1 //===-- IfConversion.cpp - Machine code if conversion pass. ---------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the machine instruction level if-conversion pass.
12 //===----------------------------------------------------------------------===//
14 #define DEBUG_TYPE "ifcvt"
15 #include "BranchFolding.h"
16 #include "llvm/Function.h"
17 #include "llvm/CodeGen/Passes.h"
18 #include "llvm/CodeGen/MachineModuleInfo.h"
19 #include "llvm/CodeGen/MachineFunctionPass.h"
20 #include "llvm/Target/TargetInstrInfo.h"
21 #include "llvm/Target/TargetLowering.h"
22 #include "llvm/Target/TargetMachine.h"
23 #include "llvm/Support/CommandLine.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/raw_ostream.h"
27 #include "llvm/ADT/DepthFirstIterator.h"
28 #include "llvm/ADT/Statistic.h"
29 #include "llvm/ADT/STLExtras.h"
32 // Hidden options for help debugging.
33 static cl::opt<int> IfCvtFnStart("ifcvt-fn-start", cl::init(-1), cl::Hidden);
34 static cl::opt<int> IfCvtFnStop("ifcvt-fn-stop", cl::init(-1), cl::Hidden);
35 static cl::opt<int> IfCvtLimit("ifcvt-limit", cl::init(-1), cl::Hidden);
36 static cl::opt<bool> DisableSimple("disable-ifcvt-simple",
37 cl::init(false), cl::Hidden);
38 static cl::opt<bool> DisableSimpleF("disable-ifcvt-simple-false",
39 cl::init(false), cl::Hidden);
40 static cl::opt<bool> DisableTriangle("disable-ifcvt-triangle",
41 cl::init(false), cl::Hidden);
42 static cl::opt<bool> DisableTriangleR("disable-ifcvt-triangle-rev",
43 cl::init(false), cl::Hidden);
44 static cl::opt<bool> DisableTriangleF("disable-ifcvt-triangle-false",
45 cl::init(false), cl::Hidden);
46 static cl::opt<bool> DisableTriangleFR("disable-ifcvt-triangle-false-rev",
47 cl::init(false), cl::Hidden);
48 static cl::opt<bool> DisableDiamond("disable-ifcvt-diamond",
49 cl::init(false), cl::Hidden);
51 STATISTIC(NumSimple, "Number of simple if-conversions performed");
52 STATISTIC(NumSimpleFalse, "Number of simple (F) if-conversions performed");
53 STATISTIC(NumTriangle, "Number of triangle if-conversions performed");
54 STATISTIC(NumTriangleRev, "Number of triangle (R) if-conversions performed");
55 STATISTIC(NumTriangleFalse,"Number of triangle (F) if-conversions performed");
56 STATISTIC(NumTriangleFRev, "Number of triangle (F/R) if-conversions performed");
57 STATISTIC(NumDiamonds, "Number of diamond if-conversions performed");
58 STATISTIC(NumIfConvBBs, "Number of if-converted blocks");
59 STATISTIC(NumDupBBs, "Number of duplicated blocks");
62 class IfConverter : public MachineFunctionPass {
64 ICNotClassfied, // BB data valid, but not classified.
65 ICSimpleFalse, // Same as ICSimple, but on the false path.
66 ICSimple, // BB is entry of an one split, no rejoin sub-CFG.
67 ICTriangleFRev, // Same as ICTriangleFalse, but false path rev condition.
68 ICTriangleRev, // Same as ICTriangle, but true path rev condition.
69 ICTriangleFalse, // Same as ICTriangle, but on the false path.
70 ICTriangle, // BB is entry of a triangle sub-CFG.
71 ICDiamond // BB is entry of a diamond sub-CFG.
74 /// BBInfo - One per MachineBasicBlock, this is used to cache the result
75 /// if-conversion feasibility analysis. This includes results from
76 /// TargetInstrInfo::AnalyzeBranch() (i.e. TBB, FBB, and Cond), and its
77 /// classification, and common tail block of its successors (if it's a
78 /// diamond shape), its size, whether it's predicable, and whether any
79 /// instruction can clobber the 'would-be' predicate.
81 /// IsDone - True if BB is not to be considered for ifcvt.
82 /// IsBeingAnalyzed - True if BB is currently being analyzed.
83 /// IsAnalyzed - True if BB has been analyzed (info is still valid).
84 /// IsEnqueued - True if BB has been enqueued to be ifcvt'ed.
85 /// IsBrAnalyzable - True if AnalyzeBranch() returns false.
86 /// HasFallThrough - True if BB may fallthrough to the following BB.
87 /// IsUnpredicable - True if BB is known to be unpredicable.
88 /// ClobbersPred - True if BB could modify predicates (e.g. has
90 /// NonPredSize - Number of non-predicated instructions.
91 /// BB - Corresponding MachineBasicBlock.
92 /// TrueBB / FalseBB- See AnalyzeBranch().
93 /// BrCond - Conditions for end of block conditional branches.
94 /// Predicate - Predicate used in the BB.
97 bool IsBeingAnalyzed : 1;
100 bool IsBrAnalyzable : 1;
101 bool HasFallThrough : 1;
102 bool IsUnpredicable : 1;
103 bool CannotBeCopied : 1;
104 bool ClobbersPred : 1;
105 unsigned NonPredSize;
106 MachineBasicBlock *BB;
107 MachineBasicBlock *TrueBB;
108 MachineBasicBlock *FalseBB;
109 SmallVector<MachineOperand, 4> BrCond;
110 SmallVector<MachineOperand, 4> Predicate;
111 BBInfo() : IsDone(false), IsBeingAnalyzed(false),
112 IsAnalyzed(false), IsEnqueued(false), IsBrAnalyzable(false),
113 HasFallThrough(false), IsUnpredicable(false),
114 CannotBeCopied(false), ClobbersPred(false), NonPredSize(0),
115 BB(0), TrueBB(0), FalseBB(0) {}
118 /// IfcvtToken - Record information about pending if-conversions to attemp:
119 /// BBI - Corresponding BBInfo.
120 /// Kind - Type of block. See IfcvtKind.
