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llvm-project/llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp

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//===-- PredicateSimplifier.cpp - Path Sensitive Simplifier -----------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Nick Lewycky and is distributed under the
// University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===------------------------------------------------------------------===//
//
// Path-sensitive optimizer. In a branch where x == y, replace uses of
// x with y. Permits further optimization, such as the elimination of
// the unreachable call:
//
// void test(int *p, int *q)
// {
// if (p != q)
// return;
//
// if (*p != *q)
// foo(); // unreachable
// }
//
//===------------------------------------------------------------------===//
//
// This optimization works by substituting %q for %p when protected by a
// conditional that assures us of that fact. Properties are stored as
// relationships between two values.
//
//===------------------------------------------------------------------===//
#define DEBUG_TYPE "predsimplify"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/Pass.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Debug.h"
#include <iostream>
using namespace llvm;
typedef DominatorTree::Node DTNodeType;
namespace {
Statistic<>
NumVarsReplaced("predsimplify", "Number of argument substitutions");
Statistic<>
NumInstruction("predsimplify", "Number of instructions removed");
Statistic<>
NumSwitchCases("predsimplify", "Number of switch cases removed");
Statistic<>
NumBranches("predsimplify", "Number of branches made unconditional");
/// Returns true if V1 is a better choice than V2. Note that it is
/// not a total ordering.
struct compare {
bool operator()(Value *V1, Value *V2) const {
if (isa<Constant>(V2)) {
if (!isa<Constant>(V1)) {
return true;
}
} else if (isa<Argument>(V2)) {
if (!isa<Constant>(V1) && !isa<Argument>(V1)) {
return true;
}
}
if (User *U1 = dyn_cast<User>(V1)) {
for (User::const_op_iterator I = U1->op_begin(), E = U1->op_end();
I != E; ++I) {
if (*I == V2) {
return true;
}
}
}
return false;
}
};
/// Used for choosing the canonical Value in a synonym set.
/// Leaves the better one in V1.
static void order(Value *&V1, Value *&V2) {
static compare c;
if (c(V1, V2))
std::swap(V1, V2);
}
/// Similar to EquivalenceClasses, this stores the set of equivalent
/// types. Beyond EquivalenceClasses, it allows the user to specify
/// which element will act as leader through a StrictWeakOrdering
/// function.
template<typename ElemTy, typename StrictWeak>
class VISIBILITY_HIDDEN Synonyms {
std::map<ElemTy, unsigned> mapping;
std::vector<ElemTy> leaders;
StrictWeak swo;
public:
typedef unsigned iterator;
typedef const unsigned const_iterator;
// Inspection
bool empty() const {
return leaders.empty();
}
iterator findLeader(ElemTy e) {
typename std::map<ElemTy, unsigned>::iterator MI = mapping.find(e);
if (MI == mapping.end()) return 0;
return MI->second;
}
const_iterator findLeader(ElemTy e) const {
typename std::map<ElemTy, unsigned>::const_iterator MI =
mapping.find(e);
if (MI == mapping.end()) return 0;
return MI->second;
}
ElemTy &getLeader(iterator I) {
assert(I != 0 && "Element zero is out of range.");
return leaders[I-1];
}
const ElemTy &getLeader(const_iterator I) const {
assert(I != 0 && "Element zero is out of range.");
return leaders[I-1];
}
#ifdef DEBUG
void debug(std::ostream &os) const {
for (unsigned i = 1, e = leaders.size()+1; i != e; ++i) {
os << i << ". " << *leaders[i-1] << ": [";
for (std::map<Value *, unsigned>::const_iterator
I = mapping.begin(), E = mapping.end(); I != E; ++I) {
if ((*I).second == i && (*I).first != leaders[i-1]) {
os << *(*I).first << " ";
}
}
os << "]\n";
}
}
#endif
// Mutators
/// Combine two sets referring to the same element, inserting the
/// elements as needed. Returns a valid iterator iff two already
/// existing disjoint synonym sets were combined. The iterator
/// points to the removed element.
