[llvm] [BOLT][NFC] Add sink block to flow CFG in profile inference (PR #95047)

[Amir Ayupov via llvm-commits]

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@@ -309,22 +309,33 @@ createFlowFunction(const BinaryFunction::BasicBlockOrderType &BlockOrder) {
   FlowFunction Func;
 
   // Add a special "dummy" source so that there is always a unique entry point.
-  // Because of the extra source, for all other blocks in FlowFunction it holds
-  // that Block.Index == BB->getIndex() + 1
   FlowBlock EntryBlock;
   EntryBlock.Index = 0;
   Func.Blocks.push_back(EntryBlock);
 
+  auto BinaryBlockIsExit = [&](const BinaryBasicBlock &BB) {
+    if (BB.successors().empty())
+      return true;
+    return false;
+  };
+
   // Create FlowBlock for every basic block in the binary function
   for (const BinaryBasicBlock *BB : BlockOrder) {
     Func.Blocks.emplace_back();
     FlowBlock &Block = Func.Blocks.back();
     Block.Index = Func.Blocks.size() - 1;
+    Block.HasSuccessors = BinaryBlockIsExit(*BB);
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aaupov wrote:

Let's call the new attribute `IsExit` so the intent is clear. 

https://github.com/llvm/llvm-project/pull/95047