//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "simplifycfg"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
using namespace llvm;
using namespace PatternMatch;
+#define DEBUG_TYPE "simplifycfg"
+
static cl::opt<unsigned>
PHINodeFoldingThreshold("phi-node-folding-threshold", cl::Hidden, cl::init(1),
cl::desc("Control the amount of phi node folding to perform (default = 1)"));
STATISTIC(NumBitMaps, "Number of switch instructions turned into bitmaps");
STATISTIC(NumLookupTables, "Number of switch instructions turned into lookup tables");
+STATISTIC(NumLookupTablesHoles, "Number of switch instructions turned into lookup tables (holes checked)");
STATISTIC(NumSinkCommons, "Number of common instructions sunk down to the end block");
STATISTIC(NumSpeculations, "Number of speculative executed instructions");
if (!cast<GEPOperator>(I)->hasAllConstantIndices())
return UINT_MAX;
return 1;
+ case Instruction::ExtractValue:
case Instruction::Load:
case Instruction::Add:
case Instruction::Sub:
case Instruction::Trunc:
case Instruction::ZExt:
case Instruction::SExt:
+ case Instruction::BitCast:
+ case Instruction::ExtractElement:
+ case Instruction::InsertElement:
return 1; // These are all cheap.
case Instruction::Call:
// branch to BB, then it must be in the 'conditional' part of the "if
// statement". If not, it definitely dominates the region.
BranchInst *BI = dyn_cast<BranchInst>(PBB->getTerminator());
- if (BI == 0 || BI->isConditional() || BI->getSuccessor(0) != BB)
+ if (!BI || BI->isConditional() || BI->getSuccessor(0) != BB)
return true;
// If we aren't allowing aggressive promotion anymore, then don't consider
// instructions in the 'if region'.
- if (AggressiveInsts == 0) return false;
+ if (!AggressiveInsts) return false;
// If we have seen this instruction before, don't count it again.
if (AggressiveInsts->count(I)) return true;
return cast<ConstantInt>
(ConstantExpr::getIntegerCast(CI, PtrTy, /*isSigned=*/false));
}
- return 0;
+ return nullptr;
}
/// GatherConstantCompares - Given a potentially 'or'd or 'and'd together
GatherConstantCompares(Value *V, std::vector<ConstantInt*> &Vals, Value *&Extra,
const DataLayout *DL, bool isEQ, unsigned &UsedICmps) {
Instruction *I = dyn_cast<Instruction>(V);
- if (I == 0) return 0;
+ if (!I) return nullptr;
// If this is an icmp against a constant, handle this as one of the cases.
if (ICmpInst *ICI = dyn_cast<ICmpInst>(I)) {
// If there are a ton of values, we don't want to make a ginormous switch.
if (Span.getSetSize().ugt(8) || Span.isEmptySet())
- return 0;
+ return nullptr;
for (APInt Tmp = Span.getLower(); Tmp != Span.getUpper(); ++Tmp)
Vals.push_back(ConstantInt::get(V->getContext(), Tmp));
UsedICmps++;
return hasAdd ? RHSVal : I->getOperand(0);
}
- return 0;
+ return nullptr;
}
// Otherwise, we can only handle an | or &, depending on isEQ.
if (I->getOpcode() != (isEQ ? Instruction::Or : Instruction::And))
- return 0;
+ return nullptr;
unsigned NumValsBeforeLHS = Vals.size();
unsigned UsedICmpsBeforeLHS = UsedICmps;
// The RHS of the or/and can't be folded in and we haven't used "Extra" yet,
// set it and return success.
- if (Extra == 0 || Extra == I->getOperand(1)) {
+ if (Extra == nullptr || Extra == I->getOperand(1)) {
Extra = I->getOperand(1);
return LHS;
}
Vals.resize(NumValsBeforeLHS);
UsedICmps = UsedICmpsBeforeLHS;
- return 0;
+ return nullptr;
}
// If the LHS can't be folded in, but Extra is available and RHS can, try to
// use LHS as Extra.
