Revert "Enhance BranchProbabilityInfo::calcUnreachableHeuristics for InvokeInst"

This reverts commit r256028.

It broke:

    LLVM :: CodeGen/Mips/eh.ll
    LLVM :: CodeGen/Mips/insn-zero-size-bb.ll

llvm-svn: 256032

llvm/lib/Analysis/BranchProbabilityInfo.cpp

@@ -147,16 +147,6 @@ bool BranchProbabilityInfo::calcUnreachableHeuristics(BasicBlock *BB) {
   if (TI->getNumSuccessors() == 1 || UnreachableEdges.empty())
     return false;
 
-  // If the terminator is an InvokeInst, check only the normal destination block
-  // as the unwind edge of InvokeInst is also very unlikely taken.
-  if (auto *II = dyn_cast<InvokeInst>(TI))
-    if (PostDominatedByUnreachable.count(II->getNormalDest())) {
-      PostDominatedByUnreachable.insert(BB);
-      // Return false here so that edge weights for InvokeInst could be decided
-      // in calcInvokeHeuristics().
-      return false;
-    }
-
   uint32_t UnreachableWeight =
     std::max(UR_TAKEN_WEIGHT / (unsigned)UnreachableEdges.size(), MIN_WEIGHT);
   for (SmallVectorImpl<unsigned>::iterator I = UnreachableEdges.begin(),