#include "llvm/Support/Debug.h"
#include "llvm/Support/InstVisitor.h"
#include <iostream>
+#include <list>
using namespace llvm;
typedef DominatorTree::Node DTNodeType;
return leaders.empty();
}
- iterator findLeader(ElemTy e) {
+ 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 {
+ const_iterator findLeader(ElemTy &e) const {
typename std::map<ElemTy, unsigned>::const_iterator MI =
mapping.find(e);
if (MI == mapping.end()) return 0;
// 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
/// 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 findOrInsert(ElemTy &e) {
iterator I = findLeader(e);
if (I) return I;
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).
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);
if (isa<Constant>(V1) && isa<Constant>(V2)) return;
if (findProperty(NE, V1, V2) != Properties.end())
- return; // found.
+ return; // no-op.
// Add the property.
SynonymIterator I1 = union_find.findOrInsert(V1),
}
}
+ 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);
+ }
+
// 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)
if (V1 == ConstantBool::getFalse())
add(Opcode, BO->getOperand(0), BO->getOperand(1), true);
break;
- case Instruction::And:
- if (V1 == ConstantBool::getTrue()) {
- add(Opcode, V1, BO->getOperand(0), false);
- add(Opcode, V1, BO->getOperand(1), false);
+ 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:
- if (V1 == ConstantBool::getFalse()) {
- add(Opcode, V1, BO->getOperand(0), false);
- add(Opcode, V1, BO->getOperand(1), false);
+ } 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:
- if (V1 == ConstantBool::getTrue()) {
- if (BO->getOperand(0) == V1)
- add(Opcode, ConstantBool::getFalse(), BO->getOperand(1), false);
- if (BO->getOperand(1) == V1)
- add(Opcode, ConstantBool::getFalse(), BO->getOperand(0), false);
+ } 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 the operands swapped.
+
+ 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));
+ }
}
- if (V1 == ConstantBool::getFalse()) {
- if (BO->getOperand(0) == ConstantBool::getTrue())
- add(Opcode, ConstantBool::getTrue(), BO->getOperand(1), false);
- if (BO->getOperand(1) == ConstantBool::getTrue())
- add(Opcode, ConstantBool::getTrue(), BO->getOperand(0), false);
+ 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;
+ } break;
default:
break;
}
} else if (SelectInst *SI = dyn_cast<SelectInst>(V2)) {
- if (Opcode != EQ && Opcode != NE) return;
-
ConstantBool *True = ConstantBool::get(Opcode==EQ),
*False = ConstantBool::get(Opcode!=EQ);
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.");
}
+
+ std::list<Value *> WorkList;
+ addToResolve(V1, WorkList);
+ addToResolve(V2, WorkList);
+ resolve(WorkList);
}
DominatorTree *DT;
/// 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 VISIBILITY_HIDDEN PredicateSimplifier : public FunctionPass {
+ class PredicateSimplifier : public FunctionPass {
public:
bool runOnFunction(Function &F);
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
private:
- /// Backwards - Try to replace the Use of the instruction with
- /// something simpler. This resolves a value by walking backwards
- /// through its definition and the operands of that definition to
- /// see if any values can now be solved for with the properties
- /// that are in effect now, but weren't at definition time.
- class Backwards : public InstVisitor<Backwards, Value &> {
- friend class InstVisitor<Backwards, Value &>;
- const PropertySet &KP;
-
- Value &visitSetCondInst(SetCondInst &SCI);
- Value &visitBinaryOperator(BinaryOperator &BO);
- Value &visitSelectInst(SelectInst &SI);
- Value &visitInstruction(Instruction &I);
-
- public:
- explicit Backwards(const PropertySet &KP) : KP(KP) {}
-
- Value *resolve(Value *V);
- };
-
/// 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
AU.addPreservedID(BreakCriticalEdgesID);
}
-Value &PredicateSimplifier::Backwards::visitSetCondInst(SetCondInst &SCI) {
- Value &vBO = visitBinaryOperator(SCI);
- if (&vBO != &SCI) return vBO;
-
- Value *SCI0 = resolve(SCI.getOperand(0)),
- *SCI1 = resolve(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::getFalse();
- case Instruction::SetNE: return *ConstantBool::getTrue();
- case Instruction::SetLE:
- case Instruction::SetGE:
- case Instruction::SetLT:
- case Instruction::SetGT:
- break;
- default:
- assert(0 && "Unknown opcode in SetCondInst.");
- break;
- }
- }
- return SCI;
-}
-
-Value &PredicateSimplifier::Backwards::visitBinaryOperator(BinaryOperator &BO) {
- Value *V = KP.canonicalize(&BO);
- if (V != &BO) return *V;
-
- Value *lhs = resolve(BO.getOperand(0)),
- *rhs = resolve(BO.getOperand(1));
-
- ConstantIntegral *CI1 = dyn_cast<ConstantIntegral>(lhs),
- *CI2 = dyn_cast<ConstantIntegral>(rhs);
-
- if (CI1 && CI2) return *ConstantExpr::get(BO.getOpcode(), CI1, CI2);
-
- return BO;
-}
-
-Value &PredicateSimplifier::Backwards::visitSelectInst(SelectInst &SI) {
- Value *V = KP.canonicalize(&SI);
- if (V != &SI) return *V;
-
- Value *Condition = resolve(SI.getCondition());
- if (ConstantBool *CB = dyn_cast<ConstantBool>(Condition))
- return *resolve(CB->getValue() ? SI.getTrueValue() : SI.getFalseValue());
- return SI;
-}
-
-Value &PredicateSimplifier::Backwards::visitInstruction(Instruction &I) {
- return *KP.canonicalize(&I);
-}
-
-Value *PredicateSimplifier::Backwards::resolve(Value *V) {
- if (isa<Constant>(V) || isa<BasicBlock>(V) || KP.empty()) return V;
-
- if (Instruction *I = dyn_cast<Instruction>(V)) return &visit(*I);
- return KP.canonicalize(V);
-}
-
void PredicateSimplifier::visitBasicBlock(BasicBlock *BB,
PropertySet &KnownProperties) {
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
void PredicateSimplifier::visitInstruction(Instruction *I,
PropertySet &KnownProperties) {
// Try to replace the whole instruction.
- Backwards resolve(KnownProperties);
- Value *V = resolve.resolve(I);
+ 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 = resolve.resolve(Oper);
+ Value *V = KnownProperties.canonicalize(Oper);
if (V != Oper) {
modified = true;
++NumVarsReplaced;
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