// the optimization. It replaces redundant values with uses of earlier
// occurences of the same value. While this is beneficial in that it eliminates
// unneeded computation, it also increases register pressure by creating large
-// live ranges, and should be used with caution on platforms that a very
+// live ranges, and should be used with caution on platforms that are very
// sensitive to register pressure.
//
//===----------------------------------------------------------------------===//
#include "llvm/Function.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/PostDominators.h"
+#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/CFG.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include <algorithm>
#include <set>
using namespace llvm;
-struct ExprLT {
- bool operator()(Value* left, Value* right) {
- if (!isa<BinaryOperator>(left) || !isa<BinaryOperator>(right))
- return left < right;
+//===----------------------------------------------------------------------===//
+// ValueTable Class
+//===----------------------------------------------------------------------===//
+
+/// This class holds the mapping between values and value numbers. It is used
+/// as an efficient mechanism to determine the expression-wise equivalence of
+/// two values.
+
+namespace {
+ class VISIBILITY_HIDDEN ValueTable {
+ public:
+ struct Expression {
+ enum ExpressionOpcode { ADD, SUB, MUL, UDIV, SDIV, FDIV, UREM, SREM,
+ FREM, SHL, LSHR, ASHR, AND, OR, XOR, ICMPEQ,
+ ICMPNE, ICMPUGT, ICMPUGE, ICMPULT, ICMPULE,
+ ICMPSGT, ICMPSGE, ICMPSLT, ICMPSLE, FCMPOEQ,
+ FCMPOGT, FCMPOGE, FCMPOLT, FCMPOLE, FCMPONE,
+ FCMPORD, FCMPUNO, FCMPUEQ, FCMPUGT, FCMPUGE,
+ FCMPULT, FCMPULE, FCMPUNE };
- BinaryOperator* BO1 = cast<BinaryOperator>(left);
- BinaryOperator* BO2 = cast<BinaryOperator>(right);
+ ExpressionOpcode opcode;
+ uint32_t leftVN;
+ uint32_t rightVN;
+
+ bool operator< (const Expression& other) const {
+ if (opcode < other.opcode)
+ return true;
+ else if (opcode > other.opcode)
+ return false;
+ else if (leftVN < other.leftVN)
+ return true;
+ else if (leftVN > other.leftVN)
+ return false;
+ else if (rightVN < other.rightVN)
+ return true;
+ else if (rightVN > other.rightVN)
+ return false;
+ else
+ return false;
+ }
+ };
- if ((*this)(BO1->getOperand(0), BO2->getOperand(0)))
- return true;
- else if ((*this)(BO2->getOperand(0), BO1->getOperand(0)))
- return false;
- else
- return (*this)(BO1->getOperand(1), BO2->getOperand(1));
+ private:
+ DenseMap<Value*, uint32_t> valueNumbering;
+ std::map<Expression, uint32_t> expressionNumbering;
+
+ std::set<Expression> maximalExpressions;
+ std::set<Value*> maximalValues;
+
+ uint32_t nextValueNumber;
+
+ Expression::ExpressionOpcode getOpcode(BinaryOperator* BO);
+ Expression::ExpressionOpcode getOpcode(CmpInst* C);
+ Expression create_expression(BinaryOperator* BO);
+ Expression create_expression(CmpInst* C);
+ public:
+ ValueTable() { nextValueNumber = 1; }
+ uint32_t lookup_or_add(Value* V);
+ uint32_t lookup(Value* V);
+ void add(Value* V, uint32_t num);
+ void clear();
+ std::set<Expression>& getMaximalExpressions() {
+ return maximalExpressions;
+
+ }
