//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the Owen Anderson and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass performs global value numbering to eliminate fully redundant
// instructions. It also performs simple dead load elimination.
//
+// Note that this pass does the value numbering itself, it does not use the
+// ValueNumbering analysis passes.
+//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "gvn"
-
#include "llvm/Transforms/Scalar.h"
#include "llvm/BasicBlock.h"
#include "llvm/Constants.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Value.h"
-#include "llvm/Analysis/Dominators.h"
-#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
#include "llvm/Support/CFG.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
using namespace llvm;
+STATISTIC(NumGVNInstr, "Number of instructions deleted");
+STATISTIC(NumGVNLoad, "Number of loads deleted");
+STATISTIC(NumGVNPRE, "Number of instructions PRE'd");
+
+static cl::opt<bool> EnablePRE("enable-pre",
+ cl::init(false), cl::Hidden);
+
//===----------------------------------------------------------------------===//
// ValueTable Class
//===----------------------------------------------------------------------===//
FCMPULT, FCMPULE, FCMPUNE, EXTRACT, INSERT,
SHUFFLE, SELECT, TRUNC, ZEXT, SEXT, FPTOUI,
FPTOSI, UITOFP, SITOFP, FPTRUNC, FPEXT,
- PTRTOINT, INTTOPTR, BITCAST, GEP, EMPTY,
- TOMBSTONE };
+ PTRTOINT, INTTOPTR, BITCAST, GEP, CALL, CONSTANT,
+ EMPTY, TOMBSTONE };
ExpressionOpcode opcode;
const Type* type;
uint32_t secondVN;
uint32_t thirdVN;
SmallVector<uint32_t, 4> varargs;
+ Value* function;
Expression() { }
Expression(ExpressionOpcode o) : opcode(o) { }
return true;
else if (type != other.type)
return false;
+ else if (function != other.function)
+ return false;
else if (firstVN != other.firstVN)
return false;
else if (secondVN != other.secondVN)
return false;
else if (type != other.type)
return true;
+ else if (function != other.function)
+ return true;
else if (firstVN != other.firstVN)
return true;
else if (secondVN != other.secondVN)
private:
DenseMap<Value*, uint32_t> valueNumbering;
DenseMap<Expression, uint32_t> expressionNumbering;
+ AliasAnalysis* AA;
+ MemoryDependenceAnalysis* MD;
+ DominatorTree* DT;
uint32_t nextValueNumber;
Expression create_expression(SelectInst* V);
Expression create_expression(CastInst* C);
Expression create_expression(GetElementPtrInst* G);
+ Expression create_expression(CallInst* C);
+ Expression create_expression(Constant* C);
public:
- ValueTable() { nextValueNumber = 1; }
+ ValueTable() : nextValueNumber(1) { }
uint32_t lookup_or_add(Value* V);
uint32_t lookup(Value* V) const;
void add(Value* V, uint32_t num);
void clear();
void erase(Value* v);
unsigned size();
+ void setAliasAnalysis(AliasAnalysis* A) { AA = A; }
+ void setMemDep(MemoryDependenceAnalysis* M) { MD = M; }
+ void setDomTree(DominatorTree* D) { DT = D; }
+ uint32_t getNextUnusedValueNumber() { return nextValueNumber; }
};
}
namespace llvm {
-template <> struct DenseMapKeyInfo<Expression> {
+template <> struct DenseMapInfo<Expression> {
static inline Expression getEmptyKey() {
return Expression(Expression::EMPTY);
}
hash = e.secondVN + hash * 37;
hash = e.thirdVN + hash * 37;
- hash = (unsigned)((uintptr_t)e.type >> 4) ^
- (unsigned)((uintptr_t)e.type >> 9) +
- hash * 37;
+ hash = ((unsigned)((uintptr_t)e.type >> 4) ^
+ (unsigned)((uintptr_t)e.type >> 9)) +
+ hash * 37;
for (SmallVector<uint32_t, 4>::const_iterator I = e.varargs.begin(),
E = e.varargs.end(); I != E; ++I)
hash = *I + hash * 37;
+ hash = ((unsigned)((uintptr_t)e.function >> 4) ^
+ (unsigned)((uintptr_t)e.function >> 9)) +
+ hash * 37;
+
return hash;
}
+ static bool isEqual(const Expression &LHS, const Expression &RHS) {
+ return LHS == RHS;
+ }
static bool isPod() { return true; }
};
}
//===----------------------------------------------------------------------===//
// ValueTable Internal Functions
//===----------------------------------------------------------------------===//
-Expression::ExpressionOpcode
- ValueTable::getOpcode(BinaryOperator* BO) {
+Expression::ExpressionOpcode ValueTable::getOpcode(BinaryOperator* BO) {
switch(BO->getOpcode()) {
- case Instruction::Add:
- return Expression::ADD;
- case Instruction::Sub:
- return Expression::SUB;
- case Instruction::Mul:
- return Expression::MUL;
- case Instruction::UDiv:
- return Expression::UDIV;
- case Instruction::SDiv:
- return Expression::SDIV;
- case Instruction::FDiv:
- return Expression::FDIV;
