--- /dev/null
+//===-- 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. Equivalent variables are
+// called SynSets; sets of synonyms. We maintain a mapping from Value *
+// to the SynSet, and the SynSet maintains the best canonical form of the
+// Value.
+//
+// Properties are stored as relationships between two SynSets.
+//
+//===------------------------------------------------------------------===//
+
+// TODO:
+// * Handle SelectInst
+// * Switch to EquivalenceClasses ADT
+// * Check handling of NAN in floating point types
+// * Don't descend into false side of branches with ConstantBool condition.
+
+#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;
+
+namespace {
+ Statistic<>
+ NumVarsReplaced("predsimplify", "Number of argument substitutions");
+ Statistic<>
+ NumResolved("predsimplify", "Number of instruction substitutions");
+ Statistic<>
+ NumSwitchCases("predsimplify", "Number of switch cases removed");
+
+ /// Used for choosing the canonical Value in a synonym set.
+ /// Leaves the better one in V1. Returns whether a swap took place.
+ static void order(Value *&V1, Value *&V2) {
+ if (isa<Constant>(V2)) {
+ if (!isa<Constant>(V1)) {
+ std::swap(V1, V2);
+ return;
+ }
+ } else if (isa<Argument>(V2)) {
+ if (!isa<Constant>(V1) && !isa<Argument>(V1)) {
+ std::swap(V1, V2);
+ return;
+ }
+ }
+ 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) {
+ std::swap(V1, V2);
+ return;
+ }
+ }
+ }
+ return;
+ }
+
+ /// 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:
+ typedef unsigned SynSet;
+ typedef std::map<Value*, unsigned>::iterator SynonymIterator;
+ typedef std::map<Value*, unsigned>::const_iterator ConstSynonymIterator;
+ typedef std::vector<Property>::iterator PropertyIterator;
+ typedef std::vector<Property>::const_iterator ConstPropertyIterator;
+
+ enum Ops {
+ EQ,
+ NE
+ };
+
+ Value *canonicalize(Value *V) const {
+ Value *C = lookup(V);
+ return C ? C : V;
+ }
+
+ Value *lookup(Value *V) const {
+ ConstSynonymIterator SI = SynonymMap.find(V);
+ if (SI == SynonymMap.end()) return NULL;
+
+ return Synonyms[SI->second];
+ }
+
+ Value *lookup(SynSet SS) const {
+ assert(SS < Synonyms.size());
+ return Synonyms[SS];
+ }
+
+ // Find a SynSet for a given Value.
+ //
+ // Given the Value *V sets SS to a valid SynSet. Returns true if it
+ // found it.
+ bool findSynSet(Value *V, SynSet &SS) const {
+ ConstSynonymIterator SI = SynonymMap.find(V);
+ if (SI != SynonymMap.end()) {
+ SS = SI->second;
+ return true;
+ }
+
+ std::vector<Value *>::const_iterator I =
+ std::find(Synonyms.begin(), Synonyms.end(), V);
+ if (I != Synonyms.end()) {
+ SS = I-Synonyms.begin();
+ return true;
+ }
+
+ return false;
+ }
+
+ bool empty() const {
+ return Synonyms.empty();
+ }
+
+ void addEqual(Value *V1, Value *V2) {
+ order(V1, V2);
+ if (isa<Constant>(V2)) return; // refuse to set false == true.
+
+ V1 = canonicalize(V1);
+ V2 = canonicalize(V2);
+
+ if (V1 == V2) return; // already equivalent.
+
+ SynSet I1, I2;
+ bool F1 = findSynSet(V1, I1),
+ F2 = findSynSet(V2, I2);
+
+ DEBUG(std::cerr << "V1: " << *V1 << " I1: " << I1
+ << " F1: " << F1 << "\n");
+ DEBUG(std::cerr << "V2: " << *V2 << " I2: " << I2
+ << " F2: " << F2 << "\n");
+
+ if (!F1 && !F2) {
+ SynSet SS = addSynSet(V1);
+ SynonymMap[V1] = SS;
+ SynonymMap[V2] = SS;
+ }
+
+ else if (!F1 && F2) {
+ SynonymMap[V1] = I2;
+ }
+
+ else if (F1 && !F2) {
+ SynonymMap[V2] = I1;
+ }
+
+ else {
+ // 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.
