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      1 //===-- AMDILCFGStructurizer.cpp - CFG Structurizer -----------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 /// \file
      9 //==-----------------------------------------------------------------------===//
     10 
     11 #include "AMDGPU.h"
     12 #include "AMDGPUInstrInfo.h"
     13 #include "AMDGPUSubtarget.h"
     14 #include "R600InstrInfo.h"
     15 #include "llvm/ADT/DepthFirstIterator.h"
     16 #include "llvm/ADT/SCCIterator.h"
     17 #include "llvm/ADT/SmallVector.h"
     18 #include "llvm/ADT/Statistic.h"
     19 #include "llvm/CodeGen/MachineDominators.h"
     20 #include "llvm/CodeGen/MachineFunction.h"
     21 #include "llvm/CodeGen/MachineFunctionAnalysis.h"
     22 #include "llvm/CodeGen/MachineFunctionPass.h"
     23 #include "llvm/CodeGen/MachineInstrBuilder.h"
     24 #include "llvm/CodeGen/MachineJumpTableInfo.h"
     25 #include "llvm/CodeGen/MachineLoopInfo.h"
     26 #include "llvm/CodeGen/MachinePostDominators.h"
     27 #include "llvm/CodeGen/MachineRegisterInfo.h"
     28 #include "llvm/IR/Dominators.h"
     29 #include "llvm/Support/Debug.h"
     30 #include "llvm/Support/raw_ostream.h"
     31 #include "llvm/Target/TargetInstrInfo.h"
     32 #include "llvm/Target/TargetMachine.h"
     33 #include <deque>
     34 
     35 using namespace llvm;
     36 
     37 #define DEBUG_TYPE "structcfg"
     38 
     39 #define DEFAULT_VEC_SLOTS 8
     40 
     41 // TODO: move-begin.
     42 
     43 //===----------------------------------------------------------------------===//
     44 //
     45 // Statistics for CFGStructurizer.
     46 //
     47 //===----------------------------------------------------------------------===//
     48 
     49 STATISTIC(numSerialPatternMatch,    "CFGStructurizer number of serial pattern "
     50     "matched");
     51 STATISTIC(numIfPatternMatch,        "CFGStructurizer number of if pattern "
     52     "matched");
     53 STATISTIC(numLoopcontPatternMatch,  "CFGStructurizer number of loop-continue "
     54     "pattern matched");
     55 STATISTIC(numClonedBlock,           "CFGStructurizer cloned blocks");
     56 STATISTIC(numClonedInstr,           "CFGStructurizer cloned instructions");
     57 
     58 namespace llvm {
     59   void initializeAMDGPUCFGStructurizerPass(PassRegistry&);
     60 }
     61 
     62 //===----------------------------------------------------------------------===//
     63 //
     64 // Miscellaneous utility for CFGStructurizer.
     65 //
     66 //===----------------------------------------------------------------------===//
     67 namespace {
     68 #define SHOWNEWINSTR(i) \
     69   DEBUG(dbgs() << "New instr: " << *i << "\n");
     70 
     71 #define SHOWNEWBLK(b, msg) \
     72 DEBUG( \
     73   dbgs() << msg << "BB" << b->getNumber() << "size " << b->size(); \
     74   dbgs() << "\n"; \
     75 );
     76 
     77 #define SHOWBLK_DETAIL(b, msg) \
     78 DEBUG( \
     79   if (b) { \
     80   dbgs() << msg << "BB" << b->getNumber() << "size " << b->size(); \
     81   b->print(dbgs()); \
     82   dbgs() << "\n"; \
     83   } \
     84 );
     85 
     86 #define INVALIDSCCNUM -1
     87 
     88 template<class NodeT>
     89 void ReverseVector(SmallVectorImpl<NodeT *> &Src) {
     90   size_t sz = Src.size();
     91   for (size_t i = 0; i < sz/2; ++i) {
     92     NodeT *t = Src[i];
     93     Src[i] = Src[sz - i - 1];
     94     Src[sz - i - 1] = t;
     95   }
     96 }
     97 
     98 } // end anonymous namespace
     99 
    100 //===----------------------------------------------------------------------===//
    101 //
    102 // supporting data structure for CFGStructurizer
    103 //
    104 //===----------------------------------------------------------------------===//
    105 
    106 
    107 namespace {
    108 
    109 class BlockInformation {
    110 public:
    111   bool IsRetired;
    112   int  SccNum;
    113   BlockInformation() : IsRetired(false), SccNum(INVALIDSCCNUM) {}
    114 };
    115 
    116 } // end anonymous namespace
    117 
    118 //===----------------------------------------------------------------------===//
    119 //
    120 // CFGStructurizer
    121 //
    122 //===----------------------------------------------------------------------===//
    123 
    124 namespace {
    125 class AMDGPUCFGStructurizer : public MachineFunctionPass {
    126 public:
    127   typedef SmallVector<MachineBasicBlock *, 32> MBBVector;
    128   typedef std::map<MachineBasicBlock *, BlockInformation *> MBBInfoMap;
    129   typedef std::map<MachineLoop *, MachineBasicBlock *> LoopLandInfoMap;
    130 
    131   enum PathToKind {
    132     Not_SinglePath = 0,
    133     SinglePath_InPath = 1,
    134     SinglePath_NotInPath = 2
    135   };
    136 
    137   static char ID;
    138 
    139   AMDGPUCFGStructurizer() :
    140       MachineFunctionPass(ID), TII(nullptr), TRI(nullptr) {
    141     initializeAMDGPUCFGStructurizerPass(*PassRegistry::getPassRegistry());
    142   }
    143 
    144    const char *getPassName() const override {
    145     return "AMDGPU Control Flow Graph structurizer Pass";
    146   }
    147 
    148   void getAnalysisUsage(AnalysisUsage &AU) const override {
    149     AU.addPreserved<MachineFunctionAnalysis>();
    150     AU.addRequired<MachineFunctionAnalysis>();
    151     AU.addRequired<MachineDominatorTree>();
    152     AU.addRequired<MachinePostDominatorTree>();
    153     AU.addRequired<MachineLoopInfo>();
    154   }
    155 
    156   /// Perform the CFG structurization
    157   bool run();
    158 
    159   /// Perform the CFG preparation
    160   /// This step will remove every unconditionnal/dead jump instructions and make
    161   /// sure all loops have an exit block
    162   bool prepare();
    163 
    164   bool runOnMachineFunction(MachineFunction &MF) override {
    165     TII = static_cast<const R600InstrInfo *>(MF.getSubtarget().getInstrInfo());
    166     TRI = &TII->getRegisterInfo();
    167     DEBUG(MF.dump(););
    168     OrderedBlks.clear();
    169     Visited.clear();
    170     FuncRep = &MF;
    171     MLI = &getAnalysis<MachineLoopInfo>();
    172     DEBUG(dbgs() << "LoopInfo:\n"; PrintLoopinfo(*MLI););
    173     MDT = &getAnalysis<MachineDominatorTree>();
    174     DEBUG(MDT->print(dbgs(), (const llvm::Module*)nullptr););
    175     PDT = &getAnalysis<MachinePostDominatorTree>();
    176     DEBUG(PDT->print(dbgs()););
    177     prepare();
    178     run();
    179     DEBUG(MF.dump(););
    180     return true;
    181   }
    182 
    183 protected:
    184   MachineDominatorTree *MDT;
    185   MachinePostDominatorTree *PDT;
    186   MachineLoopInfo *MLI;
    187   const R600InstrInfo *TII;
    188   const R600RegisterInfo *TRI;
    189 
    190   // PRINT FUNCTIONS
    191   /// Print the ordered Blocks.
    192   void printOrderedBlocks() const {
    193     size_t i = 0;
    194     for (MBBVector::const_iterator iterBlk = OrderedBlks.begin(),
    195         iterBlkEnd = OrderedBlks.end(); iterBlk != iterBlkEnd; ++iterBlk, ++i) {
    196       dbgs() << "BB" << (*iterBlk)->getNumber();
    197       dbgs() << "(" << getSCCNum(*iterBlk) << "," << (*iterBlk)->size() << ")";
    198       if (i != 0 && i % 10 == 0) {
    199         dbgs() << "\n";
    200       } else {
    201         dbgs() << " ";
    202       }
    203     }
    204   }
    205   static void PrintLoopinfo(const MachineLoopInfo &LoopInfo) {
    206     for (MachineLoop::iterator iter = LoopInfo.begin(),
    207          iterEnd = LoopInfo.end(); iter != iterEnd; ++iter) {
    208       (*iter)->print(dbgs(), 0);
    209     }
    210   }
    211 
    212   // UTILITY FUNCTIONS
    213   int getSCCNum(MachineBasicBlock *MBB) const;
    214   MachineBasicBlock *getLoopLandInfo(MachineLoop *LoopRep) const;
    215   bool hasBackEdge(MachineBasicBlock *MBB) const;
    216   static unsigned getLoopDepth(MachineLoop *LoopRep);
    217   bool isRetiredBlock(MachineBasicBlock *MBB) const;
    218   bool isActiveLoophead(MachineBasicBlock *MBB) const;
    219   PathToKind singlePathTo(MachineBasicBlock *SrcMBB, MachineBasicBlock *DstMBB,
    220       bool AllowSideEntry = true) const;
    221   int countActiveBlock(MBBVector::const_iterator It,
    222       MBBVector::const_iterator E) const;
    223   bool needMigrateBlock(MachineBasicBlock *MBB) const;
    224 
    225   // Utility Functions
    226   void reversePredicateSetter(MachineBasicBlock::iterator I);
    227   /// Compute the reversed DFS post order of Blocks
    228   void orderBlocks(MachineFunction *MF);
    229 
    230   // Function originally from CFGStructTraits
    231   void insertInstrEnd(MachineBasicBlock *MBB, int NewOpcode,
    232       DebugLoc DL = DebugLoc());
    233   MachineInstr *insertInstrBefore(MachineBasicBlock *MBB, int NewOpcode,
    234     DebugLoc DL = DebugLoc());
    235   MachineInstr *insertInstrBefore(MachineBasicBlock::iterator I, int NewOpcode);
    236   void insertCondBranchBefore(MachineBasicBlock::iterator I, int NewOpcode,
    237       DebugLoc DL);
    238   void insertCondBranchBefore(MachineBasicBlock *MBB,
    239       MachineBasicBlock::iterator I, int NewOpcode, int RegNum,
    240       DebugLoc DL);
    241   void insertCondBranchEnd(MachineBasicBlock *MBB, int NewOpcode, int RegNum);
    242   static int getBranchNzeroOpcode(int OldOpcode);
    243   static int getBranchZeroOpcode(int OldOpcode);
    244   static int getContinueNzeroOpcode(int OldOpcode);
    245   static int getContinueZeroOpcode(int OldOpcode);
    246   static MachineBasicBlock *getTrueBranch(MachineInstr *MI);
    247   static void setTrueBranch(MachineInstr *MI, MachineBasicBlock *MBB);
    248   static MachineBasicBlock *getFalseBranch(MachineBasicBlock *MBB,
    249       MachineInstr *MI);
    250   static bool isCondBranch(MachineInstr *MI);
    251   static bool isUncondBranch(MachineInstr *MI);
    252   static DebugLoc getLastDebugLocInBB(MachineBasicBlock *MBB);
    253   static MachineInstr *getNormalBlockBranchInstr(MachineBasicBlock *MBB);
    254   /// The correct naming for this is getPossibleLoopendBlockBranchInstr.