- case Instruction::URem:
- return Expression::UREM;
- case Instruction::SRem:
- return Expression::SREM;
- case Instruction::FRem:
- return Expression::FREM;
- case Instruction::Shl:
- return Expression::SHL;
- case Instruction::LShr:
- return Expression::LSHR;
- case Instruction::AShr:
- return Expression::ASHR;
- case Instruction::And:
- return Expression::AND;
- case Instruction::Or:
- return Expression::OR;
- case Instruction::Xor:
- return Expression::XOR;
-
- // THIS SHOULD NEVER HAPPEN
- default:
- assert(0 && "Binary operator with unknown opcode?");
- return Expression::ADD;
+ default: // THIS SHOULD NEVER HAPPEN
+ assert(0 && "Binary operator with unknown opcode?");
+ case Instruction::Add: return Expression::ADD;
+ case Instruction::Sub: return Expression::SUB;
+ case Instruction::Mul: return Expression::MUL;
+ case Instruction::UDiv: return Expression::UDIV;
+ case Instruction::SDiv: return Expression::SDIV;
+ case Instruction::FDiv: return Expression::FDIV;
+ case Instruction::URem: return Expression::UREM;
+ case Instruction::SRem: return Expression::SREM;
+ case Instruction::FRem: return Expression::FREM;
+ case Instruction::Shl: return Expression::SHL;
+ case Instruction::LShr: return Expression::LSHR;
+ case Instruction::AShr: return Expression::ASHR;
+ case Instruction::And: return Expression::AND;
+ case Instruction::Or: return Expression::OR;
+ case Instruction::Xor: return Expression::XOR;
}
}
Expression::ExpressionOpcode ValueTable::getOpcode(CmpInst* C) {
- if (C->getOpcode() == Instruction::ICmp) {
+ if (isa<ICmpInst>(C) || isa<VICmpInst>(C)) {
switch (C->getPredicate()) {
- case ICmpInst::ICMP_EQ:
- return Expression::ICMPEQ;
- case ICmpInst::ICMP_NE:
- return Expression::ICMPNE;
- case ICmpInst::ICMP_UGT:
- return Expression::ICMPUGT;
- case ICmpInst::ICMP_UGE:
- return Expression::ICMPUGE;
- case ICmpInst::ICMP_ULT:
- return Expression::ICMPULT;
- case ICmpInst::ICMP_ULE:
- return Expression::ICMPULE;
- case ICmpInst::ICMP_SGT:
- return Expression::ICMPSGT;
- case ICmpInst::ICMP_SGE:
- return Expression::ICMPSGE;
- case ICmpInst::ICMP_SLT:
- return Expression::ICMPSLT;
- case ICmpInst::ICMP_SLE:
- return Expression::ICMPSLE;
-
- // THIS SHOULD NEVER HAPPEN
- default:
- assert(0 && "Comparison with unknown predicate?");
- return Expression::ICMPEQ;
- }
- } else {
- switch (C->getPredicate()) {
- case FCmpInst::FCMP_OEQ:
- return Expression::FCMPOEQ;
- case FCmpInst::FCMP_OGT:
- return Expression::FCMPOGT;
- case FCmpInst::FCMP_OGE:
- return Expression::FCMPOGE;
- case FCmpInst::FCMP_OLT:
- return Expression::FCMPOLT;
- case FCmpInst::FCMP_OLE:
- return Expression::FCMPOLE;
- case FCmpInst::FCMP_ONE:
- return Expression::FCMPONE;
- case FCmpInst::FCMP_ORD:
- return Expression::FCMPORD;
- case FCmpInst::FCMP_UNO:
- return Expression::FCMPUNO;
- case FCmpInst::FCMP_UEQ:
- return Expression::FCMPUEQ;
- case FCmpInst::FCMP_UGT:
- return Expression::FCMPUGT;
- case FCmpInst::FCMP_UGE:
- return Expression::FCMPUGE;
- case FCmpInst::FCMP_ULT:
- return Expression::FCMPULT;
- case FCmpInst::FCMP_ULE:
- return Expression::FCMPULE;
- case FCmpInst::FCMP_UNE:
- return Expression::FCMPUNE;
-
- // THIS SHOULD NEVER HAPPEN
- default:
- assert(0 && "Comparison with unknown predicate?");
- return Expression::FCMPOEQ;
+ default: // THIS SHOULD NEVER HAPPEN
+ assert(0 && "Comparison with unknown predicate?");
+ case ICmpInst::ICMP_EQ: return Expression::ICMPEQ;
+ case ICmpInst::ICMP_NE: return Expression::ICMPNE;
+ case ICmpInst::ICMP_UGT: return Expression::ICMPUGT;
+ case ICmpInst::ICMP_UGE: return Expression::ICMPUGE;
+ case ICmpInst::ICMP_ULT: return Expression::ICMPULT;
+ case ICmpInst::ICMP_ULE: return Expression::ICMPULE;
+ case ICmpInst::ICMP_SGT: return Expression::ICMPSGT;
+ case ICmpInst::ICMP_SGE: return Expression::ICMPSGE;
+ case ICmpInst::ICMP_SLT: return Expression::ICMPSLT;
+ case ICmpInst::ICMP_SLE: return Expression::ICMPSLE;
}
}
+ assert((isa<FCmpInst>(C) || isa<VFCmpInst>(C)) && "Unknown compare");
+ switch (C->getPredicate()) {
+ default: // THIS SHOULD NEVER HAPPEN
+ assert(0 && "Comparison with unknown predicate?");
+ case FCmpInst::FCMP_OEQ: return Expression::FCMPOEQ;
+ case FCmpInst::FCMP_OGT: return Expression::FCMPOGT;
+ case FCmpInst::FCMP_OGE: return Expression::FCMPOGE;
+ case FCmpInst::FCMP_OLT: return Expression::FCMPOLT;
+ case FCmpInst::FCMP_OLE: return Expression::FCMPOLE;
+ case FCmpInst::FCMP_ONE: return Expression::FCMPONE;
+ case FCmpInst::FCMP_ORD: return Expression::FCMPORD;
