| //===-- 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/DerivedTypes.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 "llvm/Support/InstVisitor.h" |
| #include <iostream> |
| #include <list> |
| using namespace llvm; |
| |
| typedef DominatorTree::Node DTNodeType; |
| |
| namespace { |
| Statistic<> |
| NumVarsReplaced("predsimplify", "Number of argument substitutions"); |
| Statistic<> |
| NumInstruction("predsimplify", "Number of instructions removed"); |
| |
| class PropertySet; |
| |
| /// Similar to EquivalenceClasses, this stores the set of equivalent |
| /// types. Beyond EquivalenceClasses, it allows us to specify which |
| /// element will act as leader. |
| template<typename ElemTy> |
| class VISIBILITY_HIDDEN Synonyms { |
| std::map<ElemTy, unsigned> mapping; |
| std::vector<ElemTy> leaders; |
| PropertySet *PS; |
| |
| public: |
| typedef unsigned iterator; |
| typedef const unsigned const_iterator; |
| |
| Synonyms(PropertySet *PS) : PS(PS) {} |
| |
| // 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 && I <= leaders.size() && "Illegal leader to get."); |
| return leaders[I-1]; |
| } |
| |
| const ElemTy &getLeader(const_iterator I) const { |
| assert(I && I <= leaders.size() && "Illegal leaders to get."); |
| 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 << ". " << *getLeader(i) << ": ["; |
| 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 |
| |
| void remove(ElemTy &e) { |
| ElemTy E = e; // The parameter to erase must not be a reference to |
| mapping.erase(E); // an element contained in the map. |
| } |
| |
| /// 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 no longer existing element. |
| iterator unionSets(ElemTy E1, ElemTy E2); |
| |
| /// 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 { |
| /// Returns true if V1 is a better choice than V2. |
| bool compare(Value *V1, Value *V2) const { |
| if (isa<Constant>(V1)) { |
| if (!isa<Constant>(V2)) { |
| return true; |
| } |
| } else if (isa<Argument>(V1)) { |
| if (!isa<Constant>(V2) && !isa<Argument>(V2)) { |
| return true; |
| } |
| } |
| if (Instruction *I1 = dyn_cast<Instruction>(V1)) { |
| if (Instruction *I2 = dyn_cast<Instruction>(V2)) { |
| BasicBlock *BB1 = I1->getParent(), |
| *BB2 = I2->getParent(); |
| if (BB1 == BB2) { |
| for (BasicBlock::const_iterator I = BB1->begin(), E = BB1->end(); |
| I != E; ++I) { |
| if (&*I == I1) return true; |
| if (&*I == I2) return false; |
| } |
| assert(0 && "Instructions not found in parent BasicBlock?"); |
| } else |
| return DT->getNode(BB1)->properlyDominates(DT->getNode(BB2)); |
| } |
| } |
| return false; |
| } |
| |
| struct Property; |
| public: |
| /// Choose the canonical Value in a synonym set. |
| /// Leaves the more canonical choice in V1. |
| void order(Value *&V1, Value *&V2) const { |
| if (compare(V2, V1)) std::swap(V1, V2); |
| } |
| |
| PropertySet(DominatorTree *DT) : union_find(this), DT(DT) {} |
| |
| Synonyms<Value *> union_find; |
| |
| typedef std::vector<Property>::iterator PropertyIterator; |
| typedef std::vector<Property>::const_iterator ConstPropertyIterator; |
| typedef Synonyms<Value *>::iterator SynonymIterator; |
| |
| enum Ops { |
| EQ, |
| NE |
| }; |
| |
| Value *canonicalize(Value *V) const { |
| Value *C = lookup(V); |
| return C ? C : V; |
| } |
| |
| Value *lookup(Value *V) const { |
| SynonymIterator SI = union_find.findLeader(V); |
| if (!SI) return NULL; |
| return union_find.getLeader(SI); |
| } |
| |
| bool empty() const { |
| return union_find.empty(); |
| } |
| |
| void remove(Value *V) { |
| SynonymIterator I = union_find.findLeader(V); |
| if (!I) return; |
| |
| union_find.remove(V); |
| |
| for (PropertyIterator PI = Properties.begin(), PE = Properties.end(); |
