diff options
Diffstat (limited to 'contrib/llvm/lib/Transforms/Utils/SimplifyCFG.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 706 |
1 files changed, 589 insertions, 117 deletions
diff --git a/contrib/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/contrib/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index 36781c1..d0932f83 100644 --- a/contrib/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/contrib/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -14,6 +14,7 @@ #include "llvm/Transforms/Utils/Local.h" #include "llvm/ADT/DenseMap.h" #include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SetOperations.h" #include "llvm/ADT/SetVector.h" #include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/SmallVector.h" @@ -43,7 +44,6 @@ #include "llvm/Support/Debug.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h" -#include "llvm/Transforms/Utils/Local.h" #include "llvm/Transforms/Utils/ValueMapper.h" #include <algorithm> #include <map> @@ -73,6 +73,22 @@ static cl::opt<bool> HoistCondStores( "simplifycfg-hoist-cond-stores", cl::Hidden, cl::init(true), cl::desc("Hoist conditional stores if an unconditional store precedes")); +static cl::opt<bool> MergeCondStores( + "simplifycfg-merge-cond-stores", cl::Hidden, cl::init(true), + cl::desc("Hoist conditional stores even if an unconditional store does not " + "precede - hoist multiple conditional stores into a single " + "predicated store")); + +static cl::opt<bool> MergeCondStoresAggressively( + "simplifycfg-merge-cond-stores-aggressively", cl::Hidden, cl::init(false), + cl::desc("When merging conditional stores, do so even if the resultant " + "basic blocks are unlikely to be if-converted as a result")); + +static cl::opt<bool> SpeculateOneExpensiveInst( + "speculate-one-expensive-inst", cl::Hidden, cl::init(true), + cl::desc("Allow exactly one expensive instruction to be speculatively " + "executed")); + STATISTIC(NumBitMaps, "Number of switch instructions turned into bitmaps"); STATISTIC(NumLinearMaps, "Number of switch instructions turned into linear mapping"); STATISTIC(NumLookupTables, "Number of switch instructions turned into lookup tables"); @@ -83,13 +99,13 @@ STATISTIC(NumSpeculations, "Number of speculative executed instructions"); namespace { // The first field contains the value that the switch produces when a certain - // case group is selected, and the second field is a vector containing the cases - // composing the case group. + // case group is selected, and the second field is a vector containing the + // cases composing the case group. typedef SmallVector<std::pair<Constant *, SmallVector<ConstantInt *, 4>>, 2> SwitchCaseResultVectorTy; // The first field contains the phi node that generates a result of the switch - // and the second field contains the value generated for a certain case in the switch - // for that PHI. + // and the second field contains the value generated for a certain case in the + // switch for that PHI. typedef SmallVector<std::pair<PHINode *, Constant *>, 4> SwitchCaseResultsTy; /// ValueEqualityComparisonCase - Represents a case of a switch. @@ -124,6 +140,7 @@ class SimplifyCFGOpt { bool SimplifyReturn(ReturnInst *RI, IRBuilder<> &Builder); bool SimplifyResume(ResumeInst *RI, IRBuilder<> &Builder); + bool SimplifyCleanupReturn(CleanupReturnInst *RI); bool SimplifyUnreachable(UnreachableInst *UI); bool SimplifySwitch(SwitchInst *SI, IRBuilder<> &Builder); bool SimplifyIndirectBr(IndirectBrInst *IBI); @@ -226,6 +243,7 @@ static unsigned ComputeSpeculationCost(const User *I, "Instruction is not safe to speculatively execute!"); return TTI.getUserCost(I); } + /// If we have a merge point of an "if condition" as accepted above, /// return true if the specified value dominates the block. We /// don't handle the true generality of domination here, just a special case @@ -246,7 +264,8 @@ static unsigned ComputeSpeculationCost(const User *I, static bool DominatesMergePoint(Value *V, BasicBlock *BB, SmallPtrSetImpl<Instruction*> *AggressiveInsts, unsigned &CostRemaining, - const TargetTransformInfo &TTI) { + const TargetTransformInfo &TTI, + unsigned Depth = 0) { Instruction *I = dyn_cast<Instruction>(V); if (!I) { // Non-instructions all dominate instructions, but not all constantexprs @@ -284,15 +303,24 @@ static bool DominatesMergePoint(Value *V, BasicBlock *BB, unsigned Cost = ComputeSpeculationCost(I, TTI); - if (Cost > CostRemaining) + // Allow exactly one instruction to be speculated regardless of its cost + // (as long as it is safe to do so). + // This is intended to flatten the CFG even if the instruction is a division + // or other expensive operation. The speculation of an expensive instruction + // is expected to be undone in CodeGenPrepare if the speculation has not + // enabled further IR optimizations. + if (Cost > CostRemaining && + (!SpeculateOneExpensiveInst || !AggressiveInsts->empty() || Depth > 0)) return false; - CostRemaining -= Cost; + // Avoid unsigned wrap. + CostRemaining = (Cost > CostRemaining) ? 