121 /// NeedSubsumption - True if the to-be-predicated BB has already been
123 /// NumDups - Number of instructions that would be duplicated due
124 /// to this if-conversion. (For diamonds, the number of
125 /// identical instructions at the beginnings of both
127 /// NumDups2 - For diamonds, the number of identical instructions
128 /// at the ends of both paths.
132 bool NeedSubsumption;
135 IfcvtToken(BBInfo &b, IfcvtKind k, bool s, unsigned d, unsigned d2 = 0)
136 : BBI(b), Kind(k), NeedSubsumption(s), NumDups(d), NumDups2(d2) {}
139 /// Roots - Basic blocks that do not have successors. These are the starting
140 /// points of Graph traversal.
141 std::vector<MachineBasicBlock*> Roots;
143 /// BBAnalysis - Results of if-conversion feasibility analysis indexed by
144 /// basic block number.
145 std::vector<BBInfo> BBAnalysis;
147 const TargetLowering *TLI;
148 const TargetInstrInfo *TII;
153 IfConverter() : MachineFunctionPass(&ID), FnNum(-1) {}
155 virtual bool runOnMachineFunction(MachineFunction &MF);
156 virtual const char *getPassName() const { return "If Converter"; }
159 bool ReverseBranchCondition(BBInfo &BBI);
160 bool ValidSimple(BBInfo &TrueBBI, unsigned &Dups) const;
161 bool ValidTriangle(BBInfo &TrueBBI, BBInfo &FalseBBI,
162 bool FalseBranch, unsigned &Dups) const;
163 bool ValidDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI,
164 unsigned &Dups1, unsigned &Dups2) const;
165 void ScanInstructions(BBInfo &BBI);
166 BBInfo &AnalyzeBlock(MachineBasicBlock *BB,
167 std::vector<IfcvtToken*> &Tokens);
168 bool FeasibilityAnalysis(BBInfo &BBI, SmallVectorImpl<MachineOperand> &Cond,
169 bool isTriangle = false, bool RevBranch = false);
170 bool AnalyzeBlocks(MachineFunction &MF,
171 std::vector<IfcvtToken*> &Tokens);
172 void InvalidatePreds(MachineBasicBlock *BB);
173 void RemoveExtraEdges(BBInfo &BBI);
174 bool IfConvertSimple(BBInfo &BBI, IfcvtKind Kind);
175 bool IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind);
176 bool IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
177 unsigned NumDups1, unsigned NumDups2);
178 void PredicateBlock(BBInfo &BBI,
179 MachineBasicBlock::iterator E,
180 SmallVectorImpl<MachineOperand> &Cond);
181 void CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI,
182 SmallVectorImpl<MachineOperand> &Cond,
183 bool IgnoreBr = false);
184 void MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI);
186 bool MeetIfcvtSizeLimit(unsigned Size) const {
187 return Size > 0 && Size <= TLI->getIfCvtBlockSizeLimit();
190 // blockAlwaysFallThrough - Block ends without a terminator.
191 bool blockAlwaysFallThrough(BBInfo &BBI) const {
192 return BBI.IsBrAnalyzable && BBI.TrueBB == NULL;
195 // IfcvtTokenCmp - Used to sort if-conversion candidates.
196 static bool IfcvtTokenCmp(IfcvtToken *C1, IfcvtToken *C2) {
197 int Incr1 = (C1->Kind == ICDiamond)
198 ? -(int)(C1->NumDups + C1->NumDups2) : (int)C1->NumDups;
199 int Incr2 = (C2->Kind == ICDiamond)
200 ? -(int)(C2->NumDups + C2->NumDups2) : (int)C2->NumDups;
203 else if (Incr1 == Incr2) {
204 // Favors subsumption.
205 if (C1->NeedSubsumption == false && C2->NeedSubsumption == true)
207 else if (C1->NeedSubsumption == C2->NeedSubsumption) {
208 // Favors diamond over triangle, etc.
209 if ((unsigned)C1->Kind < (unsigned)C2->Kind)
211 else if (C1->Kind == C2->Kind)
212 return C1->BBI.BB->getNumber() < C2->BBI.BB->getNumber();
219 char IfConverter::ID = 0;
222 static RegisterPass<IfConverter>
223 X("if-converter", "If Converter");
225 FunctionPass *llvm::createIfConverterPass() { return new IfConverter(); }
227 bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
228 TLI = MF.getTarget().getTargetLowering();
229 TII = MF.getTarget().getInstrInfo();
230 if (!TII) return false;
232 DEBUG(dbgs() << "\nIfcvt: function (" << ++FnNum << ") \'"
233 << MF.getFunction()->getName() << "\'");
235 if (FnNum < IfCvtFnStart || (IfCvtFnStop != -1 && FnNum > IfCvtFnStop)) {
236 DEBUG(dbgs() << " skipped\n");
239 DEBUG(dbgs() << "\n");
242 BBAnalysis.resize(MF.getNumBlockIDs());
244 // Look for root nodes, i.e. blocks without successors.
245 for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
249 std::vector<IfcvtToken*> Tokens;
251 unsigned NumIfCvts = NumSimple + NumSimpleFalse + NumTriangle +
252 NumTriangleRev + NumTriangleFalse + NumTriangleFRev + NumDiamonds;
253 while (IfCvtLimit == -1 || (int)NumIfCvts < IfCvtLimit) {
254 // Do an initial analysis for each basic block and find all the potential
255 // candidates to perform if-conversion.
256 bool Change = AnalyzeBlocks(MF, Tokens);
257 while (!Tokens.empty()) {
258 IfcvtToken *Token = Tokens.back();
260 BBInfo &BBI = Token->BBI;
261 IfcvtKind Kind = Token->Kind;
262 unsigned NumDups = Token->NumDups;
263 unsigned NumDups2 = Token->NumDups2;
267 // If the block has been evicted out of the queue or it has already been
268 // marked dead (due to it being predicated), then skip it.
