Add a little code to prepare exception handling support in fuzzer (#3207)

fixLabels() in the fuzzer looks for invalid labels and fixes them up,
after doing some random changes to existing wasm (which checks
for types while doing so, but it may invalidate labels if we remove the
target of a branch, for example). This adds trivial support for
BrOnExn and Try there.

1 files changed, 6 insertions, 4 deletions

diff --git a/src/tools/fuzzing.h b/src/tools/fuzzing.h
index 088aa3c96..475747056 100644
--- a/src/tools/fuzzing.h
+++ b/src/tools/fuzzing.h
@@ -729,6 +729,8 @@ private:
 
       void visitBreak(Break* curr) { replaceIfInvalid(curr->name); }
 
+      void visitBrOnExn(BrOnExn* curr) { replaceIfInvalid(curr->name); }
+
       bool replaceIfInvalid(Name target) {
         if (!hasBreakTarget(target)) {
           // There is no valid parent, replace with something trivially safe.
@@ -747,17 +749,17 @@ private:
         Index i = controlFlowStack.size() - 1;
         while (1) {
           auto* curr = controlFlowStack[i];
-          if (Block* block = curr->dynCast<Block>()) {
+          if (auto* block = curr->dynCast<Block>()) {
             if (name == block->name) {
               return true;
             }
-          } else if (Loop* loop = curr->dynCast<Loop>()) {
+          } else if (auto* loop = curr->dynCast<Loop>()) {
             if (name == loop->name) {
               return true;
             }
           } else {
-            // an if, ignorable
-            assert(curr->is<If>());
+            // an if or a try, ignorable
+            assert(curr->is<If>() || curr->is<Try>());
           }
           if (i == 0) {
             return false;