iterator unionSets(ElemTy E1, ElemTy E2) {
if (swo(E1, E2)) std::swap(E1, E2);
iterator I1 = findLeader(E1);
iterator I2 = findLeader(E2);
if (!I1 && !I2) { // neither entry is in yet
leaders.push_back(E1);
I1 = leaders.size();
mapping[E1] = I1;
mapping[E2] = I1;
return false;
}
if (!I1 && I2) {
mapping[E1] = I2;
return false;
}
if (I1 && !I2) {
mapping[E2] = I1;
return false;
}
// This is the case where we have two sets, [%a1, %a2, %a3] and
// [%p1, %p2, %p3] and someone says that %a2 == %p3. We need to
// combine the two synsets.
for (std::map<Value *, unsigned>::iterator I = mapping.begin(),
E = mapping.end(); I != E; ++I) {
if (I->second == I2) I->second = I1;
else if (I->second > I2) --I->second;
}
leaders.erase(leaders.begin() + I2 - 1);
return true;
}
/// Returns an iterator pointing to the synonym set containing
/// element e. If none exists, a new one is created and returned.
iterator findOrInsert(ElemTy e) {
iterator I = findLeader(e);
if (I) return I;
leaders.push_back(e);
I = leaders.size();
mapping[e] = I;
return I;
}
};
/// Represents the set of equivalent Value*s and provides insertion
/// and fast lookup. Also stores the set of inequality relationships.
class PropertySet {
struct Property;
public:
class Synonyms<Value *, compare> union_find;
typedef std::vector<Property>::iterator PropertyIterator;
typedef std::vector<Property>::const_iterator ConstPropertyIterator;
typedef Synonyms<Value *, compare>::iterator SynonymIterator;
enum Ops {
EQ,
NE
};
Value *canonicalize(Value *V) const {
Value *C = lookup(V);
return C ? C : V;
}
Value *lookup(Value *V) const {
Synonyms<Value *, compare>::iterator SI = union_find.findLeader(V);
if (!SI) return NULL;
return union_find.getLeader(SI);
}
bool empty() const {
return union_find.empty();
}
void addEqual(Value *V1, Value *V2) {
// If %x = 0. and %y = -0., seteq %x, %y is true, but
// copysign(%x) is not the same as copysign(%y).
if (V2->getType()->isFloatingPoint()) return;
order(V1, V2);
if (isa<Constant>(V2)) return; // refuse to set false == true.
DEBUG(std::cerr << "equal: " << *V1 << " and " << *V2 << "\n");
SynonymIterator deleted = union_find.unionSets(V1, V2);
if (deleted) {
SynonymIterator replacement = union_find.findLeader(V1);
// Move Properties
for (PropertyIterator I = Properties.begin(), E = Properties.end();
I != E; ++I) {
if (I->I1 == deleted) I->I1 = replacement;
else if (I->I1 > deleted) --I->I1;
if (I->I2 == deleted) I->I2 = replacement;
else if (I->I2 > deleted) --I->I2;
}
}
addImpliedProperties(EQ, V1, V2);
}
void addNotEqual(Value *V1, Value *V2) {
// If %x = NAN then seteq %x, %x is false.
if (V2->getType()->isFloatingPoint()) return;
DEBUG(std::cerr << "not equal: " << *V1 << " and " << *V2 << "\n");
if (findProperty(NE, V1, V2) != Properties.end())
return; // found.
// Add the property.
SynonymIterator I1 = union_find.findOrInsert(V1),
I2 = union_find.findOrInsert(V2);
Properties.push_back(Property(NE, I1, I2));
addImpliedProperties(NE, V1, V2);
}
PropertyIterator findProperty(Ops Opcode, Value *V1, Value *V2) {
assert(Opcode != EQ && "Can't findProperty on EQ."
"Use the lookup method instead.");
SynonymIterator I1 = union_find.findLeader(V1),
I2 = union_find.findLeader(V2);
if (!I1 || !I2) return Properties.end();
return
find(Properties.begin(), Properties.end(), Property(Opcode, I1, I2));
}
ConstPropertyIterator
findProperty(Ops Opcode, Value *V1, Value *V2) const {
assert(Opcode != EQ && "Can't findProperty on EQ."
"Use the lookup method instead.");
SynonymIterator I1 = union_find.findLeader(V1),
I2 = union_find.findLeader(V2);
if (!I1 || !I2) return Properties.end();
return
find(Properties.begin(), Properties.end(), Property(Opcode, I1, I2));
}
private:
// Represents Head OP [Tail1, Tail2, ...]