270 BBI.IsEnqueued = false;
274 BBI.IsEnqueued = false;
278 default: assert(false && "Unexpected!");
281 case ICSimpleFalse: {
282 bool isFalse = Kind == ICSimpleFalse;
283 if ((isFalse && DisableSimpleF) || (!isFalse && DisableSimple)) break;
284 DEBUG(dbgs() << "Ifcvt (Simple" << (Kind == ICSimpleFalse ? " false" :"")
285 << "): BB#" << BBI.BB->getNumber() << " ("
286 << ((Kind == ICSimpleFalse)
287 ? BBI.FalseBB->getNumber()
288 : BBI.TrueBB->getNumber()) << ") ");
289 RetVal = IfConvertSimple(BBI, Kind);
290 DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
292 if (isFalse) NumSimpleFalse++;
299 case ICTriangleFalse:
300 case ICTriangleFRev: {
301 bool isFalse = Kind == ICTriangleFalse;
302 bool isRev = (Kind == ICTriangleRev || Kind == ICTriangleFRev);
303 if (DisableTriangle && !isFalse && !isRev) break;
304 if (DisableTriangleR && !isFalse && isRev) break;
305 if (DisableTriangleF && isFalse && !isRev) break;
306 if (DisableTriangleFR && isFalse && isRev) break;
307 DEBUG(dbgs() << "Ifcvt (Triangle");
309 DEBUG(dbgs() << " false");
311 DEBUG(dbgs() << " rev");
312 DEBUG(dbgs() << "): BB#" << BBI.BB->getNumber() << " (T:"
313 << BBI.TrueBB->getNumber() << ",F:"
314 << BBI.FalseBB->getNumber() << ") ");
315 RetVal = IfConvertTriangle(BBI, Kind);
316 DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
319 if (isRev) NumTriangleFRev++;
320 else NumTriangleFalse++;
322 if (isRev) NumTriangleRev++;
329 if (DisableDiamond) break;
330 DEBUG(dbgs() << "Ifcvt (Diamond): BB#" << BBI.BB->getNumber() << " (T:"
331 << BBI.TrueBB->getNumber() << ",F:"
332 << BBI.FalseBB->getNumber() << ") ");
333 RetVal = IfConvertDiamond(BBI, Kind, NumDups, NumDups2);
334 DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
335 if (RetVal) NumDiamonds++;
342 NumIfCvts = NumSimple + NumSimpleFalse + NumTriangle + NumTriangleRev +
343 NumTriangleFalse + NumTriangleFRev + NumDiamonds;
344 if (IfCvtLimit != -1 && (int)NumIfCvts >= IfCvtLimit)
350 MadeChange |= Change;
353 // Delete tokens in case of early exit.
354 while (!Tokens.empty()) {
355 IfcvtToken *Token = Tokens.back();
365 BranchFolder BF(false);
366 BF.OptimizeFunction(MF, TII,
367 MF.getTarget().getRegisterInfo(),
368 getAnalysisIfAvailable<MachineModuleInfo>());
374 /// findFalseBlock - BB has a fallthrough. Find its 'false' successor given
375 /// its 'true' successor.
376 static MachineBasicBlock *findFalseBlock(MachineBasicBlock *BB,
377 MachineBasicBlock *TrueBB) {
378 for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
379 E = BB->succ_end(); SI != E; ++SI) {
380 MachineBasicBlock *SuccBB = *SI;
381 if (SuccBB != TrueBB)
387 /// ReverseBranchCondition - Reverse the condition of the end of the block
388 /// branch. Swap block's 'true' and 'false' successors.
389 bool IfConverter::ReverseBranchCondition(BBInfo &BBI) {
390 if (!TII->ReverseBranchCondition(BBI.BrCond)) {
391 TII->RemoveBranch(*BBI.BB);
392 TII->InsertBranch(*BBI.BB, BBI.FalseBB, BBI.TrueBB, BBI.BrCond);
393 std::swap(BBI.TrueBB, BBI.FalseBB);
399 /// getNextBlock - Returns the next block in the function blocks ordering. If
400 /// it is the end, returns NULL.
401 static inline MachineBasicBlock *getNextBlock(MachineBasicBlock *BB) {
402 MachineFunction::iterator I = BB;
403 MachineFunction::iterator E = BB->getParent()->end();
409 /// ValidSimple - Returns true if the 'true' block (along with its
410 /// predecessor) forms a valid simple shape for ifcvt. It also returns the
411 /// number of instructions that the ifcvt would need to duplicate if performed
413 bool IfConverter::ValidSimple(BBInfo &TrueBBI, unsigned &Dups) const {
415 if (TrueBBI.IsBeingAnalyzed || TrueBBI.IsDone)
418 if (TrueBBI.IsBrAnalyzable)
421 if (TrueBBI.BB->pred_size() > 1) {
422 if (TrueBBI.CannotBeCopied ||
423 TrueBBI.NonPredSize > TLI->getIfCvtDupBlockSizeLimit())
425 Dups = TrueBBI.NonPredSize;
431 /// ValidTriangle - Returns true if the 'true' and 'false' blocks (along
432 /// with their common predecessor) forms a valid triangle shape for ifcvt.
433 /// If 'FalseBranch' is true, it checks if 'true' block's false branch
434 /// branches to the false branch rather than the other way around. It also
435 /// returns the number of instructions that the ifcvt would need to duplicate
436 /// if performed in 'Dups'.
437 bool IfConverter::ValidTriangle(BBInfo &TrueBBI, BBInfo &FalseBBI,
438 bool FalseBranch, unsigned &Dups) const {
440 if (TrueBBI.IsBeingAnalyzed || TrueBBI.IsDone)
443 if (TrueBBI.BB->pred_size() > 1) {
444 if (TrueBBI.CannotBeCopied)
447 unsigned Size = TrueBBI.NonPredSize;
448 if (TrueBBI.IsBrAnalyzable) {
449 if (TrueBBI.TrueBB && TrueBBI.BrCond.empty())
450 // Ends with an unconditional branch. It will be removed.
