CFGWalker: Allow users to ignore branches outside the function [NFC] (#5838)

A pass that just operates on locals, for example, does not care about branches outside of
the function. That means that when we see a call, then even if EH is enabled we don't need
to create a new basic block right after it (unless the call is inside a try-catch - then it might
branch to the catch, of course).

This makes CFG-using passes 9% faster compared to before this PR. This plus #5827 offset
the slowdown from #5823 and overall give an improvement compared to before.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/passes/RedundantSetElimination.cpp b/src/passes/RedundantSetElimination.cpp
index 4f82d5181..d54863639 100644
--- a/src/passes/RedundantSetElimination.cpp
+++ b/src/passes/RedundantSetElimination.cpp
@@ -68,6 +68,10 @@ struct RedundantSetElimination
     return std::make_unique<RedundantSetElimination>();
   }
 
+  // Branches outside of the function can be ignored, as we only look at locals
+  // which vanish when we leave.
+  bool ignoreBranchesOutsideOfFunc = true;
+
   Index numLocals;
 
   // In rare cases we make a change to a type that requires a refinalize.