- if (Extra == 0 || Extra == I->getOperand(0)) {
+ if (Extra == nullptr || Extra == I->getOperand(0)) {
Value *OldExtra = Extra;
Extra = I->getOperand(0);
if (Value *RHS = GatherConstantCompares(I->getOperand(1), Vals, Extra, DL,
Extra = OldExtra;
}
- return 0;
+ return nullptr;
}
static void EraseTerminatorInstAndDCECond(TerminatorInst *TI) {
- Instruction *Cond = 0;
+ Instruction *Cond = nullptr;
if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
Cond = dyn_cast<Instruction>(SI->getCondition());
} else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
/// isValueEqualityComparison - Return true if the specified terminator checks
/// to see if a value is equal to constant integer value.
Value *SimplifyCFGOpt::isValueEqualityComparison(TerminatorInst *TI) {
- Value *CV = 0;
+ Value *CV = nullptr;
if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
// Do not permit merging of large switch instructions into their
// predecessors unless there is only one predecessor.
// Otherwise, TI's block must correspond to some matched value. Find out
// which value (or set of values) this is.
- ConstantInt *TIV = 0;
+ ConstantInt *TIV = nullptr;
BasicBlock *TIBB = TI->getParent();
for (unsigned i = 0, e = PredCases.size(); i != e; ++i)
if (PredCases[i].Dest == TIBB) {
- if (TIV != 0)
+ if (TIV)
return false; // Cannot handle multiple values coming to this block.
TIV = PredCases[i].Value;
}
// Okay, we found the one constant that our value can be if we get into TI's
// BB. Find out which successor will unconditionally be branched to.
- BasicBlock *TheRealDest = 0;
+ BasicBlock *TheRealDest = nullptr;
for (unsigned i = 0, e = ThisCases.size(); i != e; ++i)
if (ThisCases[i].Value == TIV) {
TheRealDest = ThisCases[i].Dest;
}
// If not handled by any explicit cases, it is handled by the default case.
- if (TheRealDest == 0) TheRealDest = ThisDef;
+ if (!TheRealDest) TheRealDest = ThisDef;
// Remove PHI node entries for dead edges.
BasicBlock *CheckEdge = TheRealDest;
if (*SI != CheckEdge)
(*SI)->removePredecessor(TIBB);
else
- CheckEdge = 0;
+ CheckEdge = nullptr;
// Insert the new branch.
Instruction *NI = Builder.CreateBr(TheRealDest);
MDNode* MD = TI->getMetadata(LLVMContext::MD_prof);
assert(MD);
for (unsigned i = 1, e = MD->getNumOperands(); i < e; ++i) {
- ConstantInt* CI = dyn_cast<ConstantInt>(MD->getOperand(i));
- assert(CI);
+ ConstantInt *CI = cast<ConstantInt>(MD->getOperand(i));
Weights.push_back(CI->getValue().getZExtValue());
}
/// Keep halving the weights until all can fit in uint32_t.
static void FitWeights(MutableArrayRef<uint64_t> Weights) {
- while (true) {
- bool Halve = false;
- for (unsigned i = 0; i < Weights.size(); ++i)
- if (Weights[i] > UINT_MAX) {
- Halve = true;
- break;
- }
-
- if (! Halve)
- return;
-
- for (unsigned i = 0; i < Weights.size(); ++i)
- Weights[i] /= 2;
+ uint64_t Max = *std::max_element(Weights.begin(), Weights.end());
+ if (Max > UINT_MAX) {
+ unsigned Offset = 32 - countLeadingZeros(Max);
+ for (uint64_t &I : Weights)
+ I >>= Offset;
}
}
// Okay, last check. If BB is still a successor of PSI, then we must
// have an infinite loop case. If so, add an infinitely looping block
// to handle the case to preserve the behavior of the code.
- BasicBlock *InfLoopBlock = 0;
+ BasicBlock *InfLoopBlock = nullptr;
for (unsigned i = 0, e = NewSI->getNumSuccessors(); i != e; ++i)
if (NewSI->getSuccessor(i) == BB) {
- if (InfLoopBlock == 0) {
+ if (!InfLoopBlock) {
// Insert it at the end of the function, because it's either code,
// or it won't matter if it's hot. :)
InfLoopBlock = BasicBlock::Create(BB->getContext(),
// These values do not agree. Insert a select instruction before NT
// that determines the right value.