| PI != PE;) { |
| Property &P = *PI++; |
| if (P.I1 == I || P.I2 == I) Properties.erase(PI); |
| } |
| } |
| |
| 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 (V1->getType()->isFloatingPoint()) return; |
| |
| order(V1, V2); |
| if (isa<Constant>(V2)) return; // refuse to set false == true. |
| |
| if (union_find.findLeader(V1) && |
| union_find.findLeader(V1) == union_find.findLeader(V2)) |
| return; // no-op |
| |
| 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 (V1->getType()->isFloatingPoint()) return; |
| |
| // For example, %x = setne int 0, 0 causes "0 != 0". |
| if (isa<Constant>(V1) && isa<Constant>(V2)) return; |
| |
| if (findProperty(NE, V1, V2) != Properties.end()) |
| return; // no-op. |
| |
| // Add the property. |
| SynonymIterator I1 = union_find.findOrInsert(V1), |
| I2 = union_find.findOrInsert(V2); |
| |
| // Technically this means that the block is unreachable. |
| if (I1 == I2) return; |
| |
| 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 SynonymIterator 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 addToResolve(Value *V, std::list<Value *> &WorkList) { |
| if (!isa<Constant>(V) && !isa<BasicBlock>(V)) { |
| for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); |
| UI != UE; ++UI) { |
| if (!isa<Constant>(*UI) && !isa<BasicBlock>(*UI)) { |
| WorkList.push_back(*UI); |
| } |
| } |
| } |
| } |
| |
| void resolve(std::list<Value *> &WorkList) { |
| if (WorkList.empty()) return; |
| |
| Value *V = WorkList.front(); |
| WorkList.pop_front(); |
| |
| if (empty()) return; |
| |
| Instruction *I = dyn_cast<Instruction>(V); |
| if (!I) return; |
| |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) { |
| Value *lhs = canonicalize(BO->getOperand(0)), |
| *rhs = canonicalize(BO->getOperand(1)); |
| |
| ConstantIntegral *CI1 = dyn_cast<ConstantIntegral>(lhs), |
| *CI2 = dyn_cast<ConstantIntegral>(rhs); |
| |
| if (CI1 && CI2) { |
| addToResolve(BO, WorkList); |
| addEqual(BO, ConstantExpr::get(BO->getOpcode(), CI1, CI2)); |
| } else if (SetCondInst *SCI = dyn_cast<SetCondInst>(BO)) { |
| PropertySet::ConstPropertyIterator NE = |
| findProperty(PropertySet::NE, lhs, rhs); |
| |
| if (NE != Properties.end()) { |
| switch (SCI->getOpcode()) { |
| case Instruction::SetEQ: |
| addToResolve(SCI, WorkList); |
| addEqual(SCI, ConstantBool::getFalse()); |
| break; |
| case Instruction::SetNE: |
| addToResolve(SCI, WorkList); |
| addEqual(SCI, ConstantBool::getTrue()); |
| break; |
| case Instruction::SetLE: |
| case Instruction::SetGE: |
| case Instruction::SetLT: |
| case Instruction::SetGT: |
| break; |
| default: |
| assert(0 && "Unknown opcode in SetCondInst."); |
| break; |
| } |
| } |
| } |
| } else if (SelectInst *SI = dyn_cast<SelectInst>(I)) { |
| Value *Condition = canonicalize(SI->getCondition()); |
| if (ConstantBool *CB = dyn_cast<ConstantBool>(Condition)) { |
| addToResolve(SI, WorkList); |
| addEqual(SI, CB->getValue() ? SI->getTrueValue() : SI->getFalseValue()); |
| } |
| } |
| if (!WorkList.empty()) resolve(WorkList); |
| } |
| |
| 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: |
| // "seteq int %a, %b" EQ true then %a EQ %b |
| // "seteq int %a, %b" EQ false then %a NE %b |
| // "seteq int %a, %b" NE true then %a NE %b |
| // "seteq int %a, %b" NE false then %a EQ %b |
| if (ConstantBool *V1CB = dyn_cast<ConstantBool>(V1)) |
| add(Opcode, BO->getOperand(0), BO->getOperand(1),!V1CB->getValue()); |
| break; |
| case Instruction::SetNE: |
| // "setne int %a, %b" EQ true then %a NE %b |
| // "setne int %a, %b" EQ false then %a EQ %b |
| // "setne int %a, %b" NE true then %a EQ %b |
| // "setne int %a, %b" NE false then %a NE %b |
| if (ConstantBool *V1CB = dyn_cast<ConstantBool>(V1)) |