453 MachineBasicBlock *FExit = FalseBranch
454 ? TrueBBI.TrueBB : TrueBBI.FalseBB;
456 // Require a conditional branch
460 if (Size > TLI->getIfCvtDupBlockSizeLimit())
465 MachineBasicBlock *TExit = FalseBranch ? TrueBBI.FalseBB : TrueBBI.TrueBB;
466 if (!TExit && blockAlwaysFallThrough(TrueBBI)) {
467 MachineFunction::iterator I = TrueBBI.BB;
468 if (++I == TrueBBI.BB->getParent()->end())
472 return TExit && TExit == FalseBBI.BB;
476 MachineBasicBlock::iterator firstNonBranchInst(MachineBasicBlock *BB,
477 const TargetInstrInfo *TII) {
478 MachineBasicBlock::iterator I = BB->end();
479 while (I != BB->begin()) {
481 if (!I->getDesc().isBranch())
487 /// ValidDiamond - Returns true if the 'true' and 'false' blocks (along
488 /// with their common predecessor) forms a valid diamond shape for ifcvt.
489 bool IfConverter::ValidDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI,
490 unsigned &Dups1, unsigned &Dups2) const {
492 if (TrueBBI.IsBeingAnalyzed || TrueBBI.IsDone ||
493 FalseBBI.IsBeingAnalyzed || FalseBBI.IsDone)
496 MachineBasicBlock *TT = TrueBBI.TrueBB;
497 MachineBasicBlock *FT = FalseBBI.TrueBB;
499 if (!TT && blockAlwaysFallThrough(TrueBBI))
500 TT = getNextBlock(TrueBBI.BB);
501 if (!FT && blockAlwaysFallThrough(FalseBBI))
502 FT = getNextBlock(FalseBBI.BB);
505 if (TT == NULL && (TrueBBI.IsBrAnalyzable || FalseBBI.IsBrAnalyzable))
507 if (TrueBBI.BB->pred_size() > 1 || FalseBBI.BB->pred_size() > 1)
510 // FIXME: Allow true block to have an early exit?
511 if (TrueBBI.FalseBB || FalseBBI.FalseBB ||
512 (TrueBBI.ClobbersPred && FalseBBI.ClobbersPred))
515 MachineBasicBlock::iterator TI = TrueBBI.BB->begin();
516 MachineBasicBlock::iterator FI = FalseBBI.BB->begin();
517 MachineBasicBlock::iterator TIE = TrueBBI.BB->end();
518 MachineBasicBlock::iterator FIE = FalseBBI.BB->end();
519 // Skip dbg_value instructions
520 while (TI != TIE && TI->isDebugValue())
522 while (FI != FIE && FI->isDebugValue())
524 while (TI != TIE && FI != FIE) {
525 if (!TI->isIdenticalTo(FI))
532 TI = firstNonBranchInst(TrueBBI.BB, TII);
533 FI = firstNonBranchInst(FalseBBI.BB, TII);
534 MachineBasicBlock::iterator TIB = TrueBBI.BB->begin();
535 MachineBasicBlock::iterator FIB = FalseBBI.BB->begin();
536 // Skip dbg_value instructions
537 while (TI != TIB && TI->isDebugValue())
539 while (FI != FIB && FI->isDebugValue())
541 while (TI != TIB && FI != FIB) {
542 if (!TI->isIdenticalTo(FI))
552 /// ScanInstructions - Scan all the instructions in the block to determine if
553 /// the block is predicable. In most cases, that means all the instructions
554 /// in the block are isPredicable(). Also checks if the block contains any
555 /// instruction which can clobber a predicate (e.g. condition code register).
556 /// If so, the block is not predicable unless it's the last instruction.
557 void IfConverter::ScanInstructions(BBInfo &BBI) {
561 bool AlreadyPredicated = BBI.Predicate.size() > 0;
562 // First analyze the end of BB branches.
563 BBI.TrueBB = BBI.FalseBB = NULL;
566 !TII->AnalyzeBranch(*BBI.BB, BBI.TrueBB, BBI.FalseBB, BBI.BrCond);
567 BBI.HasFallThrough = BBI.IsBrAnalyzable && BBI.FalseBB == NULL;
569 if (BBI.BrCond.size()) {
570 // No false branch. This BB must end with a conditional branch and a
573 BBI.FalseBB = findFalseBlock(BBI.BB, BBI.TrueBB);
575 // Malformed bcc? True and false blocks are the same?
576 BBI.IsUnpredicable = true;
581 // Then scan all the instructions.
583 BBI.ClobbersPred = false;
584 for (MachineBasicBlock::iterator I = BBI.BB->begin(), E = BBI.BB->end();
586 if (I->isDebugValue())
589 const TargetInstrDesc &TID = I->getDesc();
590 if (TID.isNotDuplicable())
591 BBI.CannotBeCopied = true;
593 bool isPredicated = TII->isPredicated(I);
594 bool isCondBr = BBI.IsBrAnalyzable && TID.isConditionalBranch();
599 else if (!AlreadyPredicated) {
600 // FIXME: This instruction is already predicated before the
601 // if-conversion pass. It's probably something like a conditional move.
602 // Mark this block unpredicable for now.
603 BBI.IsUnpredicable = true;
608 if (BBI.ClobbersPred && !isPredicated) {
609 // Predicate modification instruction should end the block (except for
610 // already predicated instructions and end of block branches).
612 // A conditional branch is not predicable, but it may be eliminated.
616 // Predicate may have been modified, the subsequent (currently)
617 // unpredicated instructions cannot be correctly predicated.
618 BBI.IsUnpredicable = true;
622 // FIXME: Make use of PredDefs? e.g. ADDC, SUBC sets predicates but are
623 // still potentially predicable.
624 std::vector<MachineOperand> PredDefs;
625 if (TII->DefinesPredicate(I, PredDefs))
626 BBI.ClobbersPred = true;
628 if (!TII->isPredicable(I)) {
629 BBI.IsUnpredicable = true;
635 /// FeasibilityAnalysis - Determine if the block is a suitable candidate to be
636 /// predicated by the specified predicate.
637 bool IfConverter::FeasibilityAnalysis(BBInfo &BBI,
638 SmallVectorImpl<MachineOperand> &Pred,
639 bool isTriangle, bool RevBranch) {
640 // If the block is dead or unpredicable, then it cannot be predicated.
