#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>
#include <set>
#define DEBUG_TYPE "simplifycfg"
+// Chosen as 2 so as to be cheap, but still to have enough power to fold
+// a select, so the "clamp" idiom (of a min followed by a max) will be caught.
+// To catch this, we need to fold a compare and a select, hence '2' being the
+// minimum reasonable default.
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)"));
+PHINodeFoldingThreshold("phi-node-folding-threshold", cl::Hidden, cl::init(2),
+ cl::desc("Control the amount of phi node folding to perform (default = 2)"));
static cl::opt<bool>
DupRet("simplifycfg-dup-ret", cl::Hidden, cl::init(false),
cl::desc("Hoist conditional stores if an unconditional store precedes"));
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");
STATISTIC(NumLookupTablesHoles, "Number of switch instructions turned into lookup tables (holes checked)");
+STATISTIC(NumTableCmpReuses, "Number of reused switch table lookup compares");
STATISTIC(NumSinkCommons, "Number of common instructions sunk down to the end block");
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.
+ 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.
+ typedef SmallVector<std::pair<PHINode *, Constant *>, 4> SwitchCaseResultsTy;
+
/// ValueEqualityComparisonCase - Represents a case of a switch.
struct ValueEqualityComparisonCase {
ConstantInt *Value;
class SimplifyCFGOpt {
const TargetTransformInfo &TTI;
- const DataLayout *const DL;
+ const DataLayout &DL;
+ unsigned BonusInstThreshold;
+ AssumptionCache *AC;
Value *isValueEqualityComparison(TerminatorInst *TI);
BasicBlock *GetValueEqualityComparisonCases(TerminatorInst *TI,
std::vector<ValueEqualityComparisonCase> &Cases);
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);
bool SimplifyCondBranch(BranchInst *BI, IRBuilder <>&Builder);
public:
- SimplifyCFGOpt(const TargetTransformInfo &TTI, const DataLayout *DL)
- : TTI(TTI), DL(DL) {}
+ SimplifyCFGOpt(const TargetTransformInfo &TTI, const DataLayout &DL,
+ unsigned BonusInstThreshold, AssumptionCache *AC)
+ : TTI(TTI), DL(DL), BonusInstThreshold(BonusInstThreshold), AC(AC) {}
bool run(BasicBlock *BB);
};
}
-/// SafeToMergeTerminators - Return true if it is safe to merge these two
+/// Return true if it is safe to merge these two
/// terminator instructions together.
-///
static bool SafeToMergeTerminators(TerminatorInst *SI1, TerminatorInst *SI2) {
if (SI1 == SI2) return false; // Can't merge with self!
return true;
}
-/// isProfitableToFoldUnconditional - Return true if it is safe and profitable
-/// to merge these two terminator instructions together, where SI1 is an
-/// unconditional branch. PhiNodes will store all PHI nodes in common
-/// successors.
-///
+/// Return true if it is safe and profitable to merge these two terminator
+/// instructions together, where SI1 is an unconditional branch. PhiNodes will
+/// store all PHI nodes in common successors.
static bool isProfitableToFoldUnconditional(BranchInst *SI1,
BranchInst *SI2,
Instruction *Cond,
return true;
}
-/// AddPredecessorToBlock - Update PHI nodes in Succ to indicate that there will
-/// now be entries in it from the 'NewPred' block. The values that will be
-/// flowing into the PHI nodes will be the same as those coming in from
-/// ExistPred, an existing predecessor of Succ.
+/// Update PHI nodes in Succ to indicate that there will now be entries in it
+/// from the 'NewPred' block. The values that will be flowing into the PHI nodes
+/// will be the same as those coming in from ExistPred, an existing predecessor
+/// of Succ.
static void AddPredecessorToBlock(BasicBlock *Succ, BasicBlock *NewPred,
BasicBlock *ExistPred) {
if (!isa<PHINode>(Succ->begin())) return; // Quick exit if nothing to do
PN->addIncoming(PN->getIncomingValueForBlock(ExistPred), NewPred);
}
-/// ComputeSpeculationCost - Compute an abstract "cost" of speculating the
-/// given instruction, which is assumed to be safe to speculate. 1 means
-/// cheap, 2 means less cheap, and UINT_MAX means prohibitively expensive.
-static unsigned ComputeSpeculationCost(const User *I, const DataLayout *DL) {
- assert(isSafeToSpeculativelyExecute(I, DL) &&
+/// Compute an abstract "cost" of speculating the given instruction,
+/// which is assumed to be safe to speculate. TCC_Free means cheap,
+/// TCC_Basic means less cheap, and TCC_Expensive means prohibitively
+/// expensive.
+static unsigned ComputeSpeculationCost(const User *I,
+ const TargetTransformInfo &TTI) {
+ assert(isSafeToSpeculativelyExecute(I) &&
"Instruction is not safe to speculatively execute!");
- switch (Operator::getOpcode(I)) {
- default:
- // In doubt, be conservative.
- return UINT_MAX;
- case Instruction::GetElementPtr:
- // GEPs are cheap if all indices are constant.
- if (!cast<GEPOperator>(I)->hasAllConstantIndices())
- return UINT_MAX;
- return 1;
- case Instruction::ExtractValue:
- case Instruction::Load:
- case Instruction::Add:
- case Instruction::Sub:
- case Instruction::And:
- case Instruction::Or:
- case Instruction::Xor:
- case Instruction::Shl:
- case Instruction::LShr:
- case Instruction::AShr:
- case Instruction::ICmp:
- 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:
- case Instruction::Select:
- return 2;
- }
+ return TTI.getUserCost(I);
}
-
-/// DominatesMergePoint - If we have a merge point of an "if condition" as
-/// accepted above, return true if the specified value dominates the block. We
+/// 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
/// which works well enough for us.
///
/// V plus its non-dominating operands. If that cost is greater than
/// CostRemaining, false is returned and CostRemaining is undefined.
static bool DominatesMergePoint(Value *V, BasicBlock *BB,
- SmallPtrSet<Instruction*, 4> *AggressiveInsts,
+ SmallPtrSetImpl<Instruction*> *AggressiveInsts,
unsigned &CostRemaining,
- const DataLayout *DL) {
+ const TargetTransformInfo &TTI) {
Instruction *I = dyn_cast<Instruction>(V);
if (!I) {
// Non-instructions all dominate instructions, but not all constantexprs
// Okay, it looks like the instruction IS in the "condition". Check to
// see if it's a cheap instruction to unconditionally compute, and if it
// only uses stuff defined outside of the condition. If so, hoist it out.
- if (!isSafeToSpeculativelyExecute(I, DL))
+ if (!isSafeToSpeculativelyExecute(I))
return false;
- unsigned Cost = ComputeSpeculationCost(I, DL);
+ unsigned Cost = ComputeSpeculationCost(I, TTI);
if (Cost > CostRemaining)
return false;
// 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, DL))
+ if (!DominatesMergePoint(*i, BB, AggressiveInsts, CostRemaining, TTI))
return false;
// Okay, it's safe to do this! Remember this instruction.
AggressiveInsts->insert(I);
return true;
}
-/// GetConstantInt - Extract ConstantInt from value, looking through IntToPtr
+/// Extract ConstantInt from value, looking through IntToPtr
/// and PointerNullValue. Return NULL if value is not a constant int.
-static ConstantInt *GetConstantInt(Value *V, const DataLayout *DL) {
+static ConstantInt *GetConstantInt(Value *V, const DataLayout &DL) {
// Normal constant int.
ConstantInt *CI = dyn_cast<ConstantInt>(V);
- if (CI || !DL || !isa<Constant>(V) || !V->getType()->isPointerTy())
+ if (CI || !isa<Constant>(V) || !V->getType()->isPointerTy())
return CI;
// This is some kind of pointer constant. Turn it into a pointer-sized
// ConstantInt if possible.
- IntegerType *PtrTy = cast<IntegerType>(DL->getIntPtrType(V->getType()));
+ IntegerType *PtrTy = cast<IntegerType>(DL.getIntPtrType(V->getType()));
// Null pointer means 0, see SelectionDAGBuilder::getValue(const Value*).
if (isa<ConstantPointerNull>(V))
return nullptr;
}
-/// GatherConstantCompares - Given a potentially 'or'd or 'and'd together
-/// collection of icmp eq/ne instructions that compare a value against a
-/// constant, return the value being compared, and stick the constant into the
-/// Values vector.
-static Value *
-GatherConstantCompares(Value *V, std::vector<ConstantInt*> &Vals, Value *&Extra,
- const DataLayout *DL, bool isEQ, unsigned &UsedICmps) {
- Instruction *I = dyn_cast<Instruction>(V);
- 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 (ConstantInt *C = GetConstantInt(I->getOperand(1), DL)) {
- Value *RHSVal;
- ConstantInt *RHSC;
-
- if (ICI->getPredicate() == (isEQ ? ICmpInst::ICMP_EQ:ICmpInst::ICMP_NE)) {
- // (x & ~2^x) == y --> x == y || x == y|2^x
- // This undoes a transformation done by instcombine to fuse 2 compares.
- if (match(ICI->getOperand(0),
- m_And(m_Value(RHSVal), m_ConstantInt(RHSC)))) {
- APInt Not = ~RHSC->getValue();
- if (Not.isPowerOf2()) {
- Vals.push_back(C);
- Vals.push_back(
- ConstantInt::get(C->getContext(), C->getValue() | Not));
- UsedICmps++;
- return RHSVal;
- }
- }
+namespace {
+
+/// Given a chain of or (||) or and (&&) comparison of a value against a
+/// constant, this will try to recover the information required for a switch
+/// structure.
+/// It will depth-first traverse the chain of comparison, seeking for patterns
+/// like %a == 12 or %a < 4 and combine them to produce a set of integer
+/// representing the different cases for the switch.
+/// Note that if the chain is composed of '||' it will build the set of elements
+/// that matches the comparisons (i.e. any of this value validate the chain)
+/// while for a chain of '&&' it will build the set elements that make the test
+/// fail.
+struct ConstantComparesGatherer {
+ const DataLayout &DL;
+ Value *CompValue; /// Value found for the switch comparison
+ Value *Extra; /// Extra clause to be checked before the switch
+ SmallVector<ConstantInt *, 8> Vals; /// Set of integers to match in switch
+ unsigned UsedICmps; /// Number of comparisons matched in the and/or chain
+
+ /// Construct and compute the result for the comparison instruction Cond
+ ConstantComparesGatherer(Instruction *Cond, const DataLayout &DL)
+ : DL(DL), CompValue(nullptr), Extra(nullptr), UsedICmps(0) {
+ gather(Cond);
+ }
+
+ /// Prevent copy
+ ConstantComparesGatherer(const ConstantComparesGatherer &) = delete;
+ ConstantComparesGatherer &
+ operator=(const ConstantComparesGatherer &) = delete;
+
+private:
+
+ /// Try to set the current value used for the comparison, it succeeds only if
+ /// it wasn't set before or if the new value is the same as the old one
+ bool setValueOnce(Value *NewVal) {
+ if(CompValue && CompValue != NewVal) return false;
+ CompValue = NewVal;
+ return (CompValue != nullptr);
+ }
- UsedICmps++;
- Vals.push_back(C);
- return I->getOperand(0);
+ /// Try to match Instruction "I" as a comparison against a constant and
+ /// populates the array Vals with the set of values that match (or do not
+ /// match depending on isEQ).
+ /// Return false on failure. On success, the Value the comparison matched
+ /// against is placed in CompValue.
+ /// If CompValue is already set, the function is expected to fail if a match
+ /// is found but the value compared to is different.
+ bool matchInstruction(Instruction *I, bool isEQ) {
+ // If this is an icmp against a constant, handle this as one of the cases.
+ ICmpInst *ICI;
+ ConstantInt *C;
+ if (!((ICI = dyn_cast<ICmpInst>(I)) &&
+ (C = GetConstantInt(I->getOperand(1), DL)))) {
+ return false;
+ }
+
+ Value *RHSVal;
+ ConstantInt *RHSC;
+
+ // Pattern match a special case
+ // (x & ~2^x) == y --> x == y || x == y|2^x
+ // This undoes a transformation done by instcombine to fuse 2 compares.
+ if (ICI->getPredicate() == (isEQ ? ICmpInst::ICMP_EQ:ICmpInst::ICMP_NE)) {
+ if (match(ICI->getOperand(0),
+ m_And(m_Value(RHSVal), m_ConstantInt(RHSC)))) {
+ APInt Not = ~RHSC->getValue();
+ if (Not.isPowerOf2()) {
+ // If we already have a value for the switch, it has to match!
+ if(!setValueOnce(RHSVal))
+ return false;
+
+ Vals.push_back(C);
+ Vals.push_back(ConstantInt::get(C->getContext(),
+ C->getValue() | Not));
+ UsedICmps++;
+ return true;
+ }
}
- // If we have "x ult 3" comparison, for example, then we can add 0,1,2 to
- // the set.
- ConstantRange Span =
- ConstantRange::makeICmpRegion(ICI->getPredicate(), C->getValue());
-
- // Shift the range if the compare is fed by an add. This is the range
- // compare idiom as emitted by instcombine.
- bool hasAdd =
- match(I->getOperand(0), m_Add(m_Value(RHSVal), m_ConstantInt(RHSC)));
- if (hasAdd)
- Span = Span.subtract(RHSC->getValue());
-
- // If this is an and/!= check then we want to optimize "x ugt 2" into
- // x != 0 && x != 1.
- if (!isEQ)
- Span = Span.inverse();
-
- // If there are a ton of values, we don't want to make a ginormous switch.
- if (Span.getSetSize().ugt(8) || Span.isEmptySet())
- return nullptr;
-
- for (APInt Tmp = Span.getLower(); Tmp != Span.getUpper(); ++Tmp)
- Vals.push_back(ConstantInt::get(V->getContext(), Tmp));
+ // If we already have a value for the switch, it has to match!
+ if(!setValueOnce(ICI->getOperand(0)))
+ return false;
+
UsedICmps++;
- return hasAdd ? RHSVal : I->getOperand(0);
+ Vals.push_back(C);
+ return ICI->getOperand(0);
}
- return nullptr;
- }
- // Otherwise, we can only handle an | or &, depending on isEQ.