| add(Opcode, BO->getOperand(0), BO->getOperand(1), V1CB->getValue()); |
| break; |
| case Instruction::SetLT: |
| case Instruction::SetGT: |
| // "setlt/gt int %a, %b" EQ true then %a NE %b |
| // "setlt/gt int %a, %b" NE false then %a NE %b |
| |
| // "setlt int %a, %b" NE true then %a EQ %b |
| |
| if (ConstantBool *CB = dyn_cast<ConstantBool>(V1)) { |
| if (CB->getValue() ^ Opcode==NE) |
| addNotEqual(BO->getOperand(0), BO->getOperand(1)); |
| } |
| break; |
| case Instruction::SetLE: |
| case Instruction::SetGE: |
| // "setle/ge int %a, %b" EQ false then %a NE %b |
| // "setle/ge int %a, %b" NE true then %a NE %b |
| if (ConstantBool *CB = dyn_cast<ConstantBool>(V1)) { |
| if (CB->getValue() ^ Opcode==EQ) |
| addNotEqual(BO->getOperand(0), BO->getOperand(1)); |
| } |
| break; |
| case Instruction::And: { |
| // "and int %a, %b" EQ 0xff then %a EQ 0xff and %b EQ 0xff |
| // "and bool %a, %b" EQ true then %a EQ true and %b EQ true |
| // "and bool %a, %b" NE false then %a EQ true and %b EQ true |
| if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V1)) { |
| if (Opcode == EQ && CI->isAllOnesValue()) { |
| addEqual(CI, BO->getOperand(0)); |
| addEqual(CI, BO->getOperand(1)); |
| } else if (Opcode == NE && CI == ConstantBool::getFalse()) { |
| addEqual(ConstantBool::getTrue(), BO->getOperand(0)); |
| addEqual(ConstantBool::getTrue(), BO->getOperand(1)); |
| } |
| } |
| } break; |
| case Instruction::Or: { |
| // "or int %a, %b" EQ 0 then %a EQ 0 and %b EQ 0 |
| // "or bool %a, %b" EQ false then %a EQ false and %b EQ false |
| // "or bool %a, %b" NE true then %a EQ false and %b EQ false |
| if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V1)) { |
| if (Opcode == EQ && CI->isNullValue()) { |
| addEqual(CI, BO->getOperand(0)); |
| addEqual(CI, BO->getOperand(1)); |
| } else if (Opcode == NE && CI == ConstantBool::getTrue()) { |
| addEqual(ConstantBool::getFalse(), BO->getOperand(0)); |
| addEqual(ConstantBool::getFalse(), BO->getOperand(1)); |
| } |
| } |
| } break; |
| case Instruction::Xor: { |
| // "xor bool true, %a" EQ true then %a = false |
| // "xor bool true, %a" EQ false then %a = true |
| // "xor bool false, %a" EQ true then %a = true |
| // "xor bool false, %a" EQ false then %a = false |
| // 1. Repeat all of the above, with "NE false" in place of |
| // "EQ true" and "NE true" in place of "EQ false". |
| // "xor int %c, %a" EQ %c then %a = 0 |
| // "xor int %c, %a" NE %c then %a != 0 |
| // 2. Repeat all of the above, with order of operands reversed. |
| |
| Value *LHS = BO->getOperand(0), *RHS = BO->getOperand(1); |
| if (!isa<Constant>(LHS)) std::swap(LHS, RHS); |
| |
| if (ConstantBool *CB = dyn_cast<ConstantBool>(V1)) { |
| if (ConstantBool *A = dyn_cast<ConstantBool>(LHS)) { |
| addEqual(RHS, ConstantBool::get(A->getValue() ^ CB->getValue() |
| ^ Opcode==NE)); |
| } |
| } |
| else if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V1)) { |
| if (ConstantIntegral *A = dyn_cast<ConstantIntegral>(LHS)) { |
| if (A == CI) |
| add(Opcode, RHS, Constant::getNullValue(A->getType()), false); |
| } |
| } |
| } break; |
| default: |
| break; |
| } |
| } else if (SelectInst *SI = dyn_cast<SelectInst>(V2)) { |
| ConstantBool *True = ConstantBool::get(Opcode==EQ), |
| *False = ConstantBool::get(Opcode!=EQ); |
| |
| if (V1 == canonicalize(SI->getTrueValue())) |
| addEqual(SI->getCondition(), True); |
| else if (V1 == canonicalize(SI->getFalseValue())) |
| addEqual(SI->getCondition(), False); |
| } |
| |
| std::list<Value *> WorkList; |
| addToResolve(V1, WorkList); |
| addToResolve(V2, WorkList); |
| resolve(WorkList); |
| } |
| |
| DominatorTree *DT; |
| 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: |