641 if (BBI.IsDone || BBI.IsUnpredicable)
644 // If it is already predicated, check if its predicate subsumes the new
646 if (BBI.Predicate.size() && !TII->SubsumesPredicate(BBI.Predicate, Pred))
649 if (BBI.BrCond.size()) {
653 // Test predicate subsumption.
654 SmallVector<MachineOperand, 4> RevPred(Pred.begin(), Pred.end());
655 SmallVector<MachineOperand, 4> Cond(BBI.BrCond.begin(), BBI.BrCond.end());
657 if (TII->ReverseBranchCondition(Cond))
660 if (TII->ReverseBranchCondition(RevPred) ||
661 !TII->SubsumesPredicate(Cond, RevPred))
668 /// AnalyzeBlock - Analyze the structure of the sub-CFG starting from
669 /// the specified block. Record its successors and whether it looks like an
670 /// if-conversion candidate.
671 IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB,
672 std::vector<IfcvtToken*> &Tokens) {
673 BBInfo &BBI = BBAnalysis[BB->getNumber()];
675 if (BBI.IsAnalyzed || BBI.IsBeingAnalyzed)
679 BBI.IsBeingAnalyzed = true;
681 ScanInstructions(BBI);
683 // Unanalyzable or ends with fallthrough or unconditional branch.
684 if (!BBI.IsBrAnalyzable || BBI.BrCond.empty()) {
685 BBI.IsBeingAnalyzed = false;
686 BBI.IsAnalyzed = true;
690 // Do not ifcvt if either path is a back edge to the entry block.
691 if (BBI.TrueBB == BB || BBI.FalseBB == BB) {
692 BBI.IsBeingAnalyzed = false;
693 BBI.IsAnalyzed = true;
697 // Do not ifcvt if true and false fallthrough blocks are the same.
699 BBI.IsBeingAnalyzed = false;
700 BBI.IsAnalyzed = true;
704 BBInfo &TrueBBI = AnalyzeBlock(BBI.TrueBB, Tokens);
705 BBInfo &FalseBBI = AnalyzeBlock(BBI.FalseBB, Tokens);
707 if (TrueBBI.IsDone && FalseBBI.IsDone) {
708 BBI.IsBeingAnalyzed = false;
709 BBI.IsAnalyzed = true;
713 SmallVector<MachineOperand, 4> RevCond(BBI.BrCond.begin(), BBI.BrCond.end());
714 bool CanRevCond = !TII->ReverseBranchCondition(RevCond);
718 bool TNeedSub = TrueBBI.Predicate.size() > 0;
719 bool FNeedSub = FalseBBI.Predicate.size() > 0;
720 bool Enqueued = false;
721 if (CanRevCond && ValidDiamond(TrueBBI, FalseBBI, Dups, Dups2) &&
722 MeetIfcvtSizeLimit(TrueBBI.NonPredSize - (Dups + Dups2)) &&
723 MeetIfcvtSizeLimit(FalseBBI.NonPredSize - (Dups + Dups2)) &&
724 FeasibilityAnalysis(TrueBBI, BBI.BrCond) &&
725 FeasibilityAnalysis(FalseBBI, RevCond)) {
733 // Note TailBB can be empty.
734 Tokens.push_back(new IfcvtToken(BBI, ICDiamond, TNeedSub|FNeedSub, Dups,
739 if (ValidTriangle(TrueBBI, FalseBBI, false, Dups) &&
740 MeetIfcvtSizeLimit(TrueBBI.NonPredSize) &&
741 FeasibilityAnalysis(TrueBBI, BBI.BrCond, true)) {
749 Tokens.push_back(new IfcvtToken(BBI, ICTriangle, TNeedSub, Dups));
753 if (ValidTriangle(TrueBBI, FalseBBI, true, Dups) &&
754 MeetIfcvtSizeLimit(TrueBBI.NonPredSize) &&
755 FeasibilityAnalysis(TrueBBI, BBI.BrCond, true, true)) {
756 Tokens.push_back(new IfcvtToken(BBI, ICTriangleRev, TNeedSub, Dups));
760 if (ValidSimple(TrueBBI, Dups) &&
761 MeetIfcvtSizeLimit(TrueBBI.NonPredSize) &&
762 FeasibilityAnalysis(TrueBBI, BBI.BrCond)) {
763 // Simple (split, no rejoin):
770 Tokens.push_back(new IfcvtToken(BBI, ICSimple, TNeedSub, Dups));
775 // Try the other path...
776 if (ValidTriangle(FalseBBI, TrueBBI, false, Dups) &&
777 MeetIfcvtSizeLimit(FalseBBI.NonPredSize) &&
778 FeasibilityAnalysis(FalseBBI, RevCond, true)) {
779 Tokens.push_back(new IfcvtToken(BBI, ICTriangleFalse, FNeedSub, Dups));
783 if (ValidTriangle(FalseBBI, TrueBBI, true, Dups) &&
784 MeetIfcvtSizeLimit(FalseBBI.NonPredSize) &&
785 FeasibilityAnalysis(FalseBBI, RevCond, true, true)) {
786 Tokens.push_back(new IfcvtToken(BBI, ICTriangleFRev, FNeedSub, Dups));
790 if (ValidSimple(FalseBBI, Dups) &&
791 MeetIfcvtSizeLimit(FalseBBI.NonPredSize) &&
792 FeasibilityAnalysis(FalseBBI, RevCond)) {
793 Tokens.push_back(new IfcvtToken(BBI, ICSimpleFalse, FNeedSub, Dups));
798 BBI.IsEnqueued = Enqueued;
799 BBI.IsBeingAnalyzed = false;
800 BBI.IsAnalyzed = true;
804 /// AnalyzeBlocks - Analyze all blocks and find entries for all if-conversion
805 /// candidates. It returns true if any CFG restructuring is done to expose more
806 /// if-conversion opportunities.