+
+ // Collapse synonyms of V2 into V1.
+ for (SynonymIterator I = SynonymMap.begin(), E = SynonymMap.end();
+ I != E; ++I) {
+ if (I->second == I2) I->second = I1;
+ else if (I->second > I2) --I->second;
+ }
+
+ // Move Properties
+ for (PropertyIterator I = Properties.begin(), E = Properties.end();
+ I != E; ++I) {
+ if (I->S1 == I2) I->S1 = I1;
+ else if (I->S1 > I2) --I->S1;
+ if (I->S2 == I2) I->S2 = I1;
+ else if (I->S2 > I2) --I->S2;
+ }
+
+ // Remove the synonym
+ Synonyms.erase(Synonyms.begin() + I2);
+ }
+
+ addImpliedProperties(EQ, V1, V2);
+ }
+
+ void addNotEqual(Value *V1, Value *V2) {
+ DEBUG(std::cerr << "not equal: " << *V1 << " and " << *V2 << "\n");
+ bool skip_search = false;
+ V1 = canonicalize(V1);
+ V2 = canonicalize(V2);
+
+ SynSet S1, S2;
+ if (!findSynSet(V1, S1)) {
+ skip_search = true;
+ S1 = addSynSet(V1);
+ }
+ if (!findSynSet(V2, S2)) {
+ skip_search = true;
+ S2 = addSynSet(V2);
+ }
+
+ if (!skip_search) {
+ // Does the property already exist?
+ for (PropertyIterator I = Properties.begin(), E = Properties.end();
+ I != E; ++I) {
+ if (I->Opcode != NE) continue;
+
+ if ((I->S1 == S1 && I->S2 == S2) ||
+ (I->S1 == S2 && I->S2 == S1)) {
+ return; // Found.
+ }
+ }
+ }
+
+ // Add the property.
+ Properties.push_back(Property(NE, S1, S2));
+ 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.");
+
+ SynSet S1, S2;
+ if (!findSynSet(V1, S1)) return Properties.end();
+ if (!findSynSet(V2, S2)) return Properties.end();
+
+ // Does the property already exist?
+ for (PropertyIterator I = Properties.begin(), E = Properties.end();
+ I != E; ++I) {
+ if (I->Opcode != Opcode) continue;
+
+ if ((I->S1 == S1 && I->S2 == S2) ||
+ (I->S1 == S2 && I->S2 == S1)) {
+ return I; // Found.
+ }
+ }
+ return Properties.end();
+ }
+
+ ConstPropertyIterator
+ findProperty(Ops Opcode, Value *V1, Value *V2) const {
+ assert(Opcode != EQ && "Can't findProperty on EQ."
+ "Use the lookup method instead.");
+
+ SynSet S1, S2;
+ if (!findSynSet(V1, S1)) return Properties.end();
+ if (!findSynSet(V2, S2)) return Properties.end();
+
+ // Does the property already exist?
+ for (ConstPropertyIterator I = Properties.begin(),
+ E = Properties.end(); I != E; ++I) {
+ if (I->Opcode != Opcode) continue;
+
+ if ((I->S1 == S1 && I->S2 == S2) ||
+ (I->S1 == S2 && I->S2 == S1)) {
+ return I; // Found.
+ }
+ }
+ return Properties.end();
+ }
+
+ private:
+ // Represents Head OP [Tail1, Tail2, ...]
+ // For example: %x != %a, %x != %b.