SelectInst *&SI = InsertedSelects[std::make_pair(BB1V, BB2V)];
- if (SI == 0)
+ if (!SI)
SI = cast<SelectInst>
(Builder.CreateSelect(BI->getCondition(), BB1V, BB2V,
BB1V->getName()+"."+BB2V->getName()));
// Gather the PHI nodes in BBEnd.
std::map<Value*, std::pair<Value*, PHINode*> > MapValueFromBB1ToBB2;
- Instruction *FirstNonPhiInBBEnd = 0;
+ Instruction *FirstNonPhiInBBEnd = nullptr;
for (BasicBlock::iterator I = BBEnd->begin(), E = BBEnd->end();
I != E; ++I) {
if (PHINode *PN = dyn_cast<PHINode>(I)) {
// The operands should be either the same or they need to be generated
// with a PHI node after sinking. We only handle the case where there is
// a single pair of different operands.
- Value *DifferentOp1 = 0, *DifferentOp2 = 0;
+ Value *DifferentOp1 = nullptr, *DifferentOp2 = nullptr;
unsigned Op1Idx = 0;
for (unsigned I = 0, E = I1->getNumOperands(); I != E; ++I) {
if (I1->getOperand(I) == I2->getOperand(I))
BasicBlock *StoreBB, BasicBlock *EndBB) {
StoreInst *StoreToHoist = dyn_cast<StoreInst>(I);
if (!StoreToHoist)
- return 0;
+ return nullptr;
// Volatile or atomic.
if (!StoreToHoist->isSimple())
- return 0;
+ return nullptr;
Value *StorePtr = StoreToHoist->getPointerOperand();
// Could be calling an instruction that effects memory like free().
if (CurI->mayHaveSideEffects() && !isa<StoreInst>(CurI))
- return 0;
+ return nullptr;
StoreInst *SI = dyn_cast<StoreInst>(CurI);
// Found the previous store make sure it stores to the same location.
// Found the previous store, return its value operand.
return SI->getValueOperand();
else if (SI)
- return 0; // Unknown store.
+ return nullptr; // Unknown store.
}
- return 0;
+ return nullptr;
}
/// \brief Speculate a conditional basic block flattening the CFG.
SmallDenseMap<Instruction *, unsigned, 4> SinkCandidateUseCounts;
unsigned SpeculationCost = 0;
- Value *SpeculatedStoreValue = 0;
- StoreInst *SpeculatedStore = 0;
+ Value *SpeculatedStoreValue = nullptr;
+ StoreInst *SpeculatedStore = nullptr;
for (BasicBlock::iterator BBI = ThenBB->begin(),
BBE = std::prev(ThenBB->end());
BBI != BBE; ++BBI) {
// constants.
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
ConstantInt *CB = dyn_cast<ConstantInt>(PN->getIncomingValue(i));
- if (CB == 0 || !CB->getType()->isIntegerTy(1)) continue;
+ if (!CB || !CB->getType()->isIntegerTy(1)) continue;
// Okay, we now know that all edges from PredBB should be revectored to
// branch to RealDest.
// If we folded the first phi, PN dangles at this point. Refresh it. If
// we ran out of PHIs then we simplified them all.
PN = dyn_cast<PHINode>(BB->begin());
- if (PN == 0) return true;
+ if (!PN) return true;
// Don't fold i1 branches on PHIs which contain binary operators. These can
// often be turned into switches and other things.
// instructions in the predecessor blocks can be promoted as well. If
// not, we won't be able to get rid of the control flow, so it's not
// worth promoting to select instructions.