807 bool IfConverter::AnalyzeBlocks(MachineFunction &MF,
808 std::vector<IfcvtToken*> &Tokens) {
810 std::set<MachineBasicBlock*> Visited;
811 for (unsigned i = 0, e = Roots.size(); i != e; ++i) {
812 for (idf_ext_iterator<MachineBasicBlock*> I=idf_ext_begin(Roots[i],Visited),
813 E = idf_ext_end(Roots[i], Visited); I != E; ++I) {
814 MachineBasicBlock *BB = *I;
815 AnalyzeBlock(BB, Tokens);
819 // Sort to favor more complex ifcvt scheme.
820 std::stable_sort(Tokens.begin(), Tokens.end(), IfcvtTokenCmp);
825 /// canFallThroughTo - Returns true either if ToBB is the next block after BB or
826 /// that all the intervening blocks are empty (given BB can fall through to its
828 static bool canFallThroughTo(MachineBasicBlock *BB, MachineBasicBlock *ToBB) {
829 MachineFunction::iterator I = BB;
830 MachineFunction::iterator TI = ToBB;
831 MachineFunction::iterator E = BB->getParent()->end();
833 if (I == E || !I->empty())
838 /// InvalidatePreds - Invalidate predecessor BB info so it would be re-analyzed
839 /// to determine if it can be if-converted. If predecessor is already enqueued,
841 void IfConverter::InvalidatePreds(MachineBasicBlock *BB) {
842 for (MachineBasicBlock::pred_iterator PI = BB->pred_begin(),
843 E = BB->pred_end(); PI != E; ++PI) {
844 BBInfo &PBBI = BBAnalysis[(*PI)->getNumber()];
845 if (PBBI.IsDone || PBBI.BB == BB)
847 PBBI.IsAnalyzed = false;
848 PBBI.IsEnqueued = false;
852 /// InsertUncondBranch - Inserts an unconditional branch from BB to ToBB.
854 static void InsertUncondBranch(MachineBasicBlock *BB, MachineBasicBlock *ToBB,
855 const TargetInstrInfo *TII) {
856 SmallVector<MachineOperand, 0> NoCond;
857 TII->InsertBranch(*BB, ToBB, NULL, NoCond);
860 /// RemoveExtraEdges - Remove true / false edges if either / both are no longer
862 void IfConverter::RemoveExtraEdges(BBInfo &BBI) {
863 MachineBasicBlock *TBB = NULL, *FBB = NULL;
864 SmallVector<MachineOperand, 4> Cond;
865 if (!TII->AnalyzeBranch(*BBI.BB, TBB, FBB, Cond))
866 BBI.BB->CorrectExtraCFGEdges(TBB, FBB, !Cond.empty());
869 /// IfConvertSimple - If convert a simple (split, no rejoin) sub-CFG.
871 bool IfConverter::IfConvertSimple(BBInfo &BBI, IfcvtKind Kind) {
872 BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
873 BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
874 BBInfo *CvtBBI = &TrueBBI;
875 BBInfo *NextBBI = &FalseBBI;
877 SmallVector<MachineOperand, 4> Cond(BBI.BrCond.begin(), BBI.BrCond.end());
878 if (Kind == ICSimpleFalse)
879 std::swap(CvtBBI, NextBBI);
881 if (CvtBBI->IsDone ||
882 (CvtBBI->CannotBeCopied && CvtBBI->BB->pred_size() > 1)) {
883 // Something has changed. It's no longer safe to predicate this block.
884 BBI.IsAnalyzed = false;
885 CvtBBI->IsAnalyzed = false;
889 if (Kind == ICSimpleFalse)
890 if (TII->ReverseBranchCondition(Cond))
891 assert(false && "Unable to reverse branch condition!");
893 if (CvtBBI->BB->pred_size() > 1) {
894 BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
895 // Copy instructions in the true block, predicate them, and add them to
897 CopyAndPredicateBlock(BBI, *CvtBBI, Cond);
899 PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond);
901 // Merge converted block into entry block.
902 BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
903 MergeBlocks(BBI, *CvtBBI);
906 bool IterIfcvt = true;
907 if (!canFallThroughTo(BBI.BB, NextBBI->BB)) {
908 InsertUncondBranch(BBI.BB, NextBBI->BB, TII);
909 BBI.HasFallThrough = false;
910 // Now ifcvt'd block will look like this:
917 // We cannot further ifcvt this block because the unconditional branch
918 // will have to be predicated on the new condition, that will not be
919 // available if cmp executes.
923 RemoveExtraEdges(BBI);
925 // Update block info. BB can be iteratively if-converted.
928 InvalidatePreds(BBI.BB);
929 CvtBBI->IsDone = true;
931 // FIXME: Must maintain LiveIns.
935 /// IfConvertTriangle - If convert a triangle sub-CFG.
937 bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
938 BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
939 BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
940 BBInfo *CvtBBI = &TrueBBI;
941 BBInfo *NextBBI = &FalseBBI;
943 SmallVector<MachineOperand, 4> Cond(BBI.BrCond.begin(), BBI.BrCond.end());
944 if (Kind == ICTriangleFalse || Kind == ICTriangleFRev)
945 std::swap(CvtBBI, NextBBI);
947 if (CvtBBI->IsDone ||
948 (CvtBBI->CannotBeCopied && CvtBBI->BB->pred_size() > 1)) {
949 // Something has changed. It's no longer safe to predicate this block.
950 BBI.IsAnalyzed = false;
951 CvtBBI->IsAnalyzed = false;
955 if (Kind == ICTriangleFalse || Kind == ICTriangleFRev)
956 if (TII->ReverseBranchCondition(Cond))
957 assert(false && "Unable to reverse branch condition!");
959 if (Kind == ICTriangleRev || Kind == ICTriangleFRev) {
960 if (ReverseBranchCondition(*CvtBBI)) {
961 // BB has been changed, modify its predecessors (except for this
962 // one) so they don't get ifcvt'ed based on bad intel.