0 : CostRemaining - Cost; // Okay, we can only really hoist these out if their operands do // not take us over the cost threshold. for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i) - if (!DominatesMergePoint(*i, BB, AggressiveInsts, CostRemaining, TTI)) + if (!DominatesMergePoint(*i, BB, AggressiveInsts, CostRemaining, TTI, + Depth + 1)) return false; // Okay, it's safe to do this! Remember this instruction. AggressiveInsts->insert(I); @@ -970,8 +998,8 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI, // Okay, at this point, we know which new successor Pred will get. Make // sure we update the number of entries in the PHI nodes for these // successors. - for (unsigned i = 0, e = NewSuccessors.size(); i != e; ++i) - AddPredecessorToBlock(NewSuccessors[i], Pred, BB); + for (BasicBlock *NewSuccessor : NewSuccessors) + AddPredecessorToBlock(NewSuccessor, Pred, BB); Builder.SetInsertPoint(PTI); // Convert pointer to int before we switch. @@ -984,8 +1012,8 @@ bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI, SwitchInst *NewSI = Builder.CreateSwitch(CV, PredDefault, PredCases.size()); NewSI->setDebugLoc(PTI->getDebugLoc()); - for (unsigned i = 0, e = PredCases.size(); i != e; ++i) - NewSI->addCase(PredCases[i].Value, PredCases[i].Dest); + for (ValueEqualityComparisonCase &V : PredCases) + NewSI->addCase(V.Value, V.Dest); if (PredHasWeights || SuccHasWeights) { // Halve the weights if any of them cannot fit in an uint32_t @@ -1059,15 +1087,15 @@ static bool HoistThenElseCodeToIf(BranchInst *BI, BasicBlock::iterator BB1_Itr = BB1->begin(); BasicBlock::iterator BB2_Itr = BB2->begin(); - Instruction *I1 = BB1_Itr++, *I2 = BB2_Itr++; + Instruction *I1 = &*BB1_Itr++, *I2 = &*BB2_Itr++; // Skip debug info if it is not identical. DbgInfoIntrinsic *DBI1 = dyn_cast<DbgInfoIntrinsic>(I1); DbgInfoIntrinsic *DBI2 = dyn_cast<DbgInfoIntrinsic>(I2); if (!DBI1 || !DBI2 || !DBI1->isIdenticalToWhenDefined(DBI2)) { while (isa<DbgInfoIntrinsic>(I1)) - I1 = BB1_Itr++; + I1 = &*BB1_Itr++; while (isa<DbgInfoIntrinsic>(I2)) - I2 = BB2_Itr++; + I2 = &*BB2_Itr++; } if (isa<PHINode>(I1) || !I1->isIdenticalToWhenDefined(I2) || (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2))) @@ -1088,31 +1116,30 @@ static bool HoistThenElseCodeToIf(BranchInst *BI, // For a normal instruction, we just move one to right before the branch, // then replace all uses of the other with the first. Finally, we remove // the now redundant second instruction. - BIParent->getInstList().splice(BI, BB1->getInstList(), I1); + BIParent->getInstList().splice(BI->getIterator(), BB1->getInstList(), I1); if (!I2->use_empty()) I2->replaceAllUsesWith(I1); I1->intersectOptionalDataWith(I2); unsigned KnownIDs[] = { - LLVMContext::MD_tbaa, - LLVMContext::MD_range, - LLVMContext::MD_fpmath, - LLVMContext::MD_invariant_load, - LLVMContext::MD_nonnull - }; + LLVMContext::MD_tbaa, LLVMContext::MD_range, + LLVMContext::MD_fpmath, LLVMContext::MD_invariant_load, + LLVMContext::MD_nonnull, LLVMContext::MD_invariant_group, + LLVMContext::MD_align, LLVMContext::MD_dereferenceable, + LLVMContext::MD_dereferenceable_or_null}; combineMetadata(I1, I2, KnownIDs); I2->eraseFromParent(); Changed = true; - I1 = BB1_Itr++; - I2 = BB2_Itr++; + I1 = &*BB1_Itr++; + I2 = &*BB2_Itr++; // Skip debug info if it is not identical. DbgInfoIntrinsic *DBI1 = dyn_cast<DbgInfoIntrinsic>(I1); DbgInfoIntrinsic *DBI2 = dyn_cast<DbgInfoIntrinsic>(I2); if (!DBI1 || !DBI2 || !DBI1->isIdenticalToWhenDefined(DBI2)) { while (isa<DbgInfoIntrinsic>(I1)) - I1 = BB1_Itr++; + I1 = &*BB1_Itr++; while (isa<DbgInfoIntrinsic>(I2)) - I2 = BB2_Itr++; + I2 = &*BB2_Itr++; } } while (I1->isIdenticalToWhenDefined(I2)); @@ -1147,7 +1174,7 @@ HoistTerminator: // Okay, it is safe to hoist the terminator. Instruction *NT = I1->clone(); - BIParent->getInstList().insert(BI, NT); + BIParent->getInstList().insert(BI->getIterator(), NT); if (!NT->getType()->isVoidTy()) { I1->replaceAllUsesWith(NT); I2->replaceAllUsesWith(NT); @@ -1265,7 +1292,7 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) { // Cannot move control-flow-involving, volatile loads, vaarg, etc. if (isa<PHINode>(I1) || isa<PHINode>(I2) || isa<TerminatorInst>(I1) || isa<TerminatorInst>(I2) || - isa<LandingPadInst>(I1) || isa<LandingPadInst>(I2) || + I1->isEHPad() || I2->isEHPad() || isa<AllocaInst>(I1) || isa<AllocaInst>(I2) || I1->mayHaveSideEffects() || I2->mayHaveSideEffects() || I1->mayReadOrWriteMemory() || I2->mayReadOrWriteMemory() || @@ -1324,7 +1351,7 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) { if (!NewPN) { NewPN = PHINode::Create(DifferentOp1->getType(), 2, - DifferentOp1->getName() + ".sink", BBEnd->begin()); + DifferentOp1->getName() + ".sink", &BBEnd->front()); NewPN->addIncoming(DifferentOp1, BB1); NewPN->addIncoming(DifferentOp2, BB2); DEBUG(dbgs() << "Create PHI node " << *NewPN << "\n";); @@ -1339,7 +1366,8 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) { // instruction in the basic block down. bool UpdateRE1 = (I1 == BB1->begin()), UpdateRE2 = (I2 == BB2->begin()); // Sink the instruction. - BBEnd->getInstList().splice(FirstNonPhiInBBEnd, BB1->getInstList(), I1); + BBEnd->getInstList().splice(FirstNonPhiInBBEnd->getIterator(), + BB1->getInstList(), I1); if (!OldPN->use_empty()) OldPN->replaceAllUsesWith(I1); OldPN->eraseFromParent(); @@ -1355,7 +1383,7 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) { RE1 = BB1->getInstList().rend(); if (UpdateRE2) RE2 = BB2->getInstList().rend(); - FirstNonPhiInBBEnd = I1; + FirstNonPhiInBBEnd = &*I1; NumSinkCommons++; Changed = true; } @@ -1491,7 +1519,7 @@ static bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *ThenBB, for (BasicBlock::iterator BBI = ThenBB->begin(), BBE = std::prev(ThenBB->end()); BBI != BBE; ++BBI) { - Instruction *I = BBI; + Instruction *I = &*BBI; // Skip debug info. if (isa<DbgInfoIntrinsic>(I)) continue; @@ -1604,9 +1632,14 @@ static bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *ThenBB, SpeculatedStore->setOperand(0, S); } + // Metadata can be dependent on the condition we are hoisting above. + // Conservatively strip all metadata on the instruction. + for (auto &I: *ThenBB) + I.dropUnknownNonDebugMetadata(); + // Hoist the instructions. - BB->getInstList().splice(BI, ThenBB->getInstList(), ThenBB->begin(), - std::prev(ThenBB->end())); + BB->getInstList().splice(BI->getIterator(), ThenBB->getInstList(), + ThenBB->begin(), std::prev(ThenBB->end())); // Insert selects and rewrite the PHI operands. IRBuilder<true, NoFolder> Builder(BI); @@ -1747,13 +1780,13 @@ static bool FoldCondBranchOnPHI(BranchInst *BI, const DataLayout &DL) { // Check for trivial simplification. if (Value *V = SimplifyInstruction(N, DL)) { - TranslateMap[BBI] = V; + TranslateMap[&*BBI] = V; delete N; // Instruction folded away, don't need actual inst } else { // Insert the new instruction into its new home. EdgeBB->getInstList().insert(InsertPt, N); if (!BBI->use_empty()) - TranslateMap[BBI] = N; + TranslateMap[&*BBI] = N; } } @@ -1850,7 +1883,7 @@ static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI, } else { DomBlock = *pred_begin(IfBlock1); for (BasicBlock::iterator I = IfBlock1->begin();!isa<TerminatorInst>(I);++I) - if (!AggressiveInsts.count(I) && !isa<DbgInfoIntrinsic>(I)) { + if (!AggressiveInsts.count(&*I) && !isa<DbgInfoIntrinsic>(I)) { // This is not an aggressive instruction that we can promote. // Because of this, we won't be able to get rid of the control // flow, so the xform is not worth it. @@ -1863,7 +1896,7 @@ static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI, } else { DomBlock = *pred_begin(IfBlock2); for (BasicBlock::iterator I = IfBlock2->begin();!isa<TerminatorInst>(I);++I) - if (!AggressiveInsts.count(I) && !isa<DbgInfoIntrinsic>(I)) { + if (!AggressiveInsts.count(&*I) && !isa<DbgInfoIntrinsic>(I)) { // This is not an aggressive instruction that we can promote. // Because of this, we won't be able to get rid of the control // flow, so the xform is not worth it. @@ -1882,13 +1915,13 @@ static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI, // Move all 'aggressive' instructions, which are defined in the // conditional parts of the if's up to the dominating block. if (IfBlock1) - DomBlock->getInstList().splice(InsertPt, + DomBlock->getInstList().splice(InsertPt->getIterator(), IfBlock1->getInstList(), IfBlock1->begin(), - IfBlock1->getTerminator()); + IfBlock1->getTerminator()->getIterator()); if (IfBlock2) - DomBlock->getInstList().splice(InsertPt, + DomBlock->getInstList().splice(InsertPt->getIterator(), IfBlock2->getInstList(), IfBlock2->begin(), - IfBlock2->getTerminator()); + IfBlock2->getTerminator()->getIterator()); while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) { // Change the PHI node into a select instruction. @@ -2057,7 +2090,7 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, unsigned BonusInstThreshold) { BI->getSuccessor(0) == PBI->getSuccessor(1))) { for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) { - Instruction *Curr = I++; + Instruction *Curr = &*I++; if (isa<CmpInst>(Curr)) { Cond = Curr; break; @@ -2077,7 +2110,7 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, unsigned BonusInstThreshold) { return false; // Make sure the instruction after the condition is the cond branch. - BasicBlock::iterator CondIt = Cond; ++CondIt; + BasicBlock::iterator CondIt = ++Cond->getIterator(); // Ignore dbg intrinsics. while (isa<DbgInfoIntrinsic>(CondIt)) ++CondIt; @@ -2095,7 +2128,7 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, unsigned BonusInstThreshold) { // Ignore dbg intrinsics. if (isa<DbgInfoIntrinsic>(I)) continue; - if (!I->hasOneUse() || !isSafeToSpeculativelyExecute(I)) + if (!I->hasOneUse() || !isSafeToSpeculativelyExecute(&*I)) return false; // I has only one use and can be executed unconditionally. Instruction *User = dyn_cast<Instruction>(I->user_back()); @@ -2192,17 +2225,17 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, unsigned BonusInstThreshold) { Instruction *NewBonusInst = BonusInst->clone(); RemapInstruction(NewBonusInst, VMap, RF_NoModuleLevelChanges | RF_IgnoreMissingEntries); - VMap[BonusInst] = NewBonusInst; + VMap[&*BonusInst] = NewBonusInst; // If we moved a load, we cannot any longer claim any knowledge about // its potential value. The previous information might have been valid // only given the branch precondition. // For an analogous reason, we must also drop all the metadata whose // semantics we don't understand. - NewBonusInst->dropUnknownMetadata(LLVMContext::MD_dbg); + NewBonusInst->dropUnknownNonDebugMetadata(); - PredBlock->getInstList().insert(PBI, NewBonusInst); - NewBonusInst->takeName(BonusInst); + PredBlock->getInstList().insert(PBI->getIterator(), NewBonusInst); + NewBonusInst->takeName(&*BonusInst); BonusInst->setName(BonusInst->getName() + ".old"); } @@ -2211,7 +2244,7 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, unsigned BonusInstThreshold) { Instruction *New = Cond->clone(); RemapInstruction(New, VMap, RF_NoModuleLevelChanges | RF_IgnoreMissingEntries); - PredBlock->getInstList().insert(PBI, New); + PredBlock->getInstList().insert(PBI->getIterator(), New); New->takeName(Cond); Cond->setName(New->getName() + ".old"); @@ -2332,11 +2365,297 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI, unsigned BonusInstThreshold) { return false; } +// If there is only one store in BB1 and BB2, return it, otherwise return +// nullptr. +static StoreInst *findUniqueStoreInBlocks(BasicBlock *BB1, BasicBlock *BB2) { + StoreInst *S = nullptr; + for (auto *BB : {BB1, BB2}) { + if (!BB) + continue; + for (auto &I : *BB) + if (auto *SI = dyn_cast<StoreInst>(&I)) { + if (S) + // Multiple stores seen. + return nullptr; + else + S = SI; + } + } + return S; +} + +static Value *ensureValueAvailableInSuccessor(Value *V, BasicBlock *BB, + Value *AlternativeV = nullptr) { + // PHI is going to be a PHI node that allows the value V that is defined in + // BB to be referenced in BB's only successor. + // + // If AlternativeV is nullptr, the only value we care about in PHI is V. It + // doesn't matter to us what the other operand is (it'll never get used). We + // could just create a new PHI with an undef incoming value, but that could + // increase register pressure if EarlyCSE/InstCombine can't fold it with some + // other PHI. So here we directly look for some PHI in BB's successor with V + // as an incoming operand. If we find one, we use it, else we create a new + // one. + // + // If AlternativeV is not nullptr, we care about both incoming values in PHI. + // PHI must be exactly: phi <ty> [ %BB, %V ], [ %OtherBB, %AlternativeV] + // where OtherBB is the single other predecessor of BB's only successor. + PHINode *PHI = nullptr; + BasicBlock *Succ = BB->getSingleSuccessor(); + + for (auto I = Succ->begin(); isa<PHINode>(I); ++I) + if (cast<PHINode>(I)->getIncomingValueForBlock(BB) == V) { + PHI = cast<PHINode>(I); + if (!AlternativeV) + break; + + assert(std::distance(pred_begin(Succ), pred_end(Succ)) == 2); + auto PredI = pred_begin(Succ); + BasicBlock *OtherPredBB = *PredI == BB ? *++PredI : *PredI; + if (PHI->getIncomingValueForBlock(OtherPredBB) == AlternativeV) + break; + PHI = nullptr; + } + if (PHI) + return PHI; + + // If V is not an instruction defined in BB, just return it. + if (!AlternativeV && + (!isa<Instruction>(V) || cast<Instruction>(V)->getParent() != BB)) + return V; + + PHI = PHINode::Create(V->getType(), 2, "simplifycfg.merge", &Succ->front()); + PHI->addIncoming(V, BB); + for (BasicBlock *PredBB : predecessors(Succ)) + if (PredBB != BB) + PHI->addIncoming(AlternativeV ? AlternativeV : UndefValue::get(V->getType()), + PredBB); + return PHI; +} + +static bool mergeConditionalStoreToAddress(BasicBlock *PTB, BasicBlock *PFB, + BasicBlock *QTB, BasicBlock *QFB, + BasicBlock *PostBB, Value *Address, + bool InvertPCond, bool InvertQCond) { + auto IsaBitcastOfPointerType = [](const Instruction &I) { + return Operator::getOpcode(&I) == Instruction::BitCast && + I.getType()->isPointerTy(); + }; + + // If we're not in aggressive mode, we only optimize if we have some + // confidence that by optimizing we'll allow P and/or Q to be if-converted. + auto IsWorthwhile = [&](BasicBlock *BB) { + if (!BB) + return true; + // Heuristic: if the block can be if-converted/phi-folded and the + // instructions inside are all cheap (arithmetic/GEPs), it's worthwhile to + // thread this store. + unsigned N = 0; + for (auto &I : *BB) { + // Cheap instructions viable for folding. + if (isa<BinaryOperator>(I) || isa<GetElementPtrInst>(I) || + isa<StoreInst>(I)) + ++N; + // Free instructions. + else if (isa<TerminatorInst>(I) || isa<DbgInfoIntrinsic>(I) || + IsaBitcastOfPointerType(I)) + continue; + else + return false; + } + return N <= PHINodeFoldingThreshold; + }; + + if (!MergeCondStoresAggressively && (!IsWorthwhile(PTB) || + !IsWorthwhile(PFB) || + !IsWorthwhile(QTB) || + !IsWorthwhile(QFB))) + return false; + + // For every pointer, there must be exactly two stores, one coming from + // PTB or PFB, and the other from QTB or QFB. We don't support more than one + // store (to any address) in PTB,PFB or QTB,QFB. + // FIXME: We could relax this restriction with a bit more work and performance + // testing. + StoreInst *PStore = findUniqueStoreInBlocks(PTB, PFB); + StoreInst *QStore = findUniqueStoreInBlocks(QTB, QFB); + if (!PStore || !QStore) + return false; + + // Now check the stores are compatible. + if (!QStore->isUnordered() || !PStore->isUnordered()) + return false; + + // Check that sinking the store won't cause program behavior changes. Sinking + // the store out of the Q blocks won't change any behavior as we're sinking + // from a block to its unconditional successor. But we're moving a store from + // the P blocks down through the middle block (QBI) and past both QFB and QTB. + // So we need to check that there are no aliasing loads or stores in + // QBI, QTB and QFB. We also need to check there are no conflicting memory + // operations between PStore and the end of its parent block. + // + // The ideal way to do this is to query AliasAnalysis, but we don't + // preserve AA currently so that is dangerous. Be super safe and just + // check there are no other memory operations at all. + for (auto &I : *QFB->getSinglePredecessor()) + if (I.mayReadOrWriteMemory()) + return false; + for (auto &I : *QFB) + if (&I != QStore && I.mayReadOrWriteMemory()) + return false; + if (QTB) + for (auto &I : *QTB) + if (&I != QStore && I.mayReadOrWriteMemory()) + return false; + for (auto I = BasicBlock::iterator(PStore), E = PStore->getParent()->end(); + I != E; ++I) + if (&*I != PStore && I->mayReadOrWriteMemory()) + return false; + + // OK, we're going to sink the stores to PostBB. The store has to be + // conditional though, so first create the predicate. + Value *PCond = cast<BranchInst>(PFB->getSinglePredecessor()->getTerminator()) + ->getCondition(); + Value *QCond = cast<BranchInst>(QFB->getSinglePredecessor()->getTerminator()) + ->getCondition(); + + Value *PPHI = ensureValueAvailableInSuccessor(PStore->getValueOperand(), + PStore->getParent()); + Value *QPHI = ensureValueAvailableInSuccessor(QStore->getValueOperand(), + QStore->getParent(), PPHI); + + IRBuilder<> QB(&*PostBB->getFirstInsertionPt()); + + Value *PPred = PStore->getParent() == PTB ? PCond : QB.CreateNot(PCond); + Value *QPred = QStore->getParent() == QTB ? QCond : QB.CreateNot(QCond); + + if (InvertPCond) + PPred = QB.CreateNot(PPred); + if (InvertQCond) + QPred = QB.CreateNot(QPred); + Value *CombinedPred = QB.CreateOr(PPred, QPred); + + auto *T = + SplitBlockAndInsertIfThen(CombinedPred, &*QB.GetInsertPoint(), false); + QB.SetInsertPoint(T); + StoreInst *SI = cast<StoreInst>(QB.CreateStore(QPHI, Address)); + AAMDNodes AAMD; + PStore->getAAMetadata(AAMD, /*Merge=*/false); + PStore->getAAMetadata(AAMD, /*Merge=*/true); + SI->setAAMetadata(AAMD); + + QStore->eraseFromParent(); + PStore->eraseFromParent(); + + return true; +} + +static bool mergeConditionalStores(BranchInst *PBI, BranchInst *QBI) { + // The intention here is to find diamonds or triangles (see below) where each + // conditional block contains a store to the same address. Both of these + // stores are conditional, so they can't be unconditionally sunk. But it may + // be profitable to speculatively sink the stores into one merged store at the + // end, and predicate the merged store on the union of the two conditions of + // PBI and QBI. + // + // This can reduce the number of stores executed if both of the conditions are + // true, and can allow the blocks to become small enough to be if-converted. + // This optimization will also chain, so that ladders of test-and-set + // sequences can be if-converted away. + // + // We only deal with simple diamonds or triangles: + // + // PBI or PBI or a combination of the two + // / \ | \ + // PTB PFB | PFB + // \ / | / + // QBI QBI + // / \ | \ + // QTB QFB | QFB + // \ / | / + // PostBB PostBB + // + // We model triangles as a type of diamond with a nullptr "true" block. + // Triangles are canonicalized so that the fallthrough edge is represented by + // a true condition, as in the diagram above. + // + BasicBlock *PTB = PBI->getSuccessor(0); + BasicBlock *PFB = PBI->getSuccessor(1); + BasicBlock *QTB = QBI->getSuccessor(0); + BasicBlock *QFB = QBI->getSuccessor(1); + BasicBlock *PostBB = QFB->getSingleSuccessor(); + + bool InvertPCond = false, InvertQCond = false; + // Canonicalize fallthroughs to the true branches. + if (PFB == QBI->getParent()) { + std::swap(PFB, PTB); + InvertPCond = true; + } + if (QFB == PostBB) { + std::swap(QFB, QTB); + InvertQCond = true; + } + + // From this point on we can assume PTB or QTB may be fallthroughs but PFB + // and QFB may not. Model fallthroughs as a nullptr block. + if (PTB == QBI->getParent()) + PTB = nullptr; + if (QTB == PostBB) + QTB = nullptr; + + // Legality bailouts. We must have at least the non-fallthrough blocks and + // the post-dominating block, and the non-fallthroughs must only have one + // predecessor. + auto HasOnePredAndOneSucc = [](BasicBlock *BB, BasicBlock *P, BasicBlock *S) { + return BB->getSinglePredecessor() == P && + BB->getSingleSuccessor() == S; + }; + if (!PostBB || + !HasOnePredAndOneSucc(PFB, PBI->getParent(), QBI->getParent()) || + !HasOnePredAndOneSucc(QFB, QBI->getParent(), PostBB)) + return false; + if ((PTB && !HasOnePredAndOneSucc(PTB, PBI->getParent(), QBI->getParent())) || + (QTB && !HasOnePredAndOneSucc(QTB, QBI->getParent(), PostBB))) + return false; + if (PostBB->getNumUses() != 2 || QBI->getParent()->getNumUses() != 2) + return false; + + // OK, this is a sequence of two diamonds or triangles. + // Check if there are stores in PTB or PFB that are repeated in QTB or QFB. + SmallPtrSet<Value *,4> PStoreAddresses, QStoreAddresses; + for (auto *BB : {PTB, PFB}) { + if (!BB) + continue; + for (auto &I : *BB) + if (StoreInst *SI = dyn_cast<StoreInst>(&I)) + PStoreAddresses.insert(SI->getPointerOperand()); + } + for (auto *BB : {QTB, QFB}) { + if (!BB) + continue; + for (auto &I : *BB) + if (StoreInst *SI = dyn_cast<StoreInst>(&I)) + QStoreAddresses.insert(SI->getPointerOperand()); + } + + set_intersect(PStoreAddresses, QStoreAddresses); + // set_intersect mutates PStoreAddresses in place. Rename it here to make it + // clear what it contains. + auto &CommonAddresses = PStoreAddresses; + + bool Changed = false; + for (auto *Address : CommonAddresses) + Changed |= mergeConditionalStoreToAddress( + PTB, PFB, QTB, QFB, PostBB, Address, InvertPCond, InvertQCond); + return Changed; +} + /// If we have a conditional branch as a predecessor of another block, /// this function tries to simplify it. We know /// that PBI and BI are both conditional branches, and BI is in one of the /// successor blocks of PBI - PBI branches to BI. -static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI) { +static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI, + const DataLayout &DL) { assert(PBI->isConditional() && BI->isConditional()); BasicBlock *BB = BI->getParent(); @@ -2360,10 +2679,9 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI) { // simplifycfg will thread the block. if (BlockIsSimpleEnoughToThreadThrough(BB)) { pred_iterator PB = pred_begin(BB), PE = pred_end(BB); - PHINode *NewPN = PHINode::Create(Type::getInt1Ty(BB->getContext()), - std::distance(PB, PE), - BI->getCondition()->getName() + ".pr", - BB->begin()); + PHINode *NewPN = PHINode::Create( + Type::getInt1Ty(BB->getContext()), std::distance(PB, PE), + BI->getCondition()->getName() + ".pr", &BB->front()); // Okay, we're going to insert the PHI node. Since PBI is not the only // predecessor, compute the PHI'd conditional value for all of the preds. // Any predecessor where the condition is not computable we keep symbolic. @@ -2386,6 +2704,29 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI) { } } + if (auto *CE = dyn_cast<ConstantExpr>(BI->getCondition())) + if (CE->canTrap()) + return false; + + // If BI is reached from the true path of PBI and PBI's condition implies + // BI's condition, we know the direction of the BI branch. + if (PBI->getSuccessor(0) == BI->getParent() && + isImpliedCondition(PBI->getCondition(), BI->getCondition(), DL) && + PBI->getSuccessor(0) != PBI->getSuccessor(1) && + BB->getSinglePredecessor()) { + // Turn this into a branch on constant. + auto *OldCond = BI->getCondition(); + BI->setCondition(ConstantInt::getTrue(BB->getContext())); + RecursivelyDeleteTriviallyDeadInstructions(OldCond); + return true; // Nuke the branch on constant. + } + + // If both branches are conditional and both contain stores to the same + // address, remove the stores from the conditionals and create a conditional + // merged store at the end. + if (MergeCondStores && mergeConditionalStores(PBI, BI)) + return true; + // If this is a conditional branch in an empty block, and if any // predecessors are a conditional branch to one of our destinations, // fold the conditions into logical ops and one cond br. @@ -2396,11 +2737,6 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI) { if (&*BBI != BI) return false; - - if (ConstantExpr *CE = dyn_cast<ConstantExpr>(BI->getCondition())) - if (CE->canTrap()) - return false; - int PBIOp, BIOp; if (PBI->getSuccessor(0) == BI->getSuccessor(0)) PBIOp = BIOp = 0; @@ -2565,15 +2901,15 @@ static bool SimplifyTerminatorOnSelect(TerminatorInst *OldTerm, Value *Cond, BasicBlock *KeepEdge2 = TrueBB != FalseBB ? FalseBB : nullptr; // Then remove the rest. - for (unsigned I = 0, E = OldTerm->getNumSuccessors(); I != E; ++I) { - BasicBlock *Succ = OldTerm->getSuccessor(I); + for (BasicBlock *Succ : OldTerm->successors()) { // Make sure only to keep exactly one copy of each edge. if (Succ == KeepEdge1) KeepEdge1 = nullptr; else if (Succ == KeepEdge2) KeepEdge2 = nullptr; else - Succ->removePredecessor(OldTerm->getParent()); + Succ->removePredecessor(OldTerm->getParent(), + /*DontDeleteUselessPHIs=*/true); } IRBuilder<> Builder(OldTerm); @@ -2827,7 +3163,7 @@ static bool SimplifyBranchOnICmpChain(BranchInst *BI, IRBuilder<> &Builder, Values.erase(std::unique(Values.begin(), Values.end()), Values.end()); // If Extra was used, we require at least two switch values to do the - // transformation. A switch with one value is just an cond branch. + // transformation. A switch with one value is just a conditional branch. if (ExtraCase && Values.size() < 2) return false; // TODO: Preserve branch weight metadata, similarly to how @@ -2847,7 +3183,8 @@ static bool SimplifyBranchOnICmpChain(BranchInst *BI, IRBuilder<> &Builder, // then we evaluate them with an explicit branch first. Split the block // right before the condbr to handle it. if (ExtraCase) { - BasicBlock *NewBB = BB->splitBasicBlock(BI, "switch.early.test"); + BasicBlock *NewBB = + BB->splitBasicBlock(BI->getIterator(), "switch.early.test"); // Remove the uncond branch added to the old block. TerminatorInst *OldTI = BB->getTerminator(); Builder.SetInsertPoint(OldTI); @@ -2911,34 +3248,15 @@ bool SimplifyCFGOpt::SimplifyResume(ResumeInst *RI, IRBuilder<> &Builder) { return false; // Check that there are no other instructions except for debug intrinsics. - BasicBlock::iterator I = LPInst, E = RI; + BasicBlock::iterator I = LPInst->getIterator(), E = RI->getIterator(); while (++I != E) if (!isa<DbgInfoIntrinsic>(I)) return false; // Turn all invokes that unwind here into calls and delete the basic block. for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE;) { - InvokeInst *II = cast<InvokeInst>((*PI++)->getTerminator()); - SmallVector<Value*, 8> Args(II->op_begin(), II->op_end() - 3); - // Insert a call instruction before the invoke. - CallInst *Call = CallInst::Create(II->getCalledValue(), Args, "", II); - Call->takeName(II); - Call->setCallingConv(II->getCallingConv()); - Call->setAttributes(II->getAttributes()); - Call->setDebugLoc(II->getDebugLoc()); - - // Anything that used the value produced by the invoke instruction now uses - // the value produced by the call instruction. Note that we do this even - // for void functions and calls with no uses so that the callgraph edge is - // updated. - II->replaceAllUsesWith(Call); - BB->removePredecessor(II->getParent()); - - // Insert a branch to the normal destination right before the invoke. - BranchInst::Create(II->getNormalDest(), II); - - // Finally, delete the invoke instruction! - II->eraseFromParent(); + BasicBlock *Pred = *PI++; + removeUnwindEdge(Pred); } // The landingpad is now unreachable. Zap it. @@ -2946,6 +3264,124 @@ bool SimplifyCFGOpt::SimplifyResume(ResumeInst *RI, IRBuilder<> &Builder) { return true; } +bool SimplifyCFGOpt::SimplifyCleanupReturn(CleanupReturnInst *RI) { + // If this is a trivial cleanup pad that executes no instructions, it can be + // eliminated. If the cleanup pad continues to the caller, any predecessor + // that is an EH pad will be updated to continue to the caller and any + // predecessor that terminates with an invoke instruction will have its invoke + // instruction converted to a call instruction. If the cleanup pad being + // simplified does not continue to the caller, each predecessor will be + // updated to continue to the unwind destination of the cleanup pad being + // simplified. + BasicBlock *BB = RI->getParent(); + CleanupPadInst *CPInst = RI->getCleanupPad(); + if (CPInst->getParent() != BB) + // This isn't an empty cleanup. + return false; + + // Check that there are no other instructions