- BasicBlock *DomBlock = 0;
+ BasicBlock *DomBlock = nullptr;
BasicBlock *IfBlock1 = PN->getIncomingBlock(0);
BasicBlock *IfBlock2 = PN->getIncomingBlock(1);
if (cast<BranchInst>(IfBlock1->getTerminator())->isConditional()) {
- IfBlock1 = 0;
+ IfBlock1 = nullptr;
} else {
DomBlock = *pred_begin(IfBlock1);
for (BasicBlock::iterator I = IfBlock1->begin();!isa<TerminatorInst>(I);++I)
}
if (cast<BranchInst>(IfBlock2->getTerminator())->isConditional()) {
- IfBlock2 = 0;
+ IfBlock2 = nullptr;
} else {
DomBlock = *pred_begin(IfBlock2);
for (BasicBlock::iterator I = IfBlock2->begin();!isa<TerminatorInst>(I);++I)
bool llvm::FoldBranchToCommonDest(BranchInst *BI) {
BasicBlock *BB = BI->getParent();
- Instruction *Cond = 0;
+ Instruction *Cond = nullptr;
if (BI->isConditional())
Cond = dyn_cast<Instruction>(BI->getCondition());
else {
}
}
- if (Cond == 0)
+ if (!Cond)
return false;
}
- if (Cond == 0 || (!isa<CmpInst>(Cond) && !isa<BinaryOperator>(Cond)) ||
- Cond->getParent() != BB || !Cond->hasOneUse())
+ if (!Cond || (!isa<CmpInst>(Cond) && !isa<BinaryOperator>(Cond)) ||
+ Cond->getParent() != BB || !Cond->hasOneUse())
return false;
// Only allow this if the condition is a simple instruction that can be
// that feeds the branch. We later ensure that any values that _it_ uses
// were also live in the predecessor, so that we don't unnecessarily create
// register pressure or inhibit out-of-order execution.
- Instruction *BonusInst = 0;
+ Instruction *BonusInst = nullptr;
if (&*FrontIt != Cond &&
FrontIt->hasOneUse() && FrontIt->user_back() == Cond &&
isSafeToSpeculativelyExecute(FrontIt)) {
// Finally, don't infinitely unroll conditional loops.
BasicBlock *TrueDest = BI->getSuccessor(0);
- BasicBlock *FalseDest = (BI->isConditional()) ? BI->getSuccessor(1) : 0;
+ BasicBlock *FalseDest = (BI->isConditional()) ? BI->getSuccessor(1) : nullptr;
if (TrueDest == BB || FalseDest == BB)
return false;
// the common successor, verify that the same value flows in from both
// blocks.
SmallVector<PHINode*, 4> PHIs;
- if (PBI == 0 || PBI->isUnconditional() ||
+ if (!PBI || PBI->isUnconditional() ||
(BI->isConditional() &&
!SafeToMergeTerminators(BI, PBI)) ||
(!BI->isConditional() &&
}
// If we have a bonus inst, clone it into the predecessor block.
- Instruction *NewBonus = 0;
+ Instruction *NewBonus = nullptr;
if (BonusInst) {
NewBonus = BonusInst->clone();
MDBuilder(BI->getContext()).
createBranchWeights(MDWeights));
} else
- PBI->setMetadata(LLVMContext::MD_prof, NULL);
+ PBI->setMetadata(LLVMContext::MD_prof, nullptr);
} else {
// Update PHI nodes in the common successors.
for (unsigned i = 0, e = PHIs.size(); i != e; ++i) {
ConstantInt *PBI_C = cast<ConstantInt>(
PHIs[i]->getIncomingValueForBlock(PBI->getParent()));
assert(PBI_C->getType()->isIntegerTy(1));
- Instruction *MergedCond = 0;
+ Instruction *MergedCond = nullptr;
if (PBI->getSuccessor(0) == TrueDest) {
// Create (PBI_Cond and PBI_C) or (!PBI_Cond and BI_Value)
// PBI_C is true: PBI_Cond or (!PBI_Cond and BI_Value)
// If TrueBB and FalseBB are equal, only try to preserve one copy of that
// successor.