+ case FCmpInst::FCMP_UNO: return Expression::FCMPUNO;
+ case FCmpInst::FCMP_UEQ: return Expression::FCMPUEQ;
+ case FCmpInst::FCMP_UGT: return Expression::FCMPUGT;
+ case FCmpInst::FCMP_UGE: return Expression::FCMPUGE;
+ case FCmpInst::FCMP_ULT: return Expression::FCMPULT;
+ case FCmpInst::FCMP_ULE: return Expression::FCMPULE;
+ case FCmpInst::FCMP_UNE: return Expression::FCMPUNE;
+ }
}
-Expression::ExpressionOpcode
- ValueTable::getOpcode(CastInst* C) {
+Expression::ExpressionOpcode ValueTable::getOpcode(CastInst* C) {
switch(C->getOpcode()) {
- case Instruction::Trunc:
- return Expression::TRUNC;
- case Instruction::ZExt:
- return Expression::ZEXT;
- case Instruction::SExt:
- return Expression::SEXT;
- case Instruction::FPToUI:
- return Expression::FPTOUI;
- case Instruction::FPToSI:
- return Expression::FPTOSI;
- case Instruction::UIToFP:
- return Expression::UITOFP;
- case Instruction::SIToFP:
- return Expression::SITOFP;
- case Instruction::FPTrunc:
- return Expression::FPTRUNC;
- case Instruction::FPExt:
- return Expression::FPEXT;
- case Instruction::PtrToInt:
- return Expression::PTRTOINT;
- case Instruction::IntToPtr:
- return Expression::INTTOPTR;
- case Instruction::BitCast:
- return Expression::BITCAST;
-
- // THIS SHOULD NEVER HAPPEN
- default:
- assert(0 && "Cast operator with unknown opcode?");
- return Expression::BITCAST;
+ default: // THIS SHOULD NEVER HAPPEN
+ assert(0 && "Cast operator with unknown opcode?");
+ case Instruction::Trunc: return Expression::TRUNC;
+ case Instruction::ZExt: return Expression::ZEXT;
+ case Instruction::SExt: return Expression::SEXT;
+ case Instruction::FPToUI: return Expression::FPTOUI;
+ case Instruction::FPToSI: return Expression::FPTOSI;
+ case Instruction::UIToFP: return Expression::UITOFP;
+ case Instruction::SIToFP: return Expression::SITOFP;
+ case Instruction::FPTrunc: return Expression::FPTRUNC;
+ case Instruction::FPExt: return Expression::FPEXT;
+ case Instruction::PtrToInt: return Expression::PTRTOINT;
+ case Instruction::IntToPtr: return Expression::INTTOPTR;
+ case Instruction::BitCast: return Expression::BITCAST;
}
}
+Expression ValueTable::create_expression(CallInst* C) {
+ Expression e;
+
+ e.type = C->getType();
+ e.firstVN = 0;
+ e.secondVN = 0;
+ e.thirdVN = 0;
+ e.function = C->getCalledFunction();
+ e.opcode = Expression::CALL;
+
+ for (CallInst::op_iterator I = C->op_begin()+1, E = C->op_end();
+ I != E; ++I)
+ e.varargs.push_back(lookup_or_add(*I));
+
+ return e;
+}
+
Expression ValueTable::create_expression(BinaryOperator* BO) {
Expression e;
e.firstVN = lookup_or_add(BO->getOperand(0));
e.secondVN = lookup_or_add(BO->getOperand(1));
e.thirdVN = 0;
+ e.function = 0;
e.type = BO->getType();
e.opcode = getOpcode(BO);
e.firstVN = lookup_or_add(C->getOperand(0));
e.secondVN = lookup_or_add(C->getOperand(1));
e.thirdVN = 0;
+ e.function = 0;
e.type = C->getType();
e.opcode = getOpcode(C);
e.firstVN = lookup_or_add(C->getOperand(0));
e.secondVN = 0;
e.thirdVN = 0;
+ e.function = 0;
e.type = C->getType();
e.opcode = getOpcode(C);
e.firstVN = lookup_or_add(S->getOperand(0));
e.secondVN = lookup_or_add(S->getOperand(1));
e.thirdVN = lookup_or_add(S->getOperand(2));
+ e.function = 0;
e.type = S->getType();
e.opcode = Expression::SHUFFLE;
e.firstVN = lookup_or_add(E->getOperand(0));
e.secondVN = lookup_or_add(E->getOperand(1));
e.thirdVN = 0;
+ e.function = 0;
e.type = E->getType();
e.opcode = Expression::EXTRACT;
e.firstVN = lookup_or_add(I->getOperand(0));
e.secondVN = lookup_or_add(I->getOperand(1));
e.thirdVN = lookup_or_add(I->getOperand(2));
+ e.function = 0;
e.type = I->getType();
e.opcode = Expression::INSERT;
e.firstVN = lookup_or_add(I->getCondition());
e.secondVN = lookup_or_add(I->getTrueValue());
e.thirdVN = lookup_or_add(I->getFalseValue());
+ e.function = 0;
e.type = I->getType();
e.opcode = Expression::SELECT;
Expression ValueTable::create_expression(GetElementPtrInst* G) {
Expression e;
-
+
e.firstVN = lookup_or_add(G->getPointerOperand());
e.secondVN = 0;
e.thirdVN = 0;
+ e.function = 0;
e.type = G->getType();
e.opcode = Expression::GEP;
// ValueTable External Functions
//===----------------------------------------------------------------------===//
+/// add - Insert a value into the table with a specified value number.
+void ValueTable::add(Value* V, uint32_t num) {
+ valueNumbering.insert(std::make_pair(V, num));
+}
+
/// lookup_or_add - Returns the value number for the specified value, assigning
/// it a new number if it did not have one before.
