//
// 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/ScopedHashTable.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/SparseBitVector.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/Compiler.h"
+#include "llvm/Support/Debug.h"
using namespace llvm;
+STATISTIC(NumGVNInstr, "Number of instructions deleted");
+STATISTIC(NumGVNLoad, "Number of loads deleted");
+
//===----------------------------------------------------------------------===//
// 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; }
};
}
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) {
//===----------------------------------------------------------------------===//
// 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;
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->dominates(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; }
+ static bool isPod() { return true; }
+ static bool isEqual(const uint32_t& LHS, const uint32_t& RHS) {
+ return LHS == RHS;
}
-};
+ };
}
-//===----------------------------------------------------------------------===//
-// GVN Pass
-//===----------------------------------------------------------------------===//
+typedef ScopedHashTable<uint32_t, Value*> ValueNumberMap;
+typedef ScopedHashTableScope<uint32_t, Value*> ValueNumberScope;
namespace {
private:
ValueTable VN;
- DenseMap<BasicBlock*, ValueNumberedSet> availableOut;
+ DenseMap<BasicBlock*, ValueNumberScope> availableOut;
+ ValueNumberMap BaseMap;
typedef DenseMap<Value*, SmallPtrSet<Instruction*, 4> > PhiMapType;
PhiMapType phiMap;
AU.setPreservesCFG();
AU.addRequired<DominatorTree>();
AU.addRequired<MemoryDependenceAnalysis>();
+ AU.addRequired<AliasAnalysis>();
+ 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);
};
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) {
printf("{\n");
for (DenseMap<BasicBlock*, Value*>::iterator I = d.begin(),
DominatorTree &DT = getAnalysis<DominatorTree>();
Value* constVal = p->hasConstantValue();
- if (constVal) {
- if (Instruction* inst = dyn_cast<Instruction>(constVal)) {
- if (DT.dominates(inst, p))
- if (isSafeReplacement(p, inst))
- return inst;
- } else {
- return constVal;
- }
- }
+ 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;
}
/// 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);
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)
// 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);
-
PN->addIncoming(val, *PI);
}
+ AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
+ AA.copyValue(orig, PN);
+
// Attempt to collapse PHI nodes that are trivially redundant
Value* v = CollapsePhi(PN);
- if (v) {
- 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;
+ if (!v) {
+ // Cache our phi construction results
+ phiMap[orig->getPointerOperand()].insert(PN);
+ return PN;
+ }
+
+ MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
- PN->eraseFromParent();
+ MD.removeInstruction(PN);
+ PN->replaceAllUsesWith(v);
- Phis[BB] = v;
+ for (DenseMap<BasicBlock*, Value*>::iterator I = Phis.begin(),
+ E = Phis.end(); I != E; ++I)
+ if (I->second == PN)
+ I->second = v;
- return v;
- }
+ PN->eraseFromParent();
- // Cache our phi construction results
- 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
// 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()];
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
/// 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,
- SmallVector<Instruction*, 4>& toErase) {
+bool GVN::processLoad(LoadInst *L, DenseMap<Value*, LoadInst*> &lastLoad,
+ SmallVectorImpl<Instruction*> &toErase) {
if (L->isVolatile()) {
lastLoad[L->getPointerOperand()] = L;
return false;
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;
/// 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) {
- if (LoadInst* L = dyn_cast<LoadInst>(I)) {
+bool GVN::processInstruction(Instruction *I,
+ DenseMap<Value*, LoadInst*> &lastSeenLoad,
+ SmallVectorImpl<Instruction*> &toErase) {
+ if (LoadInst* L = dyn_cast<LoadInst>(I))
return processLoad(L, lastSeenLoad, toErase);
- }
+
+ // Allocations are always uniquely numbered, so we can save time and memory
+ // by fast failing them.
+ if (isa<AllocationInst>(I))
+ return false;
unsigned num = VN.lookup_or_add(I);
toErase.push_back(p);
}
// Perform value-number based elimination
- } else if (currAvail.test(num)) {
- Value* repl = find_leader(currAvail, num);
+ } else if (BaseMap.begin(num) != BaseMap.end()) {
+ Value* repl = *BaseMap.begin(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);
+ BaseMap.insert(num, I);
}
return false;
// function.
//
bool GVN::runOnFunction(Function& F) {
+ VN.setAliasAnalysis(&getAnalysis<AliasAnalysis>());
+ VN.setMemDep(&getAnalysis<MemoryDependenceAnalysis>());
+ VN.setDomTree(&getAnalysis<DominatorTree>());
+
bool changed = false;
bool shouldContinue = true;
}
+bool GVN::processBlock(DomTreeNode* DTN) {
+ BasicBlock* BB = DTN->getBlock();
+ ValueNumberScope NewScope(BaseMap);
+
+ SmallVector<Instruction*, 8> toErase;
+ DenseMap<Value*, LoadInst*> lastSeenLoad;
+ bool changed_function = false;
+
+ 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();
+
+ // 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;
+
+ toErase.clear();
+ }
+
+ for (DomTreeNode::iterator I = DTN->begin(), E = DTN->end(); I != E; ++I)
+ changed_function |= processBlock(*I);
+
+ return changed_function;
+}
+
// GVN::iterateOnFunction - Executes one iteration of GVN
bool GVN::iterateOnFunction(Function &F) {
// Clean out global sets from any previous functions
VN.clear();
availableOut.clear();
phiMap.clear();
-
- bool changed_function = false;
DominatorTree &DT = getAnalysis<DominatorTree>();
-
- SmallVector<Instruction*, 4> toErase;
-
- // Top-down walk of the dominator tree
- for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
- E = df_end(DT.getRootNode()); DI != E; ++DI) {
-
- // Get the set to update for this block
- ValueNumberedSet& currAvail = availableOut[DI->getBlock()];
- DenseMap<Value*, LoadInst*> lastSeenLoad;
-
- BasicBlock* BB = DI->getBlock();
-
- // A block inherits AVAIL_OUT from its dominator
- if (DI->getIDom() != 0)
- currAvail = availableOut[DI->getIDom()->getBlock()];
- for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
- BI != BE; ) {
- changed_function |= processInstruction(BI, currAvail,
- lastSeenLoad, toErase);
-
- NumGVNInstr += toErase.size();
-
- // Avoid iterator invalidation
- ++BI;
-
- for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
- E = toErase.end(); I != E; ++I)
- (*I)->eraseFromParent();
-
- toErase.clear();
- }
- }
-
- return changed_function;
+ // Top-down walk of the dominator tree
+ return processBlock(DT.getRootNode());
}
projects / oota-llvm.git / blobdiff