    255   ///
    256   /// BB with backward-edge could have move instructions after the branch
    257   /// instruction.  Such move instruction "belong to" the loop backward-edge.
    258   MachineInstr *getLoopendBlockBranchInstr(MachineBasicBlock *MBB);
    259   static MachineInstr *getReturnInstr(MachineBasicBlock *MBB);
    260   static MachineInstr *getContinueInstr(MachineBasicBlock *MBB);
    261   static bool isReturnBlock(MachineBasicBlock *MBB);
    262   static void cloneSuccessorList(MachineBasicBlock *DstMBB,
    263       MachineBasicBlock *SrcMBB) ;
    264   static MachineBasicBlock *clone(MachineBasicBlock *MBB);
    265   /// MachineBasicBlock::ReplaceUsesOfBlockWith doesn't serve the purpose
    266   /// because the AMDGPU instruction is not recognized as terminator fix this
    267   /// and retire this routine
    268   void replaceInstrUseOfBlockWith(MachineBasicBlock *SrcMBB,
    269       MachineBasicBlock *OldMBB, MachineBasicBlock *NewBlk);
    270   static void wrapup(MachineBasicBlock *MBB);
    271 
    272 
    273   int patternMatch(MachineBasicBlock *MBB);
    274   int patternMatchGroup(MachineBasicBlock *MBB);
    275   int serialPatternMatch(MachineBasicBlock *MBB);
    276   int ifPatternMatch(MachineBasicBlock *MBB);
    277   int loopendPatternMatch();
    278   int mergeLoop(MachineLoop *LoopRep);
    279   int loopcontPatternMatch(MachineLoop *LoopRep, MachineBasicBlock *LoopHeader);
    280 
    281   void handleLoopcontBlock(MachineBasicBlock *ContingMBB,
    282       MachineLoop *ContingLoop, MachineBasicBlock *ContMBB,
    283       MachineLoop *ContLoop);
    284   /// return true iff src1Blk->succ_size() == 0 && src1Blk and src2Blk are in
    285   /// the same loop with LoopLandInfo without explicitly keeping track of
    286   /// loopContBlks and loopBreakBlks, this is a method to get the information.
    287   bool isSameloopDetachedContbreak(MachineBasicBlock *Src1MBB,
    288       MachineBasicBlock *Src2MBB);
    289   int handleJumpintoIf(MachineBasicBlock *HeadMBB,
    290       MachineBasicBlock *TrueMBB, MachineBasicBlock *FalseMBB);
    291   int handleJumpintoIfImp(MachineBasicBlock *HeadMBB,
    292       MachineBasicBlock *TrueMBB, MachineBasicBlock *FalseMBB);
    293   int improveSimpleJumpintoIf(MachineBasicBlock *HeadMBB,
    294       MachineBasicBlock *TrueMBB, MachineBasicBlock *FalseMBB,
    295       MachineBasicBlock **LandMBBPtr);
    296   void showImproveSimpleJumpintoIf(MachineBasicBlock *HeadMBB,
    297       MachineBasicBlock *TrueMBB, MachineBasicBlock *FalseMBB,
    298       MachineBasicBlock *LandMBB, bool Detail = false);
    299   int cloneOnSideEntryTo(MachineBasicBlock *PreMBB,
    300       MachineBasicBlock *SrcMBB, MachineBasicBlock *DstMBB);
    301   void mergeSerialBlock(MachineBasicBlock *DstMBB,
    302       MachineBasicBlock *SrcMBB);
    303 
    304   void mergeIfthenelseBlock(MachineInstr *BranchMI,
    305       MachineBasicBlock *MBB, MachineBasicBlock *TrueMBB,
    306       MachineBasicBlock *FalseMBB, MachineBasicBlock *LandMBB);
    307   void mergeLooplandBlock(MachineBasicBlock *DstMBB,
    308       MachineBasicBlock *LandMBB);
    309   void mergeLoopbreakBlock(MachineBasicBlock *ExitingMBB,
    310       MachineBasicBlock *LandMBB);
    311   void settleLoopcontBlock(MachineBasicBlock *ContingMBB,
    312       MachineBasicBlock *ContMBB);
    313   /// normalizeInfiniteLoopExit change
    314   ///   B1:
    315   ///        uncond_br LoopHeader
    316   ///
    317   /// to
    318   ///   B1:
    319   ///        cond_br 1 LoopHeader dummyExit
    320   /// and return the newly added dummy exit block
    321   MachineBasicBlock *normalizeInfiniteLoopExit(MachineLoop *LoopRep);
    322   void removeUnconditionalBranch(MachineBasicBlock *MBB);
    323   /// Remove duplicate branches instructions in a block.
    324   /// For instance
    325   /// B0:
    326   ///    cond_br X B1 B2
    327   ///    cond_br X B1 B2
    328   /// is transformed to
    329   /// B0:
    330   ///    cond_br X B1 B2
    331   void removeRedundantConditionalBranch(MachineBasicBlock *MBB);
    332   void addDummyExitBlock(SmallVectorImpl<MachineBasicBlock *> &RetMBB);
    333   void removeSuccessor(MachineBasicBlock *MBB);
    334   MachineBasicBlock *cloneBlockForPredecessor(MachineBasicBlock *MBB,
    335       MachineBasicBlock *PredMBB);
    336   void migrateInstruction(MachineBasicBlock *SrcMBB,
    337       MachineBasicBlock *DstMBB, MachineBasicBlock::iterator I);
    338   void recordSccnum(MachineBasicBlock *MBB, int SCCNum);
    339   void retireBlock(MachineBasicBlock *MBB);
    340   void setLoopLandBlock(MachineLoop *LoopRep, MachineBasicBlock *MBB = nullptr);
    341 
    342   MachineBasicBlock *findNearestCommonPostDom(std::set<MachineBasicBlock *>&);
    343   /// This is work around solution for findNearestCommonDominator not available
    344   /// to post dom a proper fix should go to Dominators.h.
    345   MachineBasicBlock *findNearestCommonPostDom(MachineBasicBlock *MBB1,
    346       MachineBasicBlock *MBB2);
    347 
    348 private:
    349   MBBInfoMap BlockInfoMap;
    350   LoopLandInfoMap LLInfoMap;
    351   std::map<MachineLoop *, bool> Visited;
    352   MachineFunction *FuncRep;
    353   SmallVector<MachineBasicBlock *, DEFAULT_VEC_SLOTS> OrderedBlks;
    354 };
    355 
    356 int AMDGPUCFGStructurizer::getSCCNum(MachineBasicBlock *MBB) const {
    357   MBBInfoMap::const_iterator It = BlockInfoMap.find(MBB);
    358   if (It == BlockInfoMap.end())
    359     return INVALIDSCCNUM;
    360   return (*It).second->SccNum;
    361 }
    362 
    363 MachineBasicBlock *AMDGPUCFGStructurizer::getLoopLandInfo(MachineLoop *LoopRep)
    364     const {
    365   LoopLandInfoMap::const_iterator It = LLInfoMap.find(LoopRep);
    366   if (It == LLInfoMap.end())
    367     return nullptr;
    368   return (*It).second;
    369 }
    370 
    371 bool AMDGPUCFGStructurizer::hasBackEdge(MachineBasicBlock *MBB) const {
    372   MachineLoop *LoopRep = MLI->getLoopFor(MBB);
    373   if (!LoopRep)
    374     return false;
    375   MachineBasicBlock *LoopHeader = LoopRep->getHeader();
    376   return MBB->isSuccessor(LoopHeader);
    377 }
    378 
    379 unsigned AMDGPUCFGStructurizer::getLoopDepth(MachineLoop *LoopRep) {
    380   return LoopRep ? LoopRep->getLoopDepth() : 0;
    381 }
    382 
    383 bool AMDGPUCFGStructurizer::isRetiredBlock(MachineBasicBlock *MBB) const {
    384   MBBInfoMap::const_iterator It = BlockInfoMap.find(MBB);
    385   if (It == BlockInfoMap.end())
    386     return false;
    387   return (*It).second->IsRetired;
    388 }
    389 
    390 bool AMDGPUCFGStructurizer::isActiveLoophead(MachineBasicBlock *MBB) const {
    391   MachineLoop *LoopRep = MLI->getLoopFor(MBB);
    392   while (LoopRep && LoopRep->getHeader() == MBB) {
    393     MachineBasicBlock *LoopLand = getLoopLandInfo(LoopRep);
    394     if(!LoopLand)
    395       return true;
    396     if (!isRetiredBlock(LoopLand))
    397       return true;
    398     LoopRep = LoopRep->getParentLoop();
    399   }
    400   return false;
    401 }
    402 AMDGPUCFGStructurizer::PathToKind AMDGPUCFGStructurizer::singlePathTo(
    403     MachineBasicBlock *SrcMBB, MachineBasicBlock *DstMBB,
    404     bool AllowSideEntry) const {
    405   assert(DstMBB);
    406   if (SrcMBB == DstMBB)
    407     return SinglePath_InPath;
    408   while (SrcMBB && SrcMBB->succ_size() == 1) {
    409     SrcMBB = *SrcMBB->succ_begin();
    410     if (SrcMBB == DstMBB)
    411       return SinglePath_InPath;
    412     if (!AllowSideEntry && SrcMBB->pred_size() > 1)
    413       return Not_SinglePath;
    414   }
    415   if (SrcMBB && SrcMBB->succ_size()==0)
    416     return SinglePath_NotInPath;
    417   return Not_SinglePath;
    418 }
    419 
    420 int AMDGPUCFGStructurizer::countActiveBlock(MBBVector::const_iterator It,
    421     MBBVector::const_iterator E) const {
    422   int Count = 0;
    423   while (It != E) {
    424     if (!isRetiredBlock(*It))
    425       ++Count;
    426     ++It;
    427   }
    428   return Count;
    429 }
    430 
    431 bool AMDGPUCFGStructurizer::needMigrateBlock(MachineBasicBlock *MBB) const {
    432   unsigned BlockSizeThreshold = 30;
    433   unsigned CloneInstrThreshold = 100;
    434   bool MultiplePreds = MBB && (MBB->pred_size() > 1);
    435 
    436   if(!MultiplePreds)
    437     return false;
    438   unsigned BlkSize = MBB->size();
    439   return ((BlkSize > BlockSizeThreshold) &&
    440       (BlkSize * (MBB->pred_size() - 1) > CloneInstrThreshold));
    441 }
    442 
    443 void AMDGPUCFGStructurizer::reversePredicateSetter(
    444     MachineBasicBlock::iterator I) {
    445   while (I--) {
    446     if (I->getOpcode() == AMDGPU::PRED_X) {
    447       switch (static_cast<MachineInstr *>(I)->getOperand(2).getImm()) {
    448       case OPCODE_IS_ZERO_INT:
    449         static_cast<MachineInstr *>(I)->getOperand(2)
    450             .setImm(OPCODE_IS_NOT_ZERO_INT);
    451         return;
    452       case OPCODE_IS_NOT_ZERO_INT:
    453         static_cast<MachineInstr *>(I)->getOperand(2)
    454             .setImm(OPCODE_IS_ZERO_INT);
    455         return;
    456       case OPCODE_IS_ZERO:
    457         static_cast<MachineInstr *>(I)->getOperand(2)
    458             .setImm(OPCODE_IS_NOT_ZERO);
    459         return;
    460       case OPCODE_IS_NOT_ZERO:
    461         static_cast<MachineInstr *>(I)->getOperand(2)
    462             .setImm(OPCODE_IS_ZERO);
    463         return;
    464       default:
    465         llvm_unreachable("PRED_X Opcode invalid!");
    466       }
    467     }
    468   }
    469 }
    470 
    471 void AMDGPUCFGStructurizer::insertInstrEnd(MachineBasicBlock *MBB,
    472     int NewOpcode, DebugLoc DL) {
    473  MachineInstr *MI = MBB->getParent()
    474     ->CreateMachineInstr(TII->get(NewOpcode), DL);
    475   MBB->push_back(MI);
    476   //assume the instruction doesn't take any reg operand ...
