1 files changed, 12 insertions, 0 deletions
diff --git a/src/passes/Outlining.cpp b/src/passes/Outlining.cpp
index f799d2c7a..51d000745 100644
--- a/src/passes/Outlining.cpp
+++ b/src/passes/Outlining.cpp
@@ -100,8 +100,20 @@ struct ReconstructStringifyWalker
       existingBuilder.push(curr->iff->condition);
       ASSERT_OK(existingBuilder.visitIfStart(curr->iff));
       DBG(desc = "If Start for ");
+    } else if (reason.getElseStart()) {
+      ASSERT_OK(existingBuilder.visitElse());
+      DBG(desc = "Else Start at ");
     } else if (reason.getEnd()) {
       ASSERT_OK(existingBuilder.visitEnd());
+      // Outlining performs an unnested walk of the Wasm module, visiting
+      // each scope one at a time. IRBuilder, in contrast, expects to
+      // visit several nested scopes at a time. Thus, calling end() finalizes
+      // the control flow and places it on IRBuilder's internal stack, ready for
+      // the enclosing scope to consume its expressions off the stack. Since
+      // outlining walks unnested, the enclosing scope never arrives to retrieve
+      // its expressions off the stack, so we must call build() after visitEnd()
+      // to clear the internal stack IRBuilder manages.
+      ASSERT_OK(existingBuilder.build());
       DBG(desc = "End for ");
     } else {
       DBG(desc = "addUniqueSymbol for unimplemented control flow ");