- if (I->getOpcode() != (isEQ ? Instruction::Or : Instruction::And))
- return nullptr;
+ // If we have "x ult 3", for example, then we can add 0,1,2 to the set.
+ ConstantRange Span = ConstantRange::makeAllowedICmpRegion(
+ ICI->getPredicate(), C->getValue());
- unsigned NumValsBeforeLHS = Vals.size();
- unsigned UsedICmpsBeforeLHS = UsedICmps;
- if (Value *LHS = GatherConstantCompares(I->getOperand(0), Vals, Extra, DL,
- isEQ, UsedICmps)) {
- unsigned NumVals = Vals.size();
- unsigned UsedICmpsBeforeRHS = UsedICmps;
- if (Value *RHS = GatherConstantCompares(I->getOperand(1), Vals, Extra, DL,
- isEQ, UsedICmps)) {
- if (LHS == RHS)
- return LHS;
- Vals.resize(NumVals);
- UsedICmps = UsedICmpsBeforeRHS;
+ // Shift the range if the compare is fed by an add. This is the range
+ // compare idiom as emitted by instcombine.
+ Value *CandidateVal = I->getOperand(0);
+ if(match(I->getOperand(0), m_Add(m_Value(RHSVal), m_ConstantInt(RHSC)))) {
+ Span = Span.subtract(RHSC->getValue());
+ CandidateVal = RHSVal;
}
- // 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 == nullptr || Extra == I->getOperand(1)) {
- Extra = I->getOperand(1);
- return LHS;
+ // If this is an and/!= check, then we are looking to build the set of
+ // value that *don't* pass the and chain. I.e. to turn "x ugt 2" into
+ // x != 0 && x != 1.
+ if (!isEQ)
+ Span = Span.inverse();
+
+ // If there are a ton of values, we don't want to make a ginormous switch.
+ if (Span.getSetSize().ugt(8) || Span.isEmptySet()) {
+ return false;
}
- Vals.resize(NumValsBeforeLHS);
- UsedICmps = UsedICmpsBeforeLHS;
- return nullptr;
+ // If we already have a value for the switch, it has to match!
+ if(!setValueOnce(CandidateVal))
+ return false;
+
+ // Add all values from the range to the set
+ for (APInt Tmp = Span.getLower(); Tmp != Span.getUpper(); ++Tmp)
+ Vals.push_back(ConstantInt::get(I->getContext(), Tmp));
+
+ UsedICmps++;
+ return true;
+
}
- // If the LHS can't be folded in, but Extra is available and RHS can, try to
- // use LHS as Extra.
- if (Extra == nullptr || Extra == I->getOperand(0)) {
- Value *OldExtra = Extra;
- Extra = I->getOperand(0);
- if (Value *RHS = GatherConstantCompares(I->getOperand(1), Vals, Extra, DL,
- isEQ, UsedICmps))
- return RHS;
- assert(Vals.size() == NumValsBeforeLHS);
- Extra = OldExtra;
+ /// Given a potentially 'or'd or 'and'd together collection of icmp
+ /// eq/ne/lt/gt instructions that compare a value against a constant, extract
+ /// the value being compared, and stick the list constants into the Vals
+ /// vector.
+ /// One "Extra" case is allowed to differ from the other.
+ void gather(Value *V) {
+ Instruction *I = dyn_cast<Instruction>(V);
+ bool isEQ = (I->getOpcode() == Instruction::Or);
+
+ // Keep a stack (SmallVector for efficiency) for depth-first traversal
+ SmallVector<Value *, 8> DFT;
+
+ // Initialize
+ DFT.push_back(V);
+
+ while(!DFT.empty()) {
+ V = DFT.pop_back_val();
+
+ if (Instruction *I = dyn_cast<Instruction>(V)) {
+ // If it is a || (or && depending on isEQ), process the operands.
+ if (I->getOpcode() == (isEQ ? Instruction::Or : Instruction::And)) {
+ DFT.push_back(I->getOperand(1));
+ DFT.push_back(I->getOperand(0));
+ continue;
+ }
+
+ // Try to match the current instruction
+ if (matchInstruction(I, isEQ))
+ // Match succeed, continue the loop
+ continue;
+ }
+
+ // One element of the sequence of || (or &&) could not be match as a
+ // comparison against the same value as the others.
+ // We allow only one "Extra" case to be checked before the switch
+ if (!Extra) {
+ Extra = V;
+ continue;
+ }
+ // Failed to parse a proper sequence, abort now
+ CompValue = nullptr;
+ break;
+ }
}
+};
- return nullptr;
}
static void EraseTerminatorInstAndDCECond(TerminatorInst *TI) {
if (Cond) RecursivelyDeleteTriviallyDeadInstructions(Cond);
}
-/// isValueEqualityComparison - Return true if the specified terminator checks
+/// 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 = nullptr;
CV = SI->getCondition();
} else if (BranchInst *BI = dyn_cast<BranchInst>(TI))
if (BI->isConditional() && BI->getCondition()->hasOneUse())
- if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition()))
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition())) {
if (ICI->isEquality() && GetConstantInt(ICI->getOperand(1), DL))
CV = ICI->getOperand(0);
+ }
// Unwrap any lossless ptrtoint cast.
- if (DL && CV) {
+ if (CV) {
if (PtrToIntInst *PTII = dyn_cast<PtrToIntInst>(CV)) {
Value *Ptr = PTII->getPointerOperand();
- if (PTII->getType() == DL->getIntPtrType(Ptr->getType()))
+ if (PTII->getType() == DL.getIntPtrType(Ptr->getType()))
CV = Ptr;
}
}
return CV;
}
-/// GetValueEqualityComparisonCases - Given a value comparison instruction,
+/// Given a value comparison instruction,
/// decode all of the 'cases' that it represents and return the 'default' block.
BasicBlock *SimplifyCFGOpt::
GetValueEqualityComparisonCases(TerminatorInst *TI,
}
-/// EliminateBlockCases - Given a vector of bb/value pairs, remove any entries
+/// Given a vector of bb/value pairs, remove any entries
/// in the list that match the specified block.
static void EliminateBlockCases(BasicBlock *BB,
std::vector<ValueEqualityComparisonCase> &Cases) {
Cases.erase(std::remove(Cases.begin(), Cases.end(), BB), Cases.end());
}
-/// ValuesOverlap - Return true if there are any keys in C1 that exist in C2 as
-/// well.
+/// Return true if there are any keys in C1 that exist in C2 as well.
static bool
ValuesOverlap(std::vector<ValueEqualityComparisonCase> &C1,
std::vector<ValueEqualityComparisonCase > &C2) {
return false;
}
-/// SimplifyEqualityComparisonWithOnlyPredecessor - If TI is known to be a
-/// terminator instruction and its block is known to only have a single
-/// predecessor block, check to see if that predecessor is also a value
-/// comparison with the same value, and if that comparison determines the
-/// outcome of this comparison. If so, simplify TI. This does a very limited
-/// form of jump threading.
+/// If TI is known to be a terminator instruction and its block is known to
+/// only have a single predecessor block, check to see if that predecessor is
+/// also a value comparison with the same value, and if that comparison
+/// determines the outcome of this comparison. If so, simplify TI. This does a
+/// very limited form of jump threading.
bool SimplifyCFGOpt::
SimplifyEqualityComparisonWithOnlyPredecessor(TerminatorInst *TI,
BasicBlock *Pred,
// Collect branch weights into a vector.
SmallVector<uint32_t, 8> Weights;
- MDNode* MD = SI->getMetadata(LLVMContext::MD_prof);
+ MDNode *MD = SI->getMetadata(LLVMContext::MD_prof);
bool HasWeight = MD && (MD->getNumOperands() == 2 + SI->getNumCases());
if (HasWeight)
for (unsigned MD_i = 1, MD_e = MD->getNumOperands(); MD_i < MD_e;
++MD_i) {
- ConstantInt* CI = dyn_cast<ConstantInt>(MD->getOperand(MD_i));
- assert(CI);
+ ConstantInt *CI = mdconst::extract<ConstantInt>(MD->getOperand(MD_i));
Weights.push_back(CI->getValue().getZExtValue());
}
for (SwitchInst::CaseIt i = SI->case_end(), e = SI->case_begin(); i != e;) {
}
namespace {
- /// ConstantIntOrdering - This class implements a stable ordering of constant
+ /// This class implements a stable ordering of constant
/// integers that does not depend on their address. This is important for
/// applications that sort ConstantInt's to ensure uniqueness.
struct ConstantIntOrdering {
}
static inline bool HasBranchWeights(const Instruction* I) {
- MDNode* ProfMD = I->getMetadata(LLVMContext::MD_prof);
+ MDNode *ProfMD = I->getMetadata(LLVMContext::MD_prof);
if (ProfMD && ProfMD->getOperand(0))
if (MDString* MDS = dyn_cast<MDString>(ProfMD->getOperand(0)))
return MDS->getString().equals("branch_weights");
/// metadata.
static void GetBranchWeights(TerminatorInst *TI,
SmallVectorImpl<uint64_t> &Weights) {
- MDNode* MD = TI->getMetadata(LLVMContext::MD_prof);
+ MDNode *MD = TI->getMetadata(LLVMContext::MD_prof);
assert(MD);
for (unsigned i = 1, e = MD->getNumOperands(); i < e; ++i) {
- ConstantInt *CI = cast<ConstantInt>(MD->getOperand(i));
+ ConstantInt *CI = mdconst::extract<ConstantInt>(MD->getOperand(i));
Weights.push_back(CI->getValue().getZExtValue());
}
}
}
-/// FoldValueComparisonIntoPredecessors - The specified terminator is a value
-/// equality comparison instruction (either a switch or a branch on "X == c").
+/// The specified terminator is a value equality comparison instruction
+/// (either a switch or a branch on "X == c").
/// See if any of the predecessors of the terminator block are value comparisons
/// on the same value. If so, and if safe to do so, fold them together.
bool SimplifyCFGOpt::FoldValueComparisonIntoPredecessors(TerminatorInst *TI,
Builder.SetInsertPoint(PTI);
// Convert pointer to int before we switch.
if (CV->getType()->isPointerTy()) {
- assert(DL && "Cannot switch on pointer without DataLayout");
- CV = Builder.CreatePtrToInt(CV, DL->getIntPtrType(CV->getType()),
+ CV = Builder.CreatePtrToInt(CV, DL.getIntPtrType(CV->getType()),
"magicptr");
}
return Changed;
}
-// isSafeToHoistInvoke - If we would need to insert a select that uses the
-// value of this invoke (comments in HoistThenElseCodeToIf explain why we
-// would need to do this), we can't hoist the invoke, as there is nowhere
-// to put the select in this case.
+// If we would need to insert a select that uses the value of this invoke
+// (comments in HoistThenElseCodeToIf explain why we would need to do this), we
+// can't hoist the invoke, as there is nowhere to put the select in this case.
static bool isSafeToHoistInvoke(BasicBlock *BB1, BasicBlock *BB2,
Instruction *I1, Instruction *I2) {
for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) {
return true;
}
-/// HoistThenElseCodeToIf - Given a conditional branch that goes to BB1 and
-/// BB2, hoist any common code in the two blocks up into the branch block. The
-/// caller of this function guarantees that BI's block dominates BB1 and BB2.
-static bool HoistThenElseCodeToIf(BranchInst *BI, const DataLayout *DL) {
+static bool passingValueIsAlwaysUndefined(Value *V, Instruction *I);
+
+/// Given a conditional branch that goes to BB1 and BB2, hoist any common code
+/// in the two blocks up into the branch block. The caller of this function
+/// guarantees that BI's block dominates BB1 and BB2.
+static bool HoistThenElseCodeToIf(BranchInst *BI,
+ const TargetTransformInfo &TTI) {
// This does very trivial matching, with limited scanning, to find identical
// instructions in the two blocks. In particular, we don't want to get into
// O(M*N) situations here where M and N are the sizes of BB1 and BB2. As
if (isa<TerminatorInst>(I1))
goto HoistTerminator;
+ if (!TTI.isProfitableToHoist(I1) || !TTI.isProfitableToHoist(I2))
+ return Changed;
+
// 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.
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
+ };
+ combineMetadata(I1, I2, KnownIDs);
I2->eraseFromParent();
Changed = true;
if (BB1V == BB2V)
continue;
- if (isa<ConstantExpr>(BB1V) && !isSafeToSpeculativelyExecute(BB1V, DL))
+ // Check for passingValueIsAlwaysUndefined here because we would rather
+ // eliminate undefined control flow then converting it to a select.
+ if (passingValueIsAlwaysUndefined(BB1V, PN) ||
+ passingValueIsAlwaysUndefined(BB2V, PN))
+ return Changed;
+
+ if (isa<ConstantExpr>(BB1V) && !isSafeToSpeculativelyExecute(BB1V))
return Changed;
- if (isa<ConstantExpr>(BB2V) && !isSafeToSpeculativelyExecute(BB2V, DL))
+ if (isa<ConstantExpr>(BB2V) && !isSafeToSpeculativelyExecute(BB2V))
return Changed;
}
}
return true;
}
-/// SinkThenElseCodeToEnd - Given an unconditional branch that goes to BBEnd,
+/// Given an unconditional branch that goes to BBEnd,
/// check whether BBEnd has only two predecessors and the other predecessor
/// ends with an unconditional branch. If it is true, sink any common code
/// in the two predecessors to BBEnd.
return false;
// Gather the PHI nodes in BBEnd.
- std::map<Value*, std::pair<Value*, PHINode*> > MapValueFromBB1ToBB2;
+ SmallDenseMap<std::pair<Value *, Value *>, PHINode *> JointValueMap;
Instruction *FirstNonPhiInBBEnd = nullptr;
- for (BasicBlock::iterator I = BBEnd->begin(), E = BBEnd->end();
- I != E; ++I) {
+ for (BasicBlock::iterator I = BBEnd->begin(), E = BBEnd->end(); I != E; ++I) {
if (PHINode *PN = dyn_cast<PHINode>(I)) {
Value *BB1V = PN->getIncomingValueForBlock(BB1);
Value *BB2V = PN->getIncomingValueForBlock(BB2);
- MapValueFromBB1ToBB2[BB1V] = std::make_pair(BB2V, PN);
+ JointValueMap[std::make_pair(BB1V, BB2V)] = PN;
} else {
FirstNonPhiInBBEnd = &*I;
break;
if (!FirstNonPhiInBBEnd)
return false;
-
// This does very trivial matching, with limited scanning, to find identical
// instructions in the two blocks. We scan backward for obviously identical
// instructions in an identical order.