+ struct Property {
+ Property(Ops opcode, SynSet s1, SynSet s2)
+ : Opcode(opcode), S1(s1), S2(s2)
+ { assert(opcode != EQ && "Equality belongs in the synonym set,"
+ "not a property."); }
+
+ bool operator<(const Property &rhs) const {
+ if (Opcode != rhs.Opcode) return Opcode < rhs.Opcode;
+ if (S1 != rhs.S1) return S1 < rhs.S1;
+ return S2 < rhs.S2;
+ }
+
+ Ops Opcode;
+ SynSet S1, S2;
+ };
+
+ SynSet addSynSet(Value *V) {
+ Synonyms.push_back(V);
+ return Synonyms.size()-1;
+ }
+
+ 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 a synonym 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;
+ }
+ }
+ }
+
+ std::map<Value *, unsigned> SynonymMap;
+ std::vector<Value *> Synonyms;
+
+ public:
+ void debug(std::ostream &os) const {
+ os << Synonyms.size() << " synsets:\n";
+ for (unsigned I = 0, E = Synonyms.size(); I != E; ++I) {
+ os << I << ". " << *Synonyms[I] << "\n";
+ }
+ for (ConstSynonymIterator I = SynonymMap.begin(),E = SynonymMap.end();
+ I != E; ++I) {
+ os << *I->first << "-> #" << I->second << "\n";
+ }
+ os << Properties.size() << " properties:\n";
+ for (unsigned I = 0, E = Properties.size(); I != E; ++I) {
+ os << I << ". (" << Properties[I].Opcode << ","
+ << Properties[I].S1 << "," << Properties[I].S2 << ")\n";
+ }
+ }
+
+ 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(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,
+ DominatorTree::Node *Current, DominatorTree::Node *Next);
+ void proceedToSuccessor(PropertySet &CurrentPS,
+ DominatorTree::Node *Current, DominatorTree::Node *Next);
+
+ // Visits each instruction in the basic block.
+ void visitBasicBlock(DominatorTree::Node *DTNode,
+ PropertySet &KnownProperties);
+
+ // For each instruction, add the properties to KnownProperties.
+ void visit(Instruction *I, DominatorTree::Node *, PropertySet &);
+ void visit(TerminatorInst *TI, DominatorTree::Node *, PropertySet &);
+ void visit(BranchInst *BI, DominatorTree::Node *, PropertySet &);
+ void visit(SwitchInst *SI, DominatorTree::Node *, PropertySet);
+ void visit(LoadInst *LI, DominatorTree::Node *, PropertySet &);
+ void visit(StoreInst *SI, DominatorTree::Node *, PropertySet &);
+ void visit(BinaryOperator *BO, DominatorTree::Node *, 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 range that the properties apply to.
+Value *PredicateSimplifier::resolve(SetCondInst *SCI,
+ const PropertySet &KP) {
+ // Attempt to resolve the SetCondInst to a boolean.
+
+ Value *SCI0 = SCI->getOperand(0),
+ *SCI1 = SCI->getOperand(1);
+ 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;
+ }
+ }
+
+ SCI0 = KP.canonicalize(SCI0);
+ SCI1 = KP.canonicalize(SCI1);
+
+ ConstantIntegral *CI1 = dyn_cast<ConstantIntegral>(SCI0),
+ *CI2 = dyn_cast<ConstantIntegral>(SCI1);
+
+ if (!CI1 || !CI2) 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);
+
+ DEBUG(std::cerr << "BO->getOperand(1) = " << *BO->getOperand(1) << "\n");
+
+ 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);
+
+ DEBUG(std::cerr << "resolveBO: lhs = " << *lhs
+ << ", rhs = " << *rhs << "\n");
+ if (CI1) DEBUG(std::cerr << "CI1 = " << *CI1);
+ if (CI2) DEBUG(std::cerr << "CI2 = " << *CI2);
+
+ if (!CI1 || !CI2) return BO;
+
+ Value *V = ConstantExpr::get(BO->getOpcode(), CI1, CI2);
+ if (V) return V;
+ return BO;
+}
+
+Value *PredicateSimplifier::resolve(Value *V, const PropertySet &KP) {
+ if (isa<Constant>(V) || isa<BasicBlock>(V) || KP.empty()) return V;
+
+ V = KP.canonicalize(V);
+
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(V))
+ return resolve(BO, KP);
+
+ return V;
+}
+
+void PredicateSimplifier::visitBasicBlock(DominatorTree::Node *DTNode,
+ PropertySet &KnownProperties) {
+ BasicBlock *BB = DTNode->getBlock();
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
+ visit(I, DTNode, KnownProperties);
+ }
+}
+
+void PredicateSimplifier::visit(Instruction *I, DominatorTree::Node *DTNode,
+ PropertySet &KnownProperties) {
+ DEBUG(std::cerr << "Considering instruction " << *I << "\n");
+ DEBUG(KnownProperties.debug(std::cerr));
+
+ // Substitute values known to be equal.