    477   SHOWNEWINSTR(MI);
    478 }
    479 
    480 MachineInstr *AMDGPUCFGStructurizer::insertInstrBefore(MachineBasicBlock *MBB,
    481     int NewOpcode, DebugLoc DL) {
    482   MachineInstr *MI =
    483       MBB->getParent()->CreateMachineInstr(TII->get(NewOpcode), DL);
    484   if (MBB->begin() != MBB->end())
    485     MBB->insert(MBB->begin(), MI);
    486   else
    487     MBB->push_back(MI);
    488   SHOWNEWINSTR(MI);
    489   return MI;
    490 }
    491 
    492 MachineInstr *AMDGPUCFGStructurizer::insertInstrBefore(
    493     MachineBasicBlock::iterator I, int NewOpcode) {
    494   MachineInstr *OldMI = &(*I);
    495   MachineBasicBlock *MBB = OldMI->getParent();
    496   MachineInstr *NewMBB =
    497       MBB->getParent()->CreateMachineInstr(TII->get(NewOpcode), DebugLoc());
    498   MBB->insert(I, NewMBB);
    499   //assume the instruction doesn't take any reg operand ...
    500   SHOWNEWINSTR(NewMBB);
    501   return NewMBB;
    502 }
    503 
    504 void AMDGPUCFGStructurizer::insertCondBranchBefore(
    505     MachineBasicBlock::iterator I, int NewOpcode, DebugLoc DL) {
    506   MachineInstr *OldMI = &(*I);
    507   MachineBasicBlock *MBB = OldMI->getParent();
    508   MachineFunction *MF = MBB->getParent();
    509   MachineInstr *NewMI = MF->CreateMachineInstr(TII->get(NewOpcode), DL);
    510   MBB->insert(I, NewMI);
    511   MachineInstrBuilder MIB(*MF, NewMI);
    512   MIB.addReg(OldMI->getOperand(1).getReg(), false);
    513   SHOWNEWINSTR(NewMI);
    514   //erase later oldInstr->eraseFromParent();
    515 }
    516 
    517 void AMDGPUCFGStructurizer::insertCondBranchBefore(MachineBasicBlock *blk,
    518     MachineBasicBlock::iterator I, int NewOpcode, int RegNum,
    519     DebugLoc DL) {
    520   MachineFunction *MF = blk->getParent();
    521   MachineInstr *NewInstr = MF->CreateMachineInstr(TII->get(NewOpcode), DL);
    522   //insert before
    523   blk->insert(I, NewInstr);
    524   MachineInstrBuilder(*MF, NewInstr).addReg(RegNum, false);
    525   SHOWNEWINSTR(NewInstr);
    526 }
    527 
    528 void AMDGPUCFGStructurizer::insertCondBranchEnd(MachineBasicBlock *MBB,
    529     int NewOpcode, int RegNum) {
    530   MachineFunction *MF = MBB->getParent();
    531   MachineInstr *NewInstr =
    532     MF->CreateMachineInstr(TII->get(NewOpcode), DebugLoc());
    533   MBB->push_back(NewInstr);
    534   MachineInstrBuilder(*MF, NewInstr).addReg(RegNum, false);
    535   SHOWNEWINSTR(NewInstr);
    536 }
    537 
    538 int AMDGPUCFGStructurizer::getBranchNzeroOpcode(int OldOpcode) {
    539   switch(OldOpcode) {
    540   case AMDGPU::JUMP_COND:
    541   case AMDGPU::JUMP: return AMDGPU::IF_PREDICATE_SET;
    542   case AMDGPU::BRANCH_COND_i32:
    543   case AMDGPU::BRANCH_COND_f32: return AMDGPU::IF_LOGICALNZ_f32;
    544   default: llvm_unreachable("internal error");
    545   }
    546   return -1;
    547 }
    548 
    549 int AMDGPUCFGStructurizer::getBranchZeroOpcode(int OldOpcode) {
    550   switch(OldOpcode) {
    551   case AMDGPU::JUMP_COND:
    552   case AMDGPU::JUMP: return AMDGPU::IF_PREDICATE_SET;
    553   case AMDGPU::BRANCH_COND_i32:
    554   case AMDGPU::BRANCH_COND_f32: return AMDGPU::IF_LOGICALZ_f32;
    555   default: llvm_unreachable("internal error");
    556   }
    557   return -1;
    558 }
    559 
    560 int AMDGPUCFGStructurizer::getContinueNzeroOpcode(int OldOpcode) {
    561   switch(OldOpcode) {
    562   case AMDGPU::JUMP_COND:
    563   case AMDGPU::JUMP: return AMDGPU::CONTINUE_LOGICALNZ_i32;
    564   default: llvm_unreachable("internal error");
    565   };
    566   return -1;
    567 }
    568 
    569 int AMDGPUCFGStructurizer::getContinueZeroOpcode(int OldOpcode) {
    570   switch(OldOpcode) {
    571   case AMDGPU::JUMP_COND:
    572   case AMDGPU::JUMP: return AMDGPU::CONTINUE_LOGICALZ_i32;
    573   default: llvm_unreachable("internal error");
    574   }
    575   return -1;
    576 }
    577 
    578 MachineBasicBlock *AMDGPUCFGStructurizer::getTrueBranch(MachineInstr *MI) {
    579   return MI->getOperand(0).getMBB();
    580 }
    581 
    582 void AMDGPUCFGStructurizer::setTrueBranch(MachineInstr *MI,
    583     MachineBasicBlock *MBB) {
    584   MI->getOperand(0).setMBB(MBB);
    585 }
    586 
    587 MachineBasicBlock *
    588 AMDGPUCFGStructurizer::getFalseBranch(MachineBasicBlock *MBB,
    589     MachineInstr *MI) {
    590   assert(MBB->succ_size() == 2);
    591   MachineBasicBlock *TrueBranch = getTrueBranch(MI);
    592   MachineBasicBlock::succ_iterator It = MBB->succ_begin();
    593   MachineBasicBlock::succ_iterator Next = It;
    594   ++Next;
    595   return (*It == TrueBranch) ? *Next : *It;
    596 }
    597 
    598 bool AMDGPUCFGStructurizer::isCondBranch(MachineInstr *MI) {
    599   switch (MI->getOpcode()) {
    600     case AMDGPU::JUMP_COND:
    601     case AMDGPU::BRANCH_COND_i32:
    602     case AMDGPU::BRANCH_COND_f32: return true;
    603   default:
    604     return false;
    605   }
    606   return false;
    607 }
    608 
    609 bool AMDGPUCFGStructurizer::isUncondBranch(MachineInstr *MI) {
    610   switch (MI->getOpcode()) {
    611   case AMDGPU::JUMP:
    612   case AMDGPU::BRANCH:
    613     return true;
    614   default:
    615     return false;
    616   }
    617   return false;
    618 }
    619 
    620 DebugLoc AMDGPUCFGStructurizer::getLastDebugLocInBB(MachineBasicBlock *MBB) {
    621   //get DebugLoc from the first MachineBasicBlock instruction with debug info
    622   DebugLoc DL;
    623   for (MachineBasicBlock::iterator It = MBB->begin(); It != MBB->end();
    624       ++It) {
    625     MachineInstr *instr = &(*It);
    626     if (instr->getDebugLoc())
    627       DL = instr->getDebugLoc();
    628   }
    629   return DL;
    630 }
    631 
    632 MachineInstr *AMDGPUCFGStructurizer::getNormalBlockBranchInstr(
    633     MachineBasicBlock *MBB) {
    634   MachineBasicBlock::reverse_iterator It = MBB->rbegin();
    635   MachineInstr *MI = &*It;
    636   if (MI && (isCondBranch(MI) || isUncondBranch(MI)))
    637     return MI;
    638   return nullptr;
    639 }
    640 
    641 MachineInstr *AMDGPUCFGStructurizer::getLoopendBlockBranchInstr(
    642     MachineBasicBlock *MBB) {
    643   for (MachineBasicBlock::reverse_iterator It = MBB->rbegin(), E = MBB->rend();
    644       It != E; ++It) {
    645     // FIXME: Simplify
    646     MachineInstr *MI = &*It;
    647     if (MI) {
    648       if (isCondBranch(MI) || isUncondBranch(MI))
    649         return MI;
    650       else if (!TII->isMov(MI->getOpcode()))
    651         break;
    652     }
    653   }
    654   return nullptr;
    655 }
    656 
    657 MachineInstr *AMDGPUCFGStructurizer::getReturnInstr(MachineBasicBlock *MBB) {
    658   MachineBasicBlock::reverse_iterator It = MBB->rbegin();
    659   if (It != MBB->rend()) {
    660     MachineInstr *instr = &(*It);
    661     if (instr->getOpcode() == AMDGPU::RETURN)
    662       return instr;
    663   }
    664   return nullptr;
    665 }
    666 
    667 MachineInstr *AMDGPUCFGStructurizer::getContinueInstr(MachineBasicBlock *MBB) {
    668   MachineBasicBlock::reverse_iterator It = MBB->rbegin();
    669   if (It != MBB->rend()) {
    670     MachineInstr *MI = &(*It);
    671     if (MI->getOpcode() == AMDGPU::CONTINUE)
    672       return MI;
    673   }
    674   return nullptr;
    675 }
    676 
    677 bool AMDGPUCFGStructurizer::isReturnBlock(MachineBasicBlock *MBB) {
    678   MachineInstr *MI = getReturnInstr(MBB);
    679   bool IsReturn = (MBB->succ_size() == 0);
    680   if (MI)
    681     assert(IsReturn);
    682   else if (IsReturn)
    683     DEBUG(
    684       dbgs() << "BB" << MBB->getNumber()
    685              <<" is return block without RETURN instr\n";);
    686   return  IsReturn;
    687 }
    688 
    689 void AMDGPUCFGStructurizer::cloneSuccessorList(MachineBasicBlock *DstMBB,
    690     MachineBasicBlock *SrcMBB) {
    691   for (MachineBasicBlock::succ_iterator It = SrcMBB->succ_begin(),
    692        iterEnd = SrcMBB->succ_end(); It != iterEnd; ++It)
    693     DstMBB->addSuccessor(*It);  // *iter's predecessor is also taken care of
    694 }
    695 
    696 MachineBasicBlock *AMDGPUCFGStructurizer::clone(MachineBasicBlock *MBB) {
    697   MachineFunction *Func = MBB->getParent();
    698   MachineBasicBlock *NewMBB = Func->CreateMachineBasicBlock();
    699   Func->push_back(NewMBB);  //insert to function
    700   for (MachineBasicBlock::iterator It = MBB->begin(), E = MBB->end();
    701       It != E; ++It) {
    702     MachineInstr *MI = Func->CloneMachineInstr(It);
    703     NewMBB->push_back(MI);
    704   }
    705   return NewMBB;
    706 }
    707 
    708 void AMDGPUCFGStructurizer::replaceInstrUseOfBlockWith(
    709     MachineBasicBlock *SrcMBB, MachineBasicBlock *OldMBB,
    710     MachineBasicBlock *NewBlk) {
    711   MachineInstr *BranchMI = getLoopendBlockBranchInstr(SrcMBB);
    712   if (BranchMI && isCondBranch(BranchMI) &&
    713       getTrueBranch(BranchMI) == OldMBB)
    714     setTrueBranch(BranchMI, NewBlk);
    715 }
    716 
    717 void AMDGPUCFGStructurizer::wrapup(MachineBasicBlock *MBB) {
    718   assert((!MBB->getParent()->getJumpTableInfo()
    719           || MBB->getParent()->getJumpTableInfo()->isEmpty())
    720          && "found a jump table");
    721 
    722    //collect continue right before endloop
    723    SmallVector<MachineInstr *, DEFAULT_VEC_SLOTS> ContInstr;
    724    MachineBasicBlock::iterator Pre = MBB->begin();
    725    MachineBasicBlock::iterator E = MBB->end();
    726    MachineBasicBlock::iterator It = Pre;
    727    while (It != E) {
    728      if (Pre->getOpcode() == AMDGPU::CONTINUE
    729          && It->getOpcode() == AMDGPU::ENDLOOP)
    730        ContInstr.push_back(Pre);
    731      Pre = It;
    732      ++It;
    733    }
    734 
    735    //delete continue right before endloop
    736    for (unsigned i = 0; i < ContInstr.size(); ++i)
    737       ContInstr[i]->eraseFromParent();
    738 
    739    // TODO to fix up jump table so later phase won't be confused.  if
    740    // (jumpTableInfo->isEmpty() == false) { need to clean the jump table, but
    741    // there isn't such an interface yet.  alternatively, replace all the other
    742    // blocks in the jump table with the entryBlk //}
    743 
    744 }
    745 
    746 
    747 bool AMDGPUCFGStructurizer::prepare() {
    748   bool Changed = false;
    749 
    750   //FIXME: if not reducible flow graph, make it so ???
