Some code cleanup

Author: Aaron1011

src/librustc_mir/interpret/eval_context.rs

@@ -593,17 +593,28 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             _ => {}
         }
 
+        // Now where do we jump next?
+
+        // Determine if we leave this function normally or via unwinding.
+        let cur_unwinding = match stack_pop_info {
+            StackPopInfo::StartUnwinding => true,
+            StackPopInfo::StopUnwinding => false,
+            _ => unwinding
+        };
+
         // Usually we want to clean up (deallocate locals), but in a few rare cases we don't.
         // In that case, we return early. We also avoid validation in that case,
         // because this is CTFE and the final value will be thoroughly validated anyway.
-        let cleanup = unwinding || match frame.return_to_block {
-            StackPopCleanup::Goto{ .. } => true,
-            StackPopCleanup::None { cleanup, .. } => {
-                cleanup
-            }
+        let (cleanup, next_block) = match frame.return_to_block {
+            StackPopCleanup::Goto { ret, unwind } => {
+                (true, Some(if cur_unwinding { unwind } else { ret }))
+            },
+            StackPopCleanup::None { cleanup, .. } => (cleanup, None)
         };
+
         if !cleanup {
             assert!(self.stack.is_empty(), "only the topmost frame should ever be leaked");
+            assert!(next_block.is_none(), "tried to skip cleanup when we have a next block!");
             // Leak the locals, skip validation.
             return Ok(());
         }
@@ -613,29 +624,16 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             self.deallocate_local(local.value)?;
         }
 
-        // Now where do we jump next?
-
-        // Determine if we leave this function normally or via unwinding.
-        let cur_unwinding = match stack_pop_info {
-            StackPopInfo::StartUnwinding => true,
-            StackPopInfo::StopUnwinding => false,
-            _ => unwinding
-        };
 
         trace!("StackPopCleanup: {:?} StackPopInfo: {:?} cur_unwinding = {:?}",
                frame.return_to_block, stack_pop_info, cur_unwinding);
         if cur_unwinding {
             // Follow the unwind edge.
-            match frame.return_to_block {
-                StackPopCleanup::Goto { unwind, .. } => {
-                    let next_frame = self.frame_mut();
-                    // If `unwind` is `None`, we'll leave that function immediately again.
-                    next_frame.block = unwind;
-                    next_frame.stmt = 0;
-                },
-                StackPopCleanup::None { .. } =>
-                    bug!("Encountered StackPopCleanup::None while unwinding"),
-            }
+            let unwind = next_block.expect("Encounted StackPopCleanup::None when unwinding!");
+            let next_frame = self.frame_mut();
+            // If `unwind` is `None`, we'll leave that function immediately again.
+            next_frame.block = unwind;
+            next_frame.stmt = 0;
         } else {
             // Follow the normal return edge.
             // Validate the return value. Do this after deallocating so that we catch dangling
@@ -661,11 +659,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             }
 
             // Jump to new block -- *after* validation so that the spans make more sense.
-            match frame.return_to_block {
-                StackPopCleanup::Goto { ret, ..  } => {
-                    self.goto_block(ret)?;
-                }
-                StackPopCleanup::None { .. } => {}
+            if let Some(ret) = next_block {
+                self.goto_block(ret)?;
             }
         }