Unify return, break and continue handling

Author: matthewjasper

src/librustc_mir/build/expr/stmt.rs

@@ -1,4 +1,4 @@
-use crate::build::scope::BreakableScope;
+use crate::build::scope::BreakableTarget;
 use crate::build::{BlockAnd, BlockAndExtension, BlockFrame, Builder};
 use crate::hair::*;
 use rustc::middle::region;
@@ -98,70 +98,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 block.unit()
             }
             ExprKind::Continue { label } => {
-                let BreakableScope {
-                    continue_block,
-                    region_scope,
-                    ..
-                } = *this.find_breakable_scope(expr_span, label);
-                let continue_block = continue_block
-                    .expect("Attempted to continue in non-continuable breakable block");
-                this.exit_scope(
-                    expr_span,
-                    (region_scope, source_info),
-                    block,
-                    continue_block,
-                );
-                this.cfg.start_new_block().unit()
+                this.break_scope(block, None, BreakableTarget::Continue(label), source_info)
             }
             ExprKind::Break { label, value } => {
-                let (break_block, region_scope, destination) = {
-                    let BreakableScope {
-                        break_block,
-                        region_scope,
-                        ref break_destination,
-                        ..
-                    } = *this.find_breakable_scope(expr_span, label);
-                    (break_block, region_scope, break_destination.clone())
-                };
-                if let Some(value) = value {
-                    debug!("stmt_expr Break val block_context.push(SubExpr) : {:?}", expr2);
-                    this.block_context.push(BlockFrame::SubExpr);
-                    unpack!(block = this.into(&destination, block, value));
-                    this.block_context.pop();
-                } else {
-                    this.cfg.push_assign_unit(block, source_info, &destination)
-                }
-                this.exit_scope(expr_span, (region_scope, source_info), block, break_block);
-                this.cfg.start_new_block().unit()
+                this.break_scope(block, value, BreakableTarget::Break(label), source_info)
             }
             ExprKind::Return { value } => {
-                block = match value {
-                    Some(value) => {
-                        debug!("stmt_expr Return val block_context.push(SubExpr) : {:?}", expr2);
-                        this.block_context.push(BlockFrame::SubExpr);
-                        let result = unpack!(
-                            this.into(
-                                &Place::RETURN_PLACE,
-                                block,
-                                value
-                            )
-                        );
-                        this.block_context.pop();
-                        result
-                    }
-                    None => {
-                        this.cfg.push_assign_unit(
-                            block,
-                            source_info,
-                            &Place::RETURN_PLACE,
-                        );
-                        block
-                    }
-                };
-                let region_scope = this.region_scope_of_return_scope();
-                let return_block = this.return_block();
-                this.exit_scope(expr_span, (region_scope, source_info), block, return_block);
-                this.cfg.start_new_block().unit()
+                this.break_scope(block, value, BreakableTarget::Return, source_info)
             }
             ExprKind::InlineAsm {
                 asm,

src/librustc_mir/build/mod.rs

@@ -251,7 +251,7 @@ struct Builder<'a, 'tcx> {
 
     /// The current set of scopes, updated as we traverse;
     /// see the `scope` module for more details.
-    scopes: Vec<scope::Scope<'tcx>>,
+    scopes: scope::Scopes<'tcx>,
 
     /// The block-context: each time we build the code within an hair::Block,
     /// we push a frame here tracking whether we are building a statement or
@@ -274,10 +274,6 @@ struct Builder<'a, 'tcx> {
     /// The number of `push_unsafe_block` levels in scope.
     push_unsafe_count: usize,
 
-    /// The current set of breakables; see the `scope` module for more
-    /// details.
-    breakable_scopes: Vec<scope::BreakableScope<'tcx>>,
-
     /// The vector of all scopes that we have created thus far;
     /// we track this for debuginfo later.
     source_scopes: IndexVec<SourceScope, SourceScopeData>,
@@ -714,15 +710,14 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             fn_span: span,
             arg_count,
             is_generator,
-            scopes: vec![],
+            scopes: Default::default(),
             block_context: BlockContext::new(),
             source_scopes: IndexVec::new(),
             source_scope: OUTERMOST_SOURCE_SCOPE,
             source_scope_local_data: IndexVec::new(),
             guard_context: vec![],
             push_unsafe_count: 0,
             unpushed_unsafe: safety,
-            breakable_scopes: vec![],
             local_decls: IndexVec::from_elem_n(
                 LocalDecl::new_return_place(return_ty, return_span),
                 1,
@@ -865,7 +860,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         }
 
         let body = self.hir.mirror(ast_body);
-        self.into(&Place::RETURN_PLACE, block, body)
+        // `return_block` is called when we evaluate a `return` expression, so
+        // we just use `START_BLOCK` here.
+        self.in_breakable_scope(None, START_BLOCK, Place::RETURN_PLACE, |this| {
+            this.into(&Place::RETURN_PLACE, block, body)
+        })
     }
 
     fn get_unit_temp(&mut self) -> Place<'tcx> {