    751 
    752   DEBUG(dbgs() << "AMDGPUCFGStructurizer::prepare\n";);
    753 
    754   orderBlocks(FuncRep);
    755 
    756   SmallVector<MachineBasicBlock *, DEFAULT_VEC_SLOTS> RetBlks;
    757 
    758   // Add an ExitBlk to loop that don't have one
    759   for (MachineLoopInfo::iterator It = MLI->begin(),
    760        E = MLI->end(); It != E; ++It) {
    761     MachineLoop *LoopRep = (*It);
    762     MBBVector ExitingMBBs;
    763     LoopRep->getExitingBlocks(ExitingMBBs);
    764 
    765     if (ExitingMBBs.size() == 0) {
    766       MachineBasicBlock* DummyExitBlk = normalizeInfiniteLoopExit(LoopRep);
    767       if (DummyExitBlk)
    768         RetBlks.push_back(DummyExitBlk);
    769     }
    770   }
    771 
    772   // Remove unconditional branch instr.
    773   // Add dummy exit block iff there are multiple returns.
    774   for (SmallVectorImpl<MachineBasicBlock *>::const_iterator
    775        It = OrderedBlks.begin(), E = OrderedBlks.end(); It != E; ++It) {
    776     MachineBasicBlock *MBB = *It;
    777     removeUnconditionalBranch(MBB);
    778     removeRedundantConditionalBranch(MBB);
    779     if (isReturnBlock(MBB)) {
    780       RetBlks.push_back(MBB);
    781     }
    782     assert(MBB->succ_size() <= 2);
    783   }
    784 
    785   if (RetBlks.size() >= 2) {
    786     addDummyExitBlock(RetBlks);
    787     Changed = true;
    788   }
    789 
    790   return Changed;
    791 }
    792 
    793 bool AMDGPUCFGStructurizer::run() {
    794 
    795   //Assume reducible CFG...
    796   DEBUG(dbgs() << "AMDGPUCFGStructurizer::run\n");
    797 
    798 #ifdef STRESSTEST
    799   //Use the worse block ordering to test the algorithm.
    800   ReverseVector(orderedBlks);
    801 #endif
    802 
    803   DEBUG(dbgs() << "Ordered blocks:\n"; printOrderedBlocks(););
    804   int NumIter = 0;
    805   bool Finish = false;
    806   MachineBasicBlock *MBB;
    807   bool MakeProgress = false;
    808   int NumRemainedBlk = countActiveBlock(OrderedBlks.begin(),
    809                                         OrderedBlks.end());
    810 
    811   do {
    812     ++NumIter;
    813     DEBUG(
    814       dbgs() << "numIter = " << NumIter
    815              << ", numRemaintedBlk = " << NumRemainedBlk << "\n";
    816     );
    817 
    818     SmallVectorImpl<MachineBasicBlock *>::const_iterator It =
    819         OrderedBlks.begin();
    820     SmallVectorImpl<MachineBasicBlock *>::const_iterator E =
    821         OrderedBlks.end();
    822 
    823     SmallVectorImpl<MachineBasicBlock *>::const_iterator SccBeginIter =
    824         It;
    825     MachineBasicBlock *SccBeginMBB = nullptr;
    826     int SccNumBlk = 0;  // The number of active blocks, init to a
    827                         // maximum possible number.
    828     int SccNumIter;     // Number of iteration in this SCC.
    829 
    830     while (It != E) {
    831       MBB = *It;
    832 
    833       if (!SccBeginMBB) {
    834         SccBeginIter = It;
    835         SccBeginMBB = MBB;
    836         SccNumIter = 0;
    837         SccNumBlk = NumRemainedBlk; // Init to maximum possible number.
    838         DEBUG(
    839               dbgs() << "start processing SCC" << getSCCNum(SccBeginMBB);
    840               dbgs() << "\n";
    841         );
    842       }
    843 
    844       if (!isRetiredBlock(MBB))
    845         patternMatch(MBB);
    846 
    847       ++It;
    848 
    849       bool ContNextScc = true;
    850       if (It == E
    851           || getSCCNum(SccBeginMBB) != getSCCNum(*It)) {
    852         // Just finish one scc.
    853         ++SccNumIter;
    854         int sccRemainedNumBlk = countActiveBlock(SccBeginIter, It);
    855         if (sccRemainedNumBlk != 1 && sccRemainedNumBlk >= SccNumBlk) {
    856           DEBUG(
    857             dbgs() << "Can't reduce SCC " << getSCCNum(MBB)
    858                    << ", sccNumIter = " << SccNumIter;
    859             dbgs() << "doesn't make any progress\n";
    860           );
    861           ContNextScc = true;
    862         } else if (sccRemainedNumBlk != 1 && sccRemainedNumBlk < SccNumBlk) {
    863           SccNumBlk = sccRemainedNumBlk;
    864           It = SccBeginIter;
    865           ContNextScc = false;
    866           DEBUG(
    867             dbgs() << "repeat processing SCC" << getSCCNum(MBB)
    868                    << "sccNumIter = " << SccNumIter << '\n';
    869           );
    870         } else {
    871           // Finish the current scc.
    872           ContNextScc = true;
    873         }
    874       } else {
    875         // Continue on next component in the current scc.
    876         ContNextScc = false;
    877       }
    878 
    879       if (ContNextScc)
    880         SccBeginMBB = nullptr;
    881     } //while, "one iteration" over the function.
    882 
    883     MachineBasicBlock *EntryMBB =
    884         &*GraphTraits<MachineFunction *>::nodes_begin(FuncRep);
    885     if (EntryMBB->succ_size() == 0) {
    886       Finish = true;
    887       DEBUG(
    888         dbgs() << "Reduce to one block\n";
    889       );
    890     } else {
    891       int NewnumRemainedBlk
    892         = countActiveBlock(OrderedBlks.begin(), OrderedBlks.end());
    893       // consider cloned blocks ??
    894       if (NewnumRemainedBlk == 1 || NewnumRemainedBlk < NumRemainedBlk) {
    895         MakeProgress = true;
    896         NumRemainedBlk = NewnumRemainedBlk;
    897       } else {
    898         MakeProgress = false;
    899         DEBUG(
    900           dbgs() << "No progress\n";
    901         );
    902       }
    903     }
    904   } while (!Finish && MakeProgress);
    905 
    906   // Misc wrap up to maintain the consistency of the Function representation.
    907   wrapup(&*GraphTraits<MachineFunction *>::nodes_begin(FuncRep));
    908 
    909   // Detach retired Block, release memory.
    910   for (MBBInfoMap::iterator It = BlockInfoMap.begin(), E = BlockInfoMap.end();
    911       It != E; ++It) {
    912     if ((*It).second && (*It).second->IsRetired) {
    913       assert(((*It).first)->getNumber() != -1);
    914       DEBUG(
    915         dbgs() << "Erase BB" << ((*It).first)->getNumber() << "\n";
    916       );
    917       (*It).first->eraseFromParent();  //Remove from the parent Function.