// For example: %x != %a, %x != %b.
struct VISIBILITY_HIDDEN Property {
typedef Synonyms<Value *, compare>::iterator Iter;
Property(Ops opcode, Iter i1, Iter i2)
: Opcode(opcode), I1(i1), I2(i2)
{ assert(opcode != EQ && "Equality belongs in the synonym set, "
"not a property."); }
bool operator==(const Property &P) const {
return (Opcode == P.Opcode) &&
((I1 == P.I1 && I2 == P.I2) ||
(I1 == P.I2 && I2 == P.I1));
}
Ops Opcode;
Iter I1, I2;
};
void add(Ops Opcode, Value *V1, Value *V2, bool invert) {
switch (Opcode) {
case EQ:
if (invert) addNotEqual(V1, V2);
else addEqual(V1, V2);
break;
case NE:
if (invert) addEqual(V1, V2);
else addNotEqual(V1, V2);
break;
default:
assert(0 && "Unknown property opcode.");
}
}
// Finds the properties implied by an equivalence and adds them too.
// Example: ("seteq %a, %b", true, EQ) --> (%a, %b, EQ)
// ("seteq %a, %b", false, EQ) --> (%a, %b, NE)
void addImpliedProperties(Ops Opcode, Value *V1, Value *V2) {
order(V1, V2);
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(V2)) {
switch (BO->getOpcode()) {
case Instruction::SetEQ:
if (V1 == ConstantBool::True)
add(Opcode, BO->getOperand(0), BO->getOperand(1), false);
if (V1 == ConstantBool::False)
add(Opcode, BO->getOperand(0), BO->getOperand(1), true);
break;
case Instruction::SetNE:
if (V1 == ConstantBool::True)
add(Opcode, BO->getOperand(0), BO->getOperand(1), true);
if (V1 == ConstantBool::False)
add(Opcode, BO->getOperand(0), BO->getOperand(1), false);
break;
case Instruction::SetLT:
case Instruction::SetGT:
if (V1 == ConstantBool::True)
add(Opcode, BO->getOperand(0), BO->getOperand(1), true);
break;
case Instruction::SetLE:
case Instruction::SetGE:
if (V1 == ConstantBool::False)
add(Opcode, BO->getOperand(0), BO->getOperand(1), true);
break;
case Instruction::And:
if (V1 == ConstantBool::True) {
add(Opcode, ConstantBool::True, BO->getOperand(0), false);
add(Opcode, ConstantBool::True, BO->getOperand(1), false);
}
break;
case Instruction::Or:
if (V1 == ConstantBool::False) {
add(Opcode, ConstantBool::False, BO->getOperand(0), false);
add(Opcode, ConstantBool::False, BO->getOperand(1), false);
}
break;
case Instruction::Xor:
if (V1 == ConstantBool::True) {
if (BO->getOperand(0) == ConstantBool::True)
add(Opcode, ConstantBool::False, BO->getOperand(1), false);
if (BO->getOperand(1) == ConstantBool::True)
add(Opcode, ConstantBool::False, BO->getOperand(0), false);
}
if (V1 == ConstantBool::False) {
if (BO->getOperand(0) == ConstantBool::True)
add(Opcode, ConstantBool::True, BO->getOperand(1), false);
if (BO->getOperand(1) == ConstantBool::True)
add(Opcode, ConstantBool::True, BO->getOperand(0), false);
}
break;
default:
break;
}
} else if (SelectInst *SI = dyn_cast<SelectInst>(V2)) {
if (Opcode != EQ && Opcode != NE) return;
ConstantBool *True = (Opcode==EQ) ? ConstantBool::True
: ConstantBool::False,
*False = (Opcode==EQ) ? ConstantBool::False
: ConstantBool::True;
if (V1 == SI->getTrueValue())
addEqual(SI->getCondition(), True);
else if (V1 == SI->getFalseValue())
addEqual(SI->getCondition(), False);
else if (Opcode == EQ)
assert("Result of select not equal to either value.");
}
}
public:
#ifdef DEBUG
void debug(std::ostream &os) const {
static const char *OpcodeTable[] = { "EQ", "NE" };
union_find.debug(os);
for (std::vector<Property>::const_iterator I = Properties.begin(),
E = Properties.end(); I != E; ++I) {
os << (*I).I1 << " " << OpcodeTable[(*I).Opcode] << " "
<< (*I).I2 << "\n";
}
os << "\n";
}
#endif
std::vector<Property> Properties;
};
/// PredicateSimplifier - This class is a simplifier that replaces
/// one equivalent variable with another. It also tracks what
/// can't be equal and will solve setcc instructions when possible.
class PredicateSimplifier : public FunctionPass {
public:
bool runOnFunction(Function &F);
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
private:
// Try to replace the Use of the instruction with something simpler.
