Remove support for adding statement to all successors

This feature of MIR patch system is no longer used.

Author: tmiasko

compiler/rustc_middle/src/mir/patch.rs

@@ -150,7 +150,6 @@ impl<'tcx> MirPatch<'tcx> {
 
         let mut delta = 0;
         let mut last_bb = START_BLOCK;
-        let mut stmts_and_targets: Vec<(Statement<'_>, BasicBlock)> = Vec::new();
         for (mut loc, stmt) in new_statements {
             if loc.block != last_bb {
                 delta = 0;
@@ -159,27 +158,11 @@ impl<'tcx> MirPatch<'tcx> {
             debug!("MirPatch: adding statement {:?} at loc {:?}+{}", stmt, loc, delta);
             loc.statement_index += delta;
             let source_info = Self::source_info_for_index(&body[loc.block], loc);
-
-            // For mir-opt `Derefer` to work in all cases we need to
-            // get terminator's targets and apply the statement to all of them.
-            if loc.statement_index > body[loc.block].statements.len() {
-                let term = body[loc.block].terminator();
-                for i in term.successors() {
-                    stmts_and_targets.push((Statement { source_info, kind: stmt.clone() }, i));
-                }
-                delta += 1;
-                continue;
-            }
-
             body[loc.block]
                 .statements
                 .insert(loc.statement_index, Statement { source_info, kind: stmt });
             delta += 1;
         }
-
-        for (stmt, target) in stmts_and_targets.into_iter().rev() {
-            body[target].statements.insert(0, stmt);
-        }
     }
 
     pub fn source_info_for_index(data: &BasicBlockData<'_>, loc: Location) -> SourceInfo {