BasicBlock::InstListType::reverse_iterator RI1 = BB1->getInstList().rbegin(),
- RE1 = BB1->getInstList().rend(), RI2 = BB2->getInstList().rbegin(),
- RE2 = BB2->getInstList().rend();
+ RE1 = BB1->getInstList().rend(),
+ RI2 = BB2->getInstList().rbegin(),
+ RE2 = BB2->getInstList().rend();
// Skip debug info.
while (RI1 != RE1 && isa<DbgInfoIntrinsic>(&*RI1)) ++RI1;
if (RI1 == RE1)
return Changed;
Instruction *I1 = &*RI1, *I2 = &*RI2;
+ auto InstPair = std::make_pair(I1, I2);
// I1 and I2 should have a single use in the same PHI node, and they
// perform the same operation.
// 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() ||
!I1->hasOneUse() || !I2->hasOneUse() ||
- MapValueFromBB1ToBB2.find(I1) == MapValueFromBB1ToBB2.end() ||
- MapValueFromBB1ToBB2[I1].first != I2)
+ !JointValueMap.count(InstPair))
return Changed;
// Check whether we should swap the operands of ICmpInst.
+ // TODO: Add support of communativity.
ICmpInst *ICmp1 = dyn_cast<ICmpInst>(I1), *ICmp2 = dyn_cast<ICmpInst>(I2);
bool SwapOpnds = false;
if (ICmp1 && ICmp2 &&
// with a PHI node after sinking. We only handle the case where there is
// a single pair of different operands.
Value *DifferentOp1 = nullptr, *DifferentOp2 = nullptr;
- unsigned Op1Idx = 0;
+ unsigned Op1Idx = ~0U;
for (unsigned I = 0, E = I1->getNumOperands(); I != E; ++I) {
if (I1->getOperand(I) == I2->getOperand(I))
continue;
- // Early exit if we have more-than one pair of different operands or
- // the different operand is already in MapValueFromBB1ToBB2.
- // Early exit if we need a PHI node to replace a constant.
- if (DifferentOp1 ||
- MapValueFromBB1ToBB2.find(I1->getOperand(I)) !=
- MapValueFromBB1ToBB2.end() ||
+ // Early exit if we have more-than one pair of different operands or if
+ // we need a PHI node to replace a constant.
+ if (Op1Idx != ~0U ||
isa<Constant>(I1->getOperand(I)) ||
isa<Constant>(I2->getOperand(I))) {
// If we can't sink the instructions, undo the swapping.
DifferentOp2 = I2->getOperand(I);
}
- // We insert the pair of different operands to MapValueFromBB1ToBB2 and
- // remove (I1, I2) from MapValueFromBB1ToBB2.
- if (DifferentOp1) {
- PHINode *NewPN = PHINode::Create(DifferentOp1->getType(), 2,
- DifferentOp1->getName() + ".sink",
- BBEnd->begin());
- MapValueFromBB1ToBB2[DifferentOp1] = std::make_pair(DifferentOp2, NewPN);
+ DEBUG(dbgs() << "SINK common instructions " << *I1 << "\n");
+ DEBUG(dbgs() << " " << *I2 << "\n");
+
+ // We insert the pair of different operands to JointValueMap and
+ // remove (I1, I2) from JointValueMap.
+ if (Op1Idx != ~0U) {
+ auto &NewPN = JointValueMap[std::make_pair(DifferentOp1, DifferentOp2)];
+ if (!NewPN) {
+ NewPN =
+ PHINode::Create(DifferentOp1->getType(), 2,
+ DifferentOp1->getName() + ".sink", BBEnd->begin());
+ NewPN->addIncoming(DifferentOp1, BB1);
+ NewPN->addIncoming(DifferentOp2, BB2);
+ DEBUG(dbgs() << "Create PHI node " << *NewPN << "\n";);
+ }
// I1 should use NewPN instead of DifferentOp1.
I1->setOperand(Op1Idx, NewPN);
- NewPN->addIncoming(DifferentOp1, BB1);
- NewPN->addIncoming(DifferentOp2, BB2);
- DEBUG(dbgs() << "Create PHI node " << *NewPN << "\n";);
}
- PHINode *OldPN = MapValueFromBB1ToBB2[I1].second;
- MapValueFromBB1ToBB2.erase(I1);
+ PHINode *OldPN = JointValueMap[InstPair];
+ JointValueMap.erase(InstPair);
- DEBUG(dbgs() << "SINK common instructions " << *I1 << "\n";);
- DEBUG(dbgs() << " " << *I2 << "\n";);
// We need to update RE1 and RE2 if we are going to sink the first
// instruction in the basic block down.
bool UpdateRE1 = (I1 == BB1->begin()), UpdateRE2 = (I2 == BB2->begin());
if (!I2->use_empty())
I2->replaceAllUsesWith(I1);
I1->intersectOptionalDataWith(I2);
+ // TODO: Use combineMetadata here to preserve what metadata we can
+ // (analogous to the hoisting case above).
I2->eraseFromParent();
if (UpdateRE1)
///
/// \returns true if the conditional block is removed.
static bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *ThenBB,
- const DataLayout *DL) {
+ const TargetTransformInfo &TTI) {
// Be conservative for now. FP select instruction can often be expensive.
Value *BrCond = BI->getCondition();
if (isa<FCmpInst>(BrCond))
if (isa<DbgInfoIntrinsic>(I))
continue;
- // Only speculatively execution a single instruction (not counting the
+ // Only speculatively execute a single instruction (not counting the
// terminator) for now.
++SpeculationCost;
if (SpeculationCost > 1)
return false;
// Don't hoist the instruction if it's unsafe or expensive.
- if (!isSafeToSpeculativelyExecute(I, DL) &&
- !(HoistCondStores &&
- (SpeculatedStoreValue = isSafeToSpeculateStore(I, BB, ThenBB,
- EndBB))))
+ if (!isSafeToSpeculativelyExecute(I) &&
+ !(HoistCondStores && (SpeculatedStoreValue = isSafeToSpeculateStore(
+ I, BB, ThenBB, EndBB))))
return false;
if (!SpeculatedStoreValue &&
- ComputeSpeculationCost(I, DL) > PHINodeFoldingThreshold)
+ ComputeSpeculationCost(I, TTI) >
+ PHINodeFoldingThreshold * TargetTransformInfo::TCC_Basic)
return false;
// Store the store speculation candidate.
if (ThenV == OrigV)
continue;
+ // Don't convert to selects if we could remove undefined behavior instead.
+ if (passingValueIsAlwaysUndefined(OrigV, PN) ||
+ passingValueIsAlwaysUndefined(ThenV, PN))
+ return false;
+
HaveRewritablePHIs = true;
ConstantExpr *OrigCE = dyn_cast<ConstantExpr>(OrigV);
ConstantExpr *ThenCE = dyn_cast<ConstantExpr>(ThenV);
if (!OrigCE && !ThenCE)
continue; // Known safe and cheap.
- if ((ThenCE && !isSafeToSpeculativelyExecute(ThenCE, DL)) ||
- (OrigCE && !isSafeToSpeculativelyExecute(OrigCE, DL)))
+ if ((ThenCE && !isSafeToSpeculativelyExecute(ThenCE)) ||
+ (OrigCE && !isSafeToSpeculativelyExecute(OrigCE)))
return false;
- unsigned OrigCost = OrigCE ? ComputeSpeculationCost(OrigCE, DL) : 0;
- unsigned ThenCost = ThenCE ? ComputeSpeculationCost(ThenCE, DL) : 0;
- if (OrigCost + ThenCost > 2 * PHINodeFoldingThreshold)
+ unsigned OrigCost = OrigCE ? ComputeSpeculationCost(OrigCE, TTI) : 0;
+ unsigned ThenCost = ThenCE ? ComputeSpeculationCost(ThenCE, TTI) : 0;
+ unsigned MaxCost = 2 * PHINodeFoldingThreshold *
+ TargetTransformInfo::TCC_Basic;
+ if (OrigCost + ThenCost > MaxCost)
return false;
// Account for the cost of an unfolded ConstantExpr which could end up
return false;
}
-/// BlockIsSimpleEnoughToThreadThrough - Return true if we can thread a branch
-/// across this block.
+/// Return true if we can thread a branch across this block.
static bool BlockIsSimpleEnoughToThreadThrough(BasicBlock *BB) {
BranchInst *BI = cast<BranchInst>(BB->getTerminator());
unsigned Size = 0;
return true;
}
-/// FoldCondBranchOnPHI - If we have a conditional branch on a PHI node value
-/// that is defined in the same block as the branch and if any PHI entries are
-/// constants, thread edges corresponding to that entry to be branches to their
-/// ultimate destination.
-static bool FoldCondBranchOnPHI(BranchInst *BI, const DataLayout *DL) {
+/// If we have a conditional branch on a PHI node value that is defined in the
+/// same block as the branch and if any PHI entries are constants, thread edges
+/// corresponding to that entry to be branches to their ultimate destination.
+static bool FoldCondBranchOnPHI(BranchInst *BI, const DataLayout &DL) {
BasicBlock *BB = BI->getParent();
PHINode *PN = dyn_cast<PHINode>(BI->getCondition());
// NOTE: we currently cannot transform this case if the PHI node is used
return false;
}
-/// FoldTwoEntryPHINode - Given a BB that starts with the specified two-entry
-/// PHI node, see if we can eliminate it.
-static bool FoldTwoEntryPHINode(PHINode *PN, const DataLayout *DL) {
+/// Given a BB that starts with the specified two-entry PHI node,
+/// see if we can eliminate it.
+static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI,
+ const DataLayout &DL) {
// Ok, this is a two entry PHI node. Check to see if this is a simple "if
// statement", which has a very simple dominance structure. Basically, we
// are trying to find the condition that is being branched on, which
SmallPtrSet<Instruction*, 4> AggressiveInsts;
unsigned MaxCostVal0 = PHINodeFoldingThreshold,
MaxCostVal1 = PHINodeFoldingThreshold;
+ MaxCostVal0 *= TargetTransformInfo::TCC_Basic;
+ MaxCostVal1 *= TargetTransformInfo::TCC_Basic;
for (BasicBlock::iterator II = BB->begin(); isa<PHINode>(II);) {
PHINode *PN = cast<PHINode>(II++);
}
if (!DominatesMergePoint(PN->getIncomingValue(0), BB, &AggressiveInsts,
- MaxCostVal0, DL) ||
+ MaxCostVal0, TTI) ||
!DominatesMergePoint(PN->getIncomingValue(1), BB, &AggressiveInsts,
- MaxCostVal1, DL))
+ MaxCostVal1, TTI))
return false;
}
return true;
}
-/// SimplifyCondBranchToTwoReturns - If we found a conditional branch that goes
-/// to two returning blocks, try to merge them together into one return,
+/// If we found a conditional branch that goes to two returning blocks,
+/// try to merge them together into one return,
/// introducing a select if the return values disagree.
static bool SimplifyCondBranchToTwoReturns(BranchInst *BI,
IRBuilder<> &Builder) {
return true;
}
-/// ExtractBranchMetadata - Given a conditional BranchInstruction, retrieve the
-/// probabilities of the branch taking each edge. Fills in the two APInt
-/// parameters and return true, or returns false if no or invalid metadata was
-/// found.
+/// Given a conditional BranchInstruction, retrieve the probabilities of the
+/// branch taking each edge. Fills in the two APInt parameters and returns true,
+/// or returns false if no or invalid metadata was found.
static bool ExtractBranchMetadata(BranchInst *BI,
uint64_t &ProbTrue, uint64_t &ProbFalse) {
assert(BI->isConditional() &&
"Looking for probabilities on unconditional branch?");
MDNode *ProfileData = BI->getMetadata(LLVMContext::MD_prof);
if (!ProfileData || ProfileData->getNumOperands() != 3) return false;
- ConstantInt *CITrue = dyn_cast<ConstantInt>(ProfileData->getOperand(1));
- ConstantInt *CIFalse = dyn_cast<ConstantInt>(ProfileData->getOperand(2));
+ ConstantInt *CITrue =
+ mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(1));
+ ConstantInt *CIFalse =
+ mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(2));
if (!CITrue || !CIFalse) return false;
ProbTrue = CITrue->getValue().getZExtValue();
ProbFalse = CIFalse->getValue().getZExtValue();
return true;
}
-/// checkCSEInPredecessor - Return true if the given instruction is available
+/// Return true if the given instruction is available
/// in its predecessor block. If yes, the instruction will be removed.
-///
static bool checkCSEInPredecessor(Instruction *Inst, BasicBlock *PB) {
if (!isa<BinaryOperator>(Inst) && !isa<CmpInst>(Inst))
return false;
return false;
}
-/// FoldBranchToCommonDest - If this basic block is simple enough, and if a
-/// predecessor branches to us and one of our successors, fold the block into
-/// the predecessor and use logical operations to pick the right destination.
-bool llvm::FoldBranchToCommonDest(BranchInst *BI, const DataLayout *DL) {
+/// If this basic block is simple enough, and if a predecessor branches to us
+/// and one of our successors, fold the block into the predecessor and use
+/// logical operations to pick the right destination.
+bool llvm::FoldBranchToCommonDest(BranchInst *BI, unsigned BonusInstThreshold) {
BasicBlock *BB = BI->getParent();
Instruction *Cond = nullptr;
Cond->getParent() != BB || !Cond->hasOneUse())
return false;
- // Only allow this if the condition is a simple instruction that can be
- // executed unconditionally. It must be in the same block as the branch, and
- // must be at the front of the block.
- BasicBlock::iterator FrontIt = BB->front();
-
- // Ignore dbg intrinsics.