    918     }
    919     delete (*It).second;
    920   }
    921   BlockInfoMap.clear();
    922   LLInfoMap.clear();
    923 
    924   if (!Finish) {
    925     DEBUG(FuncRep->viewCFG());
    926     llvm_unreachable("IRREDUCIBLE_CFG");
    927   }
    928 
    929   return true;
    930 }
    931 
    932 
    933 
    934 void AMDGPUCFGStructurizer::orderBlocks(MachineFunction *MF) {
    935   int SccNum = 0;
    936   MachineBasicBlock *MBB;
    937   for (scc_iterator<MachineFunction *> It = scc_begin(MF); !It.isAtEnd();
    938        ++It, ++SccNum) {
    939     const std::vector<MachineBasicBlock *> &SccNext = *It;
    940     for (std::vector<MachineBasicBlock *>::const_iterator
    941          blockIter = SccNext.begin(), blockEnd = SccNext.end();
    942          blockIter != blockEnd; ++blockIter) {
    943       MBB = *blockIter;
    944       OrderedBlks.push_back(MBB);
    945       recordSccnum(MBB, SccNum);
    946     }
    947   }
    948 
    949   //walk through all the block in func to check for unreachable
    950   typedef GraphTraits<MachineFunction *> GTM;
    951   MachineFunction::iterator It = GTM::nodes_begin(MF), E = GTM::nodes_end(MF);
    952   for (; It != E; ++It) {
    953     MachineBasicBlock *MBB = &(*It);
    954     SccNum = getSCCNum(MBB);
    955     if (SccNum == INVALIDSCCNUM)
    956       dbgs() << "unreachable block BB" << MBB->getNumber() << "\n";
    957   }
    958 }
    959 
    960 int AMDGPUCFGStructurizer::patternMatch(MachineBasicBlock *MBB) {
    961   int NumMatch = 0;
    962   int CurMatch;
    963 
    964   DEBUG(
    965         dbgs() << "Begin patternMatch BB" << MBB->getNumber() << "\n";
    966   );
    967 
    968   while ((CurMatch = patternMatchGroup(MBB)) > 0)
    969     NumMatch += CurMatch;
    970 
    971   DEBUG(
    972         dbgs() << "End patternMatch BB" << MBB->getNumber()
    973       << ", numMatch = " << NumMatch << "\n";
    974   );
    975 
    976   return NumMatch;
    977 }
    978 
    979 int AMDGPUCFGStructurizer::patternMatchGroup(MachineBasicBlock *MBB) {
    980   int NumMatch = 0;
    981   NumMatch += loopendPatternMatch();
    982   NumMatch += serialPatternMatch(MBB);
    983   NumMatch += ifPatternMatch(MBB);
    984   return NumMatch;
    985 }
    986 
    987 
    988 int AMDGPUCFGStructurizer::serialPatternMatch(MachineBasicBlock *MBB) {
    989   if (MBB->succ_size() != 1)
    990     return 0;
    991 
    992   MachineBasicBlock *childBlk = *MBB->succ_begin();
    993   if (childBlk->pred_size() != 1 || isActiveLoophead(childBlk))
    994     return 0;
    995 
    996   mergeSerialBlock(MBB, childBlk);
    997   ++numSerialPatternMatch;
    998   return 1;
    999 }
   1000 
   1001 int AMDGPUCFGStructurizer::ifPatternMatch(MachineBasicBlock *MBB) {
   1002   //two edges
   1003   if (MBB->succ_size() != 2)
   1004     return 0;
   1005   if (hasBackEdge(MBB))
   1006     return 0;
   1007   MachineInstr *BranchMI = getNormalBlockBranchInstr(MBB);
   1008   if (!BranchMI)
   1009     return 0;
   1010 
   1011   assert(isCondBranch(BranchMI));
   1012   int NumMatch = 0;
   1013 
   1014   MachineBasicBlock *TrueMBB = getTrueBranch(BranchMI);
   1015   NumMatch += serialPatternMatch(TrueMBB);
   1016   NumMatch += ifPatternMatch(TrueMBB);
   1017   MachineBasicBlock *FalseMBB = getFalseBranch(MBB, BranchMI);
   1018   NumMatch += serialPatternMatch(FalseMBB);
   1019   NumMatch += ifPatternMatch(FalseMBB);
   1020   MachineBasicBlock *LandBlk;
   1021   int Cloned = 0;
   1022 
   1023   assert (!TrueMBB->succ_empty() || !FalseMBB->succ_empty());
   1024   // TODO: Simplify
   1025   if (TrueMBB->succ_size() == 1 && FalseMBB->succ_size() == 1
   1026     && *TrueMBB->succ_begin() == *FalseMBB->succ_begin()) {
   1027     // Diamond pattern
   1028     LandBlk = *TrueMBB->succ_begin();
   1029   } else if (TrueMBB->succ_size() == 1 && *TrueMBB->succ_begin() == FalseMBB) {
   1030     // Triangle pattern, false is empty
   1031     LandBlk = FalseMBB;
   1032     FalseMBB = nullptr;
   1033   } else if (FalseMBB->succ_size() == 1
   1034              && *FalseMBB->succ_begin() == TrueMBB) {
   1035     // Triangle pattern, true is empty
   1036     // We reverse the predicate to make a triangle, empty false pattern;
   1037     std::swap(TrueMBB, FalseMBB);
   1038     reversePredicateSetter(MBB->end());
   1039     LandBlk = FalseMBB;
   1040     FalseMBB = nullptr;
   1041   } else if (FalseMBB->succ_size() == 1
   1042              && isSameloopDetachedContbreak(TrueMBB, FalseMBB)) {
   1043     LandBlk = *FalseMBB->succ_begin();
   1044   } else if (TrueMBB->succ_size() == 1
   1045     && isSameloopDetachedContbreak(FalseMBB, TrueMBB)) {
   1046     LandBlk = *TrueMBB->succ_begin();
   1047   } else {
   1048     return NumMatch + handleJumpintoIf(MBB, TrueMBB, FalseMBB);
   1049   }
   1050 
   1051   // improveSimpleJumpinfoIf can handle the case where landBlk == NULL but the
   1052   // new BB created for landBlk==NULL may introduce new challenge to the
   1053   // reduction process.
   1054   if (LandBlk &&
   1055       ((TrueMBB && TrueMBB->pred_size() > 1)
   1056       || (FalseMBB && FalseMBB->pred_size() > 1))) {
   1057      Cloned += improveSimpleJumpintoIf(MBB, TrueMBB, FalseMBB, &LandBlk);
   1058   }
   1059 
   1060   if (TrueMBB && TrueMBB->pred_size() > 1) {
   1061     TrueMBB = cloneBlockForPredecessor(TrueMBB, MBB);
   1062     ++Cloned;
   1063   }
   1064 
   1065   if (FalseMBB && FalseMBB->pred_size() > 1) {
   1066     FalseMBB = cloneBlockForPredecessor(FalseMBB, MBB);
   1067     ++Cloned;
   1068   }
   1069 
   1070   mergeIfthenelseBlock(BranchMI, MBB, TrueMBB, FalseMBB, LandBlk);
   1071 
   1072   ++numIfPatternMatch;
   1073 
   1074   numClonedBlock += Cloned;
   1075 
   1076   return 1 + Cloned + NumMatch;
   1077 }
   1078 
   1079 int AMDGPUCFGStructurizer::loopendPatternMatch() {
   1080   std::deque<MachineLoop *> NestedLoops;
   1081   for (auto &It: *MLI)
   1082     for (MachineLoop *ML : depth_first(It))
   1083       NestedLoops.push_front(ML);
   1084 
   1085   if (NestedLoops.size() == 0)
   1086     return 0;
   1087 
   1088   // Process nested loop outside->inside (we did push_front),
   1089   // so "continue" to a outside loop won't be mistaken as "break"
   1090   // of the current loop.
   1091   int Num = 0;
   1092   for (MachineLoop *ExaminedLoop : NestedLoops) {
   1093     if (ExaminedLoop->getNumBlocks() == 0 || Visited[ExaminedLoop])
   1094       continue;
   1095     DEBUG(dbgs() << "Processing:\n"; ExaminedLoop->dump(););
   1096     int NumBreak = mergeLoop(ExaminedLoop);
   1097     if (NumBreak == -1)
   1098       break;
   1099     Num += NumBreak;
   1100   }
   1101   return Num;
   1102 }
   1103 
   1104 int AMDGPUCFGStructurizer::mergeLoop(MachineLoop *LoopRep) {
   1105   MachineBasicBlock *LoopHeader = LoopRep->getHeader();
   1106   MBBVector ExitingMBBs;
   1107   LoopRep->getExitingBlocks(ExitingMBBs);
   1108   assert(!ExitingMBBs.empty() && "Infinite Loop not supported");
   1109   DEBUG(dbgs() << "Loop has " << ExitingMBBs.size() << " exiting blocks\n";);
   1110   // We assume a single ExitBlk
   1111   MBBVector ExitBlks;
   1112   LoopRep->getExitBlocks(ExitBlks);
   1113   SmallPtrSet<MachineBasicBlock *, 2> ExitBlkSet;
   1114   for (unsigned i = 0, e = ExitBlks.size(); i < e; ++i)
   1115     ExitBlkSet.insert(ExitBlks[i]);
   1116   assert(ExitBlkSet.size() == 1);
   1117   MachineBasicBlock *ExitBlk = *ExitBlks.begin();
   1118   assert(ExitBlk && "Loop has several exit block");
   1119   MBBVector LatchBlks;
   1120   typedef GraphTraits<Inverse<MachineBasicBlock*> > InvMBBTraits;
   1121   InvMBBTraits::ChildIteratorType PI = InvMBBTraits::child_begin(LoopHeader),
   1122       PE = InvMBBTraits::child_end(LoopHeader);
   1123   for (; PI != PE; PI++) {
   1124     if (LoopRep->contains(*PI))
   1125       LatchBlks.push_back(*PI);
   1126   }
   1127 
   1128   for (unsigned i = 0, e = ExitingMBBs.size(); i < e; ++i)
   1129     mergeLoopbreakBlock(ExitingMBBs[i], ExitBlk);
   1130   for (unsigned i = 0, e = LatchBlks.size(); i < e; ++i)
   1131     settleLoopcontBlock(LatchBlks[i], LoopHeader);
   1132   int Match = 0;
   1133   do {
   1134     Match = 0;
   1135     Match += serialPatternMatch(LoopHeader);
   1136     Match += ifPatternMatch(LoopHeader);
   1137   } while (Match > 0);
   1138   mergeLooplandBlock(LoopHeader, ExitBlk);
   1139   MachineLoop *ParentLoop = LoopRep->getParentLoop();
   1140   if (ParentLoop)
   1141     MLI->changeLoopFor(LoopHeader, ParentLoop);
   1142   else
   1143     MLI->removeBlock(LoopHeader);
   1144   Visited[LoopRep] = true;
   1145   return 1;
   1146 }
   1147 
   1148 int AMDGPUCFGStructurizer::loopcontPatternMatch(MachineLoop *LoopRep,
   1149     MachineBasicBlock *LoopHeader) {
   1150   int NumCont = 0;
   1151   SmallVector<MachineBasicBlock *, DEFAULT_VEC_SLOTS> ContMBB;
   1152   typedef GraphTraits<Inverse<MachineBasicBlock *> > GTIM;
   1153   GTIM::ChildIteratorType It = GTIM::child_begin(LoopHeader),
   1154       E = GTIM::child_end(LoopHeader);
   1155   for (; It != E; ++It) {
   1156     MachineBasicBlock *MBB = *It;
   1157     if (LoopRep->contains(MBB)) {
   1158       handleLoopcontBlock(MBB, MLI->getLoopFor(MBB),
   1159                           LoopHeader, LoopRep);
   1160       ContMBB.push_back(MBB);
   1161       ++NumCont;
   1162     }
   1163   }
   1164 
   1165   for (SmallVectorImpl<MachineBasicBlock *>::iterator It = ContMBB.begin(),
   1166       E = ContMBB.end(); It != E; ++It) {
   1167     (*It)->removeSuccessor(LoopHeader, true);
   1168   }
   1169 
   1170   numLoopcontPatternMatch += NumCont;
   1171 
   1172   return NumCont;
   1173 }
   1174 
   1175 
   1176 bool AMDGPUCFGStructurizer::isSameloopDetachedContbreak(
   1177     MachineBasicBlock *Src1MBB, MachineBasicBlock *Src2MBB) {
   1178   if (Src1MBB->succ_size() == 0) {
   1179     MachineLoop *LoopRep = MLI->getLoopFor(Src1MBB);
   1180     if (LoopRep&& LoopRep == MLI->getLoopFor(Src2MBB)) {
   1181       MachineBasicBlock *&TheEntry = LLInfoMap[LoopRep];
   1182       if (TheEntry) {
   1183         DEBUG(
   1184           dbgs() << "isLoopContBreakBlock yes src1 = BB"
   1185                  << Src1MBB->getNumber()
   1186                  << " src2 = BB" << Src2MBB->getNumber() << "\n";
   1187         );
   1188         return true;
   1189       }
   1190     }
   1191   }
   1192   return false;
   1193 }
   1194 
   1195 int AMDGPUCFGStructurizer::handleJumpintoIf(MachineBasicBlock *HeadMBB,