uint32_t ValueTable::lookup_or_add(Value* V) {
if (VI != valueNumbering.end())
return VI->second;
-
- if (BinaryOperator* BO = dyn_cast<BinaryOperator>(V)) {
+ if (CallInst* C = dyn_cast<CallInst>(V)) {
+ if (AA->doesNotAccessMemory(C)) {
+ Expression e = create_expression(C);
+
+ DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
+ if (EI != expressionNumbering.end()) {
+ valueNumbering.insert(std::make_pair(V, EI->second));
+ return EI->second;
+ } else {
+ expressionNumbering.insert(std::make_pair(e, nextValueNumber));
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+
+ return nextValueNumber++;
+ }
+ } else if (AA->onlyReadsMemory(C)) {
+ Expression e = create_expression(C);
+
+ if (expressionNumbering.find(e) == expressionNumbering.end()) {
+ expressionNumbering.insert(std::make_pair(e, nextValueNumber));
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ }
+
+ Instruction* local_dep = MD->getDependency(C);
+
+ if (local_dep == MemoryDependenceAnalysis::None) {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ } else if (local_dep != MemoryDependenceAnalysis::NonLocal) {
+ if (!isa<CallInst>(local_dep)) {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ }
+
+ CallInst* local_cdep = cast<CallInst>(local_dep);
+
+ if (local_cdep->getCalledFunction() != C->getCalledFunction() ||
+ local_cdep->getNumOperands() != C->getNumOperands()) {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ } else if (!C->getCalledFunction()) {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ } else {
+ for (unsigned i = 1; i < C->getNumOperands(); ++i) {
+ uint32_t c_vn = lookup_or_add(C->getOperand(i));
+ uint32_t cd_vn = lookup_or_add(local_cdep->getOperand(i));
+ if (c_vn != cd_vn) {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ }
+ }
+
+ uint32_t v = lookup_or_add(local_cdep);
+ valueNumbering.insert(std::make_pair(V, v));
+ return v;
+ }
+ }
+
+
+ DenseMap<BasicBlock*, Value*> deps;
+ MD->getNonLocalDependency(C, deps);
+ CallInst* cdep = 0;
+
+ for (DenseMap<BasicBlock*, Value*>::iterator I = deps.begin(),
+ E = deps.end(); I != E; ++I) {
+ if (I->second == MemoryDependenceAnalysis::None) {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+
+ return nextValueNumber++;
+ } else if (I->second != MemoryDependenceAnalysis::NonLocal) {
+ if (DT->properlyDominates(I->first, C->getParent())) {
+ if (CallInst* CD = dyn_cast<CallInst>(I->second))
+ cdep = CD;
+ else {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ }
+ } else {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ }
+ }
+ }
+
+ if (!cdep) {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ }
+
+ if (cdep->getCalledFunction() != C->getCalledFunction() ||
+ cdep->getNumOperands() != C->getNumOperands()) {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ } else if (!C->getCalledFunction()) {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ } else {
+ for (unsigned i = 1; i < C->getNumOperands(); ++i) {
+ uint32_t c_vn = lookup_or_add(C->getOperand(i));
+ uint32_t cd_vn = lookup_or_add(cdep->getOperand(i));
+ if (c_vn != cd_vn) {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ }
+ }
+
+ uint32_t v = lookup_or_add(cdep);
+ valueNumbering.insert(std::make_pair(V, v));
+ return v;
+ }
+
+ } else {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
+ }
+ } else if (BinaryOperator* BO = dyn_cast<BinaryOperator>(V)) {
Expression e = create_expression(BO);
DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
/// the value has not yet been numbered.
uint32_t ValueTable::lookup(Value* V) const {
DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
- if (VI != valueNumbering.end())
- return VI->second;
- else
- assert(0 && "Value not numbered?");
-
- return 0;
+ assert(VI != valueNumbering.end() && "Value not numbered?");
+ return VI->second;
}
/// clear - Remove all entries from the ValueTable
}
//===----------------------------------------------------------------------===//
-// ValueNumberedSet Class
+// GVN Pass
//===----------------------------------------------------------------------===//
-namespace {
-class ValueNumberedSet {
- private:
- SmallPtrSet<Value*, 8> contents;
- BitVector numbers;
- public:
- ValueNumberedSet() { numbers.resize(1); }
- ValueNumberedSet(const ValueNumberedSet& other) {
- numbers = other.numbers;
- contents = other.contents;
- }
-
- typedef SmallPtrSet<Value*, 8>::iterator iterator;
-
- iterator begin() { return contents.begin(); }
- iterator end() { return contents.end(); }
-
- bool insert(Value* v) { return contents.insert(v); }
- void insert(iterator I, iterator E) { contents.insert(I, E); }
- void erase(Value* v) { contents.erase(v); }
- unsigned count(Value* v) { return contents.count(v); }
- size_t size() { return contents.size(); }
-
- void set(unsigned i) {
- if (i >= numbers.size())
- numbers.resize(i+1);
-
- numbers.set(i);
- }
-
- void operator=(const ValueNumberedSet& other) {
- contents = other.contents;
- numbers = other.numbers;
- }
-
- void reset(unsigned i) {
- if (i < numbers.size())
- numbers.reset(i);
- }
-
- bool test(unsigned i) {
- if (i >= numbers.size())
- return false;
-
- return numbers.test(i);
- }
-
- void clear() {
- contents.clear();
- numbers.clear();
+
+namespace llvm {
+ template<> struct DenseMapInfo<uint32_t> {
+ static inline uint32_t getEmptyKey() { return ~0; }
+ static inline uint32_t getTombstoneKey() { return ~0 - 1; }
+ static unsigned getHashValue(const uint32_t& Val) { return Val * 37; }
+ static bool isPod() { return true; }
+ static bool isEqual(const uint32_t& LHS, const uint32_t& RHS) {
+ return LHS == RHS;
}
-};
+ };
}
-//===----------------------------------------------------------------------===//
-// GVN Pass
-//===----------------------------------------------------------------------===//
+namespace {
+ struct VISIBILITY_HIDDEN ValueNumberScope {
+ ValueNumberScope* parent;
+ DenseMap<uint32_t, Value*> table;
+
+ ValueNumberScope(ValueNumberScope* p) : parent(p) { }
+ };
+}
namespace {
private:
ValueTable VN;
-
- DenseMap<BasicBlock*, ValueNumberedSet> availableOut;
+ DenseMap<BasicBlock*, ValueNumberScope*> localAvail;
typedef DenseMap<Value*, SmallPtrSet<Instruction*, 4> > PhiMapType;
PhiMapType phiMap;
// This transformation requires dominator postdominator info
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesCFG();
AU.addRequired<DominatorTree>();
AU.addRequired<MemoryDependenceAnalysis>();
+ AU.addRequired<AliasAnalysis>();
+
+ AU.addPreserved<DominatorTree>();
+ AU.addPreserved<AliasAnalysis>();
AU.addPreserved<MemoryDependenceAnalysis>();
}
// Helper fuctions
// FIXME: eliminate or document these better
- Value* find_leader(ValueNumberedSet& vals, uint32_t v) ;
- void val_insert(ValueNumberedSet& s, Value* v);
bool processLoad(LoadInst* L,
- DenseMap<Value*, LoadInst*>& lastLoad,
- SmallVector<Instruction*, 4>& toErase);
+ DenseMap<Value*, LoadInst*> &lastLoad,
+ SmallVectorImpl<Instruction*> &toErase);
bool processInstruction(Instruction* I,
- ValueNumberedSet& currAvail,
DenseMap<Value*, LoadInst*>& lastSeenLoad,
- SmallVector<Instruction*, 4>& toErase);
+ SmallVectorImpl<Instruction*> &toErase);
bool processNonLocalLoad(LoadInst* L,
- SmallVector<Instruction*, 4>& toErase);
+ SmallVectorImpl<Instruction*> &toErase);
+ bool processBlock(DomTreeNode* DTN);
Value *GetValueForBlock(BasicBlock *BB, LoadInst* orig,
DenseMap<BasicBlock*, Value*> &Phis,
bool top_level = false);
- void dump(DenseMap<BasicBlock*, Value*>& d);
+ void dump(DenseMap<uint32_t, Value*>& d);
+ bool iterateOnFunction(Function &F);
+ Value* CollapsePhi(PHINode* p);
+ bool isSafeReplacement(PHINode* p, Instruction* inst);
+ bool performPRE(Function& F);
+ Value* lookupNumber(BasicBlock* BB, uint32_t num);
};
char GVN::ID = 0;
-
}
// createGVNPass - The public interface to this file...