- while (isa<DbgInfoIntrinsic>(FrontIt)) ++FrontIt;
-
- // Allow a single instruction to be hoisted in addition to the compare
- // 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 = nullptr;
- if (&*FrontIt != Cond &&
- FrontIt->hasOneUse() && FrontIt->user_back() == Cond &&
- isSafeToSpeculativelyExecute(FrontIt, DL)) {
- BonusInst = &*FrontIt;
- ++FrontIt;
-
- // Ignore dbg intrinsics.
- while (isa<DbgInfoIntrinsic>(FrontIt)) ++FrontIt;
- }
-
- // Only a single bonus inst is allowed.
- if (&*FrontIt != Cond)
- return false;
-
// Make sure the instruction after the condition is the cond branch.
BasicBlock::iterator CondIt = Cond; ++CondIt;
if (&*CondIt != BI)
return false;
+ // Only allow this transformation if computing the condition doesn't involve
+ // too many instructions and these involved instructions can be executed
+ // unconditionally. We denote all involved instructions except the condition
+ // as "bonus instructions", and only allow this transformation when the
+ // number of the bonus instructions does not exceed a certain threshold.
+ unsigned NumBonusInsts = 0;
+ for (auto I = BB->begin(); Cond != I; ++I) {
+ // Ignore dbg intrinsics.
+ if (isa<DbgInfoIntrinsic>(I))
+ continue;
+ 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());
+ if (User == nullptr || User->getParent() != BB)
+ return false;
+ // I is used in the same BB. Since BI uses Cond and doesn't have more slots
+ // to use any other instruction, User must be an instruction between next(I)
+ // and Cond.
+ ++NumBonusInsts;
+ // Early exits once we reach the limit.
+ if (NumBonusInsts > BonusInstThreshold)
+ return false;
+ }
+
// Cond is known to be a compare or binary operator. Check to make sure that
// neither operand is a potentially-trapping constant expression.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Cond->getOperand(0)))
continue;
}
- // Ensure that any values used in the bonus instruction are also used
- // by the terminator of the predecessor. This means that those values
- // must already have been resolved, so we won't be inhibiting the
- // out-of-order core by speculating them earlier. We also allow
- // instructions that are used by the terminator's condition because it
- // exposes more merging opportunities.
- bool UsedByBranch = (BonusInst && BonusInst->hasOneUse() &&
- BonusInst->user_back() == Cond);
-
- if (BonusInst && !UsedByBranch) {
- // Collect the values used by the bonus inst
- SmallPtrSet<Value*, 4> UsedValues;
- for (Instruction::op_iterator OI = BonusInst->op_begin(),
- OE = BonusInst->op_end(); OI != OE; ++OI) {
- Value *V = *OI;
- if (!isa<Constant>(V) && !isa<Argument>(V))
- UsedValues.insert(V);
- }
-
- SmallVector<std::pair<Value*, unsigned>, 4> Worklist;
- Worklist.push_back(std::make_pair(PBI->getOperand(0), 0));
-
- // Walk up to four levels back up the use-def chain of the predecessor's
- // terminator to see if all those values were used. The choice of four
- // levels is arbitrary, to provide a compile-time-cost bound.
- while (!Worklist.empty()) {
- std::pair<Value*, unsigned> Pair = Worklist.back();
- Worklist.pop_back();
-
- if (Pair.second >= 4) continue;
- UsedValues.erase(Pair.first);
- if (UsedValues.empty()) break;
-
- if (Instruction *I = dyn_cast<Instruction>(Pair.first)) {
- for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end();
- OI != OE; ++OI)
- Worklist.push_back(std::make_pair(OI->get(), Pair.second+1));
- }
- }
-
- if (!UsedValues.empty()) return false;
- }
-
DEBUG(dbgs() << "FOLDING BRANCH TO COMMON DEST:\n" << *PBI << *BB);
IRBuilder<> Builder(PBI);
PBI->swapSuccessors();
}
- // If we have a bonus inst, clone it into the predecessor block.
- Instruction *NewBonus = nullptr;
- if (BonusInst) {
- NewBonus = BonusInst->clone();
+ // If we have bonus instructions, clone them into the predecessor block.
+ // Note that there may be multiple predecessor blocks, so we cannot move
+ // bonus instructions to a predecessor block.
+ ValueToValueMapTy VMap; // maps original values to cloned values
+ // We already make sure Cond is the last instruction before BI. Therefore,
+ // all instructions before Cond other than DbgInfoIntrinsic are bonus
+ // instructions.
+ for (auto BonusInst = BB->begin(); Cond != BonusInst; ++BonusInst) {
+ if (isa<DbgInfoIntrinsic>(BonusInst))
+ continue;
+ Instruction *NewBonusInst = BonusInst->clone();
+ RemapInstruction(NewBonusInst, VMap,
+ RF_NoModuleLevelChanges | RF_IgnoreMissingEntries);
+ 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.
- NewBonus->dropUnknownMetadata(LLVMContext::MD_dbg);
+ NewBonusInst->dropUnknownNonDebugMetadata();
- PredBlock->getInstList().insert(PBI, NewBonus);
- NewBonus->takeName(BonusInst);
- BonusInst->setName(BonusInst->getName()+".old");
+ PredBlock->getInstList().insert(PBI, NewBonusInst);
+ NewBonusInst->takeName(BonusInst);
+ BonusInst->setName(BonusInst->getName() + ".old");
}
// Clone Cond into the predecessor basic block, and or/and the
// two conditions together.
Instruction *New = Cond->clone();
- if (BonusInst) New->replaceUsesOfWith(BonusInst, NewBonus);
+ RemapInstruction(New, VMap,
+ RF_NoModuleLevelChanges | RF_IgnoreMissingEntries);
PredBlock->getInstList().insert(PBI, New);
New->takeName(Cond);
- Cond->setName(New->getName()+".old");
+ Cond->setName(New->getName() + ".old");
if (BI->isConditional()) {
Instruction *NewCond =
return false;
}
-/// SimplifyCondBranchToCondBranch - If we have a conditional branch as a
-/// predecessor of another block, this function tries to simplify it. We know
+/// 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) {
// The weight to CommonDest should be PredCommon * SuccTotal +
// PredOther * SuccCommon.
// The weight to OtherDest should be PredOther * SuccOther.
- SmallVector<uint64_t, 2> NewWeights;
- NewWeights.push_back(PredCommon * (SuccCommon + SuccOther) +
- PredOther * SuccCommon);
- NewWeights.push_back(PredOther * SuccOther);
+ uint64_t NewWeights[2] = {PredCommon * (SuccCommon + SuccOther) +
+ PredOther * SuccCommon,
+ PredOther * SuccOther};
// Halve the weights if any of them cannot fit in an uint32_t
FitWeights(NewWeights);
- SmallVector<uint32_t, 2> MDWeights(NewWeights.begin(),NewWeights.end());
PBI->setMetadata(LLVMContext::MD_prof,
- MDBuilder(BI->getContext()).
- createBranchWeights(MDWeights));
+ MDBuilder(BI->getContext())
+ .createBranchWeights(NewWeights[0], NewWeights[1]));
}
// OtherDest may have phi nodes. If so, add an entry from PBI's
return true;
}
-// SimplifyTerminatorOnSelect - Simplifies a terminator by replacing it with a
-// branch to TrueBB if Cond is true or to FalseBB if Cond is false.
+// Simplifies a terminator by replacing it with a branch to TrueBB if Cond is
+// true or to FalseBB if Cond is false.
// Takes care of updating the successors and removing the old terminator.
// Also makes sure not to introduce new successors by assuming that edges to
// non-successor TrueBBs and FalseBBs aren't reachable.
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;
return true;
}
-// SimplifySwitchOnSelect - Replaces
+// Replaces
// (switch (select cond, X, Y)) on constant X, Y
// with a branch - conditional if X and Y lead to distinct BBs,
// unconditional otherwise.
TrueWeight, FalseWeight);
}
-// SimplifyIndirectBrOnSelect - Replaces
+// Replaces
// (indirectbr (select cond, blockaddress(@fn, BlockA),
// blockaddress(@fn, BlockB)))
// with
0, 0);
}
-/// TryToSimplifyUncondBranchWithICmpInIt - This is called when we find an icmp
-/// instruction (a seteq/setne with a constant) as the only instruction in a
+/// This is called when we find an icmp instruction
+/// (a seteq/setne with a constant) as the only instruction in a
/// block that ends with an uncond branch. We are looking for a very specific
/// pattern that occurs when "A == 1 || A == 2 || A == 3" gets simplified. In
/// this case, we merge the first two "or's of icmp" into a switch, but then the
/// We prefer to split the edge to 'end' so that there is a true/false entry to
/// the PHI, merging the third icmp into the switch.
static bool TryToSimplifyUncondBranchWithICmpInIt(
- ICmpInst *ICI, IRBuilder<> &Builder, const TargetTransformInfo &TTI,
- const DataLayout *DL) {
+ ICmpInst *ICI, IRBuilder<> &Builder, const DataLayout &DL,
+ const TargetTransformInfo &TTI, unsigned BonusInstThreshold,
+ AssumptionCache *AC) {
BasicBlock *BB = ICI->getParent();
// If the block has any PHIs in it or the icmp has multiple uses, it is too
ICI->eraseFromParent();
}
// BB is now empty, so it is likely to simplify away.
- return SimplifyCFG(BB, TTI, DL) | true;
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
}
// Ok, the block is reachable from the default dest. If the constant we're
ICI->replaceAllUsesWith(V);
ICI->eraseFromParent();
// BB is now empty, so it is likely to simplify away.
- return SimplifyCFG(BB, TTI, DL) | true;
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
}
// The use of the icmp has to be in the 'end' block, by the only PHI node in
return true;
}
-/// SimplifyBranchOnICmpChain - The specified branch is a conditional branch.
+/// The specified branch is a conditional branch.
/// Check to see if it is branching on an or/and chain of icmp instructions, and
/// fold it into a switch instruction if so.
-static bool SimplifyBranchOnICmpChain(BranchInst *BI, const DataLayout *DL,
- IRBuilder<> &Builder) {
+static bool SimplifyBranchOnICmpChain(BranchInst *BI, IRBuilder<> &Builder,
+ const DataLayout &DL) {
Instruction *Cond = dyn_cast<Instruction>(BI->getCondition());
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 = nullptr;
- std::vector<ConstantInt*> Values;
- bool TrueWhenEqual = true;
- Value *ExtraCase = nullptr;
- unsigned UsedICmps = 0;
-
- if (Cond->getOpcode() == Instruction::Or) {
- CompVal = GatherConstantCompares(Cond, Values, ExtraCase, DL, true,
- UsedICmps);
- } else if (Cond->getOpcode() == Instruction::And) {
- CompVal = GatherConstantCompares(Cond, Values, ExtraCase, DL, false,
- UsedICmps);
- TrueWhenEqual = false;
- }
+
+ // Try to gather values from a chain of and/or to be turned into a switch
+ ConstantComparesGatherer ConstantCompare(Cond, DL);
+ // Unpack the result
+ SmallVectorImpl<ConstantInt*> &Values = ConstantCompare.Vals;
+ Value *CompVal = ConstantCompare.CompValue;
+ unsigned UsedICmps = ConstantCompare.UsedICmps;
+ Value *ExtraCase = ConstantCompare.Extra;
// If we didn't have a multiply compared value, fail.
if (!CompVal) return false;
if (UsedICmps <= 1)
return false;
+ bool TrueWhenEqual = (Cond->getOpcode() == Instruction::Or);
+
// There might be duplicate constants in the list, which the switch
// instruction can't handle, remove them now.
array_pod_sort(Values.begin(), Values.end(), ConstantIntSortPredicate);
Builder.SetInsertPoint(BI);
// Convert pointer to int before we switch.
if (CompVal->getType()->isPointerTy()) {
- assert(DL && "Cannot switch on pointer without DataLayout");
- CompVal = Builder.CreatePtrToInt(CompVal,
- DL->getIntPtrType(CompVal->getType()),
- "magicptr");
+ CompVal = Builder.CreatePtrToInt(
+ CompVal, DL.getIntPtrType(CompVal->getType()), "magicptr");
}
// Create the new switch instruction now.
return true;
}
+// FIXME: This seems like a pretty common thing to want to do. Consider
+// whether there is a more accessible place to put this.
+static void convertInvokeToCall(InvokeInst *II) {
+ 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);
+ II->getUnwindDest()->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();
+}
+
bool SimplifyCFGOpt::SimplifyResume(ResumeInst *RI, IRBuilder<> &Builder) {
// If this is a trivial landing pad that just continues unwinding the caught
// exception then zap the landing pad, turning its invokes into calls.
return false;
// Turn all invokes that unwind here into calls and delete the basic block.
- bool InvokeRequiresTableEntry = false;
- bool Changed = false;
for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE;) {
InvokeInst *II = cast<InvokeInst>((*PI++)->getTerminator());
+ convertInvokeToCall(II);
+ }
- if (II->hasFnAttr(Attribute::UWTable)) {
- // Don't remove an `invoke' instruction if the ABI requires an entry into
- // the table.
- InvokeRequiresTableEntry = true;
- continue;
- }
+ // The landingpad is now unreachable. Zap it.
+ BB->eraseFromParent();
+ return true;
+}
- SmallVector<Value*, 8> Args(II->op_begin(), II->op_end() - 3);
+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();
+ Instruction *CPInst = dyn_cast<CleanupPadInst>(BB->getFirstNonPHI());
+ if (!CPInst)
+ // This isn't an empty cleanup.
+ return false;
- // 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());
+ // Check that there are no other instructions except for debug intrinsics.
+ BasicBlock::iterator I = CPInst, E = RI;
+ while (++I != E)
+ if (!isa<DbgInfoIntrinsic>(I))
+ return false;
- // 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());
+ // If the cleanup return we are simplifying unwinds to the caller, this
+ // will set UnwindDest to nullptr.
+ BasicBlock *UnwindDest = RI->getUnwindDest();
+
+ // 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 = UnwindDest->getFirstNonPHI();
+ 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);
+ }
+ }
+ }
- // Insert a branch to the normal destination right before the invoke.
- BranchInst::Create(II->getNormalDest(), II);
+ // Sink any remaining PHI nodes directly into UnwindDest.