   1196     MachineBasicBlock *TrueMBB, MachineBasicBlock *FalseMBB) {
   1197   int Num = handleJumpintoIfImp(HeadMBB, TrueMBB, FalseMBB);
   1198   if (Num == 0) {
   1199     DEBUG(
   1200       dbgs() << "handleJumpintoIf swap trueBlk and FalseBlk" << "\n";
   1201     );
   1202     Num = handleJumpintoIfImp(HeadMBB, FalseMBB, TrueMBB);
   1203   }
   1204   return Num;
   1205 }
   1206 
   1207 int AMDGPUCFGStructurizer::handleJumpintoIfImp(MachineBasicBlock *HeadMBB,
   1208     MachineBasicBlock *TrueMBB, MachineBasicBlock *FalseMBB) {
   1209   int Num = 0;
   1210   MachineBasicBlock *DownBlk;
   1211 
   1212   //trueBlk could be the common post dominator
   1213   DownBlk = TrueMBB;
   1214 
   1215   DEBUG(
   1216     dbgs() << "handleJumpintoIfImp head = BB" << HeadMBB->getNumber()
   1217            << " true = BB" << TrueMBB->getNumber()
   1218            << ", numSucc=" << TrueMBB->succ_size()
   1219            << " false = BB" << FalseMBB->getNumber() << "\n";
   1220   );
   1221 
   1222   while (DownBlk) {
   1223     DEBUG(
   1224       dbgs() << "check down = BB" << DownBlk->getNumber();
   1225     );
   1226 
   1227     if (singlePathTo(FalseMBB, DownBlk) == SinglePath_InPath) {
   1228       DEBUG(
   1229         dbgs() << " working\n";
   1230       );
   1231 
   1232       Num += cloneOnSideEntryTo(HeadMBB, TrueMBB, DownBlk);
   1233       Num += cloneOnSideEntryTo(HeadMBB, FalseMBB, DownBlk);
   1234 
   1235       numClonedBlock += Num;
   1236       Num += serialPatternMatch(*HeadMBB->succ_begin());
   1237       Num += serialPatternMatch(*std::next(HeadMBB->succ_begin()));
   1238       Num += ifPatternMatch(HeadMBB);
   1239       assert(Num > 0);
   1240 
   1241       break;
   1242     }
   1243     DEBUG(
   1244       dbgs() << " not working\n";
   1245     );
   1246     DownBlk = (DownBlk->succ_size() == 1) ? (*DownBlk->succ_begin()) : nullptr;
   1247   } // walk down the postDomTree
   1248 
   1249   return Num;
   1250 }
   1251 
   1252 void AMDGPUCFGStructurizer::showImproveSimpleJumpintoIf(
   1253     MachineBasicBlock *HeadMBB, MachineBasicBlock *TrueMBB,
   1254     MachineBasicBlock *FalseMBB, MachineBasicBlock *LandMBB, bool Detail) {
   1255   dbgs() << "head = BB" << HeadMBB->getNumber()
   1256          << " size = " << HeadMBB->size();
   1257   if (Detail) {
   1258     dbgs() << "\n";
   1259     HeadMBB->print(dbgs());
   1260     dbgs() << "\n";
   1261   }
   1262 
   1263   if (TrueMBB) {
   1264     dbgs() << ", true = BB" << TrueMBB->getNumber() << " size = "
   1265            << TrueMBB->size() << " numPred = " << TrueMBB->pred_size();
   1266     if (Detail) {
   1267       dbgs() << "\n";
   1268       TrueMBB->print(dbgs());
   1269       dbgs() << "\n";
   1270     }
   1271   }
   1272   if (FalseMBB) {
   1273     dbgs() << ", false = BB" << FalseMBB->getNumber() << " size = "
   1274            << FalseMBB->size() << " numPred = " << FalseMBB->pred_size();
   1275     if (Detail) {
   1276       dbgs() << "\n";
   1277       FalseMBB->print(dbgs());
   1278       dbgs() << "\n";
   1279     }
   1280   }
   1281   if (LandMBB) {
   1282     dbgs() << ", land = BB" << LandMBB->getNumber() << " size = "
   1283            << LandMBB->size() << " numPred = " << LandMBB->pred_size();
   1284     if (Detail) {
   1285       dbgs() << "\n";
   1286       LandMBB->print(dbgs());
   1287       dbgs() << "\n";
   1288     }
   1289   }
   1290 
   1291     dbgs() << "\n";
   1292 }
   1293 
   1294 int AMDGPUCFGStructurizer::improveSimpleJumpintoIf(MachineBasicBlock *HeadMBB,
   1295     MachineBasicBlock *TrueMBB, MachineBasicBlock *FalseMBB,
   1296     MachineBasicBlock **LandMBBPtr) {
   1297   bool MigrateTrue = false;
   1298   bool MigrateFalse = false;
   1299 
   1300   MachineBasicBlock *LandBlk = *LandMBBPtr;
   1301 
   1302   assert((!TrueMBB || TrueMBB->succ_size() <= 1)
   1303          && (!FalseMBB || FalseMBB->succ_size() <= 1));
   1304 
   1305   if (TrueMBB == FalseMBB)
   1306     return 0;
   1307 
   1308   MigrateTrue = needMigrateBlock(TrueMBB);
   1309   MigrateFalse = needMigrateBlock(FalseMBB);
   1310 
   1311   if (!MigrateTrue && !MigrateFalse)
   1312     return 0;
   1313 
   1314   // If we need to migrate either trueBlk and falseBlk, migrate the rest that
   1315   // have more than one predecessors.  without doing this, its predecessor
   1316   // rather than headBlk will have undefined value in initReg.
   1317   if (!MigrateTrue && TrueMBB && TrueMBB->pred_size() > 1)
   1318     MigrateTrue = true;
   1319   if (!MigrateFalse && FalseMBB && FalseMBB->pred_size() > 1)
   1320     MigrateFalse = true;
   1321 
   1322   DEBUG(
   1323     dbgs() << "before improveSimpleJumpintoIf: ";
   1324     showImproveSimpleJumpintoIf(HeadMBB, TrueMBB, FalseMBB, LandBlk, 0);
   1325   );
   1326 
   1327   // org: headBlk => if () {trueBlk} else {falseBlk} => landBlk
   1328   //
   1329   // new: headBlk => if () {initReg = 1; org trueBlk branch} else
   1330   //      {initReg = 0; org falseBlk branch }
   1331   //      => landBlk => if (initReg) {org trueBlk} else {org falseBlk}
   1332   //      => org landBlk
   1333   //      if landBlk->pred_size() > 2, put the about if-else inside
   1334   //      if (initReg !=2) {...}
   1335   //
   1336   // add initReg = initVal to headBlk
   1337 
   1338   const TargetRegisterClass * I32RC = TRI->getCFGStructurizerRegClass(MVT::i32);
   1339   if (!MigrateTrue || !MigrateFalse) {
   1340     // XXX: We have an opportunity here to optimize the "branch into if" case
   1341     // here.  Branch into if looks like this:
   1342     //                        entry
   1343     //                       /     |
   1344     //           diamond_head       branch_from
   1345     //             /      \           |
   1346     // diamond_false        diamond_true
   1347     //             \      /
   1348     //               done
   1349     //
   1350     // The diamond_head block begins the "if" and the diamond_true block
   1351     // is the block being "branched into".
   1352     //
   1353     // If MigrateTrue is true, then TrueBB is the block being "branched into"
   1354     // and if MigrateFalse is true, then FalseBB is the block being
   1355     // "branched into"
   1356     //
   1357     // Here is the pseudo code for how I think the optimization should work:
   1358     // 1. Insert MOV GPR0, 0 before the branch instruction in diamond_head.
   1359     // 2. Insert MOV GPR0, 1 before the branch instruction in branch_from.
   1360     // 3. Move the branch instruction from diamond_head into its own basic
   1361     //    block (new_block).
   1362     // 4. Add an unconditional branch from diamond_head to new_block
   1363     // 5. Replace the branch instruction in branch_from with an unconditional
   1364     //    branch to new_block.  If branch_from has multiple predecessors, then
   1365     //    we need to replace the True/False block in the branch
   1366     //    instruction instead of replacing it.
   1367     // 6. Change the condition of the branch instruction in new_block from
   1368     //    COND to (COND || GPR0)
   1369     //
   1370     // In order insert these MOV instruction, we will need to use the
   1371     // RegisterScavenger.  Usually liveness stops being tracked during
   1372     // the late machine optimization passes, however if we implement
   1373     // bool TargetRegisterInfo::requiresRegisterScavenging(
   1374     //                                                const MachineFunction &MF)
   1375     // and have it return true, liveness will be tracked correctly
   1376     // by generic optimization passes.  We will also need to make sure that
   1377     // all of our target-specific passes that run after regalloc and before
   1378     // the CFGStructurizer track liveness and we will need to modify this pass
   1379     // to correctly track liveness.
   1380     //
   1381     // After the above changes, the new CFG should look like this:
   1382     //                        entry
   1383     //                       /     |
   1384     //           diamond_head       branch_from
   1385     //                       \     /
   1386     //                      new_block
   1387     //                      /      |
   1388     //         diamond_false        diamond_true
   1389     //                      \      /
   1390     //                        done
   1391     //
   1392     // Without this optimization, we are forced to duplicate the diamond_true
   1393     // block and we will end up with a CFG like this:
   1394     //
   1395     //                        entry
   1396     //                       /     |
   1397     //           diamond_head       branch_from
   1398     //             /      \                   |
   1399     // diamond_false        diamond_true      diamond_true (duplicate)
   1400     //             \      /                   |
   1401     //               done --------------------|
   1402     //
   1403     // Duplicating diamond_true can be very costly especially if it has a
   1404     // lot of instructions.
   1405     return 0;
   1406   }
   1407 
   1408   int NumNewBlk = 0;
   1409 
   1410   bool LandBlkHasOtherPred = (LandBlk->pred_size() > 2);
   1411 
   1412   //insert AMDGPU::ENDIF to avoid special case "input landBlk == NULL"
   1413   MachineBasicBlock::iterator I = insertInstrBefore(LandBlk, AMDGPU::ENDIF);
   1414 
   1415   if (LandBlkHasOtherPred) {
   1416     llvm_unreachable("Extra register needed to handle CFG");
   1417     unsigned CmpResReg =
   1418       HeadMBB->getParent()->getRegInfo().createVirtualRegister(I32RC);
   1419     llvm_unreachable("Extra compare instruction needed to handle CFG");
   1420     insertCondBranchBefore(LandBlk, I, AMDGPU::IF_PREDICATE_SET,
   1421         CmpResReg, DebugLoc());
   1422   }
   1423 
   1424   // XXX: We are running this after RA, so creating virtual registers will
   1425   // cause an assertion failure in the PostRA scheduling pass.
   1426   unsigned InitReg =
   1427     HeadMBB->getParent()->getRegInfo().createVirtualRegister(I32RC);
   1428   insertCondBranchBefore(LandBlk, I, AMDGPU::IF_PREDICATE_SET, InitReg,
   1429       DebugLoc());
   1430 
   1431   if (MigrateTrue) {
   1432     migrateInstruction(TrueMBB, LandBlk, I);
   1433     // need to uncondionally insert the assignment to ensure a path from its
   1434     // predecessor rather than headBlk has valid value in initReg if
   1435     // (initVal != 1).