963 for (MachineBasicBlock::pred_iterator PI = CvtBBI->BB->pred_begin(),
964 E = CvtBBI->BB->pred_end(); PI != E; ++PI) {
965 MachineBasicBlock *PBB = *PI;
968 BBInfo &PBBI = BBAnalysis[PBB->getNumber()];
969 if (PBBI.IsEnqueued) {
970 PBBI.IsAnalyzed = false;
971 PBBI.IsEnqueued = false;
977 bool HasEarlyExit = CvtBBI->FalseBB != NULL;
978 bool DupBB = CvtBBI->BB->pred_size() > 1;
980 BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
981 // Copy instructions in the true block, predicate them, and add them to
983 CopyAndPredicateBlock(BBI, *CvtBBI, Cond, true);
985 // Predicate the 'true' block after removing its branch.
986 CvtBBI->NonPredSize -= TII->RemoveBranch(*CvtBBI->BB);
987 PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond);
989 // Now merge the entry of the triangle with the true block.
990 BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
991 MergeBlocks(BBI, *CvtBBI);
994 // If 'true' block has a 'false' successor, add an exit branch to it.
996 SmallVector<MachineOperand, 4> RevCond(CvtBBI->BrCond.begin(),
997 CvtBBI->BrCond.end());
998 if (TII->ReverseBranchCondition(RevCond))
999 assert(false && "Unable to reverse branch condition!");
1000 TII->InsertBranch(*BBI.BB, CvtBBI->FalseBB, NULL, RevCond);
1001 BBI.BB->addSuccessor(CvtBBI->FalseBB);
1004 // Merge in the 'false' block if the 'false' block has no other
1005 // predecessors. Otherwise, add an unconditional branch to 'false'.
1006 bool FalseBBDead = false;
1007 bool IterIfcvt = true;
1008 bool isFallThrough = canFallThroughTo(BBI.BB, NextBBI->BB);
1009 if (!isFallThrough) {
1010 // Only merge them if the true block does not fallthrough to the false
1011 // block. By not merging them, we make it possible to iteratively
1012 // ifcvt the blocks.
1013 if (!HasEarlyExit &&
1014 NextBBI->BB->pred_size() == 1 && !NextBBI->HasFallThrough) {
1015 MergeBlocks(BBI, *NextBBI);
1018 InsertUncondBranch(BBI.BB, NextBBI->BB, TII);
1019 BBI.HasFallThrough = false;
1021 // Mixed predicated and unpredicated code. This cannot be iteratively
1026 RemoveExtraEdges(BBI);
1028 // Update block info. BB can be iteratively if-converted.
1031 InvalidatePreds(BBI.BB);
1032 CvtBBI->IsDone = true;
1034 NextBBI->IsDone = true;
1036 // FIXME: Must maintain LiveIns.
1040 /// IfConvertDiamond - If convert a diamond sub-CFG.
1042 bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
1043 unsigned NumDups1, unsigned NumDups2) {
1044 BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
1045 BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
1046 MachineBasicBlock *TailBB = TrueBBI.TrueBB;
1047 // True block must fall through or end with an unanalyzable terminator.
1049 if (blockAlwaysFallThrough(TrueBBI))
1050 TailBB = FalseBBI.TrueBB;
1051 assert((TailBB || !TrueBBI.IsBrAnalyzable) && "Unexpected!");
1054 if (TrueBBI.IsDone || FalseBBI.IsDone ||
1055 TrueBBI.BB->pred_size() > 1 ||
1056 FalseBBI.BB->pred_size() > 1) {
1057 // Something has changed. It's no longer safe to predicate these blocks.
1058 BBI.IsAnalyzed = false;
1059 TrueBBI.IsAnalyzed = false;
1060 FalseBBI.IsAnalyzed = false;
1064 // Merge the 'true' and 'false' blocks by copying the instructions
1065 // from the 'false' block to the 'true' block. That is, unless the true
1066 // block would clobber the predicate, in that case, do the opposite.
1067 BBInfo *BBI1 = &TrueBBI;
1068 BBInfo *BBI2 = &FalseBBI;
1069 SmallVector<MachineOperand, 4> RevCond(BBI.BrCond.begin(), BBI.BrCond.end());
1070 if (TII->ReverseBranchCondition(RevCond))
1071 assert(false && "Unable to reverse branch condition!");
1072 SmallVector<MachineOperand, 4> *Cond1 = &BBI.BrCond;
1073 SmallVector<MachineOperand, 4> *Cond2 = &RevCond;
1075 // Figure out the more profitable ordering.
1076 bool DoSwap = false;
1077 if (TrueBBI.ClobbersPred && !FalseBBI.ClobbersPred)
1079 else if (TrueBBI.ClobbersPred == FalseBBI.ClobbersPred) {
1080 if (TrueBBI.NonPredSize > FalseBBI.NonPredSize)
1084 std::swap(BBI1, BBI2);
1085 std::swap(Cond1, Cond2);
1088 // Remove the conditional branch from entry to the blocks.
1089 BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
1091 // Remove the duplicated instructions at the beginnings of both paths.
1092 MachineBasicBlock::iterator DI1 = BBI1->BB->begin();
1093 MachineBasicBlock::iterator DI2 = BBI2->BB->begin();
1094 BBI1->NonPredSize -= NumDups1;
1095 BBI2->NonPredSize -= NumDups1;
1096 while (NumDups1 != 0) {
1101 BBI.BB->splice(BBI.BB->end(), BBI1->BB, BBI1->BB->begin(), DI1);
1102 BBI2->BB->erase(BBI2->BB->begin(), DI2);
1104 // Predicate the 'true' block after removing its branch.
1105 BBI1->NonPredSize -= TII->RemoveBranch(*BBI1->BB);
1106 DI1 = BBI1->BB->end();
1107 for (unsigned i = 0; i != NumDups2; ++i)
1109 BBI1->BB->erase(DI1, BBI1->BB->end());
1110 PredicateBlock(*BBI1, BBI1->BB->end(), *Cond1);
1112 // Predicate the 'false' block.
1113 BBI2->NonPredSize -= TII->RemoveBranch(*BBI2->BB);
1114 DI2 = BBI2->BB->end();
1115 while (NumDups2 != 0) {
1119 PredicateBlock(*BBI2, DI2, *Cond2);
1121 // Merge the true block into the entry of the diamond.