+ Instruction *InsertPt = UnwindDest->getFirstNonPHI();
+ for (BasicBlock::iterator I = BB->begin(), IE = BB->getFirstNonPHI();
+ 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;
- // Finally, delete the invoke instruction!
- II->eraseFromParent();
- Changed = true;
+ // 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);
+ }
}
- if (!InvokeRequiresTableEntry)
- // The landingpad is now unreachable. Zap it.
- BB->eraseFromParent();
+ 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++;
+ TerminatorInst *TI = PredBB->getTerminator();
+ if (UnwindDest == nullptr) {
+ if (auto *II = dyn_cast<InvokeInst>(TI)) {
+ // The cleanup return being simplified continues to the caller and this
+ // predecessor terminated with an invoke instruction. Convert the
+ // invoke to a call.
+ // This call updates the predecessor/successor chain.
+ convertInvokeToCall(II);
+ } else {
+ // In the remaining cases the predecessor's terminator unwinds to the
+ // block we are removing. We need to create a new instruction that
+ // unwinds to the caller. Simply setting the unwind destination to
+ // nullptr would leave the objects internal data in an inconsistent
+ // state.
+ // FIXME: Consider whether it is better to update setUnwindDest to
+ // keep things consistent.
+ if (auto *CRI = dyn_cast<CleanupReturnInst>(TI)) {
+ auto *NewCRI = CleanupReturnInst::Create(CRI->getCleanupPad(),
+ nullptr, CRI);
+ NewCRI->takeName(CRI);
+ NewCRI->setDebugLoc(CRI->getDebugLoc());
+ CRI->eraseFromParent();
+ } else if (auto *CEP = dyn_cast<CatchEndPadInst>(TI)) {
+ auto *NewCEP = CatchEndPadInst::Create(CEP->getContext(), nullptr,
+ CEP);
+ NewCEP->takeName(CEP);
+ NewCEP->setDebugLoc(CEP->getDebugLoc());
+ CEP->eraseFromParent();
+ } else if (auto *TPI = dyn_cast<TerminatePadInst>(TI)) {
+ SmallVector<Value *, 3> TerminatePadArgs;
+ for (Value *Operand : TPI->arg_operands())
+ TerminatePadArgs.push_back(Operand);
+ auto *NewTPI = TerminatePadInst::Create(TPI->getContext(), nullptr,
+ TerminatePadArgs, TPI);
+ NewTPI->takeName(TPI);
+ NewTPI->setDebugLoc(TPI->getDebugLoc());
+ TPI->eraseFromParent();
+ } else {
+ llvm_unreachable("Unexpected predecessor to cleanup pad.");
+ }
+ }
+ } else {
+ // If the predecessor did not terminate with an invoke instruction, it
+ // must be some variety of EH pad.
+ TerminatorInst *TI = PredBB->getTerminator();
+ // FIXME: Introducing an EH terminator base class would simplify this.
+ if (auto *II = dyn_cast<InvokeInst>(TI))
+ II->setUnwindDest(UnwindDest);
+ else if (auto *CRI = dyn_cast<CleanupReturnInst>(TI))
+ CRI->setUnwindDest(UnwindDest);
+ else if (auto *CEP = dyn_cast<CatchEndPadInst>(TI))
+ CEP->setUnwindDest(UnwindDest);
+ else if (auto *TPI = dyn_cast<TerminatePadInst>(TI))
+ TPI->setUnwindDest(UnwindDest);
+ else
+ llvm_unreachable("Unexpected predecessor to cleanup pad.");
+ }
+ }
- return Changed;
+ // The cleanup pad is now unreachable. Zap it.
+ BB->eraseFromParent();
+ return true;
}
bool SimplifyCFGOpt::SimplifyReturn(ReturnInst *RI, IRBuilder<> &Builder) {
}
// If we eliminated all predecessors of the block, delete the block now.
- if (pred_begin(BB) == pred_end(BB))
+ if (pred_empty(BB))
// We know there are no successors, so just nuke the block.
BB->eraseFromParent();
--i; --e;
Changed = true;
}
- // If the default value is unreachable, figure out the most popular
- // destination and make it the default.
- if (SI->getDefaultDest() == BB) {
- std::map<BasicBlock*, std::pair<unsigned, unsigned> > Popularity;
- for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
- i != e; ++i) {
- std::pair<unsigned, unsigned> &entry =
- Popularity[i.getCaseSuccessor()];
- if (entry.first == 0) {
- entry.first = 1;
- entry.second = i.getCaseIndex();
- } else {
- entry.first++;
- }
- }
-
- // Find the most popular block.
- unsigned MaxPop = 0;
- unsigned MaxIndex = 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 ||
- (I->second.first == MaxPop && MaxIndex > I->second.second)) {
- MaxPop = I->second.first;
- MaxIndex = I->second.second;
- MaxBlock = I->first;
- }
- }
- if (MaxBlock) {
- // Make this the new default, allowing us to delete any explicit
- // edges to it.
- SI->setDefaultDest(MaxBlock);
- Changed = true;
-
- // If MaxBlock has phinodes in it, remove MaxPop-1 entries from
- // it.
- if (isa<PHINode>(MaxBlock->begin()))
- for (unsigned i = 0; i != MaxPop-1; ++i)
- MaxBlock->removePredecessor(SI->getParent());
-
- for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
- i != e; ++i)
- if (i.getCaseSuccessor() == MaxBlock) {
- SI->removeCase(i);
- --i; --e;
- }
- }
- }
} else if (InvokeInst *II = dyn_cast<InvokeInst>(TI)) {
if (II->getUnwindDest() == BB) {
// Convert the invoke to a call instruction. This would be a good
}
// If this block is now dead, remove it.
- if (pred_begin(BB) == pred_end(BB) &&
+ if (pred_empty(BB) &&
BB != &BB->getParent()->getEntryBlock()) {
// We know there are no successors, so just nuke the block.
BB->eraseFromParent();
return Changed;
}
-/// TurnSwitchRangeIntoICmp - Turns a switch with that contains only a
-/// integer range comparison into a sub, an icmp and a branch.
-static bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) {
- assert(SI->getNumCases() > 1 && "Degenerate switch?");
+static bool CasesAreContiguous(SmallVectorImpl<ConstantInt *> &Cases) {
+ assert(Cases.size() >= 1);
- // Make sure all cases point to the same destination and gather the values.
- SmallVector<ConstantInt *, 16> Cases;
- SwitchInst::CaseIt I = SI->case_begin();
- Cases.push_back(I.getCaseValue());
- SwitchInst::CaseIt PrevI = I++;
- for (SwitchInst::CaseIt E = SI->case_end(); I != E; PrevI = I++) {
- if (PrevI.getCaseSuccessor() != I.getCaseSuccessor())
+ array_pod_sort(Cases.begin(), Cases.end(), ConstantIntSortPredicate);
+ for (size_t I = 1, E = Cases.size(); I != E; ++I) {
+ if (Cases[I - 1]->getValue() != Cases[I]->getValue() + 1)
return false;
- Cases.push_back(I.getCaseValue());
}
- assert(Cases.size() == SI->getNumCases() && "Not all cases gathered");
+ return true;
+}
- // Sort the case values, then check if they form a range we can transform.
- array_pod_sort(Cases.begin(), Cases.end(), ConstantIntSortPredicate);
- for (unsigned I = 1, E = Cases.size(); I != E; ++I) {
- if (Cases[I-1]->getValue() != Cases[I]->getValue()+1)
- return false;
+/// Turn a switch with two reachable destinations into an integer range
+/// comparison and branch.
+static bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) {
+ assert(SI->getNumCases() > 1 && "Degenerate switch?");
+
+ bool HasDefault =
+ !isa<UnreachableInst>(SI->getDefaultDest()->getFirstNonPHIOrDbg());
+
+ // Partition the cases into two sets with different destinations.
+ BasicBlock *DestA = HasDefault ? SI->getDefaultDest() : nullptr;
+ BasicBlock *DestB = nullptr;
+ SmallVector <ConstantInt *, 16> CasesA;
+ SmallVector <ConstantInt *, 16> CasesB;
+
+ for (SwitchInst::CaseIt I : SI->cases()) {
+ BasicBlock *Dest = I.getCaseSuccessor();
+ if (!DestA) DestA = Dest;
+ if (Dest == DestA) {
+ CasesA.push_back(I.getCaseValue());
+ continue;
+ }
+ if (!DestB) DestB = Dest;
+ if (Dest == DestB) {
+ CasesB.push_back(I.getCaseValue());
+ continue;
+ }
+ return false; // More than two destinations.
}
- Constant *Offset = ConstantExpr::getNeg(Cases.back());
- Constant *NumCases = ConstantInt::get(Offset->getType(), SI->getNumCases());
+ assert(DestA && DestB && "Single-destination switch should have been folded.");
+ assert(DestA != DestB);
+ assert(DestB != SI->getDefaultDest());
+ assert(!CasesB.empty() && "There must be non-default cases.");
+ assert(!CasesA.empty() || HasDefault);
+
+ // Figure out if one of the sets of cases form a contiguous range.
+ SmallVectorImpl<ConstantInt *> *ContiguousCases = nullptr;
+ BasicBlock *ContiguousDest = nullptr;
+ BasicBlock *OtherDest = nullptr;
+ if (!CasesA.empty() && CasesAreContiguous(CasesA)) {
+ ContiguousCases = &CasesA;
+ ContiguousDest = DestA;
+ OtherDest = DestB;
+ } else if (CasesAreContiguous(CasesB)) {
+ ContiguousCases = &CasesB;
+ ContiguousDest = DestB;
+ OtherDest = DestA;
+ } else
+ return false;
+
+ // Start building the compare and branch.
+
+ Constant *Offset = ConstantExpr::getNeg(ContiguousCases->back());
+ Constant *NumCases = ConstantInt::get(Offset->getType(), ContiguousCases->size());
Value *Sub = SI->getCondition();
if (!Offset->isNullValue())
- Sub = Builder.CreateAdd(Sub, Offset, Sub->getName()+".off");
+ Sub = Builder.CreateAdd(Sub, Offset, Sub->getName() + ".off");
+
Value *Cmp;
// If NumCases overflowed, then all possible values jump to the successor.
- if (NumCases->isNullValue() && SI->getNumCases() != 0)
+ if (NumCases->isNullValue() && !ContiguousCases->empty())
Cmp = ConstantInt::getTrue(SI->getContext());
else
Cmp = Builder.CreateICmpULT(Sub, NumCases, "switch");
- BranchInst *NewBI = Builder.CreateCondBr(
- Cmp, SI->case_begin().getCaseSuccessor(), SI->getDefaultDest());
+ BranchInst *NewBI = Builder.CreateCondBr(Cmp, ContiguousDest, OtherDest);
// Update weight for the newly-created conditional branch.
- SmallVector<uint64_t, 8> Weights;
- bool HasWeights = HasBranchWeights(SI);
- if (HasWeights) {
+ if (HasBranchWeights(SI)) {
+ SmallVector<uint64_t, 8> Weights;
GetBranchWeights(SI, Weights);
if (Weights.size() == 1 + SI->getNumCases()) {
- // Combine all weights for the cases to be the true weight of NewBI.
- // We assume that the sum of all weights for a Terminator can fit into 32
- // bits.
- uint32_t NewTrueWeight = 0;
- for (unsigned I = 1, E = Weights.size(); I != E; ++I)
- NewTrueWeight += (uint32_t)Weights[I];
+ uint64_t TrueWeight = 0;
+ uint64_t FalseWeight = 0;
+ for (size_t I = 0, E = Weights.size(); I != E; ++I) {
+ if (SI->getSuccessor(I) == ContiguousDest)
+ TrueWeight += Weights[I];
+ else
+ FalseWeight += Weights[I];
+ }
+ while (TrueWeight > UINT32_MAX || FalseWeight > UINT32_MAX) {
+ TrueWeight /= 2;
+ FalseWeight /= 2;
+ }
NewBI->setMetadata(LLVMContext::MD_prof,
- MDBuilder(SI->getContext()).
- createBranchWeights(NewTrueWeight,
- (uint32_t)Weights[0]));
+ MDBuilder(SI->getContext()).createBranchWeights(
+ (uint32_t)TrueWeight, (uint32_t)FalseWeight));
}
}
- // Prune obsolete incoming values off the successor's PHI nodes.
- for (BasicBlock::iterator BBI = SI->case_begin().getCaseSuccessor()->begin();
- isa<PHINode>(BBI); ++BBI) {
- for (unsigned I = 0, E = SI->getNumCases()-1; I != E; ++I)
+ // Prune obsolete incoming values off the successors' PHI nodes.
+ for (auto BBI = ContiguousDest->begin(); isa<PHINode>(BBI); ++BBI) {
+ unsigned PreviousEdges = ContiguousCases->size();
+ if (ContiguousDest == SI->getDefaultDest()) ++PreviousEdges;
+ for (unsigned I = 0, E = PreviousEdges - 1; I != E; ++I)
+ cast<PHINode>(BBI)->removeIncomingValue(SI->getParent());
+ }
+ for (auto BBI = OtherDest->begin(); isa<PHINode>(BBI); ++BBI) {
+ unsigned PreviousEdges = SI->getNumCases() - ContiguousCases->size();
+ if (OtherDest == SI->getDefaultDest()) ++PreviousEdges;
+ for (unsigned I = 0, E = PreviousEdges - 1; I != E; ++I)
cast<PHINode>(BBI)->removeIncomingValue(SI->getParent());
}
+
+ // Drop the switch.
SI->eraseFromParent();
return true;
}
-/// EliminateDeadSwitchCases - Compute masked bits for the condition of a switch
+/// Compute masked bits for the condition of a switch
/// and use it to remove dead cases.
-static bool EliminateDeadSwitchCases(SwitchInst *SI) {
+static bool EliminateDeadSwitchCases(SwitchInst *SI, AssumptionCache *AC,
+ const DataLayout &DL) {
Value *Cond = SI->getCondition();
unsigned Bits = Cond->getType()->getIntegerBitWidth();
APInt KnownZero(Bits, 0), KnownOne(Bits, 0);
- computeKnownBits(Cond, KnownZero, KnownOne);
+ computeKnownBits(Cond, KnownZero, KnownOne, DL, 0, AC, SI);
// Gather dead cases.