Value *resolve(SetCondInst *SCI, const PropertySet &);
Value *resolve(BinaryOperator *BO, const PropertySet &);
Value *resolve(SelectInst *SI, const PropertySet &);
Value *resolve(Value *V, const PropertySet &);
// Used by terminator instructions to proceed from the current basic
// block to the next. Verifies that "current" dominates "next",
// then calls visitBasicBlock.
void proceedToSuccessor(PropertySet &CurrentPS, PropertySet &NextPS,
DTNodeType *Current, DTNodeType *Next);
void proceedToSuccessor(PropertySet &CurrentPS,
DTNodeType *Current, DTNodeType *Next);
// Visits each instruction in the basic block.
void visitBasicBlock(DTNodeType *DTNode, PropertySet &KnownProperties);
// Tries to simplify each Instruction and add new properties to
// the PropertySet. Returns true if it erase the instruction.
void visitInstruction(Instruction *I, DTNodeType *, PropertySet &);
// For each instruction, add the properties to KnownProperties.
void visit(TerminatorInst *TI, DTNodeType *, PropertySet &);
void visit(BranchInst *BI, DTNodeType *, PropertySet &);
void visit(SwitchInst *SI, DTNodeType *, PropertySet);
void visit(LoadInst *LI, DTNodeType *, PropertySet &);
void visit(StoreInst *SI, DTNodeType *, PropertySet &);
void visit(BinaryOperator *BO, DTNodeType *, PropertySet &);
DominatorTree *DT;
bool modified;
};
RegisterPass<PredicateSimplifier> X("predsimplify",
"Predicate Simplifier");
}
FunctionPass *llvm::createPredicateSimplifierPass() {
return new PredicateSimplifier();
}
bool PredicateSimplifier::runOnFunction(Function &F) {
DT = &getAnalysis<DominatorTree>();
modified = false;
PropertySet KnownProperties;
visitBasicBlock(DT->getRootNode(), KnownProperties);
return modified;
}
void PredicateSimplifier::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<DominatorTree>();
}
// resolve catches cases addProperty won't because it wasn't used as a
// condition in the branch, and that visit won't, because the instruction
// was defined outside of the scope that the properties apply to.
Value *PredicateSimplifier::resolve(SetCondInst *SCI,
const PropertySet &KP) {
// Attempt to resolve the SetCondInst to a boolean.
Value *SCI0 = resolve(SCI->getOperand(0), KP),
*SCI1 = resolve(SCI->getOperand(1), KP);
ConstantIntegral *CI1 = dyn_cast<ConstantIntegral>(SCI0),
*CI2 = dyn_cast<ConstantIntegral>(SCI1);
if (!CI1 || !CI2) {
PropertySet::ConstPropertyIterator NE =
KP.findProperty(PropertySet::NE, SCI0, SCI1);
if (NE != KP.Properties.end()) {
switch (SCI->getOpcode()) {
case Instruction::SetEQ:
return ConstantBool::False;
case Instruction::SetNE:
return ConstantBool::True;
case Instruction::SetLE:
case Instruction::SetGE:
case Instruction::SetLT:
case Instruction::SetGT:
break;
default:
assert(0 && "Unknown opcode in SetCondInst.");
break;
}
}
return SCI;
}
switch(SCI->getOpcode()) {
case Instruction::SetLE:
case Instruction::SetGE:
case Instruction::SetEQ:
if (CI1->getRawValue() == CI2->getRawValue())
return ConstantBool::True;
else
return ConstantBool::False;
case Instruction::SetLT:
case Instruction::SetGT:
case Instruction::SetNE:
if (CI1->getRawValue() == CI2->getRawValue())
return ConstantBool::False;
else
return ConstantBool::True;
default:
assert(0 && "Unknown opcode in SetContInst.");
break;
}
}
Value *PredicateSimplifier::resolve(BinaryOperator *BO,
const PropertySet &KP) {
if (SetCondInst *SCI = dyn_cast<SetCondInst>(BO))
return resolve(SCI, KP);
Value *lhs = resolve(BO->getOperand(0), KP),
*rhs = resolve(BO->getOperand(1), KP);