static RegisterPass<GVN> X("gvn",
"Global Value Numbering");
-STATISTIC(NumGVNInstr, "Number of instructions deleted");
-STATISTIC(NumGVNLoad, "Number of loads deleted");
-
-/// find_leader - Given a set and a value number, return the first
-/// element of the set with that value number, or 0 if no such element
-/// is present
-Value* GVN::find_leader(ValueNumberedSet& vals, uint32_t v) {
- if (!vals.test(v))
- return 0;
-
- for (ValueNumberedSet::iterator I = vals.begin(), E = vals.end();
- I != E; ++I)
- if (v == VN.lookup(*I))
- return *I;
-
- assert(0 && "No leader found, but present bit is set?");
- return 0;
-}
-
-/// val_insert - Insert a value into a set only if there is not a value
-/// with the same value number already in the set
-void GVN::val_insert(ValueNumberedSet& s, Value* v) {
- uint32_t num = VN.lookup(v);
- if (!s.test(num))
- s.insert(v);
-}
-
-void GVN::dump(DenseMap<BasicBlock*, Value*>& d) {
+void GVN::dump(DenseMap<uint32_t, Value*>& d) {
printf("{\n");
- for (DenseMap<BasicBlock*, Value*>::iterator I = d.begin(),
+ for (DenseMap<uint32_t, Value*>::iterator I = d.begin(),
E = d.end(); I != E; ++I) {
- if (I->second == MemoryDependenceAnalysis::None)
- printf("None\n");
- else
+ printf("%d\n", I->first);
I->second->dump();
}
printf("}\n");
}
+Value* GVN::CollapsePhi(PHINode* p) {
+ DominatorTree &DT = getAnalysis<DominatorTree>();
+ Value* constVal = p->hasConstantValue();
+
+ if (!constVal) return 0;
+
+ Instruction* inst = dyn_cast<Instruction>(constVal);
+ if (!inst)
+ return constVal;
+
+ if (DT.dominates(inst, p))
+ if (isSafeReplacement(p, inst))
+ return inst;
+ return 0;
+}
+
+bool GVN::isSafeReplacement(PHINode* p, Instruction* inst) {
+ if (!isa<PHINode>(inst))
+ return true;
+
+ for (Instruction::use_iterator UI = p->use_begin(), E = p->use_end();
+ UI != E; ++UI)
+ if (PHINode* use_phi = dyn_cast<PHINode>(UI))
+ if (use_phi->getParent() == inst->getParent())
+ return false;
+
+ return true;
+}
/// GetValueForBlock - Get the value to use within the specified basic block.
/// available values are in Phis.
Value *GVN::GetValueForBlock(BasicBlock *BB, LoadInst* orig,
- DenseMap<BasicBlock*, Value*> &Phis,
- bool top_level) {
+ DenseMap<BasicBlock*, Value*> &Phis,
+ bool top_level) {
// If we have already computed this value, return the previously computed val.
DenseMap<BasicBlock*, Value*>::iterator V = Phis.find(BB);
if (V != Phis.end() && !top_level) return V->second;
+ // If the block is unreachable, just return undef, since this path
+ // can't actually occur at runtime.
+ if (!getAnalysis<DominatorTree>().isReachableFromEntry(BB))
+ return Phis[BB] = UndefValue::get(orig->getType());
+
BasicBlock* singlePred = BB->getSinglePredecessor();
if (singlePred) {
Value *ret = GetValueForBlock(singlePred, orig, Phis);
Phis[BB] = ret;
return ret;
}
+
// Otherwise, the idom is the loop, so we need to insert a PHI node. Do so
// now, then get values to fill in the incoming values for the PHI.
- PHINode *PN = new PHINode(orig->getType(), orig->getName()+".rle",
- BB->begin());
+ PHINode *PN = PHINode::Create(orig->getType(), orig->getName()+".rle",
+ BB->begin());
PN->reserveOperandSpace(std::distance(pred_begin(BB), pred_end(BB)));
if (Phis.count(BB) == 0)
Phis.insert(std::make_pair(BB, PN));
- bool all_same = true;
- Value* first = 0;
-
// Fill in the incoming values for the block.