BasicBlock *KeepEdge1 = TrueBB;
- BasicBlock *KeepEdge2 = TrueBB != FalseBB ? FalseBB : 0;
+ 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);
// Make sure only to keep exactly one copy of each edge.
if (Succ == KeepEdge1)
- KeepEdge1 = 0;
+ KeepEdge1 = nullptr;
else if (Succ == KeepEdge2)
- KeepEdge2 = 0;
+ KeepEdge2 = nullptr;
else
Succ->removePredecessor(OldTerm->getParent());
}
Builder.SetCurrentDebugLocation(OldTerm->getDebugLoc());
// Insert an appropriate new terminator.
- if ((KeepEdge1 == 0) && (KeepEdge2 == 0)) {
+ if (!KeepEdge1 && !KeepEdge2) {
if (TrueBB == FalseBB)
// We were only looking for one successor, and it was present.
// Create an unconditional branch to it.
// One of the selected values was a successor, but the other wasn't.
// Insert an unconditional branch to the one that was found;
// the edge to the one that wasn't must be unreachable.
- if (KeepEdge1 == 0)
+ if (!KeepEdge1)
// Only TrueBB was found.
Builder.CreateBr(TrueBB);
else
// 'V' and this block is the default case for the switch. In this case we can
// fold the compared value into the switch to simplify things.
BasicBlock *Pred = BB->getSinglePredecessor();
- if (Pred == 0 || !isa<SwitchInst>(Pred->getTerminator())) return false;
+ if (!Pred || !isa<SwitchInst>(Pred->getTerminator())) return false;
SwitchInst *SI = cast<SwitchInst>(Pred->getTerminator());
if (SI->getCondition() != V)
// the block.
BasicBlock *SuccBlock = BB->getTerminator()->getSuccessor(0);
PHINode *PHIUse = dyn_cast<PHINode>(ICI->user_back());
- if (PHIUse == 0 || PHIUse != &SuccBlock->front() ||
+ if (PHIUse == nullptr || PHIUse != &SuccBlock->front() ||
isa<PHINode>(++BasicBlock::iterator(PHIUse)))
return false;
static bool SimplifyBranchOnICmpChain(BranchInst *BI, const DataLayout *DL,
IRBuilder<> &Builder) {
Instruction *Cond = dyn_cast<Instruction>(BI->getCondition());
- if (Cond == 0) return false;
+ if (!Cond) return false;
// Change br (X == 0 | X == 1), T, F into a switch instruction.
// If this is a bunch of seteq's or'd together, or if it's a bunch of
// 'setne's and'ed together, collect them.
- Value *CompVal = 0;
+ Value *CompVal = nullptr;
std::vector<ConstantInt*> Values;
bool TrueWhenEqual = true;
- Value *ExtraCase = 0;
+ Value *ExtraCase = nullptr;
unsigned UsedICmps = 0;
if (Cond->getOpcode() == Instruction::Or) {
}
// If we didn't have a multiply compared value, fail.
- if (CompVal == 0) return false;
+ if (!CompVal) return false;
// Avoid turning single icmps into a switch.
if (UsedICmps <= 1)
// Find the most popular block.
unsigned MaxPop = 0;
unsigned MaxIndex = 0;
- BasicBlock *MaxBlock = 0;
+ BasicBlock *MaxBlock = nullptr;
for (std::map<BasicBlock*, std::pair<unsigned, unsigned> >::iterator
I = Popularity.begin(), E = Popularity.end(); I != E; ++I) {
if (I->second.first > MaxPop ||
Value *Cond = SI->getCondition();
unsigned Bits = Cond->getType()->getIntegerBitWidth();
APInt KnownZero(Bits, 0), KnownOne(Bits, 0);
- ComputeMaskedBits(Cond, KnownZero, KnownOne);
+ computeKnownBits(Cond, KnownZero, KnownOne);
// Gather dead cases.
SmallVector<ConstantInt*, 8> DeadCases;
BasicBlock *BB,
int *PhiIndex) {
if (BB->getFirstNonPHIOrDbg() != BB->getTerminator())
- return NULL; // BB must be empty to be a candidate for simplification.