| /// Forwards - Adds new properties into PropertySet and uses them to |
| /// simplify instructions. Because new properties sometimes apply to |
| /// a transition from one BasicBlock to another, this will use the |
| /// PredicateSimplifier::proceedToSuccessor(s) interface to enter the |
| /// basic block with the new PropertySet. |
| class Forwards : public InstVisitor<Forwards> { |
| friend class InstVisitor<Forwards>; |
| PredicateSimplifier *PS; |
| public: |
| PropertySet &KP; |
| |
| Forwards(PredicateSimplifier *PS, PropertySet &KP) : PS(PS), KP(KP) {} |
| |
| // Tries to simplify each Instruction and add new properties to |
| // the PropertySet. Returns true if it erase the instruction. |
| //void visitInstruction(Instruction *I); |
| |
| void visitTerminatorInst(TerminatorInst &TI); |
| void visitBranchInst(BranchInst &BI); |
| void visitSwitchInst(SwitchInst &SI); |
| |
| void visitAllocaInst(AllocaInst &AI); |
| void visitLoadInst(LoadInst &LI); |
| void visitStoreInst(StoreInst &SI); |
| void visitBinaryOperator(BinaryOperator &BO); |
| }; |
| |
| // Used by terminator instructions to proceed from the current basic |
| // block to the next. Verifies that "current" dominates "next", |
| // then calls visitBasicBlock. |
| void proceedToSuccessors(PropertySet &CurrentPS, BasicBlock *Current); |
| void proceedToSuccessor(PropertySet &Properties, BasicBlock *Next); |
| |
| // Visits each instruction in the basic block. |
| void visitBasicBlock(BasicBlock *Block, PropertySet &KnownProperties); |
| |
| // Tries to simplify each Instruction and add new properties to |
| // the PropertySet. |
| void visitInstruction(Instruction *I, PropertySet &); |
| |
| DominatorTree *DT; |
| bool modified; |
| }; |
| |
| RegisterPass<PredicateSimplifier> X("predsimplify", |
| "Predicate Simplifier"); |
| |
| template <typename ElemTy> |
| typename Synonyms<ElemTy>::iterator |
| Synonyms<ElemTy>::unionSets(ElemTy E1, ElemTy E2) { |
| PS->order(E1, E2); |
| |
| iterator I1 = findLeader(E1), |
| 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 0; |
| } |
| |
| if (!I1 && I2) { |
| mapping[E1] = I2; |
| std::swap(getLeader(I2), E1); |
| return 0; |
| } |
| |
| if (I1 && !I2) { |
| mapping[E2] = I1; |
| return 0; |
| } |
| |
| if (I1 == I2) return 0; |
| |
| // 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. |
| |
| if (I1 > I2) --I1; |
| |
| 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 I2; |
| } |
| } |
| |
| FunctionPass *llvm::createPredicateSimplifierPass() { |
| return new PredicateSimplifier(); |
| } |
| |
| bool PredicateSimplifier::runOnFunction(Function &F) { |
| DT = &getAnalysis<DominatorTree>(); |
| |
| modified = false; |
| PropertySet KnownProperties(DT); |
| visitBasicBlock(DT->getRootNode()->getBlock(), KnownProperties); |
| return modified; |
| } |
| |
| void PredicateSimplifier::getAnalysisUsage(AnalysisUsage &AU) const { |
| AU.addRequiredID(BreakCriticalEdgesID); |
| AU.addRequired<DominatorTree>(); |
| AU.setPreservesCFG(); |
| AU.addPreservedID(BreakCriticalEdgesID); |
| } |
| |
| void PredicateSimplifier::visitBasicBlock(BasicBlock *BB, |
| PropertySet &KnownProperties) { |
| for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) { |
| visitInstruction(I++, KnownProperties); |
| } |
| } |
| |
| void PredicateSimplifier::visitInstruction(Instruction *I, |
| PropertySet &KnownProperties) { |
| // Try to replace the whole instruction. |
| Value *V = KnownProperties.canonicalize(I); |
| if (V != I) { |
| modified = true; |
| ++NumInstruction; |
| DEBUG(std::cerr << "Removing " << *I); |
| KnownProperties.remove(I); |
| I->replaceAllUsesWith(V); |
| I->eraseFromParent(); |
| return; |
| } |
| |
| // Try to substitute operands. |
