Profile MIR passes.

compiler/rustc_mir_transform/src/simplify.rs

@@ -74,7 +74,7 @@ pub fn simplify_cfg<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
 }
 
 impl<'tcx> MirPass<'tcx> for SimplifyCfg {
-    fn name(&self) -> &str {
+    fn name(&self) -> &'static str {
         &self.name()
     }