   1436     llvm_unreachable("Extra register needed to handle CFG");
   1437   }
   1438   insertInstrBefore(I, AMDGPU::ELSE);
   1439 
   1440   if (MigrateFalse) {
   1441     migrateInstruction(FalseMBB, LandBlk, I);
   1442     // need to uncondionally insert the assignment to ensure a path from its
   1443     // predecessor rather than headBlk has valid value in initReg if
   1444     // (initVal != 0)
   1445     llvm_unreachable("Extra register needed to handle CFG");
   1446   }
   1447 
   1448   if (LandBlkHasOtherPred) {
   1449     // add endif
   1450     insertInstrBefore(I, AMDGPU::ENDIF);
   1451 
   1452     // put initReg = 2 to other predecessors of landBlk
   1453     for (MachineBasicBlock::pred_iterator PI = LandBlk->pred_begin(),
   1454          PE = LandBlk->pred_end(); PI != PE; ++PI) {
   1455       MachineBasicBlock *MBB = *PI;
   1456       if (MBB != TrueMBB && MBB != FalseMBB)
   1457         llvm_unreachable("Extra register needed to handle CFG");
   1458     }
   1459   }
   1460   DEBUG(
   1461     dbgs() << "result from improveSimpleJumpintoIf: ";
   1462     showImproveSimpleJumpintoIf(HeadMBB, TrueMBB, FalseMBB, LandBlk, 0);
   1463   );
   1464 
   1465   // update landBlk
   1466   *LandMBBPtr = LandBlk;
   1467 
   1468   return NumNewBlk;
   1469 }
   1470 
   1471 void AMDGPUCFGStructurizer::handleLoopcontBlock(MachineBasicBlock *ContingMBB,
   1472     MachineLoop *ContingLoop, MachineBasicBlock *ContMBB,
   1473     MachineLoop *ContLoop) {
   1474   DEBUG(dbgs() << "loopcontPattern cont = BB" << ContingMBB->getNumber()
   1475                << " header = BB" << ContMBB->getNumber() << "\n";
   1476         dbgs() << "Trying to continue loop-depth = "
   1477                << getLoopDepth(ContLoop)
   1478                << " from loop-depth = " << getLoopDepth(ContingLoop) << "\n";);
   1479   settleLoopcontBlock(ContingMBB, ContMBB);
   1480 }
   1481 
   1482 void AMDGPUCFGStructurizer::mergeSerialBlock(MachineBasicBlock *DstMBB,
   1483     MachineBasicBlock *SrcMBB) {
   1484   DEBUG(
   1485     dbgs() << "serialPattern BB" << DstMBB->getNumber()
   1486            << " <= BB" << SrcMBB->getNumber() << "\n";
   1487   );
   1488   DstMBB->splice(DstMBB->end(), SrcMBB, SrcMBB->begin(), SrcMBB->end());
   1489 
   1490   DstMBB->removeSuccessor(SrcMBB, true);
   1491   cloneSuccessorList(DstMBB, SrcMBB);
   1492 
   1493   removeSuccessor(SrcMBB);
   1494   MLI->removeBlock(SrcMBB);
   1495   retireBlock(SrcMBB);
   1496 }
   1497 
   1498 void AMDGPUCFGStructurizer::mergeIfthenelseBlock(MachineInstr *BranchMI,
   1499     MachineBasicBlock *MBB, MachineBasicBlock *TrueMBB,
   1500     MachineBasicBlock *FalseMBB, MachineBasicBlock *LandMBB) {
   1501   assert (TrueMBB);
   1502   DEBUG(
   1503     dbgs() << "ifPattern BB" << MBB->getNumber();
   1504     dbgs() << "{  ";
   1505     if (TrueMBB) {
   1506       dbgs() << "BB" << TrueMBB->getNumber();
   1507     }
   1508     dbgs() << "  } else ";
   1509     dbgs() << "{  ";
   1510     if (FalseMBB) {
   1511       dbgs() << "BB" << FalseMBB->getNumber();
   1512     }
   1513     dbgs() << "  }\n ";
   1514     dbgs() << "landBlock: ";
   1515     if (!LandMBB) {
   1516       dbgs() << "NULL";
   1517     } else {
   1518       dbgs() << "BB" << LandMBB->getNumber();
   1519     }
   1520     dbgs() << "\n";
   1521   );
   1522 
   1523   int OldOpcode = BranchMI->getOpcode();
   1524   DebugLoc BranchDL = BranchMI->getDebugLoc();
   1525 
   1526 //    transform to
   1527 //    if cond
   1528 //       trueBlk
   1529 //    else
   1530 //       falseBlk
   1531 //    endif
   1532 //    landBlk
   1533 
   1534   MachineBasicBlock::iterator I = BranchMI;
   1535   insertCondBranchBefore(I, getBranchNzeroOpcode(OldOpcode),
   1536       BranchDL);
   1537 
   1538   if (TrueMBB) {
   1539     MBB->splice(I, TrueMBB, TrueMBB->begin(), TrueMBB->end());
   1540     MBB->removeSuccessor(TrueMBB, true);
   1541     if (LandMBB && TrueMBB->succ_size()!=0)
   1542       TrueMBB->removeSuccessor(LandMBB, true);
   1543     retireBlock(TrueMBB);
   1544     MLI->removeBlock(TrueMBB);
   1545   }
   1546 
   1547   if (FalseMBB) {
   1548     insertInstrBefore(I, AMDGPU::ELSE);
   1549     MBB->splice(I, FalseMBB, FalseMBB->begin(),
   1550                    FalseMBB->end());
   1551     MBB->removeSuccessor(FalseMBB, true);
   1552     if (LandMBB && FalseMBB->succ_size() != 0)
   1553       FalseMBB->removeSuccessor(LandMBB, true);
   1554     retireBlock(FalseMBB);
   1555     MLI->removeBlock(FalseMBB);
   1556   }
   1557   insertInstrBefore(I, AMDGPU::ENDIF);
   1558 
   1559   BranchMI->eraseFromParent();
   1560 
   1561   if (LandMBB && TrueMBB && FalseMBB)
   1562     MBB->addSuccessor(LandMBB);
   1563 
   1564 }
   1565 
   1566 void AMDGPUCFGStructurizer::mergeLooplandBlock(MachineBasicBlock *DstBlk,
   1567     MachineBasicBlock *LandMBB) {
   1568   DEBUG(dbgs() << "loopPattern header = BB" << DstBlk->getNumber()
   1569                << " land = BB" << LandMBB->getNumber() << "\n";);
   1570 
   1571   insertInstrBefore(DstBlk, AMDGPU::WHILELOOP, DebugLoc());
   1572   insertInstrEnd(DstBlk, AMDGPU::ENDLOOP, DebugLoc());
   1573   DstBlk->replaceSuccessor(DstBlk, LandMBB);
   1574 }
   1575 
   1576 
   1577 void AMDGPUCFGStructurizer::mergeLoopbreakBlock(MachineBasicBlock *ExitingMBB,
   1578     MachineBasicBlock *LandMBB) {
   1579   DEBUG(dbgs() << "loopbreakPattern exiting = BB" << ExitingMBB->getNumber()
   1580                << " land = BB" << LandMBB->getNumber() << "\n";);
   1581   MachineInstr *BranchMI = getLoopendBlockBranchInstr(ExitingMBB);
   1582   assert(BranchMI && isCondBranch(BranchMI));
   1583   DebugLoc DL = BranchMI->getDebugLoc();
   1584   MachineBasicBlock *TrueBranch = getTrueBranch(BranchMI);
   1585   MachineBasicBlock::iterator I = BranchMI;
   1586   if (TrueBranch != LandMBB)
   1587     reversePredicateSetter(I);
   1588   insertCondBranchBefore(ExitingMBB, I, AMDGPU::IF_PREDICATE_SET, AMDGPU::PREDICATE_BIT, DL);
   1589   insertInstrBefore(I, AMDGPU::BREAK);
   1590   insertInstrBefore(I, AMDGPU::ENDIF);
   1591   //now branchInst can be erase safely
   1592   BranchMI->eraseFromParent();
   1593   //now take care of successors, retire blocks
   1594   ExitingMBB->removeSuccessor(LandMBB, true);
   1595 }
   1596 
   1597 void AMDGPUCFGStructurizer::settleLoopcontBlock(MachineBasicBlock *ContingMBB,
   1598     MachineBasicBlock *ContMBB) {
   1599   DEBUG(dbgs() << "settleLoopcontBlock conting = BB"
   1600                << ContingMBB->getNumber()
   1601                << ", cont = BB" << ContMBB->getNumber() << "\n";);
   1602 
   1603   MachineInstr *MI = getLoopendBlockBranchInstr(ContingMBB);
   1604   if (MI) {
   1605     assert(isCondBranch(MI));
   1606     MachineBasicBlock::iterator I = MI;
   1607     MachineBasicBlock *TrueBranch = getTrueBranch(MI);
   1608     int OldOpcode = MI->getOpcode();
   1609     DebugLoc DL = MI->getDebugLoc();
   1610 
   1611     bool UseContinueLogical = ((&*ContingMBB->rbegin()) == MI);
   1612 
   1613     if (!UseContinueLogical) {
   1614       int BranchOpcode =
   1615           TrueBranch == ContMBB ? getBranchNzeroOpcode(OldOpcode) :
   1616           getBranchZeroOpcode(OldOpcode);
   1617       insertCondBranchBefore(I, BranchOpcode, DL);
   1618       // insertEnd to ensure phi-moves, if exist, go before the continue-instr.
   1619       insertInstrEnd(ContingMBB, AMDGPU::CONTINUE, DL);
   1620       insertInstrEnd(ContingMBB, AMDGPU::ENDIF, DL);
   1621     } else {
   1622       int BranchOpcode =
   1623           TrueBranch == ContMBB ? getContinueNzeroOpcode(OldOpcode) :
   1624           getContinueZeroOpcode(OldOpcode);
   1625       insertCondBranchBefore(I, BranchOpcode, DL);
   1626     }
   1627 
   1628     MI->eraseFromParent();
   1629   } else {
   1630     // if we've arrived here then we've already erased the branch instruction
   1631     // travel back up the basic block to see the last reference of our debug
   1632     // location we've just inserted that reference here so it should be
   1633     // representative insertEnd to ensure phi-moves, if exist, go before the
   1634     // continue-instr.
