51 STATISTIC(NumTailDups, "Number of tail duplicated blocks");
53           "Number of instructions added due to tail duplication");
55           "Number of instructions removed due to tail duplication");
59 // Heuristic for tail duplication.
61     "tail-dup-size",
62     cl::desc("Maximum instructions to consider tail duplicating"), cl::init(2),
66     "tail-dup-indirect-size",
67     cl::desc("Maximum instructions to consider tail duplicating blocks that "
72     TailDupPredSize("tail-dup-pred-size",
74                              "same time) to consider tail duplicating blocks."),
78     TailDupSuccSize("tail-dup-succ-size",
80                              "same time) to consider tail duplicating blocks."),
84     TailDupVerify("tail-dup-verify",
88 static cl::opt<unsigned> TailDupLimit("tail-dup-limit", cl::init(~0U),
158 /// Tail duplicate the block and cleanup.
252   // Eliminate some of the copies inserted by tail duplication to maintain  in tailDuplicateAndUpdate()
277 /// through. Tail-duplicate their instructions into their predecessors to
283     LLVM_DEBUG(dbgs() << "\n*** Before tail-duplicating\n");  in tailDuplicateBlocks()
481 /// After FromBB is tail duplicated into its predecessor blocks, the successors
525         // This register is defined in the tail block.  in updateSuccessorsPHIs()
545         // Live in tail block, must also be live in predecessors.  in updateSuccessorsPHIs()
567   // When doing tail-duplication during layout, the block ordering is in flux,  in shouldTailDuplicate()
573   // Don't try to tail-duplicate single-block loops.  in shouldTailDuplicate()
611   // to allow undoing the effects of tail merging and other optimizations  in shouldTailDuplicate()
621   // Check the instructions in the block to determine whether tail-duplication  in shouldTailDuplicate()
625     // Non-duplicable things shouldn't be tail-duplicated.  in shouldTailDuplicate()
629     // tail duplication of some basic blocks, that would be duplicated otherwise.  in shouldTailDuplicate()
673   // any subregisters. Due to a bug, tail duplication may add a new operand  in shouldTailDuplicate()
675   // demonstrated by test/CodeGen/Hexagon/tail-dup-subreg-abort.ll.  in shouldTailDuplicate()
676   // Disable tail duplication for this case for now, until the problem is  in shouldTailDuplicate()
841 /// \p TDBBs             A vector to keep track of all blocks tail-duplicated
850   LLVM_DEBUG(dbgs() << "\n*** Tail-duplicating " << printMBBReference(*TailBB)  in tailDuplicate()
861   // Iterate through all the unique predecessors and tail-duplicate this  in tailDuplicate()
924     // Update branches in pred to jump to tail's layout successor if needed.  in tailDuplicate()
957     // If there are still tail instructions, abort the merge  in tailDuplicate()
991       // Update branches in PrevBB based on Tail's layout successor.  in tailDuplicate()