ConstantIntegral *CI1 = dyn_cast<ConstantIntegral>(lhs);
ConstantIntegral *CI2 = dyn_cast<ConstantIntegral>(rhs);
if (!CI1 || !CI2) return BO;
Value *V = ConstantExpr::get(BO->getOpcode(), CI1, CI2);
if (V) return V;
return BO;
}
Value *PredicateSimplifier::resolve(SelectInst *SI, const PropertySet &KP) {
Value *Condition = resolve(SI->getCondition(), KP);
if (Condition == ConstantBool::True)
return resolve(SI->getTrueValue(), KP);
else if (Condition == ConstantBool::False)
return resolve(SI->getFalseValue(), KP);
return SI;
}
Value *PredicateSimplifier::resolve(Value *V, const PropertySet &KP) {
if (isa<Constant>(V) || isa<BasicBlock>(V) || KP.empty()) return V;
V = KP.canonicalize(V);
DEBUG(std::cerr << "peering into " << *V << "\n");
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(V))
return resolve(BO, KP);
else if (SelectInst *SI = dyn_cast<SelectInst>(V))
return resolve(SI, KP);
return V;
}
void PredicateSimplifier::visitBasicBlock(DTNodeType *DTNode,
PropertySet &KnownProperties) {
BasicBlock *BB = DTNode->getBlock();
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
visitInstruction(I, DTNode, KnownProperties);
}
}
void PredicateSimplifier::visitInstruction(Instruction *I,
DTNodeType *DTNode,
PropertySet &KnownProperties) {
DEBUG(std::cerr << "Considering instruction " << *I << "\n");
DEBUG(KnownProperties.debug(std::cerr));
// Try to replace the whole instruction.
Value *V = resolve(I, KnownProperties);
assert(V && "resolve not supposed to return NULL.");
if (V != I) {
modified = true;
++NumInstruction;
I->replaceAllUsesWith(V);
return;
}
// Try to substitute operands.
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
Value *Oper = I->getOperand(i);
Value *V = resolve(Oper, KnownProperties);
assert(V && "resolve not supposed to return NULL.");
if (V != Oper) {
modified = true;
++NumVarsReplaced;
DEBUG(std::cerr << "resolving " << *I);
I->setOperand(i, V);
DEBUG(std::cerr << "into " << *I);
}
}
if (TerminatorInst *TI = dyn_cast<TerminatorInst>(I))
visit(TI, DTNode, KnownProperties);
else if (LoadInst *LI = dyn_cast<LoadInst>(I))
visit(LI, DTNode, KnownProperties);
else if (StoreInst *SI = dyn_cast<StoreInst>(I))
visit(SI, DTNode, KnownProperties);
else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I))
visit(BO, DTNode, KnownProperties);
}
void PredicateSimplifier::proceedToSuccessor(PropertySet &CurrentPS,
PropertySet &NextPS,
DTNodeType *Current,
DTNodeType *Next) {
if (Next->getBlock()->getSinglePredecessor() == Current->getBlock())
proceedToSuccessor(NextPS, Current, Next);
else
proceedToSuccessor(CurrentPS, Current, Next);
}
void PredicateSimplifier::proceedToSuccessor(PropertySet &KP,
DTNodeType *Current,
DTNodeType *Next) {
if (Current->properlyDominates(Next))
visitBasicBlock(Next, KP);
}
void PredicateSimplifier::visit(TerminatorInst *TI, DTNodeType *Node,
PropertySet &KP) {
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
visit(BI, Node, KP);
return;
}
if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
visit(SI, Node, KP);
return;
}
for (unsigned i = 0, E = TI->getNumSuccessors(); i != E; ++i) {
BasicBlock *BB = TI->getSuccessor(i);
PropertySet KPcopy(KP);
proceedToSuccessor(KPcopy, Node, DT->getNode(TI->getSuccessor(i)));
}
}
void PredicateSimplifier::visit(BranchInst *BI, DTNodeType *Node,
PropertySet &KP) {
if (BI->isUnconditional()) {
proceedToSuccessor(KP, Node, DT->getNode(BI->getSuccessor(0)));
return;
}
Value *Condition = BI->getCondition();
BasicBlock *TrueDest = BI->getSuccessor(0),
*FalseDest = BI->getSuccessor(1);