   1635     insertInstrEnd(ContingMBB, AMDGPU::CONTINUE,
   1636         getLastDebugLocInBB(ContingMBB));
   1637   }
   1638 }
   1639 
   1640 int AMDGPUCFGStructurizer::cloneOnSideEntryTo(MachineBasicBlock *PreMBB,
   1641     MachineBasicBlock *SrcMBB, MachineBasicBlock *DstMBB) {
   1642   int Cloned = 0;
   1643   assert(PreMBB->isSuccessor(SrcMBB));
   1644   while (SrcMBB && SrcMBB != DstMBB) {
   1645     assert(SrcMBB->succ_size() == 1);
   1646     if (SrcMBB->pred_size() > 1) {
   1647       SrcMBB = cloneBlockForPredecessor(SrcMBB, PreMBB);
   1648       ++Cloned;
   1649     }
   1650 
   1651     PreMBB = SrcMBB;
   1652     SrcMBB = *SrcMBB->succ_begin();
   1653   }
   1654 
   1655   return Cloned;
   1656 }
   1657 
   1658 MachineBasicBlock *
   1659 AMDGPUCFGStructurizer::cloneBlockForPredecessor(MachineBasicBlock *MBB,
   1660     MachineBasicBlock *PredMBB) {
   1661   assert(PredMBB->isSuccessor(MBB) &&
   1662          "succBlk is not a prececessor of curBlk");
   1663 
   1664   MachineBasicBlock *CloneMBB = clone(MBB);  //clone instructions
   1665   replaceInstrUseOfBlockWith(PredMBB, MBB, CloneMBB);
   1666   //srcBlk, oldBlk, newBlk
   1667 
   1668   PredMBB->replaceSuccessor(MBB, CloneMBB);
   1669 
   1670   // add all successor to cloneBlk
   1671   cloneSuccessorList(CloneMBB, MBB);
   1672 
   1673   numClonedInstr += MBB->size();
   1674 
   1675   DEBUG(
   1676     dbgs() << "Cloned block: " << "BB"
   1677            << MBB->getNumber() << "size " << MBB->size() << "\n";
   1678   );
   1679 
   1680   SHOWNEWBLK(CloneMBB, "result of Cloned block: ");
   1681 
   1682   return CloneMBB;
   1683 }
   1684 
   1685 void AMDGPUCFGStructurizer::migrateInstruction(MachineBasicBlock *SrcMBB,
   1686     MachineBasicBlock *DstMBB, MachineBasicBlock::iterator I) {
   1687   MachineBasicBlock::iterator SpliceEnd;
   1688   //look for the input branchinstr, not the AMDGPU branchinstr
   1689   MachineInstr *BranchMI = getNormalBlockBranchInstr(SrcMBB);
   1690   if (!BranchMI) {
   1691     DEBUG(
   1692       dbgs() << "migrateInstruction don't see branch instr\n" ;
   1693     );
   1694     SpliceEnd = SrcMBB->end();
   1695   } else {
   1696     DEBUG(dbgs() << "migrateInstruction see branch instr: " << *BranchMI);
   1697     SpliceEnd = BranchMI;
   1698   }
   1699   DEBUG(
   1700     dbgs() << "migrateInstruction before splice dstSize = " << DstMBB->size()
   1701       << "srcSize = " << SrcMBB->size() << "\n";
   1702   );
   1703 
   1704   //splice insert before insertPos
   1705   DstMBB->splice(I, SrcMBB, SrcMBB->begin(), SpliceEnd);
   1706 
   1707   DEBUG(
   1708     dbgs() << "migrateInstruction after splice dstSize = " << DstMBB->size()
   1709       << "srcSize = " << SrcMBB->size() << '\n';
   1710   );
   1711 }
   1712 
   1713 MachineBasicBlock *
   1714 AMDGPUCFGStructurizer::normalizeInfiniteLoopExit(MachineLoop* LoopRep) {
   1715   MachineBasicBlock *LoopHeader = LoopRep->getHeader();
   1716   MachineBasicBlock *LoopLatch = LoopRep->getLoopLatch();
   1717 
   1718   if (!LoopHeader || !LoopLatch)
   1719     return nullptr;
   1720   MachineInstr *BranchMI = getLoopendBlockBranchInstr(LoopLatch);
   1721   // Is LoopRep an infinite loop ?
   1722   if (!BranchMI || !isUncondBranch(BranchMI))
   1723     return nullptr;
   1724 
   1725   MachineBasicBlock *DummyExitBlk = FuncRep->CreateMachineBasicBlock();
   1726   FuncRep->push_back(DummyExitBlk);  //insert to function
   1727   SHOWNEWBLK(DummyExitBlk, "DummyExitBlock to normalize infiniteLoop: ");
   1728   DEBUG(dbgs() << "Old branch instr: " << *BranchMI << "\n";);
   1729   LLVMContext &Ctx = LoopHeader->getParent()->getFunction()->getContext();
   1730   Ctx.emitError("Extra register needed to handle CFG");
   1731   return nullptr;
   1732 }
   1733 
   1734 void AMDGPUCFGStructurizer::removeUnconditionalBranch(MachineBasicBlock *MBB) {
   1735   MachineInstr *BranchMI;
   1736 
   1737   // I saw two unconditional branch in one basic block in example
   1738   // test_fc_do_while_or.c need to fix the upstream on this to remove the loop.
   1739   while ((BranchMI = getLoopendBlockBranchInstr(MBB))
   1740           && isUncondBranch(BranchMI)) {
   1741     DEBUG(dbgs() << "Removing uncond branch instr: " << *BranchMI);
   1742     BranchMI->eraseFromParent();
   1743   }
   1744 }
   1745 
   1746 void AMDGPUCFGStructurizer::removeRedundantConditionalBranch(
   1747     MachineBasicBlock *MBB) {
   1748   if (MBB->succ_size() != 2)
   1749     return;
   1750   MachineBasicBlock *MBB1 = *MBB->succ_begin();
   1751   MachineBasicBlock *MBB2 = *std::next(MBB->succ_begin());
   1752   if (MBB1 != MBB2)
   1753     return;
   1754 
   1755   MachineInstr *BranchMI = getNormalBlockBranchInstr(MBB);
   1756   assert(BranchMI && isCondBranch(BranchMI));
   1757   DEBUG(dbgs() << "Removing unneeded cond branch instr: " << *BranchMI);
   1758   BranchMI->eraseFromParent();
   1759   SHOWNEWBLK(MBB1, "Removing redundant successor");
   1760   MBB->removeSuccessor(MBB1, true);
   1761 }
   1762 
   1763 void AMDGPUCFGStructurizer::addDummyExitBlock(
   1764     SmallVectorImpl<MachineBasicBlock*> &RetMBB) {
   1765   MachineBasicBlock *DummyExitBlk = FuncRep->CreateMachineBasicBlock();
   1766   FuncRep->push_back(DummyExitBlk);  //insert to function
   1767   insertInstrEnd(DummyExitBlk, AMDGPU::RETURN);
   1768 
   1769   for (SmallVectorImpl<MachineBasicBlock *>::iterator It = RetMBB.begin(),
   1770        E = RetMBB.end(); It != E; ++It) {
   1771     MachineBasicBlock *MBB = *It;
   1772     MachineInstr *MI = getReturnInstr(MBB);
   1773     if (MI)
   1774       MI->eraseFromParent();
   1775     MBB->addSuccessor(DummyExitBlk);
   1776     DEBUG(
   1777       dbgs() << "Add dummyExitBlock to BB" << MBB->getNumber()
   1778              << " successors\n";
   1779     );
   1780   }
   1781   SHOWNEWBLK(DummyExitBlk, "DummyExitBlock: ");
   1782 }
   1783 
   1784 void AMDGPUCFGStructurizer::removeSuccessor(MachineBasicBlock *MBB) {
   1785   while (MBB->succ_size())
   1786     MBB->removeSuccessor(*MBB->succ_begin());
   1787 }
   1788 
   1789 void AMDGPUCFGStructurizer::recordSccnum(MachineBasicBlock *MBB,
   1790     int SccNum) {
   1791   BlockInformation *&srcBlkInfo = BlockInfoMap[MBB];
   1792   if (!srcBlkInfo)
   1793     srcBlkInfo = new BlockInformation();
   1794   srcBlkInfo->SccNum = SccNum;
   1795 }
   1796 
   1797 void AMDGPUCFGStructurizer::retireBlock(MachineBasicBlock *MBB) {
   1798   DEBUG(
   1799         dbgs() << "Retiring BB" << MBB->getNumber() << "\n";
   1800   );
   1801 
   1802   BlockInformation *&SrcBlkInfo = BlockInfoMap[MBB];
   1803 
   1804   if (!SrcBlkInfo)
   1805     SrcBlkInfo = new BlockInformation();
   1806 
   1807   SrcBlkInfo->IsRetired = true;
   1808   assert(MBB->succ_size() == 0 && MBB->pred_size() == 0
   1809          && "can't retire block yet");
   1810 }
   1811 
   1812 void AMDGPUCFGStructurizer::setLoopLandBlock(MachineLoop *loopRep,
   1813     MachineBasicBlock *MBB) {
   1814   MachineBasicBlock *&TheEntry = LLInfoMap[loopRep];
   1815   if (!MBB) {
   1816     MBB = FuncRep->CreateMachineBasicBlock();
   1817     FuncRep->push_back(MBB);  //insert to function
   1818     SHOWNEWBLK(MBB, "DummyLandingBlock for loop without break: ");
   1819   }
   1820   TheEntry = MBB;
   1821   DEBUG(
   1822     dbgs() << "setLoopLandBlock loop-header = BB"
   1823            << loopRep->getHeader()->getNumber()
   1824            << "  landing-block = BB" << MBB->getNumber() << "\n";
   1825   );
   1826 }
   1827 
   1828 MachineBasicBlock *
   1829 AMDGPUCFGStructurizer::findNearestCommonPostDom(MachineBasicBlock *MBB1,
   1830     MachineBasicBlock *MBB2) {
   1831 
   1832   if (PDT->dominates(MBB1, MBB2))
   1833     return MBB1;
   1834   if (PDT->dominates(MBB2, MBB1))
   1835     return MBB2;
   1836 
   1837   MachineDomTreeNode *Node1 = PDT->getNode(MBB1);
   1838   MachineDomTreeNode *Node2 = PDT->getNode(MBB2);
   1839 
   1840   // Handle newly cloned node.
   1841   if (!Node1 && MBB1->succ_size() == 1)
   1842     return findNearestCommonPostDom(*MBB1->succ_begin(), MBB2);
   1843   if (!Node2 && MBB2->succ_size() == 1)
   1844     return findNearestCommonPostDom(MBB1, *MBB2->succ_begin());
   1845 
   1846   if (!Node1 || !Node2)
   1847     return nullptr;
   1848 
   1849   Node1 = Node1->getIDom();
   1850   while (Node1) {
   1851     if (PDT->dominates(Node1, Node2))
   1852       return Node1->getBlock();
   1853     Node1 = Node1->getIDom();
   1854   }
   1855 
   1856   return nullptr;
   1857 }
   1858 
   1859 MachineBasicBlock *
   1860 AMDGPUCFGStructurizer::findNearestCommonPostDom(
   1861     std::set<MachineBasicBlock *> &MBBs) {
   1862   MachineBasicBlock *CommonDom;
   1863   std::set<MachineBasicBlock *>::const_iterator It = MBBs.begin();
   1864   std::set<MachineBasicBlock *>::const_iterator E = MBBs.end();
   1865   for (CommonDom = *It; It != E && CommonDom; ++It) {
   1866     MachineBasicBlock *MBB = *It;
   1867     if (MBB != CommonDom)
   1868       CommonDom = findNearestCommonPostDom(MBB, CommonDom);
   1869   }
   1870 
   1871   DEBUG(
   1872     dbgs() << "Common post dominator for exit blocks is ";
   1873     if (CommonDom)
   1874           dbgs() << "BB" << CommonDom->getNumber() << "\n";
   1875     else
   1876       dbgs() << "NULL\n";
   1877   );
   1878 
   1879   return CommonDom;
   1880 }
   1881 
   1882 char AMDGPUCFGStructurizer::ID = 0;
   1883 
   1884 } // end anonymous namespace
   1885 
   1886 
   1887 INITIALIZE_PASS_BEGIN(AMDGPUCFGStructurizer, "amdgpustructurizer",
   1888                       "AMDGPU CFG Structurizer", false, false)
   1889 INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
   1890 INITIALIZE_PASS_DEPENDENCY(MachinePostDominatorTree)
   1891 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
   1892 INITIALIZE_PASS_END(AMDGPUCFGStructurizer, "amdgpustructurizer",
   1893                       "AMDGPU CFG Structurizer", false, false)
   1894 
   1895 FunctionPass *llvm::createAMDGPUCFGStructurizerPass() {
   1896   return new AMDGPUCFGStructurizer();
   1897 }
   1898