Revert "[TailDuplicator] Add maximum predecessors and successors to consider tail duplicating blocks (#78582)"

This reverts commit 86a7828.

Now, we only consider computed GOTOs.

Author: dianqk

llvm/lib/CodeGen/TailDuplicator.cpp

@@ -67,18 +67,6 @@ static cl::opt<unsigned> TailDupIndirectBranchSize(
              "end with indirect branches."), cl::init(20),
     cl::Hidden);
 
-static cl::opt<unsigned>
-    TailDupPredSize("tail-dup-pred-size",
-                    cl::desc("Maximum predecessors (maximum successors at the "
-                             "same time) to consider tail duplicating blocks."),
-                    cl::init(16), cl::Hidden);
-
-static cl::opt<unsigned>
-    TailDupSuccSize("tail-dup-succ-size",
-                    cl::desc("Maximum successors (maximum predecessors at the "
-                             "same time) to consider tail duplicating blocks."),
-                    cl::init(16), cl::Hidden);
-
 static cl::opt<bool>
     TailDupVerify("tail-dup-verify",
                   cl::desc("Verify sanity of PHI instructions during taildup"),
@@ -573,14 +561,6 @@ bool TailDuplicator::shouldTailDuplicate(bool IsSimple,
   if (TailBB.isSuccessor(&TailBB))
     return false;
 
-  // Duplicating a BB which has both multiple predecessors and successors will
-  // result in a complex CFG and also may cause huge amount of PHI nodes. If we
-  // want to remove this limitation, we have to address
-  // https://github.com/llvm/llvm-project/issues/78578.
-  if (TailBB.pred_size() > TailDupPredSize &&
-      TailBB.succ_size() > TailDupSuccSize)
-    return false;
-
   // Set the limit on the cost to duplicate. When optimizing for size,
   // duplicate only one, because one branch instruction can be eliminated to
   // compensate for the duplication.