if (Condition == ConstantBool::True) {
FalseDest->removePredecessor(BI->getParent());
BI->setUnconditionalDest(TrueDest);
modified = true;
++NumBranches;
proceedToSuccessor(KP, Node, DT->getNode(TrueDest));
return;
} else if (Condition == ConstantBool::False) {
TrueDest->removePredecessor(BI->getParent());
BI->setUnconditionalDest(FalseDest);
modified = true;
++NumBranches;
proceedToSuccessor(KP, Node, DT->getNode(FalseDest));
return;
}
PropertySet TrueProperties(KP), FalseProperties(KP);
DEBUG(std::cerr << "true set:\n");
TrueProperties.addEqual(ConstantBool::True, Condition);
DEBUG(TrueProperties.debug(std::cerr));
DEBUG(std::cerr << "false set:\n");
FalseProperties.addEqual(ConstantBool::False, Condition);
DEBUG(FalseProperties.debug(std::cerr));
PropertySet KPcopy(KP);
proceedToSuccessor(KP, TrueProperties, Node, DT->getNode(TrueDest));
proceedToSuccessor(KPcopy, FalseProperties, Node, DT->getNode(FalseDest));
}
void PredicateSimplifier::visit(SwitchInst *SI, DTNodeType *DTNode,
PropertySet KP) {
Value *Condition = SI->getCondition();
assert(Condition == KP.canonicalize(Condition) &&
"Instruction wasn't already canonicalized?");
// If there's an NEProperty covering this SwitchInst, we may be able to
// eliminate one of the cases.
for (PropertySet::ConstPropertyIterator I = KP.Properties.begin(),
E = KP.Properties.end(); I != E; ++I) {
if (I->Opcode != PropertySet::NE) continue;
Value *V1 = KP.union_find.getLeader(I->I1),
*V2 = KP.union_find.getLeader(I->I2);
// Find a Property with a ConstantInt on one side and our
// Condition on the other.
ConstantInt *CI = NULL;
if (V1 == Condition)
CI = dyn_cast<ConstantInt>(V2);
else if (V2 == Condition)
CI = dyn_cast<ConstantInt>(V1);
if (!CI) continue;
unsigned i = SI->findCaseValue(CI);
if (i != 0) { // zero is reserved for the default case.
SI->getSuccessor(i)->removePredecessor(SI->getParent());
SI->removeCase(i);
modified = true;
++NumSwitchCases;
}
}
// Set the EQProperty in each of the cases BBs,
// and the NEProperties in the default BB.
PropertySet DefaultProperties(KP);
DTNodeType *Node = DT->getNode(SI->getParent()),
*DefaultNode = DT->getNode(SI->getSuccessor(0));
if (!Node->dominates(DefaultNode)) DefaultNode = NULL;
for (unsigned I = 1, E = SI->getNumCases(); I < E; ++I) {
ConstantInt *CI = SI->getCaseValue(I);
BasicBlock *SuccBB = SI->getSuccessor(I);
PropertySet copy(KP);
if (SuccBB->getSinglePredecessor()) {
PropertySet NewProperties(KP);
NewProperties.addEqual(Condition, CI);
proceedToSuccessor(copy, NewProperties, DTNode, DT->getNode(SuccBB));
} else
proceedToSuccessor(copy, DTNode, DT->getNode(SuccBB));
if (DefaultNode)
DefaultProperties.addNotEqual(Condition, CI);
}
if (DefaultNode)
proceedToSuccessor(DefaultProperties, DTNode, DefaultNode);
}
void PredicateSimplifier::visit(LoadInst *LI, DTNodeType *,
PropertySet &KP) {
Value *Ptr = LI->getPointerOperand();
KP.addNotEqual(Constant::getNullValue(Ptr->getType()), Ptr);
}
void PredicateSimplifier::visit(StoreInst *SI, DTNodeType *,
PropertySet &KP) {
Value *Ptr = SI->getPointerOperand();
KP.addNotEqual(Constant::getNullValue(Ptr->getType()), Ptr);
}
void PredicateSimplifier::visit(BinaryOperator *BO, DTNodeType *,
PropertySet &KP) {
Instruction::BinaryOps ops = BO->getOpcode();
switch (ops) {
case Instruction::Div:
case Instruction::Rem: {
Value *Divisor = BO->getOperand(1);
KP.addNotEqual(Constant::getNullValue(Divisor->getType()), Divisor);
break;
}
default:
break;
}
}
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