[Outlining] Filter in nested control flow (#7411)

Fixes a bug where stringify walker was not removing outlining candidates
with restricted expressions because they were in nested control flow.

Author: ashleynh

src/passes/hash-stringify-walker.cpp

@@ -204,6 +204,7 @@ std::vector<SuffixTree::RepeatedSubstring> StringifyProcessor::filter(
     void walk(Expression* curr) {
       hasFilterValue = false;
       Super::walk(curr);
+      flushControlFlowQueue();
     }
 
     void addUniqueSymbol(SeparatorReason reason) {}

src/passes/stringify-walker-impl.h

@@ -42,9 +42,7 @@ inline void StringifyWalker<SubType>::doWalkFunction(Function* func) {
   addUniqueSymbol(SeparatorReason::makeFuncStart(func));
   Super::walk(func->body);
   addUniqueSymbol(SeparatorReason::makeEnd());
-  while (!controlFlowQueue.empty()) {
-    dequeueControlFlow();
-  }
+  flushControlFlowQueue();
 }
 
 template<typename SubType>

src/passes/stringify-walker.h

@@ -191,7 +191,11 @@ struct StringifyWalker
   static void scan(SubType* self, Expression** currp);
   static void doVisitExpression(SubType* self, Expression** currp);
 
-private:
+  void flushControlFlowQueue() {
+    while (!controlFlowQueue.empty()) {
+      dequeueControlFlow();
+    }
+  }
   void dequeueControlFlow();
 };
 

test/lit/passes/outlining.wast

@@ -1109,3 +1109,58 @@
     unreachable
   )
 )
+
+;; Tests that restricted expressions (local.set) are filtered from outlining
+;; even when nested within control flow.
+(module
+  ;; CHECK:      (type $0 (func))
+
+  ;; CHECK:      (func $a (type $0)
+  ;; CHECK-NEXT:  (local $x i32)
+  ;; CHECK-NEXT:  (if
+  ;; CHECK-NEXT:   (i32.const 0)
+  ;; CHECK-NEXT:   (then
+  ;; CHECK-NEXT:    (local.set $x
+  ;; CHECK-NEXT:     (i32.const 1)
+  ;; CHECK-NEXT:    )
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $a
+    (local $x i32)
+    (block
+      (if
+        (i32.const 0)
+        (then
+          (local.set $x
+            (i32.const 1)
+          )
+        )
+      )
+    )
+  )
+  ;; CHECK:      (func $b (type $0)
+  ;; CHECK-NEXT:  (local $x i32)
+  ;; CHECK-NEXT:  (if
+  ;; CHECK-NEXT:   (i32.const 0)
+  ;; CHECK-NEXT:   (then
+  ;; CHECK-NEXT:    (local.set $x
+  ;; CHECK-NEXT:     (i32.const 1)
+  ;; CHECK-NEXT:    )
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $b
+    (local $x i32)
+    (block
+      (if
+        (i32.const 0)
+        (then
+          (local.set $x
+            (i32.const 1)
+          )
+        )
+      )
+    )
+  )
+)