1122 MergeBlocks(BBI, *BBI1);
1123 MergeBlocks(BBI, *BBI2);
1125 // If the if-converted block falls through or unconditionally branches into
1126 // the tail block, and the tail block does not have other predecessors, then
1127 // fold the tail block in as well. Otherwise, unless it falls through to the
1128 // tail, add a unconditional branch to it.
1130 BBInfo TailBBI = BBAnalysis[TailBB->getNumber()];
1131 if (TailBB->pred_size() == 1 && !TailBBI.HasFallThrough) {
1132 BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
1133 MergeBlocks(BBI, TailBBI);
1134 TailBBI.IsDone = true;
1136 InsertUncondBranch(BBI.BB, TailBB, TII);
1137 BBI.HasFallThrough = false;
1141 RemoveExtraEdges(BBI);
1143 // Update block info.
1144 BBI.IsDone = TrueBBI.IsDone = FalseBBI.IsDone = true;
1145 InvalidatePreds(BBI.BB);
1147 // FIXME: Must maintain LiveIns.
1151 /// PredicateBlock - Predicate instructions from the start of the block to the
1152 /// specified end with the specified condition.
1153 void IfConverter::PredicateBlock(BBInfo &BBI,
1154 MachineBasicBlock::iterator E,
1155 SmallVectorImpl<MachineOperand> &Cond) {
1156 for (MachineBasicBlock::iterator I = BBI.BB->begin(); I != E; ++I) {
1157 if (I->isDebugValue() || TII->isPredicated(I))
1159 if (!TII->PredicateInstruction(I, Cond)) {
1161 dbgs() << "Unable to predicate " << *I << "!\n";
1163 llvm_unreachable(0);
1167 std::copy(Cond.begin(), Cond.end(), std::back_inserter(BBI.Predicate));
1169 BBI.IsAnalyzed = false;
1170 BBI.NonPredSize = 0;
1175 /// CopyAndPredicateBlock - Copy and predicate instructions from source BB to
1176 /// the destination block. Skip end of block branches if IgnoreBr is true.
1177 void IfConverter::CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI,
1178 SmallVectorImpl<MachineOperand> &Cond,
1180 MachineFunction &MF = *ToBBI.BB->getParent();
1182 for (MachineBasicBlock::iterator I = FromBBI.BB->begin(),
1183 E = FromBBI.BB->end(); I != E; ++I) {
1184 const TargetInstrDesc &TID = I->getDesc();
1185 bool isPredicated = TII->isPredicated(I);
1186 // Do not copy the end of the block branches.
1187 if (IgnoreBr && !isPredicated && TID.isBranch())
1190 MachineInstr *MI = MF.CloneMachineInstr(I);
1191 ToBBI.BB->insert(ToBBI.BB->end(), MI);
1192 ToBBI.NonPredSize++;
1194 if (!isPredicated && !MI->isDebugValue())
1195 if (!TII->PredicateInstruction(MI, Cond)) {
1197 dbgs() << "Unable to predicate " << *I << "!\n";
1199 llvm_unreachable(0);
1203 std::vector<MachineBasicBlock *> Succs(FromBBI.BB->succ_begin(),
1204 FromBBI.BB->succ_end());
1205 MachineBasicBlock *NBB = getNextBlock(FromBBI.BB);
1206 MachineBasicBlock *FallThrough = FromBBI.HasFallThrough ? NBB : NULL;
1208 for (unsigned i = 0, e = Succs.size(); i != e; ++i) {
1209 MachineBasicBlock *Succ = Succs[i];
1210 // Fallthrough edge can't be transferred.
1211 if (Succ == FallThrough)
1213 ToBBI.BB->addSuccessor(Succ);
1216 std::copy(FromBBI.Predicate.begin(), FromBBI.Predicate.end(),
1217 std::back_inserter(ToBBI.Predicate));
1218 std::copy(Cond.begin(), Cond.end(), std::back_inserter(ToBBI.Predicate));
1220 ToBBI.ClobbersPred |= FromBBI.ClobbersPred;
1221 ToBBI.IsAnalyzed = false;
1226 /// MergeBlocks - Move all instructions from FromBB to the end of ToBB.
1228 void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI) {
1229 ToBBI.BB->splice(ToBBI.BB->end(),
1230 FromBBI.BB, FromBBI.BB->begin(), FromBBI.BB->end());
1232 // Redirect all branches to FromBB to ToBB.
1233 std::vector<MachineBasicBlock *> Preds(FromBBI.BB->pred_begin(),
1234 FromBBI.BB->pred_end());
1235 for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
1236 MachineBasicBlock *Pred = Preds[i];
1237 if (Pred == ToBBI.BB)
1239 Pred->ReplaceUsesOfBlockWith(FromBBI.BB, ToBBI.BB);
1242 std::vector<MachineBasicBlock *> Succs(FromBBI.BB->succ_begin(),
1243 FromBBI.BB->succ_end());
1244 MachineBasicBlock *NBB = getNextBlock(FromBBI.BB);
1245 MachineBasicBlock *FallThrough = FromBBI.HasFallThrough ? NBB : NULL;
1247 for (unsigned i = 0, e = Succs.size(); i != e; ++i) {
1248 MachineBasicBlock *Succ = Succs[i];
1249 // Fallthrough edge can't be transferred.
1250 if (Succ == FallThrough)
1252 FromBBI.BB->removeSuccessor(Succ);
1253 ToBBI.BB->addSuccessor(Succ);
1256 // Now FromBBI always falls through to the next block!
1257 if (NBB && !FromBBI.BB->isSuccessor(NBB))
1258 FromBBI.BB->addSuccessor(NBB);
1260 std::copy(FromBBI.Predicate.begin(), FromBBI.Predicate.end(),
1261 std::back_inserter(ToBBI.Predicate));
1262 FromBBI.Predicate.clear();
1264 ToBBI.NonPredSize += FromBBI.NonPredSize;
1265 FromBBI.NonPredSize = 0;
1267 ToBBI.ClobbersPred |= FromBBI.ClobbersPred;
1268 ToBBI.HasFallThrough = FromBBI.HasFallThrough;
1269 ToBBI.IsAnalyzed = false;
1270 FromBBI.IsAnalyzed = false;