+ std::set<Value*>& getMaximalValues() { return maximalValues; }
+ void erase(Value* v);
+ };
+}
+
+//===----------------------------------------------------------------------===//
+// ValueTable Internal Functions
+//===----------------------------------------------------------------------===//
+ValueTable::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;
+ }
+}
+
+ValueTable::Expression::ExpressionOpcode ValueTable::getOpcode(CmpInst* C) {
+ if (C->getOpcode() == Instruction::ICmp) {
+ 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;
+ }
+ }
+}
+
+ValueTable::Expression ValueTable::create_expression(BinaryOperator* BO) {
+ Expression e;
+
+ e.leftVN = lookup_or_add(BO->getOperand(0));
+ e.rightVN = lookup_or_add(BO->getOperand(1));
+ e.opcode = getOpcode(BO);
+
+ maximalExpressions.insert(e);
+
+ return e;
+}
+
+ValueTable::Expression ValueTable::create_expression(CmpInst* C) {
+ Expression e;
+
+ e.leftVN = lookup_or_add(C->getOperand(0));
+ e.rightVN = lookup_or_add(C->getOperand(1));
+ e.opcode = getOpcode(C);
+
+ maximalExpressions.insert(e);
+
+ return e;
+}
+
+//===----------------------------------------------------------------------===//
+// ValueTable External Functions
+//===----------------------------------------------------------------------===//
+
+/// 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) {
+ maximalValues.insert(V);
+
+ DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
+ if (VI != valueNumbering.end())
+ return VI->second;
+
+
+ if (BinaryOperator* BO = dyn_cast<BinaryOperator>(V)) {
+ Expression e = create_expression(BO);
+
+ std::map<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 (CmpInst* C = dyn_cast<CmpInst>(V)) {
+ Expression e = create_expression(C);
+
+ std::map<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 {
+ valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ return nextValueNumber++;
}
-};
+}
+
+/// lookup - Returns the value number of the specified value. Fails if
+/// the value has not yet been numbered.
+uint32_t ValueTable::lookup(Value* V) {
+ DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
+ if (VI != valueNumbering.end())
+ return VI->second;
+ else
+ assert(0 && "Value not numbered?");
+
+ return 0;
+}
+
+/// add - Add the specified value with the given value number, removing
+/// its old number, if any
+void ValueTable::add(Value* V, uint32_t num) {
+ DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
+ if (VI != valueNumbering.end())
+ valueNumbering.erase(VI);
+ valueNumbering.insert(std::make_pair(V, num));
+}
+
+/// clear - Remove all entries from the ValueTable and the maximal sets
+void ValueTable::clear() {
+ valueNumbering.clear();
+ expressionNumbering.clear();
+ maximalExpressions.clear();
+ maximalValues.clear();
+ nextValueNumber = 1;
+}
+
+/// erase - Remove a value from the value numbering and maximal sets
+void ValueTable::erase(Value* V) {
+ maximalValues.erase(V);
+ valueNumbering.erase(V);
+ if (BinaryOperator* BO = dyn_cast<BinaryOperator>(V))
+ maximalExpressions.erase(create_expression(BO));
+ else if (CmpInst* C = dyn_cast<CmpInst>(V))
+ maximalExpressions.erase(create_expression(C));
+}
+
