2 files changed, 23 insertions, 3 deletions
diff --git a/src/passes/ExtractFunction.cpp b/src/passes/ExtractFunction.cpp
index b342efc3b..b91d2c406 100644
--- a/src/passes/ExtractFunction.cpp
+++ b/src/passes/ExtractFunction.cpp
@@ -23,12 +23,18 @@
 
 namespace wasm {
 
-Name TO_LEAVE("_bytearray_join"); // TODO: commandline param
 
 struct ExtractFunction : public Pass {
   void run(PassRunner* runner, Module* module) override {
+    auto* leave = getenv("BYN_LEAVE");
+    if (!leave) {
+      std::cerr << "usage: set BYN_LEAVE in the env\n";
+      abort();
+    }
+    Name LEAVE(leave);
+    std::cerr << "keeping " << LEAVE << "\n";
     for (auto& func : module->functions) {
-      if (func->name != TO_LEAVE) {
+      if (func->name != LEAVE) {
         // wipe out the body
         func->body = module->allocator.alloc<Unreachable>();
       }
diff --git a/src/passes/RelooperJumpThreading.cpp b/src/passes/RelooperJumpThreading.cpp
index 7f74220d5..bd257c568 100644
--- a/src/passes/RelooperJumpThreading.cpp
+++ b/src/passes/RelooperJumpThreading.cpp
@@ -182,7 +182,21 @@ private:
       assert(labelChecksInOrigin[num] == 0);
       if (labelSetsInOrigin[num] != labelSets[num]) {
         assert(labelSetsInOrigin[num] < labelSets[num]);
-        return true; // label set somewhere outside of origin TODO: if set in the if body here, it might be safe in some cases
+        // the label is set outside of the origin
+        // if the only other location is inside the if body, then it is ok - it must be in a loop
+        // and returning to the top of the loop body, so we don't need to do anything for that
+        // label setting anyhow
+        std::map<Index, Index> labelChecksInIfTrue;
+        std::map<Index, Index> labelSetsInIfTrue;
+        LabelUseFinder finder(labelIndex, labelChecksInIfTrue, labelSetsInIfTrue);
+        finder.walk(iff->ifTrue);
+        if (labelSetsInOrigin[num] + labelSetsInIfTrue[num] < labelSets[num]) {
+          // label set somewhere we can't see now, could be irreducible control flow
+          // TODO: one case where this happens is instead of an if-chain, we have
+          //       ifs and a switch on label|0, in separate elements. perhaps not
+          //       emitting switches on label|0 in the relooper would avoid that.
+          return true;
+        }
       }
       iff = isLabelCheckingIf(iff->ifFalse, labelIndex);
     }