[SjLj] Replace recursive block marking algorithm with iterative algor…

…ithm

Summary:
Some programs run into a stack overflow issue. This change avoids this
problem by replacing the recursive algorithm with the iterative version.

Reviewers: MatzeB, t.p.northover, dblaikie

Reviewed By: MatzeB

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D35105

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307860 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SjLjEHPrepare.cpp

@@ -125,8 +125,11 @@ static void MarkBlocksLiveIn(BasicBlock *BB,
   if (!LiveBBs.insert(BB).second)
     return; // already been here.
 
-  for (BasicBlock *PredBB : predecessors(BB))
-    MarkBlocksLiveIn(PredBB, LiveBBs);
+  df_iterator_default_set<BasicBlock*> Visited;
+
+  for (BasicBlock *B : inverse_depth_first_ext(BB, Visited))
+    LiveBBs.insert(B);
+
 }
 
 /// substituteLPadValues - Substitute the values returned by the landingpad