except for debug intrinsics. + BasicBlock::iterator I = CPInst->getIterator(), E = RI->getIterator(); + while (++I != E) + if (!isa<DbgInfoIntrinsic>(I)) + return false; + + // If the cleanup return we are simplifying unwinds to the caller, this will + // set UnwindDest to nullptr. + BasicBlock *UnwindDest = RI->getUnwindDest(); + Instruction *DestEHPad = UnwindDest ? UnwindDest->getFirstNonPHI() : nullptr; + + // We're about to remove BB from the control flow. Before we do, sink any + // PHINodes into the unwind destination. Doing this before changing the + // control flow avoids some potentially slow checks, since we can currently + // be certain that UnwindDest and BB have no common predecessors (since they + // are both EH pads). + if (UnwindDest) { + // First, go through the PHI nodes in UnwindDest and update any nodes that + // reference the block we are removing + for (BasicBlock::iterator I = UnwindDest->begin(), + IE = DestEHPad->getIterator(); + I != IE; ++I) { + PHINode *DestPN = cast<PHINode>(I); + + int Idx = DestPN->getBasicBlockIndex(BB); + // Since BB unwinds to UnwindDest, it has to be in the PHI node. + assert(Idx != -1); + // This PHI node has an incoming value that corresponds to a control + // path through the cleanup pad we are removing. If the incoming + // value is in the cleanup pad, it must be a PHINode (because we + // verified above that the block is otherwise empty). Otherwise, the + // value is either a constant or a value that dominates the cleanup + // pad being removed. + // + // Because BB and UnwindDest are both EH pads, all of their + // predecessors must unwind to these blocks, and since no instruction + // can have multiple unwind destinations, there will be no overlap in + // incoming blocks between SrcPN and DestPN. + Value *SrcVal = DestPN->getIncomingValue(Idx); + PHINode *SrcPN = dyn_cast<PHINode>(SrcVal); + + // Remove the entry for the block we are deleting. + DestPN->removeIncomingValue(Idx, false); + + if (SrcPN && SrcPN->getParent() == BB) { + // If the incoming value was a PHI node in the cleanup pad we are + // removing, we need to merge that PHI node's incoming values into + // DestPN. + for (unsigned SrcIdx = 0, SrcE = SrcPN->getNumIncomingValues(); + SrcIdx != SrcE; ++SrcIdx) { + DestPN->addIncoming(SrcPN->getIncomingValue(SrcIdx), + SrcPN->getIncomingBlock(SrcIdx)); + } + } else { + // Otherwise, the incoming value came from above BB and + // so we can just reuse it. We must associate all of BB's + // predecessors with this value. + for (auto *pred : predecessors(BB)) { + DestPN->addIncoming(SrcVal, pred); + } + } + } + + // Sink any remaining PHI nodes directly into UnwindDest. + Instruction *InsertPt = DestEHPad; + for (BasicBlock::iterator I = BB->begin(), + IE = BB->getFirstNonPHI()->getIterator(); + I != IE;) { + // The iterator must be incremented here because the instructions are + // being moved to another block. + PHINode *PN = cast<PHINode>(I++); + if (PN->use_empty()) + // If the PHI node has no uses, just leave it. It will be erased + // when we erase BB below. + continue; + + // Otherwise, sink this PHI node into UnwindDest. + // Any predecessors to UnwindDest which are not already represented + // must be back edges which inherit the value from the path through + // BB. In this case, the PHI value must reference itself. + for (auto *pred : predecessors(UnwindDest)) + if (pred != BB) + PN->addIncoming(PN, pred); + PN->moveBefore(InsertPt); + } + } + + for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE;) { + // The iterator must be updated here because we are removing this pred. + BasicBlock *PredBB = *PI++; + if (UnwindDest == nullptr) { + removeUnwindEdge(PredBB); + } else { + TerminatorInst *TI = PredBB->getTerminator(); + TI->replaceUsesOfWith(BB, UnwindDest); + } + } + + // The cleanup pad is now unreachable. Zap it. + BB->eraseFromParent(); + return true; +} + bool SimplifyCFGOpt::SimplifyReturn(ReturnInst *RI, IRBuilder<> &Builder) { BasicBlock *BB = RI->getParent(); if (!BB->getFirstNonPHIOrDbg()->isTerminator()) return false; @@ -3003,8 +3439,8 @@ bool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) { // If there are any instructions immediately before the unreachable that can // be removed, do so. - while (UI != BB->begin()) { - BasicBlock::iterator BBI = UI; + while (UI->getIterator() != BB->begin()) { + BasicBlock::iterator BBI = UI->getIterator(); --BBI; // Do not delete instructions that can have side effects which might cause // the unreachable to not be reachable; specifically, calls and volatile @@ -3075,26 +3511,18 @@ bool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) { --i; --e; Changed = true; } - } else if (InvokeInst *II = dyn_cast<InvokeInst>(TI)) { - if (II->getUnwindDest() == BB) { - // Convert the invoke to a call instruction. This would be a good - // place to note that the call does not throw though. - BranchInst *BI = Builder.CreateBr(II->getNormalDest()); - II->removeFromParent(); // Take out of symbol table - - // Insert the call now... - SmallVector<Value*, 8> Args(II->op_begin(), II->op_end()-3); - Builder.SetInsertPoint(BI); - CallInst *CI = Builder.CreateCall(II->getCalledValue(), - Args, II->getName()); - CI->setCallingConv(II->getCallingConv()); - CI->setAttributes(II->getAttributes()); - // If the invoke produced a value, the call does now instead. - II->replaceAllUsesWith(CI); - delete II; - Changed = true; - } + } else if ((isa<InvokeInst>(TI) && + cast<InvokeInst>(TI)->getUnwindDest() == BB) || + isa<CatchSwitchInst>(TI)) { + removeUnwindEdge(TI->getParent()); + Changed = true; + } else if (isa<CleanupReturnInst>(TI)) { + new UnreachableInst(TI->getContext(), TI); + TI->eraseFromParent(); + Changed = true; } + // TODO: We can remove a catchswitch if all it's catchpads end in + // unreachable. } // If this block is now dead, remove it. @@ -3249,6 +3677,29 @@ static bool EliminateDeadSwitchCases(SwitchInst *SI, AssumptionCache *AC, } } + // If we can prove that the cases must cover all possible values, the + // default destination becomes dead and we can remove it. If we know some + // of the bits in the value, we can use that to more precisely compute the + // number of possible unique case values. + bool HasDefault = + !isa<UnreachableInst>(SI->getDefaultDest()->getFirstNonPHIOrDbg()); + const unsigned NumUnknownBits = Bits - + (KnownZero.Or(KnownOne)).countPopulation(); + assert(NumUnknownBits <= Bits); + if (HasDefault && DeadCases.empty() && + NumUnknownBits < 64 /* avoid overflow */ && + SI->getNumCases() == (1ULL << NumUnknownBits)) { + DEBUG(dbgs() << "SimplifyCFG: switch default is dead.\n"); + BasicBlock *NewDefault = SplitBlockPredecessors(SI->getDefaultDest(), + SI->getParent(), ""); + SI->setDefaultDest(&*NewDefault); + SplitBlock(&*NewDefault, &NewDefault->front()); + auto *OldTI = NewDefault->getTerminator(); + new UnreachableInst(SI->getContext(), OldTI); + EraseTerminatorInstAndDCECond(OldTI); + return true; + } + SmallVector<uint64_t, 8> Weights; bool HasWeight = HasBranchWeights(SI); if (HasWeight) { @@ -3439,7 +3890,7 @@ GetCaseResults(SwitchInst *SI, ConstantInt *CaseVal, BasicBlock *CaseDest, } else if (isa<DbgInfoIntrinsic>(I)) { // Skip debug intrinsic. continue; - } else if (Constant *C = ConstantFold(I, DL, ConstantPool)) { + } else if (Constant *C = ConstantFold(&*I, DL, ConstantPool)) { // Instruction is side-effect free and constant. // If the instruction has uses outside this block or a phi node slot for @@ -3456,7 +3907,7 @@ GetCaseResults(SwitchInst *SI, ConstantInt *CaseVal, BasicBlock *CaseDest, return false; } - ConstantPool.insert(std::make_pair(I, C)); + ConstantPool.insert(std::make_pair(&*I, C)); } else { break; } @@ -3664,7 +4115,7 @@ namespace { /// Return true if a table with TableSize elements of /// type ElementType would fit in a target-legal register. static bool WouldFitInRegister(const DataLayout &DL, uint64_t TableSize, - const Type *ElementType); + Type *ElementType); private: // Depending on the contents of the table, it can be represented in @@ -3880,8 +4331,8 @@ Value *SwitchLookupTable::BuildLookup(Value *Index, IRBuilder<> &Builder) { bool SwitchLookupTable::WouldFitInRegister(const DataLayout &DL, uint64_t TableSize, - const Type *ElementType) { - const IntegerType *IT = dyn_cast<IntegerType>(ElementType); + Type *ElementType) { + auto *IT = dyn_cast<IntegerType>(ElementType); if (!IT) return false; // FIXME: If the type is wider than it needs to be, e.g. i8 but all values @@ -3992,7 +4443,7 @@ static void reuseTableCompare(User *PhiUser, BasicBlock *PhiBlock, assert((CaseConst == TrueConst || CaseConst == FalseConst) && "Expect true or false as compare result."); } - + // Check if the branch instruction dominates the phi node. It's a simple // dominance check, but sufficient for our needs. // Although this check is invariant in the calling loops, it's better to do it @@ -4422,7 +4873,7 @@ bool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI, IRBuilder<> &Builder){ return true; // If the Terminator is the only non-phi instruction, simplify the block. - BasicBlock::iterator I = BB->getFirstNonPHIOrDbg(); + BasicBlock::iterator I = BB->getFirstNonPHIOrDbg()->getIterator(); if (I->isTerminator() && BB != &BB->getParent()->getEntryBlock() && TryToSimplifyUncondBranchFromEmptyBlock(BB)) return true; @@ -4457,6 +4908,16 @@ bool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI, IRBuilder<> &Builder){ return false; } +static BasicBlock *allPredecessorsComeFromSameSource(BasicBlock *BB) { + BasicBlock *PredPred = nullptr; + for (auto *P : predecessors(BB)) { + BasicBlock *PPred = P->getSinglePredecessor(); + if (!PPred || (PredPred && PredPred != PPred)) + return nullptr; + PredPred = PPred; + } + return PredPred; +} bool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) { BasicBlock *BB = BI->getParent(); @@ -4537,9 +4998,17 @@ bool SimplifyCFGOpt::SimplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder) { for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) if (BranchInst *PBI = dyn_cast<BranchInst>((*PI)->getTerminator())) if (PBI != BI && PBI->isConditional()) - if (SimplifyCondBranchToCondBranch(PBI, BI)) + if (SimplifyCondBranchToCondBranch(PBI, BI, DL)) return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true; + // Look for diamond patterns. + if (MergeCondStores) + if (BasicBlock *PrevBB = allPredecessorsComeFromSameSource(BB)) + if (BranchInst *PBI = dyn_cast<BranchInst>(PrevBB->getTerminator())) + if (PBI != BI && PBI->isConditional()) + if (mergeConditionalStores(PBI, BI)) + return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true; + return false; } @@ -4663,6 +5132,9 @@ bool SimplifyCFGOpt::run(BasicBlock *BB) { if (SimplifyReturn(RI, Builder)) return true; } else if (ResumeInst *RI = dyn_cast<ResumeInst>(BB->getTerminator())) { if (SimplifyResume(RI, Builder)) return true; + } else if (CleanupReturnInst *RI = + dyn_cast<CleanupReturnInst>(BB->getTerminator())) { + if (SimplifyCleanupReturn(RI)) return true; } else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) { if (SimplifySwitch(SI, Builder)) return true; } else if (UnreachableInst *UI = |