SmallVector<ConstantInt*, 8> DeadCases;
}
}
+ // If we can prove that the cases must cover all possible values, the
+ // default destination becomes dead and we can remove it.
+ bool HasDefault =
+ !isa<UnreachableInst>(SI->getDefaultDest()->getFirstNonPHIOrDbg());
+ if (HasDefault && Bits < 64 /* avoid overflow */ &&
+ SI->getNumCases() == (1ULL << Bits)) {
+ DEBUG(dbgs() << "SimplifyCFG: switch default is dead.\n");
+ BasicBlock *NewDefault = SplitBlockPredecessors(SI->getDefaultDest(),
+ SI->getParent(), "");
+ SI->setDefaultDest(NewDefault);
+ SplitBlock(NewDefault, NewDefault->begin());
+ auto *OldTI = NewDefault->getTerminator();
+ new UnreachableInst(SI->getContext(), OldTI);
+ EraseTerminatorInstAndDCECond(OldTI);
+ return true;
+ }
+
SmallVector<uint64_t, 8> Weights;
bool HasWeight = HasBranchWeights(SI);
if (HasWeight) {
return !DeadCases.empty();
}
-/// FindPHIForConditionForwarding - If BB would be eligible for simplification
-/// by TryToSimplifyUncondBranchFromEmptyBlock (i.e. it is empty and terminated
+/// If BB would be eligible for simplification by
+/// TryToSimplifyUncondBranchFromEmptyBlock (i.e. it is empty and terminated
/// by an unconditional branch), look at the phi node for BB in the successor
/// block and see if the incoming value is equal to CaseValue. If so, return
/// the phi node, and set PhiIndex to BB's index in the phi node.
return nullptr;
}
-/// ForwardSwitchConditionToPHI - Try to forward the condition of a switch
-/// instruction to a phi node dominated by the switch, if that would mean that
-/// some of the destination blocks of the switch can be folded away.
+/// Try to forward the condition of a switch instruction to a phi node
+/// dominated by the switch, if that would mean that some of the destination
+/// blocks of the switch can be folded away.
/// Returns true if a change is made.
static bool ForwardSwitchConditionToPHI(SwitchInst *SI) {
typedef DenseMap<PHINode*, SmallVector<int,4> > ForwardingNodesMap;
return Changed;
}
-/// ValidLookupTableConstant - Return true if the backend will be able to handle
+/// 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())
isa<UndefValue>(C);
}
-/// LookupConstant - If V is a Constant, return it. Otherwise, try to look up
+/// If V is a Constant, return it. Otherwise, try to look up
/// its constant value in ConstantPool, returning 0 if it's not there.
static Constant *LookupConstant(Value *V,
const SmallDenseMap<Value*, Constant*>& ConstantPool) {
return ConstantPool.lookup(V);
}
-/// ConstantFold - Try to fold instruction I into a constant. This works for
+/// Try to fold instruction I into a constant. This works for
/// simple instructions such as binary operations where both operands are
/// constant or can be replaced by constants from the ConstantPool. Returns the
/// resulting constant on success, 0 otherwise.
static Constant *
-ConstantFold(Instruction *I,
- const SmallDenseMap<Value *, Constant *> &ConstantPool,
- const DataLayout *DL) {
+ConstantFold(Instruction *I, const DataLayout &DL,
+ const SmallDenseMap<Value *, Constant *> &ConstantPool) {
if (SelectInst *Select = dyn_cast<SelectInst>(I)) {
Constant *A = LookupConstant(Select->getCondition(), ConstantPool);
if (!A)
return nullptr;
}
- if (CmpInst *Cmp = dyn_cast<CmpInst>(I))
+ if (CmpInst *Cmp = dyn_cast<CmpInst>(I)) {
return ConstantFoldCompareInstOperands(Cmp->getPredicate(), COps[0],
COps[1], DL);
+ }
return ConstantFoldInstOperands(I->getOpcode(), I->getType(), COps, DL);
}
-/// GetCaseResults - Try to determine the resulting constant values in phi nodes
+/// Try to determine the resulting constant values in phi nodes
/// at the common destination basic block, *CommonDest, for one of the case
/// destionations CaseDest corresponding to value CaseVal (0 for the default
/// case), of a switch instruction SI.
static bool
-GetCaseResults(SwitchInst *SI,
- ConstantInt *CaseVal,
- BasicBlock *CaseDest,
+GetCaseResults(SwitchInst *SI, ConstantInt *CaseVal, BasicBlock *CaseDest,
BasicBlock **CommonDest,
- SmallVectorImpl<std::pair<PHINode *, Constant *> > &Res,
- const DataLayout *DL) {
+ SmallVectorImpl<std::pair<PHINode *, Constant *>> &Res,
+ const DataLayout &DL) {
// The block from which we enter the common destination.
BasicBlock *Pred = SI->getParent();
} else if (isa<DbgInfoIntrinsic>(I)) {
// Skip debug intrinsic.
continue;
- } else if (Constant *C = ConstantFold(I, ConstantPool, DL)) {
+ } 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
+ // the block, it is not safe to bypass the instruction since it would then
+ // no longer dominate all its uses.
+ for (auto &Use : I->uses()) {
+ User *User = Use.getUser();
+ if (Instruction *I = dyn_cast<Instruction>(User))
+ if (I->getParent() == CaseDest)
+ continue;
+ if (PHINode *Phi = dyn_cast<PHINode>(User))
+ if (Phi->getIncomingBlock(Use) == CaseDest)
+ continue;
+ return false;
+ }
+
ConstantPool.insert(std::make_pair(I, C));
} else {
break;
if (!ConstVal)
return false;
- // Note: If the constant comes from constant-propagating the case value
- // through the CaseDest basic block, it will be safe to remove the
- // instructions in that block. They cannot be used (except in the phi nodes
- // we visit) outside CaseDest, because that block does not dominate its
- // successor. If it did, we would not be in this phi node.
-
// Be conservative about which kinds of constants we support.
if (!ValidLookupTableConstant(ConstVal))
return false;
return Res.size() > 0;
}
+// Helper function used to add CaseVal to the list of cases that generate
+// Result.
+static void MapCaseToResult(ConstantInt *CaseVal,
+ SwitchCaseResultVectorTy &UniqueResults,
+ Constant *Result) {
+ for (auto &I : UniqueResults) {
+ if (I.first == Result) {
+ I.second.push_back(CaseVal);
+ return;
+ }
+ }
+ UniqueResults.push_back(std::make_pair(Result,
+ SmallVector<ConstantInt*, 4>(1, CaseVal)));
+}
+
+// Helper function that initializes a map containing
+// results for the PHI node of the common destination block for a switch
+// instruction. Returns false if multiple PHI nodes have been found or if
+// there is not a common destination block for the switch.
+static bool InitializeUniqueCases(SwitchInst *SI, PHINode *&PHI,
+ BasicBlock *&CommonDest,
+ SwitchCaseResultVectorTy &UniqueResults,
+ Constant *&DefaultResult,
+ const DataLayout &DL) {
+ for (auto &I : SI->cases()) {
+ ConstantInt *CaseVal = I.getCaseValue();
+
+ // Resulting value at phi nodes for this case value.
+ SwitchCaseResultsTy Results;
+ if (!GetCaseResults(SI, CaseVal, I.getCaseSuccessor(), &CommonDest, Results,
+ DL))
+ return false;
+
+ // Only one value per case is permitted
+ if (Results.size() > 1)
+ return false;
+ MapCaseToResult(CaseVal, UniqueResults, Results.begin()->second);
+
+ // Check the PHI consistency.
+ if (!PHI)
+ PHI = Results[0].first;
+ else if (PHI != Results[0].first)
+ return false;
+ }
+ // Find the default result value.
+ SmallVector<std::pair<PHINode *, Constant *>, 1> DefaultResults;
+ BasicBlock *DefaultDest = SI->getDefaultDest();
+ GetCaseResults(SI, nullptr, SI->getDefaultDest(), &CommonDest, DefaultResults,
+ DL);
+ // If the default value is not found abort unless the default destination
+ // is unreachable.
+ DefaultResult =
+ DefaultResults.size() == 1 ? DefaultResults.begin()->second : nullptr;
+ if ((!DefaultResult &&
+ !isa<UnreachableInst>(DefaultDest->getFirstNonPHIOrDbg())))
+ return false;
+
+ return true;
+}
+
+// Helper function that checks if it is possible to transform a switch with only
+// two cases (or two cases + default) that produces a result into a select.
+// Example:
+// switch (a) {
+// case 10: %0 = icmp eq i32 %a, 10
+// return 10; %1 = select i1 %0, i32 10, i32 4
+// case 20: ----> %2 = icmp eq i32 %a, 20
+// return 2; %3 = select i1 %2, i32 2, i32 %1
+// default:
+// return 4;
+// }
+static Value *
+ConvertTwoCaseSwitch(const SwitchCaseResultVectorTy &ResultVector,
+ Constant *DefaultResult, Value *Condition,
+ IRBuilder<> &Builder) {
+ assert(ResultVector.size() == 2 &&
+ "We should have exactly two unique results at this point");
+ // If we are selecting between only two cases transform into a simple
+ // select or a two-way select if default is possible.
+ if (ResultVector[0].second.size() == 1 &&
+ ResultVector[1].second.size() == 1) {
+ ConstantInt *const FirstCase = ResultVector[0].second[0];
+ ConstantInt *const SecondCase = ResultVector[1].second[0];
+
+ bool DefaultCanTrigger = DefaultResult;
+ Value *SelectValue = ResultVector[1].first;
+ if (DefaultCanTrigger) {
+ Value *const ValueCompare =
+ Builder.CreateICmpEQ(Condition, SecondCase, "switch.selectcmp");
+ SelectValue = Builder.CreateSelect(ValueCompare, ResultVector[1].first,
+ DefaultResult, "switch.select");
+ }
+ Value *const ValueCompare =
+ Builder.CreateICmpEQ(Condition, FirstCase, "switch.selectcmp");
+ return Builder.CreateSelect(ValueCompare, ResultVector[0].first, SelectValue,
+ "switch.select");
+ }
+
+ return nullptr;
+}
+
+// Helper function to cleanup a switch instruction that has been converted into
+// a select, fixing up PHI nodes and basic blocks.
+static void RemoveSwitchAfterSelectConversion(SwitchInst *SI, PHINode *PHI,
+ Value *SelectValue,
+ IRBuilder<> &Builder) {
+ BasicBlock *SelectBB = SI->getParent();
+ while (PHI->getBasicBlockIndex(SelectBB) >= 0)
+ PHI->removeIncomingValue(SelectBB);
+ PHI->addIncoming(SelectValue, SelectBB);
+
+ Builder.CreateBr(PHI->getParent());
+
+ // Remove the switch.
+ for (unsigned i = 0, e = SI->getNumSuccessors(); i < e; ++i) {
+ BasicBlock *Succ = SI->getSuccessor(i);
+
+ if (Succ == PHI->getParent())
+ continue;
+ Succ->removePredecessor(SelectBB);
+ }
+ SI->eraseFromParent();
+}
+
+/// If the switch is only used to initialize one or more
+/// phi nodes in a common successor block with only two different
+/// constant values, replace the switch with select.
+static bool SwitchToSelect(SwitchInst *SI, IRBuilder<> &Builder,
+ AssumptionCache *AC, const DataLayout &DL) {
+ Value *const Cond = SI->getCondition();
+ PHINode *PHI = nullptr;
+ BasicBlock *CommonDest = nullptr;
+ Constant *DefaultResult;
+ SwitchCaseResultVectorTy UniqueResults;
+ // Collect all the cases that will deliver the same value from the switch.
+ if (!InitializeUniqueCases(SI, PHI, CommonDest, UniqueResults, DefaultResult,
+ DL))
+ return false;
+ // Selects choose between maximum two values.
+ if (UniqueResults.size() != 2)
+ return false;
+ assert(PHI != nullptr && "PHI for value select not found");
+
+ Builder.SetInsertPoint(SI);
+ Value *SelectValue = ConvertTwoCaseSwitch(
+ UniqueResults,
+ DefaultResult, Cond, Builder);
+ if (SelectValue) {
+ RemoveSwitchAfterSelectConversion(SI, PHI, SelectValue, Builder);
+ return true;
+ }
+ // The switch couldn't be converted into a select.
+ return false;
+}
+
namespace {
- /// SwitchLookupTable - This class represents a lookup table that can be used
- /// to replace a switch.
+ /// This class represents a lookup table that can be used to replace a switch.
class SwitchLookupTable {
public:
- /// SwitchLookupTable - Create a lookup table to use as a switch replacement
- /// with the contents of Values, using DefaultValue to fill any holes in the
- /// table.
- SwitchLookupTable(Module &M,
- uint64_t TableSize,
- ConstantInt *Offset,
- const SmallVectorImpl<std::pair<ConstantInt*, Constant*> >& Values,
- Constant *DefaultValue,
- const DataLayout *DL);
-
- /// BuildLookup - Build instructions with Builder to retrieve the value at
+ /// Create a lookup table to use as a switch replacement with the contents
+ /// of Values, using DefaultValue to fill any holes in the table.
+ SwitchLookupTable(
+ Module &M, uint64_t TableSize, ConstantInt *Offset,
+ const SmallVectorImpl<std::pair<ConstantInt *, Constant *>> &Values,
+ Constant *DefaultValue, const DataLayout &DL);
+
+ /// Build instructions with Builder to retrieve the value at
/// the position given by Index in the lookup table.
Value *BuildLookup(Value *Index, IRBuilder<> &Builder);
- /// WouldFitInRegister - Return true if a table with TableSize elements of
+ /// 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);
+ static bool WouldFitInRegister(const DataLayout &DL, uint64_t TableSize,
+ Type *ElementType);
private:
// Depending on the contents of the table, it can be represented in
// store that single value and return it for each lookup.
SingleValueKind,
+ // For tables where there is a linear relationship between table index
+ // and values. We calculate the result with a simple multiplication
+ // and addition instead of a table lookup.