+//===----------------------------------------------------------------------===//
+// GVNPRE Pass
+//===----------------------------------------------------------------------===//
namespace {
bool runOnFunction(Function &F);
public:
static char ID; // Pass identification, replacement for typeid
- GVNPRE() : FunctionPass((intptr_t)&ID) { nextValueNumber = 0; }
+ GVNPRE() : FunctionPass((intptr_t)&ID) { }
private:
- uint32_t nextValueNumber;
- typedef std::map<Value*, uint32_t, ExprLT> ValueTable;
+ ValueTable VN;
+ std::vector<Instruction*> createdExpressions;
+ std::map<BasicBlock*, std::set<Value*> > availableOut;
+ std::map<BasicBlock*, std::set<Value*> > anticipatedIn;
+
+ // This transformation requires dominator postdominator info
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequired<DominatorTree>();
// Helper fuctions
// FIXME: eliminate or document these better
- void dump(ValueTable& VN, std::set<Value*, ExprLT>& s);
- void clean(ValueTable VN, std::set<Value*, ExprLT>& set);
- bool add(ValueTable& VN, std::set<Value*, ExprLT>& MS, Value* V);
- Value* find_leader(ValueTable VN, std::set<Value*, ExprLT>& vals, uint32_t v);
- void phi_translate(ValueTable& VN, std::set<Value*, ExprLT>& MS,
- std::set<Value*, ExprLT>& anticIn, BasicBlock* B,
- std::set<Value*, ExprLT>& out);
-
- void topo_sort(ValueTable& VN, std::set<Value*, ExprLT>& set,
+ void dump(const std::set<Value*>& s) const;
+ void clean(std::set<Value*>& set);
+ Value* find_leader(std::set<Value*>& vals,
+ uint32_t v);
+ Value* phi_translate(Value* V, BasicBlock* pred, BasicBlock* succ);
+ void phi_translate_set(std::set<Value*>& anticIn, BasicBlock* pred,
+ BasicBlock* succ, std::set<Value*>& out);
+
+ void topo_sort(std::set<Value*>& set,
std::vector<Value*>& vec);
- // For a given block, calculate the generated expressions, temporaries,
- // and the AVAIL_OUT set
- void CalculateAvailOut(ValueTable& VN, std::set<Value*, ExprLT>& MS,
- DominatorTree::DomTreeNode* DI,
- std::set<Value*, ExprLT>& currExps,
- std::set<PHINode*>& currPhis,
- std::set<Value*, ExprLT>& currTemps,
- std::set<Value*, ExprLT>& currAvail,
- std::map<BasicBlock*, std::set<Value*, ExprLT> > availOut);
+ void cleanup();
+ bool elimination();
+
+ void val_insert(std::set<Value*>& s, Value* v);
+ void val_replace(std::set<Value*>& s, Value* v);
+ bool dependsOnInvoke(Value* V);
+ void buildsets_availout(BasicBlock::iterator I,
+ std::set<Value*>& currAvail,
+ std::set<PHINode*>& currPhis,
+ std::set<Value*>& currExps,
+ std::set<Value*>& currTemps);
+ void buildsets_anticout(BasicBlock* BB,
+ std::set<Value*>& anticOut,
+ std::set<BasicBlock*>& visited);
+ bool buildsets_anticin(BasicBlock* BB,
+ std::set<Value*>& anticOut,
+ std::set<Value*>& currExps,
+ std::set<Value*>& currTemps,
+ std::set<BasicBlock*>& visited);
+ unsigned buildsets(Function& F);
+
+ void insertion_pre(Value* e, BasicBlock* BB,
+ std::map<BasicBlock*, Value*>& avail,
+ std::set<Value*>& new_set);
+ unsigned insertion_mergepoint(std::vector<Value*>& workList,
+ df_iterator<DomTreeNode*> D,
+ std::set<Value*>& new_set);
+ bool insertion(Function& F);
};
}
+// createGVNPREPass - The public interface to this file...