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
Value* val = GetValueForBlock(*PI, orig, Phis);
- if (first == 0)
- first = val;
- else if (all_same && first != val)
- all_same = false;
-
PN->addIncoming(val, *PI);
}
- if (all_same) {
- MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
-
- MD.removeInstruction(PN);
- PN->replaceAllUsesWith(first);
-
- SmallVector<BasicBlock*, 4> toRemove;
- for (DenseMap<BasicBlock*, Value*>::iterator I = Phis.begin(),
- E = Phis.end(); I != E; ++I)
- if (I->second == PN)
- toRemove.push_back(I->first);
- for (SmallVector<BasicBlock*, 4>::iterator I = toRemove.begin(),
- E= toRemove.end(); I != E; ++I)
- Phis[*I] = first;
-
- PN->eraseFromParent();
-
- Phis[BB] = first;
-
- return first;
+ AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
+ AA.copyValue(orig, PN);
+
+ // Attempt to collapse PHI nodes that are trivially redundant
+ Value* v = CollapsePhi(PN);
+ if (!v) {
+ // Cache our phi construction results
+ phiMap[orig->getPointerOperand()].insert(PN);
+ return PN;
}
+
+ MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
+
+ MD.removeInstruction(PN);
+ PN->replaceAllUsesWith(v);
+
+ for (DenseMap<BasicBlock*, Value*>::iterator I = Phis.begin(),
+ E = Phis.end(); I != E; ++I)
+ if (I->second == PN)
+ I->second = v;
+
+ PN->eraseFromParent();
- phiMap[orig->getPointerOperand()].insert(PN);
- return PN;
+ Phis[BB] = v;
+ return v;
}
+/// processNonLocalLoad - Attempt to eliminate a load whose dependencies are
+/// non-local by performing PHI construction.
bool GVN::processNonLocalLoad(LoadInst* L,
- SmallVector<Instruction*, 4>& toErase) {
+ SmallVectorImpl<Instruction*> &toErase) {
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
+ // Find the non-local dependencies of the load
DenseMap<BasicBlock*, Value*> deps;
MD.getNonLocalDependency(L, deps);
DenseMap<BasicBlock*, Value*> repl;
+ // Filter out useless results (non-locals, etc)
for (DenseMap<BasicBlock*, Value*>::iterator I = deps.begin(), E = deps.end();
- I != E; ++I)
- if (I->second == MemoryDependenceAnalysis::None) {
+ I != E; ++I) {
+ if (I->second == MemoryDependenceAnalysis::None)
return false;
- } else if (I->second == MemoryDependenceAnalysis::NonLocal) {
+
+ if (I->second == MemoryDependenceAnalysis::NonLocal)
continue;
- }else if (StoreInst* S = dyn_cast<StoreInst>(I->second)) {
- if (S->getPointerOperand() == L->getPointerOperand())
- repl[I->first] = S->getOperand(0);
- else
+
+ if (StoreInst* S = dyn_cast<StoreInst>(I->second)) {
+ if (S->getPointerOperand() != L->getPointerOperand())
return false;
+ repl[I->first] = S->getOperand(0);
} else if (LoadInst* LD = dyn_cast<LoadInst>(I->second)) {
- if (LD->getPointerOperand() == L->getPointerOperand())
- repl[I->first] = LD;
- else
+ if (LD->getPointerOperand() != L->getPointerOperand())
return false;
+ repl[I->first] = LD;
} else {
return false;
}
+ }
+ // Use cached PHI construction information from previous runs
SmallPtrSet<Instruction*, 4>& p = phiMap[L->getPointerOperand()];
for (SmallPtrSet<Instruction*, 4>::iterator I = p.begin(), E = p.end();
I != E; ++I) {
L->replaceAllUsesWith(*I);
toErase.push_back(L);
NumGVNLoad++;
-
return true;
- } else {
- repl.insert(std::make_pair((*I)->getParent(), *I));
}
+
+ repl.insert(std::make_pair((*I)->getParent(), *I));
}
+ // Perform PHI construction
SmallPtrSet<BasicBlock*, 4> visited;
Value* v = GetValueForBlock(L->getParent(), L, repl, true);
return true;
}
-bool GVN::processLoad(LoadInst* L,
- DenseMap<Value*, LoadInst*>& lastLoad,
- SmallVector<Instruction*, 4>& toErase) {
+/// processLoad - Attempt to eliminate a load, first by eliminating it
+/// locally, and then attempting non-local elimination if that fails.
+bool GVN::processLoad(LoadInst *L, DenseMap<Value*, LoadInst*> &lastLoad,
+ SmallVectorImpl<Instruction*> &toErase) {
if (L->isVolatile()) {
lastLoad[L->getPointerOperand()] = L;
return false;
bool deletedLoad = false;
+ // Walk up the dependency chain until we either find
+ // a dependency we can use, or we can't walk any further
while (dep != MemoryDependenceAnalysis::None &&
dep != MemoryDependenceAnalysis::NonLocal &&
(isa<LoadInst>(dep) || isa<StoreInst>(dep))) {
dep = MD.getDependency(L, dep);
}
}
-
+
+ if (dep != MemoryDependenceAnalysis::None &&
+ dep != MemoryDependenceAnalysis::NonLocal &&
+ isa<AllocationInst>(dep)) {
+ // Check that this load is actually from the
+ // allocation we found
+ Value* v = L->getOperand(0);
+ while (true) {
+ if (BitCastInst *BC = dyn_cast<BitCastInst>(v))
+ v = BC->getOperand(0);
+ else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(v))
+ v = GEP->getOperand(0);
+ else
+ break;
+ }
+ if (v == dep) {
+ // If this load depends directly on an allocation, there isn't
+ // anything stored there; therefore, we can optimize this load
+ // to undef.
