Do not emit extra rescue region during cloning of ensure if there is …

…nothing there yet. This removes one set of extra empty BBs that current CFG creation is not removing during optimize().
jruby · Nov 28, 2017 · cd61c27 · cd61c27
1 parent 13542d0
commit cd61c27
Showing 1 changed file with 13 additions and 7 deletions.
diff --git a/core/src/main/java/org/jruby/ir/IRBuilder.java b/core/src/main/java/org/jruby/ir/IRBuilder.java
@@ -221,6 +221,19 @@ public void emitBody(IRBuilder b) {
         }
 
         public void cloneIntoHostScope(IRBuilder builder) {
+            // $! should be restored before the ensure block is run
+            if (savedGlobalException != null) {
+                // We need make sure on all outgoing paths in optimized short-hand rescues we restore the backtrace
+                if (!needsBacktrace) builder.addInstr(builder.manager.needsBacktrace(true));
+                builder.addInstr(new PutGlobalVarInstr("$!", savedGlobalException));
+            }
+
+            // Sometimes we process a rescue and it hits something like non-local flow like a 'next' and
+            // there are no actual instrs pushed yet (but ebi has reserved a frame for it -- e.g. the rescue/ensure
+            // the next is in).  Since it is doing nothing we have nothing to clone.  By skipping this we prevent
+            // setting exception regions and simplify CFG construction.
+            if (instrs.size() == 0) return;
+
             SimpleCloneInfo ii = new SimpleCloneInfo(builder.scope, true);
 
             // Clone required labels.
@@ -231,13 +244,6 @@ public void cloneIntoHostScope(IRBuilder builder) {
                 if (i instanceof LabelInstr) ii.renameLabel(((LabelInstr)i).getLabel());
             }
 
-            // $! should be restored before the ensure block is run
-            if (savedGlobalException != null) {
-                // We need make sure on all outgoing paths in optimized short-hand rescues we restore the backtrace
-                if (!needsBacktrace) builder.addInstr(builder.manager.needsBacktrace(true));
-                builder.addInstr(new PutGlobalVarInstr("$!", savedGlobalException));
-            }
-
             // Clone instructions now
             builder.addInstr(new LabelInstr(ii.getRenamedLabel(start)));
             builder.addInstr(new ExceptionRegionStartMarkerInstr(bodyRescuer));