+ 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);
+ }
+ }
+
+ Value *V = resolve(I, KnownProperties);
+ assert(V && "resolve not supposed to return NULL.");
+ if (V != I) {
+ modified = true;
+ ++NumResolved;
+ I->replaceAllUsesWith(V);
+ I->eraseFromParent();
+ }
+
+ 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, DominatorTree::Node *Current,
+ DominatorTree::Node *Next) {
+ if (Next->getBlock()->getSinglePredecessor() == Current->getBlock())
+ proceedToSuccessor(NextPS, Current, Next);
+ else
+ proceedToSuccessor(CurrentPS, Current, Next);
+}
+
+void PredicateSimplifier::proceedToSuccessor(PropertySet &KP,
+ DominatorTree::Node *Current, DominatorTree::Node *Next) {
+ if (Current->properlyDominates(Next))
+ visitBasicBlock(Next, KP);
+}
+
+void PredicateSimplifier::visit(TerminatorInst *TI,
+ DominatorTree::Node *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,
+ DominatorTree::Node *Node, PropertySet &KP){
+ if (BI->isUnconditional()) {
+ proceedToSuccessor(KP, Node, DT->getNode(BI->getSuccessor(0)));
+ return;
+ }
+
+ Value *Condition = BI->getCondition();
+
+ PropertySet TrueProperties(KP), FalseProperties(KP);
+ DEBUG(std::cerr << "true set:\n");
+ TrueProperties.addEqual(ConstantBool::True, Condition);
+ DEBUG(std::cerr << "false set:\n");
+ FalseProperties.addEqual(ConstantBool::False, Condition);
+
+ BasicBlock *TrueDest = BI->getSuccessor(0),
+ *FalseDest = BI->getSuccessor(1);
+
+ PropertySet KPcopy(KP);
+ proceedToSuccessor(KP, TrueProperties, Node, DT->getNode(TrueDest));
+ proceedToSuccessor(KPcopy, FalseProperties, Node, DT->getNode(FalseDest));
+}
+
+void PredicateSimplifier::visit(SwitchInst *SI,
+ DominatorTree::Node *DTNode, PropertySet KP) {
+ Value *Condition = SI->getCondition();
+
+ // If there's an NEProperty covering this SwitchInst, we may be able to
+ // eliminate one of the cases.
+ PropertySet::SynSet S;
+
+ if (KP.findSynSet(Condition, S)) {
+ for (PropertySet::ConstPropertyIterator I = KP.Properties.begin(),
+ E = KP.Properties.end(); I != E; ++I) {
+ if (I->Opcode != PropertySet::NE) continue;
+ if (I->S1 != S && I->S2 != S) continue;
+
+ // Is one side a number?
+ ConstantInt *CI = dyn_cast<ConstantInt>(KP.lookup(I->S1));
+ if (!CI) CI = dyn_cast<ConstantInt>(KP.lookup(I->S2));
+
+ if (CI) {
+ unsigned i = SI->findCaseValue(CI);
+ if (i != 0) {
+ 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);
+
+ DominatorTree::Node *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,
+ DominatorTree::Node *, PropertySet &KP) {
+ Value *Ptr = LI->getPointerOperand();
+ KP.addNotEqual(Constant::getNullValue(Ptr->getType()), Ptr);
+}
+
+void PredicateSimplifier::visit(StoreInst *SI,
+ DominatorTree::Node *, PropertySet &KP) {
+ Value *Ptr = SI->getPointerOperand();
+ KP.addNotEqual(Constant::getNullValue(Ptr->getType()), Ptr);
+}
+
+void PredicateSimplifier::visit(BinaryOperator *BO,
+ DominatorTree::Node *, PropertySet &KP) {
+ Instruction::BinaryOps ops = BO->getOpcode();
+ if (ops != Instruction::Div && ops != Instruction::Rem) return;
+
+ Value *Divisor = BO->getOperand(1);
+ const Type *Ty = cast<Type>(Divisor->getType());
+ KP.addNotEqual(Constant::getNullValue(Ty), Divisor);
+
+ // Some other things we could do:
+ // In f=x*y, if x != 1 && y != 1 then f != x && f != y.
+ // In f=x+y, if x != 0 then f != y and if y != 0 then f != x.
+}
projects / oota-llvm.git / commitdiff