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

[Amir Ayupov via llvm-commits]

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@@ -360,25 +371,37 @@ createFlowFunction(const BinaryFunction::BasicBlockOrderType &BlockOrder) {
   // Add dummy edges to the extra sources. If there are multiple entry blocks,
   // add an unlikely edge from 0 to the subsequent ones
   assert(InDegree[0] == 0 && "dummy entry blocks shouldn't have predecessors");
-  for (uint64_t I = 1; I < Func.Blocks.size(); I++) {
+  for (uint64_t I = 1; I < BlockOrder.size() + 1; I++) {
     const BinaryBasicBlock *BB = BlockOrder[I - 1];
     if (BB->isEntryPoint() || InDegree[I] == 0) {
       Func.Jumps.emplace_back();
       FlowJump &Jump = Func.Jumps.back();
-      Jump.Source = 0;
+      Jump.Source = Func.Entry;
       Jump.Target = I;
       if (!BB->isEntryPoint())
         Jump.IsUnlikely = true;
     }
   }
 
+  // Add dummy edges from the exit blocks to the sink block.
+  for (uint64_t I = 1; I < BlockOrder.size() + 1; I++) {
+    FlowBlock &Block = Func.Blocks[I];
+    if (Block.HasSuccessors) {
+      Func.Jumps.emplace_back();
+      FlowJump &Jump = Func.Jumps.back();
+      Jump.Source = I;
+      Jump.Target = Func.Sink;
+    }
+  }
+
   // Create necessary metadata for the flow function
   for (FlowJump &Jump : Func.Jumps) {
     assert(Jump.Source < Func.Blocks.size());
     Func.Blocks[Jump.Source].SuccJumps.push_back(&Jump);
     assert(Jump.Target < Func.Blocks.size());
     Func.Blocks[Jump.Target].PredJumps.push_back(&Jump);
   }
+
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aaupov wrote:

nit: avoid spurious changes

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