| for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) { |
| Value *Oper = I->getOperand(i); |
| Value *V = KnownProperties.canonicalize(Oper); |
| if (V != Oper) { |
| modified = true; |
| ++NumVarsReplaced; |
| DEBUG(std::cerr << "Resolving " << *I); |
| I->setOperand(i, V); |
| DEBUG(std::cerr << "into " << *I); |
| } |
| } |
| |
| Forwards visit(this, KnownProperties); |
| visit.visit(*I); |
| } |
| |
| void PredicateSimplifier::proceedToSuccessors(PropertySet &KP, |
| BasicBlock *BBCurrent) { |
| DTNodeType *Current = DT->getNode(BBCurrent); |
| for (DTNodeType::iterator I = Current->begin(), E = Current->end(); |
| I != E; ++I) { |
| PropertySet Copy(KP); |
| visitBasicBlock((*I)->getBlock(), Copy); |
| } |
| } |
| |
| void PredicateSimplifier::proceedToSuccessor(PropertySet &KP, BasicBlock *BB) { |
| visitBasicBlock(BB, KP); |
| } |
| |
| void PredicateSimplifier::Forwards::visitTerminatorInst(TerminatorInst &TI) { |
| PS->proceedToSuccessors(KP, TI.getParent()); |
| } |
| |
| void PredicateSimplifier::Forwards::visitBranchInst(BranchInst &BI) { |
| BasicBlock *BB = BI.getParent(); |
| |
| if (BI.isUnconditional()) { |
| PS->proceedToSuccessors(KP, BB); |
| return; |
| } |
| |
| Value *Condition = BI.getCondition(); |
| |
| BasicBlock *TrueDest = BI.getSuccessor(0), |
| *FalseDest = BI.getSuccessor(1); |
| |
| if (isa<ConstantBool>(Condition) || TrueDest == FalseDest) { |
| PS->proceedToSuccessors(KP, BB); |
| return; |
| } |
| |
| DTNodeType *Node = PS->DT->getNode(BB); |
| for (DTNodeType::iterator I = Node->begin(), E = Node->end(); I != E; ++I) { |
| BasicBlock *Dest = (*I)->getBlock(); |
| PropertySet DestProperties(KP); |
| |
| if (Dest == TrueDest) |
| DestProperties.addEqual(ConstantBool::getTrue(), Condition); |
| else if (Dest == FalseDest) |
| DestProperties.addEqual(ConstantBool::getFalse(), Condition); |
| |
| PS->proceedToSuccessor(DestProperties, Dest); |
| } |
| } |
| |
| void PredicateSimplifier::Forwards::visitSwitchInst(SwitchInst &SI) { |
| Value *Condition = SI.getCondition(); |
| |
| // Set the EQProperty in each of the cases BBs, |
| // and the NEProperties in the default BB. |
| PropertySet DefaultProperties(KP); |
| |
| DTNodeType *Node = PS->DT->getNode(SI.getParent()); |
| for (DTNodeType::iterator I = Node->begin(), E = Node->end(); I != E; ++I) { |
| BasicBlock *BB = (*I)->getBlock(); |
| |
| PropertySet BBProperties(KP); |
| if (BB == SI.getDefaultDest()) { |
| for (unsigned i = 1, e = SI.getNumCases(); i < e; ++i) |
| if (SI.getSuccessor(i) != BB) |
| BBProperties.addNotEqual(Condition, SI.getCaseValue(i)); |
| } else if (ConstantInt *CI = SI.findCaseDest(BB)) { |
| BBProperties.addEqual(Condition, CI); |
| } |
| PS->proceedToSuccessor(BBProperties, BB); |
| } |
| } |
| |
| void PredicateSimplifier::Forwards::visitAllocaInst(AllocaInst &AI) { |
| KP.addNotEqual(Constant::getNullValue(AI.getType()), &AI); |
| } |
| |
| void PredicateSimplifier::Forwards::visitLoadInst(LoadInst &LI) { |
| Value *Ptr = LI.getPointerOperand(); |
| KP.addNotEqual(Constant::getNullValue(Ptr->getType()), Ptr); |
| } |
| |
| void PredicateSimplifier::Forwards::visitStoreInst(StoreInst &SI) { |
| Value *Ptr = SI.getPointerOperand(); |
| KP.addNotEqual(Constant::getNullValue(Ptr->getType()), Ptr); |
| } |
| |
| void PredicateSimplifier::Forwards::visitBinaryOperator(BinaryOperator &BO) { |
| Instruction::BinaryOps ops = BO.getOpcode(); |
| |
| switch (ops) { |
| case Instruction::UDiv: |
| case Instruction::SDiv: |
| case Instruction::FDiv: |
| case Instruction::Rem: { |
| Value *Divisor = BO.getOperand(1); |
| KP.addNotEqual(Constant::getNullValue(Divisor->getType()), Divisor); |
| break; |
| } |
| default: |
| break; |
| } |
| } |