151               cl::desc("Perform tail duplication during placement. "
162 // Heuristic for tail duplication.
165     cl::desc("Instruction cutoff for tail duplication during layout. "
170 // Heuristic for aggressive tail duplication.
173     cl::desc("Instruction cutoff for aggressive tail duplication during "
178 // Heuristic for tail duplication.
188 // Heuristic for tail duplication if profile count is used in cost model.
191     cl::desc("If profile count information is used in tail duplication cost "
192              "model, the gained fall through number from tail duplication "
200              "triangle tail duplication heuristic to kick in. 0 to disable."),
387   /// Member variable for convenience. It may be removed by duplication deep
404   /// Placement decisions can open up new tail duplication opportunities, but
405   /// since tail duplication affects placement decisions of later blocks, it
409   /// Partial tail duplication threshold.
412   /// True:  use block profile count to compute tail duplication cost.
413   /// False: use block frequency to compute tail duplication cost.
442   /// The return value is used to model tail duplication cost.
553   /// Check the edge frequencies to see if tail duplication will increase
809 /// Check the edge frequencies to see if tail duplication will increase
811 /// \p Succ would not be chosen otherwise. Tail duplication of \p Succ is
813 /// considering duplication.
1109   // Did we pick the triangle edge? If tail-duplication is profitable, do  in getBestTrellisSuccessor()
1117     // Check to see if tail-duplication would be profitable.  in getBestTrellisSuccessor()
1156   // Number of possible duplication.  in canTailDuplicateUnplacedPreds()
1171         // This will result in a trellis after tail duplication, so we don't  in canTailDuplicateUnplacedPreds()
1173         // of a trellis tail duplication can continue to be profitable.  in canTailDuplicateUnplacedPreds()
1195         // duplication and for this test.  in canTailDuplicateUnplacedPreds()
1202         // to trellises created by tail-duplication, so we just look for the  in canTailDuplicateUnplacedPreds()
1211   // No possible duplication in current filter set.  in canTailDuplicateUnplacedPreds()
1221   // The integrated tail duplication is really designed for increasing  in canTailDuplicateUnplacedPreds()
1230   // If the duplication candidate has more unplaced predecessors than  in canTailDuplicateUnplacedPreds()
1231   // successors, the extra duplication can't bring more fallthrough.  in canTailDuplicateUnplacedPreds()
1242   // In this example Dup has 2 successors and 3 predecessors, duplication of Dup  in canTailDuplicateUnplacedPreds()
1244   // but the duplication into Pred3 can't increase fallthrough.  in canTailDuplicateUnplacedPreds()
1246   // A small number of extra duplication may not hurt too much. We need a better  in canTailDuplicateUnplacedPreds()
1316     // If PDom isn't eligible for duplication, this isn't the kind of triangle  in precomputeTriangleChains()
1594 /// with a boolean indicating if tail duplication is necessary.
1630   // tail-duplication. We keep this vector so we can perform the probability  in selectBestSuccessor()
1644       // If tail duplication would make Succ profitable, place it.  in selectBestSuccessor()
1665   // Handle the tail duplication candidates in order of decreasing probability.  in selectBestSuccessor()
1901     // Placement may have changed tail duplication opportunities.  in buildChain()
3091   // at the end because repeating the tail duplication can increase the number  in repeatedlyTailDuplicateBlock()
3121   LLVM_DEBUG(dbgs() << "Redoing tail duplication for Succ#" << BB->getNumber()  in maybeTailDuplicateBlock()
3194     // We can do partial duplication with precise profile information.  in maybeTailDuplicateBlock()
3204   // Update UnscheduledPredecessors to reflect tail-duplication.  in maybeTailDuplicateBlock()
3235 // The size cost of duplication is the instruction size of the duplicated block.
3383   // So we can change one duplication into fallthrough.  in findDuplicateCandidates()
3458     // At O3 we should be more willing to copy blocks for tail duplication. This  in runOnMachineFunction()