+ return nullptr; // BB must be empty to be a candidate for simplification.
if (!BB->getSinglePredecessor())
- return NULL; // BB must be dominated by the switch.
+ return nullptr; // BB must be dominated by the switch.
BranchInst *Branch = dyn_cast<BranchInst>(BB->getTerminator());
if (!Branch || !Branch->isUnconditional())
- return NULL; // Terminator must be unconditional branch.
+ return nullptr; // Terminator must be unconditional branch.
BasicBlock *Succ = Branch->getSuccessor(0);
return PHI;
}
- return NULL;
+ return nullptr;
}
/// ForwardSwitchConditionToPHI - Try to forward the condition of a switch
/// ValidLookupTableConstant - Return true if the backend will be able to handle
/// initializing an array of constants like C.
static bool ValidLookupTableConstant(Constant *C) {
+ if (C->isThreadDependent())
+ return false;
+ if (C->isDLLImportDependent())
+ return false;
+
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
return CE->isGEPWithNoNotionalOverIndexing();
if (SelectInst *Select = dyn_cast<SelectInst>(I)) {
Constant *A = LookupConstant(Select->getCondition(), ConstantPool);
if (!A)
- return 0;
+ return nullptr;
if (A->isAllOnesValue())
return LookupConstant(Select->getTrueValue(), ConstantPool);
if (A->isNullValue())
return LookupConstant(Select->getFalseValue(), ConstantPool);
- return 0;
+ return nullptr;
}
SmallVector<Constant *, 4> COps;
if (Constant *A = LookupConstant(I->getOperand(N), ConstantPool))
COps.push_back(A);
else
- return 0;
+ return nullptr;
}
if (CmpInst *Cmp = dyn_cast<CmpInst>(I))
const SmallVectorImpl<std::pair<ConstantInt*, Constant*> >& Values,
Constant *DefaultValue,
const DataLayout *DL)
- : SingleValue(0), BitMap(0), BitMapElementTy(0), Array(0) {
+ : SingleValue(nullptr), BitMap(nullptr), BitMapElementTy(nullptr),
+ Array(nullptr) {
assert(Values.size() && "Can't build lookup table without values!");
assert(TableSize >= Values.size() && "Can't fit values in table!");
TableContents[Idx] = CaseRes;
if (CaseRes != SingleValue)
- SingleValue = 0;
+ SingleValue = nullptr;
}
// Fill in any holes in the table with the default result.
}
if (DefaultValue != SingleValue)
- SingleValue = 0;
+ SingleValue = nullptr;
}
// If each element in the table contains the same value, we only need to store
ConstantInt *MinCaseVal = CI.getCaseValue();
ConstantInt *MaxCaseVal = CI.getCaseValue();
- BasicBlock *CommonDest = 0;
+ BasicBlock *CommonDest = nullptr;
typedef SmallVector<std::pair<ConstantInt*, Constant*>, 4> ResultListTy;
SmallDenseMap<PHINode*, ResultListTy> ResultLists;
SmallDenseMap<PHINode*, Constant*> DefaultResults;
uint64_t TableSize = RangeSpread.getLimitedValue() + 1;
bool TableHasHoles = (NumResults < TableSize);
- // If the table has holes, we need a constant result for the default case.
+ // If the table has holes, we need a constant result for the default case
+ // or a bitmask that fits in a register.
SmallVector<std::pair<PHINode*, Constant*>, 4> DefaultResultsList;
- if (TableHasHoles && !GetCaseResults(SI, 0, SI->getDefaultDest(), &CommonDest,
- DefaultResultsList, DL))
- return false;
+ bool HasDefaultResults = false;
+ if (TableHasHoles) {
+ HasDefaultResults = GetCaseResults(SI, nullptr, SI->getDefaultDest(),
+ &CommonDest, DefaultResultsList, DL);
+ }
+ bool NeedMask = (TableHasHoles && !HasDefaultResults);
+ if (NeedMask) {
+ // As an extra penalty for the validity test we require more cases.
+ if (SI->getNumCases() < 4) // FIXME: Find best threshold value (benchmark).