+ LinearMapKind,
+
// For small tables with integer elements, we can pack them into a bitmap
// that fits into a target-legal register. Values are retrieved by
// shift and mask operations.
ConstantInt *BitMap;
IntegerType *BitMapElementTy;
+ // For LinearMapKind, these are the constants used to derive the value.
+ ConstantInt *LinearOffset;
+ ConstantInt *LinearMultiplier;
+
// For ArrayKind, this is the array.
GlobalVariable *Array;
};
}
-SwitchLookupTable::SwitchLookupTable(Module &M,
- uint64_t TableSize,
- ConstantInt *Offset,
- const SmallVectorImpl<std::pair<ConstantInt*, Constant*> >& Values,
- Constant *DefaultValue,
- const DataLayout *DL)
+SwitchLookupTable::SwitchLookupTable(
+ Module &M, uint64_t TableSize, ConstantInt *Offset,
+ const SmallVectorImpl<std::pair<ConstantInt *, Constant *>> &Values,
+ Constant *DefaultValue, const DataLayout &DL)
: SingleValue(nullptr), BitMap(nullptr), BitMapElementTy(nullptr),
- Array(nullptr) {
+ LinearOffset(nullptr), LinearMultiplier(nullptr), Array(nullptr) {
assert(Values.size() && "Can't build lookup table without values!");
assert(TableSize >= Values.size() && "Can't fit values in table!");
return;
}
+ // Check if we can derive the value with a linear transformation from the
+ // table index.
+ if (isa<IntegerType>(ValueType)) {
+ bool LinearMappingPossible = true;
+ APInt PrevVal;
+ APInt DistToPrev;
+ assert(TableSize >= 2 && "Should be a SingleValue table.");
+ // Check if there is the same distance between two consecutive values.
+ for (uint64_t I = 0; I < TableSize; ++I) {
+ ConstantInt *ConstVal = dyn_cast<ConstantInt>(TableContents[I]);
+ if (!ConstVal) {
+ // This is an undef. We could deal with it, but undefs in lookup tables
+ // are very seldom. It's probably not worth the additional complexity.
+ LinearMappingPossible = false;
+ break;
+ }
+ APInt Val = ConstVal->getValue();
+ if (I != 0) {
+ APInt Dist = Val - PrevVal;
+ if (I == 1) {
+ DistToPrev = Dist;
+ } else if (Dist != DistToPrev) {
+ LinearMappingPossible = false;
+ break;
+ }
+ }
+ PrevVal = Val;
+ }
+ if (LinearMappingPossible) {
+ LinearOffset = cast<ConstantInt>(TableContents[0]);
+ LinearMultiplier = ConstantInt::get(M.getContext(), DistToPrev);
+ Kind = LinearMapKind;
+ ++NumLinearMaps;
+ return;
+ }
+ }
+
// If the type is integer and the table fits in a register, build a bitmap.
if (WouldFitInRegister(DL, TableSize, ValueType)) {
IntegerType *IT = cast<IntegerType>(ValueType);
switch (Kind) {
case SingleValueKind:
return SingleValue;
+ case LinearMapKind: {
+ // Derive the result value from the input value.
+ Value *Result = Builder.CreateIntCast(Index, LinearMultiplier->getType(),
+ false, "switch.idx.cast");
+ if (!LinearMultiplier->isOne())
+ Result = Builder.CreateMul(Result, LinearMultiplier, "switch.idx.mult");
+ if (!LinearOffset->isZero())
+ Result = Builder.CreateAdd(Result, LinearOffset, "switch.offset");
+ return Result;
+ }
case BitMapKind: {
// Type of the bitmap (e.g. i59).
IntegerType *MapTy = BitMap->getType();
"switch.masked");
}
case ArrayKind: {
+ // Make sure the table index will not overflow when treated as signed.
+ IntegerType *IT = cast<IntegerType>(Index->getType());
+ uint64_t TableSize = Array->getInitializer()->getType()
+ ->getArrayNumElements();
+ if (TableSize > (1ULL << (IT->getBitWidth() - 1)))
+ Index = Builder.CreateZExt(Index,
+ IntegerType::get(IT->getContext(),
+ IT->getBitWidth() + 1),
+ "switch.tableidx.zext");
+
Value *GEPIndices[] = { Builder.getInt32(0), Index };
- Value *GEP = Builder.CreateInBoundsGEP(Array, GEPIndices,
- "switch.gep");
+ Value *GEP = Builder.CreateInBoundsGEP(Array->getValueType(), Array,
+ GEPIndices, "switch.gep");
return Builder.CreateLoad(GEP, "switch.load");
}
}
llvm_unreachable("Unknown lookup table kind!");
}
-bool SwitchLookupTable::WouldFitInRegister(const DataLayout *DL,
+bool SwitchLookupTable::WouldFitInRegister(const DataLayout &DL,
uint64_t TableSize,
- const Type *ElementType) {
- if (!DL)
- return false;
- 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
// Avoid overflow, fitsInLegalInteger uses unsigned int for the width.
if (TableSize >= UINT_MAX/IT->getBitWidth())
return false;
- return DL->fitsInLegalInteger(TableSize * IT->getBitWidth());
+ return DL.fitsInLegalInteger(TableSize * IT->getBitWidth());
}
-/// ShouldBuildLookupTable - Determine whether a lookup table should be built
-/// for this switch, based on the number of cases, size of the table and the
-/// types of the results.
-static bool ShouldBuildLookupTable(SwitchInst *SI,
- uint64_t TableSize,
- const TargetTransformInfo &TTI,
- const DataLayout *DL,
- const SmallDenseMap<PHINode*, Type*>& ResultTypes) {
+/// Determine whether a lookup table should be built for this switch, based on
+/// the number of cases, size of the table, and the types of the results.
+static bool
+ShouldBuildLookupTable(SwitchInst *SI, uint64_t TableSize,
+ const TargetTransformInfo &TTI, const DataLayout &DL,
+ const SmallDenseMap<PHINode *, Type *> &ResultTypes) {
if (SI->getNumCases() > TableSize || TableSize >= UINT64_MAX / 10)
return false; // TableSize overflowed, or mul below might overflow.
bool AllTablesFitInRegister = true;
bool HasIllegalType = false;
- for (SmallDenseMap<PHINode*, Type*>::const_iterator I = ResultTypes.begin(),
- E = ResultTypes.end(); I != E; ++I) {
- Type *Ty = I->second;
+ for (const auto &I : ResultTypes) {
+ Type *Ty = I.second;
// Saturate this flag to true.
HasIllegalType = HasIllegalType || !TTI.isTypeLegal(Ty);
return SI->getNumCases() * 10 >= TableSize * 4;
}
-/// SwitchToLookupTable - If the switch is only used to initialize one or more
-/// phi nodes in a common successor block with different constant values,
-/// replace the switch with lookup tables.
-static bool SwitchToLookupTable(SwitchInst *SI,
- IRBuilder<> &Builder,
- const TargetTransformInfo &TTI,
- const DataLayout* DL) {
+/// Try to reuse the switch table index compare. Following pattern:
+/// \code
+/// if (idx < tablesize)
+/// r = table[idx]; // table does not contain default_value
+/// else
+/// r = default_value;
+/// if (r != default_value)
+/// ...
+/// \endcode
+/// Is optimized to:
+/// \code
+/// cond = idx < tablesize;
+/// if (cond)
+/// r = table[idx];
+/// else
+/// r = default_value;
+/// if (cond)
+/// ...
+/// \endcode
+/// Jump threading will then eliminate the second if(cond).
+static void reuseTableCompare(User *PhiUser, BasicBlock *PhiBlock,
+ BranchInst *RangeCheckBranch, Constant *DefaultValue,
+ const SmallVectorImpl<std::pair<ConstantInt*, Constant*> >& Values) {
+
+ ICmpInst *CmpInst = dyn_cast<ICmpInst>(PhiUser);
+ if (!CmpInst)
+ return;
+
+ // We require that the compare is in the same block as the phi so that jump
+ // threading can do its work afterwards.
+ if (CmpInst->getParent() != PhiBlock)
+ return;
+
+ Constant *CmpOp1 = dyn_cast<Constant>(CmpInst->getOperand(1));
+ if (!CmpOp1)
+ return;
+
+ Value *RangeCmp = RangeCheckBranch->getCondition();
+ Constant *TrueConst = ConstantInt::getTrue(RangeCmp->getType());
+ Constant *FalseConst = ConstantInt::getFalse(RangeCmp->getType());
+
+ // Check if the compare with the default value is constant true or false.
+ Constant *DefaultConst = ConstantExpr::getICmp(CmpInst->getPredicate(),
+ DefaultValue, CmpOp1, true);
+ if (DefaultConst != TrueConst && DefaultConst != FalseConst)
+ return;
+
+ // Check if the compare with the case values is distinct from the default
+ // compare result.
+ for (auto ValuePair : Values) {
+ Constant *CaseConst = ConstantExpr::getICmp(CmpInst->getPredicate(),
+ ValuePair.second, CmpOp1, true);
+ if (!CaseConst || CaseConst == DefaultConst)
+ return;
+ 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
+ // at this late stage. Practically we do it at most once for a switch.
+ BasicBlock *BranchBlock = RangeCheckBranch->getParent();
+ for (auto PI = pred_begin(PhiBlock), E = pred_end(PhiBlock); PI != E; ++PI) {
+ BasicBlock *Pred = *PI;
+ if (Pred != BranchBlock && Pred->getUniquePredecessor() != BranchBlock)
+ return;
+ }
+
+ if (DefaultConst == FalseConst) {
+ // The compare yields the same result. We can replace it.
+ CmpInst->replaceAllUsesWith(RangeCmp);
+ ++NumTableCmpReuses;
+ } else {
+ // The compare yields the same result, just inverted. We can replace it.
+ Value *InvertedTableCmp = BinaryOperator::CreateXor(RangeCmp,
+ ConstantInt::get(RangeCmp->getType(), 1), "inverted.cmp",
+ RangeCheckBranch);
+ CmpInst->replaceAllUsesWith(InvertedTableCmp);
+ ++NumTableCmpReuses;
+ }
+}
+
+/// If the switch is only used to initialize one or more phi nodes in a common
+/// successor block with different constant values, replace the switch with
+/// lookup tables.
+static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
+ const DataLayout &DL,
+ const TargetTransformInfo &TTI) {
assert(SI->getNumCases() > 1 && "Degenerate switch?");
// Only build lookup table when we have a target that supports it.
return false;
// Figure out the corresponding result for each case value and phi node in the
- // common destination, as well as the the min and max case values.
+ // common destination, as well as the min and max case values.
assert(SI->case_begin() != SI->case_end());
SwitchInst::CaseIt CI = SI->case_begin();
ConstantInt *MinCaseVal = CI.getCaseValue();
return false;
// Append the result from this case to the list for each phi.
- for (ResultsTy::iterator I = Results.begin(), E = Results.end(); I!=E; ++I) {
- if (!ResultLists.count(I->first))
- PHIs.push_back(I->first);
- ResultLists[I->first].push_back(std::make_pair(CaseVal, I->second));
+ for (const auto &I : Results) {
+ PHINode *PHI = I.first;
+ Constant *Value = I.second;
+ if (!ResultLists.count(PHI))
+ PHIs.push_back(PHI);
+ ResultLists[PHI].push_back(std::make_pair(CaseVal, Value));
}
}
// Keep track of the result types.
- for (size_t I = 0, E = PHIs.size(); I != E; ++I) {
- PHINode *PHI = PHIs[I];
+ for (PHINode *PHI : PHIs) {
ResultTypes[PHI] = ResultLists[PHI][0].second->getType();
}
// 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;
- bool HasDefaultResults = false;
- if (TableHasHoles) {
- HasDefaultResults = GetCaseResults(SI, nullptr, SI->getDefaultDest(),
- &CommonDest, DefaultResultsList, DL);
- }
+ bool 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)))
+ if (!DL.fitsInLegalInteger(TableSize))
return false;
}
- for (size_t I = 0, E = DefaultResultsList.size(); I != E; ++I) {
- PHINode *PHI = DefaultResultsList[I].first;
- Constant *Result = DefaultResultsList[I].second;
+ for (const auto &I : DefaultResultsList) {
+ PHINode *PHI = I.first;
+ Constant *Result = I.second;
DefaultResults[PHI] = Result;
}
"It is impossible for a switch to have more entries than the max "
"representable value of its input integer type's size.");
- // If we have a fully covered lookup table, unconditionally branch to the
- // lookup table BB. Otherwise, check if the condition value is within the case
- // range. If it is so, branch to the new BB. Otherwise branch to SI's default
- // destination.
- const bool GeneratingCoveredLookupTable = MaxTableSize == TableSize;
- if (GeneratingCoveredLookupTable) {
+ // If the default destination is unreachable, or if the lookup table covers
+ // all values of the conditional variable, branch directly to the lookup table
+ // BB. Otherwise, check that the condition is within the case range.
+ const bool DefaultIsReachable =
+ !isa<UnreachableInst>(SI->getDefaultDest()->getFirstNonPHIOrDbg());
+ const bool GeneratingCoveredLookupTable = (MaxTableSize == TableSize);
+ BranchInst *RangeCheckBranch = nullptr;
+
+ if (!DefaultIsReachable || GeneratingCoveredLookupTable) {
Builder.CreateBr(LookupBB);
- SI->getDefaultDest()->removePredecessor(SI->getParent());
+ // Note: We call removeProdecessor later since we need to be able to get the
+ // PHI value for the default case in case we're using a bit mask.
} else {
Value *Cmp = Builder.CreateICmpULT(TableIndex, ConstantInt::get(
- MinCaseVal->getType(), TableSize));
- Builder.CreateCondBr(Cmp, LookupBB, SI->getDefaultDest());
+ MinCaseVal->getType(), TableSize));
+ RangeCheckBranch = Builder.CreateCondBr(Cmp, LookupBB, SI->getDefaultDest());
}
// Populate the BB that does the lookups.
CommonDest->getParent(),
CommonDest);
+ // Make the mask's bitwidth at least 8bit and a power-of-2 to avoid
+ // unnecessary illegal types.