+ MD.removeInstruction(L);
+
+ L->replaceAllUsesWith(UndefValue::get(L->getType()));
+ toErase.push_back(L);
+ deletedLoad = true;
+ NumGVNLoad++;
+ }
+ }
+
if (!deletedLoad)
last = L;
return deletedLoad;
}
-/// buildsets_availout - When calculating availability, handle an instruction
+Value* GVN::lookupNumber(BasicBlock* BB, uint32_t num) {
+ DenseMap<BasicBlock*, ValueNumberScope*>::iterator I = localAvail.find(BB);
+ if (I == localAvail.end())
+ return 0;
+
+ ValueNumberScope* locals = I->second;
+
+ while (locals) {
+ DenseMap<uint32_t, Value*>::iterator I = locals->table.find(num);
+ if (I != locals->table.end())
+ return I->second;
+ else
+ locals = locals->parent;
+ }
+
+ return 0;
+}
+
+/// processInstruction - When calculating availability, handle an instruction
/// by inserting it into the appropriate sets
-bool GVN::processInstruction(Instruction* I,
- ValueNumberedSet& currAvail,
- DenseMap<Value*, LoadInst*>& lastSeenLoad,
- SmallVector<Instruction*, 4>& toErase) {
+bool GVN::processInstruction(Instruction *I,
+ DenseMap<Value*, LoadInst*> &lastSeenLoad,
+ SmallVectorImpl<Instruction*> &toErase) {
if (LoadInst* L = dyn_cast<LoadInst>(I)) {
- return processLoad(L, lastSeenLoad, toErase);
+ bool changed = processLoad(L, lastSeenLoad, toErase);
+
+ if (!changed) {
+ unsigned num = VN.lookup_or_add(L);
+ localAvail[I->getParent()]->table.insert(std::make_pair(num, L));
+ }
+
+ return changed;
}
+ uint32_t nextNum = VN.getNextUnusedValueNumber();
unsigned num = VN.lookup_or_add(I);
- if (currAvail.test(num)) {
- Value* repl = find_leader(currAvail, num);
+ // Allocations are always uniquely numbered, so we can save time and memory
+ // by fast failing them.
+ if (isa<AllocationInst>(I) || isa<TerminatorInst>(I)) {
+ localAvail[I->getParent()]->table.insert(std::make_pair(num, I));
+ return false;
+ }
+
+ // Collapse PHI nodes
+ if (PHINode* p = dyn_cast<PHINode>(I)) {
+ Value* constVal = CollapsePhi(p);
+
+ if (constVal) {
+ for (PhiMapType::iterator PI = phiMap.begin(), PE = phiMap.end();
+ PI != PE; ++PI)
+ if (PI->second.count(p))
+ PI->second.erase(p);
+
+ p->replaceAllUsesWith(constVal);
+ toErase.push_back(p);
+ } else {
+ localAvail[I->getParent()]->table.insert(std::make_pair(num, I));
+ }
+
+ // If the number we were assigned was a brand new VN, then we don't
+ // need to do a lookup to see if the number already exists
+ // somewhere in the domtree: it can't!
+ } else if (num == nextNum) {
+ localAvail[I->getParent()]->table.insert(std::make_pair(num, I));
+
+ // Perform value-number based elimination
+ } else if (Value* repl = lookupNumber(I->getParent(), num)) {
+ // Remove it!
+ MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
+ MD.removeInstruction(I);
VN.erase(I);
I->replaceAllUsesWith(repl);
toErase.push_back(I);
return true;
- } else if (!I->isTerminator()) {
- currAvail.set(num);
- currAvail.insert(I);
+ } else {
+ localAvail[I->getParent()]->table.insert(std::make_pair(num, I));
}
return false;
// GVN::runOnFunction - This is the main transformation entry point for a
// function.
//
-bool GVN::runOnFunction(Function &F) {
- // Clean out global sets from any previous functions
- VN.clear();
- availableOut.clear();
- phiMap.clear();
-
- bool changed_function = false;
+bool GVN::runOnFunction(Function& F) {
+ VN.setAliasAnalysis(&getAnalysis<AliasAnalysis>());
+ VN.setMemDep(&getAnalysis<MemoryDependenceAnalysis>());
+ VN.setDomTree(&getAnalysis<DominatorTree>());
- DominatorTree &DT = getAnalysis<DominatorTree>();
+ bool changed = false;
+ bool shouldContinue = true;
- SmallVector<Instruction*, 4> toErase;
+ while (shouldContinue) {
+ shouldContinue = iterateOnFunction(F);
+ changed |= shouldContinue;
+ }
- // Top-down walk of the dominator tree
- for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
- E = df_end(DT.getRootNode()); DI != E; ++DI) {
+ return changed;
+}
+
+
+bool GVN::processBlock(DomTreeNode* DTN) {
+ BasicBlock* BB = DTN->getBlock();
+
+ SmallVector<Instruction*, 8> toErase;
+ DenseMap<Value*, LoadInst*> lastSeenLoad;
+ bool changed_function = false;
+
+ if (DTN->getIDom())
+ localAvail[BB] =
+ new ValueNumberScope(localAvail[DTN->getIDom()->getBlock()]);
+ else
+ localAvail[BB] = new ValueNumberScope(0);
+
+ for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
+ BI != BE;) {
+ changed_function |= processInstruction(BI, lastSeenLoad, toErase);
+ if (toErase.empty()) {
+ ++BI;
+ continue;
+ }
+
+ // If we need some instructions deleted, do it now.
+ NumGVNInstr += toErase.size();
- // Get the set to update for this block
- ValueNumberedSet& currAvail = availableOut[DI->getBlock()];
- DenseMap<Value*, LoadInst*> lastSeenLoad;
+ // Avoid iterator invalidation.
+ bool AtStart = BI == BB->begin();
+ if (!AtStart)
+ --BI;
+
+ for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
+ E = toErase.end(); I != E; ++I)
+ (*I)->eraseFromParent();
+
+ if (AtStart)
+ BI = BB->begin();
+ else
+ ++BI;
- BasicBlock* BB = DI->getBlock();
+ toErase.clear();
+ }
- // A block inherits AVAIL_OUT from its dominator
- if (DI->getIDom() != 0)
- currAvail = availableOut[DI->getIDom()->getBlock()];
+ return changed_function;
+}
- for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
- BI != BE; ) {
- changed_function |= processInstruction(BI, currAvail,
- lastSeenLoad, toErase);
+/// performPRE - Perform a purely local form of PRE that looks for diamond
+/// control flow patterns and attempts to perform simple PRE at the join point.
+bool GVN::performPRE(Function& F) {
+ bool changed = false;
+ SmallVector<std::pair<TerminatorInst*, unsigned>, 4> toSplit;
+ for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
+ DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
+ BasicBlock* CurrentBlock = *DI;
+
+ // Nothing to PRE in the entry block.
