don't turn unreachable ifs into br_ifs, they are dead anyhow, and would need special handling to emit valid code

1 files changed, 2 insertions, 0 deletions

diff --git a/src/passes/RemoveUnusedBrs.cpp b/src/passes/RemoveUnusedBrs.cpp
index 8994c7fe2..f0db1eee6 100644
--- a/src/passes/RemoveUnusedBrs.cpp
+++ b/src/passes/RemoveUnusedBrs.cpp
@@ -31,6 +31,8 @@ namespace wasm {
 // condition and possible value, and the possible value must
 // not have side effects (as they would run unconditionally)
 static bool canTurnIfIntoBrIf(Expression* ifCondition, Expression* brValue, PassOptions& options) {
+  // if the if isn't even taken, this is all dead code anyhow
+  if (ifCondition->type == unreachable) return false;
   if (!brValue) return true;
   EffectAnalyzer value(options, brValue);
   if (value.hasSideEffects()) return false;