+ uint64_t TableSizePowOf2 = NextPowerOf2(std::max(7ULL, TableSize - 1ULL));
+ APInt MaskInt(TableSizePowOf2, 0);
+ APInt One(TableSizePowOf2, 1);
// 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() -
AddPredecessorToBlock(SI->getDefaultDest(), MaskBB, SI->getParent());
}
+ if (!DefaultIsReachable || GeneratingCoveredLookupTable) {
+ // We cached PHINodes in PHIs, to avoid accessing deleted PHINodes later,
+ // do not delete PHINodes here.
+ SI->getDefaultDest()->removePredecessor(SI->getParent(),
+ /*DontDeleteUselessPHIs=*/true);
+ }
+
bool ReturnedEarly = false;
for (size_t I = 0, E = PHIs.size(); I != E; ++I) {
PHINode *PHI = PHIs[I];
+ const ResultListTy &ResultList = ResultLists[PHI];
// 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],
- DV, DL);
+ SwitchLookupTable Table(Mod, TableSize, MinCaseVal, ResultList, DV, DL);
Value *Result = Table.BuildLookup(TableIndex, Builder);
break;
}
+ // Do a small peephole optimization: re-use the switch table compare if
+ // possible.
+ if (!TableHasHoles && HasDefaultResults && RangeCheckBranch) {
+ BasicBlock *PhiBlock = PHI->getParent();
+ // Search for compare instructions which use the phi.
+ for (auto *User : PHI->users()) {
+ reuseTableCompare(User, PhiBlock, RangeCheckBranch, DV, ResultList);
+ }
+ }
+
PHI->addIncoming(Result, LookupBB);
}
// see if that predecessor totally determines the outcome of this switch.
if (BasicBlock *OnlyPred = BB->getSinglePredecessor())
if (SimplifyEqualityComparisonWithOnlyPredecessor(SI, OnlyPred, Builder))
- return SimplifyCFG(BB, TTI, DL) | true;
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
Value *Cond = SI->getCondition();
if (SelectInst *Select = dyn_cast<SelectInst>(Cond))
if (SimplifySwitchOnSelect(SI, Select))
- return SimplifyCFG(BB, TTI, DL) | true;
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
// If the block only contains the switch, see if we can fold the block
// away into any preds.
++BBI;
if (SI == &*BBI)
if (FoldValueComparisonIntoPredecessors(SI, Builder))
- return SimplifyCFG(BB, TTI, DL) | true;
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
}
// Try to transform the switch into an icmp and a branch.
if (TurnSwitchRangeIntoICmp(SI, Builder))
- return SimplifyCFG(BB, TTI, DL) | true;
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
// Remove unreachable cases.
- if (EliminateDeadSwitchCases(SI))
- return SimplifyCFG(BB, TTI, DL) | true;
+ if (EliminateDeadSwitchCases(SI, AC, DL))
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
+
+ if (SwitchToSelect(SI, Builder, AC, DL))
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
if (ForwardSwitchConditionToPHI(SI))
- return SimplifyCFG(BB, TTI, DL) | true;
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
- if (SwitchToLookupTable(SI, Builder, TTI, DL))
- return SimplifyCFG(BB, TTI, DL) | true;
+ if (SwitchToLookupTable(SI, Builder, DL, TTI))
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
return false;
}
SmallPtrSet<Value *, 8> Succs;
for (unsigned i = 0, e = IBI->getNumDestinations(); i != e; ++i) {
BasicBlock *Dest = IBI->getDestination(i);
- if (!Dest->hasAddressTaken() || !Succs.insert(Dest)) {
+ if (!Dest->hasAddressTaken() || !Succs.insert(Dest).second) {
Dest->removePredecessor(BB);
IBI->removeDestination(i);
--i; --e;
if (SelectInst *SI = dyn_cast<SelectInst>(IBI->getAddress())) {
if (SimplifyIndirectBrOnSelect(IBI, SI))
- return SimplifyCFG(BB, TTI, DL) | true;
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
}
return Changed;
}
+/// Given an block with only a single landing pad and a unconditional branch
+/// try to find another basic block which this one can be merged with. This
+/// handles cases where we have multiple invokes with unique landing pads, but
+/// a shared handler.
+///
+/// We specifically choose to not worry about merging non-empty blocks
+/// here. That is a PRE/scheduling problem and is best solved elsewhere. In
+/// practice, the optimizer produces empty landing pad blocks quite frequently
+/// when dealing with exception dense code. (see: instcombine, gvn, if-else
+/// sinking in this file)
+///
+/// This is primarily a code size optimization. We need to avoid performing
+/// any transform which might inhibit optimization (such as our ability to
+/// specialize a particular handler via tail commoning). We do this by not
+/// merging any blocks which require us to introduce a phi. Since the same
+/// values are flowing through both blocks, we don't loose any ability to
+/// specialize. If anything, we make such specialization more likely.
+///
+/// TODO - This transformation could remove entries from a phi in the target
+/// block when the inputs in the phi are the same for the two blocks being
+/// merged. In some cases, this could result in removal of the PHI entirely.
+static bool TryToMergeLandingPad(LandingPadInst *LPad, BranchInst *BI,
+ BasicBlock *BB) {
+ auto Succ = BB->getUniqueSuccessor();
+ assert(Succ);
+ // If there's a phi in the successor block, we'd likely have to introduce
+ // a phi into the merged landing pad block.
+ if (isa<PHINode>(*Succ->begin()))
+ return false;
+
+ for (BasicBlock *OtherPred : predecessors(Succ)) {
+ if (BB == OtherPred)
+ continue;
+ BasicBlock::iterator I = OtherPred->begin();
+ LandingPadInst *LPad2 = dyn_cast<LandingPadInst>(I);
+ if (!LPad2 || !LPad2->isIdenticalTo(LPad))
+ continue;
+ for (++I; isa<DbgInfoIntrinsic>(I); ++I) {}
+ BranchInst *BI2 = dyn_cast<BranchInst>(I);
+ if (!BI2 || !BI2->isIdenticalTo(BI))
+ continue;
+
+ // We've found an identical block. Update our predeccessors to take that
+ // path instead and make ourselves dead.
+ SmallSet<BasicBlock *, 16> Preds;
+ Preds.insert(pred_begin(BB), pred_end(BB));
+ for (BasicBlock *Pred : Preds) {
+ InvokeInst *II = cast<InvokeInst>(Pred->getTerminator());
+ assert(II->getNormalDest() != BB &&
+ II->getUnwindDest() == BB && "unexpected successor");
+ II->setUnwindDest(OtherPred);
+ }
+
+ // The debug info in OtherPred doesn't cover the merged control flow that
+ // used to go through BB. We need to delete it or update it.
+ for (auto I = OtherPred->begin(), E = OtherPred->end();
+ I != E;) {
+ Instruction &Inst = *I; I++;
+ if (isa<DbgInfoIntrinsic>(Inst))
+ Inst.eraseFromParent();
+ }
+
+ SmallSet<BasicBlock *, 16> Succs;
+ Succs.insert(succ_begin(BB), succ_end(BB));
+ for (BasicBlock *Succ : Succs) {
+ Succ->removePredecessor(BB);
+ }
+
+ IRBuilder<> Builder(BI);
+ Builder.CreateUnreachable();
+ BI->eraseFromParent();
+ return true;
+ }
+ return false;
+}
+
bool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI, IRBuilder<> &Builder){
BasicBlock *BB = BI->getParent();
return true;
// If the Terminator is the only non-phi instruction, simplify the block.
- BasicBlock::iterator I = BB->getFirstNonPHIOrDbgOrLifetime();
+ BasicBlock::iterator I = BB->getFirstNonPHIOrDbg();
if (I->isTerminator() && BB != &BB->getParent()->getEntryBlock() &&
TryToSimplifyUncondBranchFromEmptyBlock(BB))
return true;
for (++I; isa<DbgInfoIntrinsic>(I); ++I)
;
if (I->isTerminator() &&
- TryToSimplifyUncondBranchWithICmpInIt(ICI, Builder, TTI, DL))
+ TryToSimplifyUncondBranchWithICmpInIt(ICI, Builder, DL, TTI,
+ BonusInstThreshold, AC))
return true;
}
+ // See if we can merge an empty landing pad block with another which is
+ // equivalent.
+ if (LandingPadInst *LPad = dyn_cast<LandingPadInst>(I)) {
+ for (++I; isa<DbgInfoIntrinsic>(I); ++I) {}
+ if (I->isTerminator() &&
+ TryToMergeLandingPad(LPad, BI, BB))
+ return true;
+ }
+
// If this basic block is ONLY a compare and a branch, and if a predecessor
// branches to us and our successor, fold the comparison into the
// predecessor and use logical operations to update the incoming value
// for PHI nodes in common successor.
- if (FoldBranchToCommonDest(BI, DL))
- return SimplifyCFG(BB, TTI, DL) | true;
+ if (FoldBranchToCommonDest(BI, BonusInstThreshold))
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
return false;
}
// switch.
if (BasicBlock *OnlyPred = BB->getSinglePredecessor())
if (SimplifyEqualityComparisonWithOnlyPredecessor(BI, OnlyPred, Builder))
- return SimplifyCFG(BB, TTI, DL) | true;
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
// This block must be empty, except for the setcond inst, if it exists.
// Ignore dbg intrinsics.
++I;
if (&*I == BI) {
if (FoldValueComparisonIntoPredecessors(BI, Builder))
- return SimplifyCFG(BB, TTI, DL) | true;
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
} else if (&*I == cast<Instruction>(BI->getCondition())){
++I;
// Ignore dbg intrinsics.
while (isa<DbgInfoIntrinsic>(I))
++I;
if (&*I == BI && FoldValueComparisonIntoPredecessors(BI, Builder))
- return SimplifyCFG(BB, TTI, DL) | true;
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
}
}
// Try to turn "br (X == 0 | X == 1), T, F" into a switch instruction.
- if (SimplifyBranchOnICmpChain(BI, DL, Builder))
+ if (SimplifyBranchOnICmpChain(BI, Builder, DL))
return true;
// If this basic block is ONLY a compare and a branch, and if a predecessor
// branches to us and one of our successors, fold the comparison into the
// predecessor and use logical operations to pick the right destination.
- if (FoldBranchToCommonDest(BI, DL))
- return SimplifyCFG(BB, TTI, DL) | true;
+ if (FoldBranchToCommonDest(BI, BonusInstThreshold))
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
// We have a conditional branch to two blocks that are only reachable
// from BI. We know that the condbr dominates the two blocks, so see if
// can hoist it up to the branching block.
if (BI->getSuccessor(0)->getSinglePredecessor()) {
if (BI->getSuccessor(1)->getSinglePredecessor()) {
- if (HoistThenElseCodeToIf(BI, DL))
- return SimplifyCFG(BB, TTI, DL) | true;
+ if (HoistThenElseCodeToIf(BI, TTI))
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
} else {
// If Successor #1 has multiple preds, we may be able to conditionally
// execute Successor #0 if it branches to Successor #1.
TerminatorInst *Succ0TI = BI->getSuccessor(0)->getTerminator();
if (Succ0TI->getNumSuccessors() == 1 &&
Succ0TI->getSuccessor(0) == BI->getSuccessor(1))
- if (SpeculativelyExecuteBB(BI, BI->getSuccessor(0), DL))
- return SimplifyCFG(BB, TTI, DL) | true;
+ if (SpeculativelyExecuteBB(BI, BI->getSuccessor(0), TTI))
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
}
} else if (BI->getSuccessor(1)->getSinglePredecessor()) {
// If Successor #0 has multiple preds, we may be able to conditionally
TerminatorInst *Succ1TI = BI->getSuccessor(1)->getTerminator();
if (Succ1TI->getNumSuccessors() == 1 &&
Succ1TI->getSuccessor(0) == BI->getSuccessor(0))
- if (SpeculativelyExecuteBB(BI, BI->getSuccessor(1), DL))
- return SimplifyCFG(BB, TTI, DL) | true;
+ if (SpeculativelyExecuteBB(BI, BI->getSuccessor(1), TTI))
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
}
// If this is a branch on a phi node in the current block, thread control
if (PHINode *PN = dyn_cast<PHINode>(BI->getCondition()))
if (PN->getParent() == BI->getParent())
if (FoldCondBranchOnPHI(BI, DL))
- return SimplifyCFG(BB, TTI, DL) | true;
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
// Scan predecessor blocks for conditional branches.
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))
- return SimplifyCFG(BB, TTI, DL) | true;
+ return SimplifyCFG(BB, TTI, BonusInstThreshold, AC) | true;
return false;
}
// Remove basic blocks that have no predecessors (except the entry block)...
// or that just have themself as a predecessor. These are unreachable.
- if ((pred_begin(BB) == pred_end(BB) &&
+ if ((pred_empty(BB) &&
BB != &BB->getParent()->getEntryBlock()) ||
BB->getSinglePredecessor() == BB) {
DEBUG(dbgs() << "Removing BB: \n" << *BB);
// eliminate it, do so now.
if (PHINode *PN = dyn_cast<PHINode>(BB->begin()))
if (PN->getNumIncomingValues() == 2)
- Changed |= FoldTwoEntryPHINode(PN, DL);
+ Changed |= FoldTwoEntryPHINode(PN, TTI, DL);
Builder.SetInsertPoint(BB->getTerminator());
if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator())) {
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 =
return Changed;
}
-/// SimplifyCFG - This function is used to do simplification of a CFG. For
-/// example, it adjusts branches to branches to eliminate the extra hop, it
+/// This function is used to do simplification of a CFG.
+/// For example, it adjusts branches to branches to eliminate the extra hop,
/// eliminates unreachable basic blocks, and does other "peephole" optimization
/// of the CFG. It returns true if a modification was made.
///
bool llvm::SimplifyCFG(BasicBlock *BB, const TargetTransformInfo &TTI,
- const DataLayout *DL) {
- return SimplifyCFGOpt(TTI, DL).run(BB);
+ unsigned BonusInstThreshold, AssumptionCache *AC) {
+ return SimplifyCFGOpt(TTI, BB->getModule()->getDataLayout(),
+ BonusInstThreshold, AC).run(BB);
}
projects / oota-llvm.git / blobdiff