+ if (CurrentBlock == &F.getEntryBlock()) continue;
+
+ for (BasicBlock::iterator BI = CurrentBlock->begin(),
+ BE = CurrentBlock->end(); BI != BE; ) {
+ if (isa<AllocationInst>(BI) || isa<TerminatorInst>(BI) ||
+ isa<PHINode>(BI) || BI->mayReadFromMemory() ||
+ BI->mayWriteToMemory()) {
+ BI++;
+ continue;
+ }
- NumGVNInstr += toErase.size();
+ uint32_t valno = VN.lookup(BI);
- // Avoid iterator invalidation
- ++BI;
+ // Look for the predecessors for PRE opportunities. We're
+ // only trying to solve the basic diamond case, where
+ // a value is computed in the successor and one predecessor,
+ // but not the other. We also explicitly disallow cases
+ // where the successor is its own predecessor, because they're
+ // more complicated to get right.
+ unsigned numWith = 0;
+ unsigned numWithout = 0;
+ BasicBlock* PREPred = 0;
+ DenseMap<BasicBlock*, Value*> predMap;
+ for (pred_iterator PI = pred_begin(CurrentBlock),
+ PE = pred_end(CurrentBlock); PI != PE; ++PI) {
+ // We're not interested in PRE where the block is its
+ // own predecessor, on in blocks with predecessors
+ // that are not reachable.
+ if (*PI == CurrentBlock) {
+ numWithout = 2;
+ break;
+ } else if (!localAvail.count(*PI)) {
+ numWithout = 2;
+ break;
+ }
+
+ DenseMap<uint32_t, Value*>::iterator predV =
+ localAvail[*PI]->table.find(valno);
+ if (predV == localAvail[*PI]->table.end()) {
+ PREPred = *PI;
+ numWithout++;
+ } else if (predV->second == BI) {
+ numWithout = 2;
+ } else {
+ predMap[*PI] = predV->second;
+ numWith++;
+ }
+ }
+
+ // Don't do PRE when it might increase code size, i.e. when
+ // we would need to insert instructions in more than one pred.
+ if (numWithout != 1 || numWith == 0) {
+ BI++;
+ continue;
+ }
+
+ // We can't do PRE safely on a critical edge, so instead we schedule
+ // the edge to be split and perform the PRE the next time we iterate
+ // on the function.
+ unsigned succNum = 0;
+ for (unsigned i = 0, e = PREPred->getTerminator()->getNumSuccessors();
+ i != e; ++i)
+ if (PREPred->getTerminator()->getSuccessor(i) == PREPred) {
+ succNum = i;
+ break;
+ }
+
+ if (isCriticalEdge(PREPred->getTerminator(), succNum)) {
+ toSplit.push_back(std::make_pair(PREPred->getTerminator(), succNum));
+ changed = true;
+ BI++;
+ continue;
+ }
+
+ // Instantiate the expression the in predecessor that lacked it.
+ // Because we are going top-down through the block, all value numbers
+ // will be available in the predecessor by the time we need them. Any
+ // that weren't original present will have been instantiated earlier
+ // in this loop.
+ Instruction* PREInstr = BI->clone();
+ bool success = true;
+ for (unsigned i = 0; i < BI->getNumOperands(); ++i) {
+ Value* op = BI->getOperand(i);
+ if (isa<Argument>(op) || isa<Constant>(op) || isa<GlobalValue>(op))
+ PREInstr->setOperand(i, op);
+ else if (!lookupNumber(PREPred, VN.lookup(op))) {
+ success = false;
+ break;
+ } else
+ PREInstr->setOperand(i, lookupNumber(PREPred, VN.lookup(op)));
+ }
+
+ // Fail out if we encounter an operand that is not available in
+ // the PRE predecessor. This is typically because of loads which
+ // are not value numbered precisely.
+ if (!success) {
+ delete PREInstr;
+ BI++;
+ continue;
+ }
+
+ PREInstr->insertBefore(PREPred->getTerminator());
+ PREInstr->setName(BI->getName() + ".pre");
+ predMap[PREPred] = PREInstr;
+ VN.add(PREInstr, valno);
+ NumGVNPRE++;
+
+ // Update the availability map to include the new instruction.
+ localAvail[PREPred]->table.insert(std::make_pair(valno, PREInstr));
+
+ // Create a PHI to make the value available in this block.
+ PHINode* Phi = PHINode::Create(BI->getType(),
+ BI->getName() + ".pre-phi",
+ CurrentBlock->begin());
+ for (pred_iterator PI = pred_begin(CurrentBlock),
+ PE = pred_end(CurrentBlock); PI != PE; ++PI)
+ Phi->addIncoming(predMap[*PI], *PI);
+
+ VN.add(Phi, valno);
+ localAvail[CurrentBlock]->table[valno] = Phi;
+
+ BI->replaceAllUsesWith(Phi);
+ VN.erase(BI);
- for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
- E = toErase.end(); I != E; ++I)
- (*I)->eraseFromParent();
+ Instruction* erase = BI;
+ BI++;
+ erase->eraseFromParent();
- toErase.clear();
+ changed = true;
}
}
- return changed_function;
+ for (SmallVector<std::pair<TerminatorInst*, unsigned>, 4>::iterator
+ I = toSplit.begin(), E = toSplit.end(); I != E; ++I)
+ SplitCriticalEdge(I->first, I->second, this);
+
+ return changed;
+}
+
+// GVN::iterateOnFunction - Executes one iteration of GVN
+bool GVN::iterateOnFunction(Function &F) {
+ // Clean out global sets from any previous functions
+ VN.clear();
+ phiMap.clear();
+
+ for (DenseMap<BasicBlock*, ValueNumberScope*>::iterator
+ I = localAvail.begin(), E = localAvail.end(); I != E; ++I)
+ delete I->second;
+ localAvail.clear();
+
+ DominatorTree &DT = getAnalysis<DominatorTree>();
+
+ // Top-down walk of the dominator tree
+ bool changed = false;
+ for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
+ DE = df_end(DT.getRootNode()); DI != DE; ++DI)
+ changed |= processBlock(*DI);
+
+ if (EnablePRE)
+ changed |= performPRE(F);
+
+ return changed;
}
projects / oota-llvm.git / blobdiff