+ return false;
+ if (!(DL && DL->fitsInLegalInteger(TableSize)))
+ return false;
+ }
for (size_t I = 0, E = DefaultResultsList.size(); I != E; ++I) {
PHINode *PHI = DefaultResultsList[I].first;
// Populate the BB that does the lookups.
Builder.SetInsertPoint(LookupBB);
+
+ if (NeedMask) {
+ // Before doing the lookup we do the hole check.
+ // The LookupBB is therefore re-purposed to do the hole check
+ // and we create a new LookupBB.
+ BasicBlock *MaskBB = LookupBB;
+ MaskBB->setName("switch.hole_check");
+ LookupBB = BasicBlock::Create(Mod.getContext(),
+ "switch.lookup",
+ CommonDest->getParent(),
+ CommonDest);
+
+ // Build bitmask; fill in a 1 bit for every case.
+ APInt MaskInt(TableSize, 0);
+ APInt One(TableSize, 1);
+ const ResultListTy &ResultList = ResultLists[PHIs[0]];
+ for (size_t I = 0, E = ResultList.size(); I != E; ++I) {
+ uint64_t Idx = (ResultList[I].first->getValue() -
+ MinCaseVal->getValue()).getLimitedValue();
+ MaskInt |= One << Idx;
+ }
+ ConstantInt *TableMask = ConstantInt::get(Mod.getContext(), MaskInt);
+
+ // Get the TableIndex'th bit of the bitmask.
+ // If this bit is 0 (meaning hole) jump to the default destination,
+ // else continue with table lookup.
+ IntegerType *MapTy = TableMask->getType();
+ Value *MaskIndex = Builder.CreateZExtOrTrunc(TableIndex, MapTy,
+ "switch.maskindex");
+ Value *Shifted = Builder.CreateLShr(TableMask, MaskIndex,
+ "switch.shifted");
+ Value *LoBit = Builder.CreateTrunc(Shifted,
+ Type::getInt1Ty(Mod.getContext()),
+ "switch.lobit");
+ Builder.CreateCondBr(LoBit, LookupBB, SI->getDefaultDest());
+
+ Builder.SetInsertPoint(LookupBB);
+ AddPredecessorToBlock(SI->getDefaultDest(), MaskBB, SI->getParent());
+ }
+
bool ReturnedEarly = false;
for (size_t I = 0, E = PHIs.size(); I != E; ++I) {
PHINode *PHI = PHIs[I];
+ // If using a bitmask, use any value to fill the lookup table holes.
+ Constant *DV = NeedMask ? ResultLists[PHI][0].second : DefaultResults[PHI];
SwitchLookupTable Table(Mod, TableSize, MinCaseVal, ResultLists[PHI],
- DefaultResults[PHI], DL);
+ DV, DL);
Value *Result = Table.BuildLookup(TableIndex, Builder);
SI->eraseFromParent();
++NumLookupTables;
+ if (NeedMask)
+ ++NumLookupTablesHoles;
return true;
}
// from BI. We know that the condbr dominates the two blocks, so see if
// there is any identical code in the "then" and "else" blocks. If so, we
// can hoist it up to the branching block.
- if (BI->getSuccessor(0)->getSinglePredecessor() != 0) {
- if (BI->getSuccessor(1)->getSinglePredecessor() != 0) {
+ if (BI->getSuccessor(0)->getSinglePredecessor()) {
+ if (BI->getSuccessor(1)->getSinglePredecessor()) {
if (HoistThenElseCodeToIf(BI))
return SimplifyCFG(BB, TTI, DL) | true;
} else {
if (SpeculativelyExecuteBB(BI, BI->getSuccessor(0)))
return SimplifyCFG(BB, TTI, DL) | true;
}
- } else if (BI->getSuccessor(1)->getSinglePredecessor() != 0) {
+ } else if (BI->getSuccessor(1)->getSinglePredecessor()) {
// If Successor #0 has multiple preds, we may be able to conditionally
// execute Successor #1 if it branches to successor #0.
TerminatorInst *Succ1TI = BI->getSuccessor(1)->getTerminator();
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