'a Statement<'tcx>,
 }
 
 impl<'a, 'tcx> StatementDeclMarker<'a, 'tcx> {
-    pub fn new(local_count: usize, statement: &'a Statement<'tcx>) -> Self {
-        Self { used_locals: IndexVec::from_elem_n(0, local_count), statement }
+    pub fn new(
+        used_locals: &'a mut IndexVec<Local, usize>,
+        statement: &'a Statement<'tcx>,
+    ) -> Self {
+        Self { used_locals, statement }
     }
 }
 
@@ -457,7 +460,11 @@ impl<'a, 'tcx> Visitor<'tcx> for StatementDeclMarker<'a, 'tcx> {
             }
         }
 
-        self.used_locals[*local] += 1;
+        let use_count = &mut self.used_locals[*local];
+        // If this is the local we're removing...
+        if *use_count != 0 {
+            *use_count -= 1;
+        }
     }
 }
 
@@ -504,17 +511,8 @@ impl<'a, 'tcx> MutVisitor<'tcx> for RemoveStatements<'a, 'tcx> {
                 trace!("removing statement {:?}", stmt);
                 self.modified = true;
 
-                let mut visitor = StatementDeclMarker::new(self.used_locals.len(), stmt);
+                let mut visitor = StatementDeclMarker::new(self.used_locals, stmt);
                 visitor.visit_statement(stmt, Location { block, statement_index: i });
-
-                for (local, count) in visitor.used_locals.iter_enumerated() {
-                    let used_count = &mut self.used_locals[local];
-
-                    // If this is the local we're removing...
-                    if *used_count != 0 {
-                        *used_count -= count;
-                    }
-                }
             }
 
             i += 1;
Original file line number	Diff line number	Diff line change
`@@ -438,13 +438,16 @@ impl<'a, 'tcx> Visitor<'tcx> for DeclMarker<'a, 'tcx> {`
`438`	`438`	`}`
`439`	`439`
`440`	`440`	`struct StatementDeclMarker<'a, 'tcx> {`
`441`		`- used_locals: IndexVec<Local, usize>,`
	`441`	`+ used_locals: &'a mut IndexVec<Local, usize>,`
`442`	`442`	`statement: &'a Statement<'tcx>,`
`443`	`443`	`}`
`444`	`444`
`445`	`445`	`impl<'a, 'tcx> StatementDeclMarker<'a, 'tcx> {`
`446`		`- pub fn new(local_count: usize, statement: &'a Statement<'tcx>) -> Self {`
`447`		`- Self { used_locals: IndexVec::from_elem_n(0, local_count), statement }`
	`446`	`+ pub fn new(`
	`447`	`+ used_locals: &'a mut IndexVec<Local, usize>,`
	< 8000 code>448	`+ statement: &'a Statement<'tcx>,`
	`449`	`+ ) -> Self {`
	`450`	`+ Self { used_locals, statement }`
`448`	`451`	`}`
`449`	`452`	`}`
`450`	`453`
`@@ -457,7 +460,11 @@ impl<'a, 'tcx> Visitor<'tcx> for StatementDeclMarker<'a, 'tcx> {`
`457`	`460`	`}`
`458`	`461`	`}`
`459`	`462`
`460`		`- self.used_locals[*local] += 1;`
	`463`	`+ let use_count = &mut self.used_locals[*local];`
	`464`	`+ // If this is the local we're removing...`
	`465`	`+ if *use_count != 0 {`
	`466`	`+ *use_count -= 1;`
	`467`	`+ }`
`461`	`468`	`}`
`462`	`469`	`}`
`463`	`470`
`@@ -504,17 +511,8 @@ impl<'a, 'tcx> MutVisitor<'tcx> for RemoveStatements<'a, 'tcx> {`
`504`	`511`	`trace!("removing statement {:?}", stmt);`
`505`	`512`	`self.modified = true;`
`506`	`513`
`507`		`- let mut visitor = StatementDeclMarker::new(self.used_locals.len(), stmt);`
	`514`	`+ let mut visitor = StatementDeclMarker::new(self.used_locals, stmt);`
`508`	`515`	`visitor.visit_statement(stmt, Location { block, statement_index: i });`
`509`		`-`
`510`		`- for (local, count) in visitor.used_locals.iter_enumerated() {`
`511`		`- let used_count = &mut self.used_locals[local];`
`512`		`-`
`513`		`- // If this is the local we're removing...`
`514`		`- if *used_count != 0 {`
`515`		`- *used_count -= count;`
`516`		`- }`
`517`		`- }`
`518`	`516`	`}`
`519`	`517`
`520`	`518`	`i += 1;`