[BPI] Use BasicBlock::isEHPad() to check exception handling block.

There is no need to iterate all predecessors of current block, check if
current block is the invoke unwind destination of any predcessor.
We can directly call `BasicBlock::isEHPad()` to check if current block
is a exception handling block.

Author: Enna1

llvm/lib/Analysis/BranchProbabilityInfo.cpp

@@ -787,12 +787,9 @@ BranchProbabilityInfo::getInitialEstimatedBlockWeight(const BasicBlock *BB) {
                ? static_cast<uint32_t>(BlockExecWeight::NORETURN)
                : static_cast<uint32_t>(BlockExecWeight::UNREACHABLE);
 
-  // Check if the block is 'unwind' handler of  some invoke instruction.
-  for (const auto *Pred : predecessors(BB))
-    if (Pred)
-      if (const auto *II = dyn_cast<InvokeInst>(Pred->getTerminator()))
-        if (II->getUnwindDest() == BB)
-          return static_cast<uint32_t>(BlockExecWeight::UNWIND);
+  // Check if the block is an exception handling block.
+  if (BB->isEHPad())
+    return static_cast<uint32_t>(BlockExecWeight::UNWIND);
 
   // Check if the block contains 'cold' call.
   for (const auto &I : *BB)