FunctionPass *llvm::createGVNPREPass() { return new GVNPRE(); }
RegisterPass<GVNPRE> X("gvnpre",
"Global Value Numbering/Partial Redundancy Elimination");
+STATISTIC(NumInsertedVals, "Number of values inserted");
+STATISTIC(NumInsertedPhis, "Number of PHI nodes inserted");
+STATISTIC(NumEliminated, "Number of redundant instructions eliminated");
-bool GVNPRE::add(ValueTable& VN, std::set<Value*, ExprLT>& MS, Value* V) {
- std::pair<ValueTable::iterator, bool> ret = VN.insert(std::make_pair(V, nextValueNumber));
- if (ret.second)
- nextValueNumber++;
- if (isa<BinaryOperator>(V) || isa<PHINode>(V))
- MS.insert(V);
- return ret.second;
-}
-
-Value* GVNPRE::find_leader(GVNPRE::ValueTable VN,
- std::set<Value*, ExprLT>& vals,
- uint32_t v) {
- for (std::set<Value*, ExprLT>::iterator I = vals.begin(), E = vals.end();
+/// 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* GVNPRE::find_leader(std::set<Value*>& vals, uint32_t v) {
+ for (std::set<Value*>::iterator I = vals.begin(), E = vals.end();
I != E; ++I)
- if (VN[*I] == v)
+ if (v == VN.lookup(*I))
return *I;
return 0;
}
-void GVNPRE::phi_translate(GVNPRE::ValueTable& VN,
- std::set<Value*, ExprLT>& MS,
- std::set<Value*, ExprLT>& anticIn, BasicBlock* B,
- std::set<Value*, ExprLT>& out) {
- BasicBlock* succ = B->getTerminator()->getSuccessor(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 GVNPRE::val_insert(std::set<Value*>& s, Value* v) {
+ uint32_t num = VN.lookup(v);
+ Value* leader = find_leader(s, num);
+ if (leader == 0)
+ s.insert(v);
+}
+
+/// val_replace - Insert a value into a set, replacing any values already in
+/// the set that have the same value number
+void GVNPRE::val_replace(std::set<Value*>& s, Value* v) {
+ uint32_t num = VN.lookup(v);
+ Value* leader = find_leader(s, num);
+ while (leader != 0) {
+ s.erase(leader);
+ leader = find_leader(s, num);
+ }
+ s.insert(v);
+}
+
+/// phi_translate - Given a value, its parent block, and a predecessor of its
+/// parent, translate the value into legal for the predecessor block. This
+/// means translating its operands (and recursively, their operands) through
+/// any phi nodes in the parent into values available in the predecessor
+Value* GVNPRE::phi_translate(Value* V, BasicBlock* pred, BasicBlock* succ) {
+ if (V == 0)
+ return 0;
- for (std::set<Value*, ExprLT>::iterator I = anticIn.begin(), E = anticIn.end();
- I != E; ++I) {
- if (!isa<BinaryOperator>(*I)) {
- if (PHINode* p = dyn_cast<PHINode>(*I)) {
- if (p->getParent() == succ)
- out.insert(p);
- } else {
- out.insert(*I);
- }
- } else {
- BinaryOperator* BO = cast<BinaryOperator>(*I);
- Value* lhs = find_leader(VN, anticIn, VN[BO->getOperand(0)]);
- if (lhs == 0)
- continue;
-
- if (PHINode* p = dyn_cast<PHINode>(lhs))
- if (p->getParent() == succ) {
- lhs = p->getIncomingValueForBlock(B);
- out.insert(lhs);
- }
-
- Value* rhs = find_leader(VN, anticIn, VN[BO->getOperand(1)]);
- if (rhs == 0)
- continue;
+ if (BinaryOperator* BO = dyn_cast<BinaryOperator>(V)) {
+ Value* newOp1 = 0;
+ if (isa<Instruction>(BO->getOperand(0)))
+ newOp1 = phi_translate(find_leader(anticipatedIn[succ],
+ VN.lookup(BO->getOperand(0))),
+ pred, succ);
+ else
+ newOp1 = BO->getOperand(0);
+
+ if (newOp1 == 0)
+ return 0;
+
+ Value* newOp2 = 0;
+ if (isa<Instruction>(BO->getOperand(1)))
+ newOp2 = phi_translate(find_leader(anticipatedIn[succ],
+ VN.lookup(BO->getOperand(1))),
+ pred, succ);
+ else
+ newOp2 = BO->getOperand(1);
+
+ if (newOp2 == 0)
+ return 0;
+
+ if (newOp1 != BO->getOperand(0) || newOp2 != BO->getOperand(1)) {
+ Instruction* newVal = BinaryOperator::create(BO->getOpcode(),
+ newOp1, newOp2,
+ BO->getName()+".expr");
- if (PHINode* p = dyn_cast<PHINode>(rhs))
- if (p->getParent() == succ) {
- rhs = p->getIncomingValueForBlock(B);
- out.insert(rhs);
- }
+ uint32_t v = VN.lookup_or_add(newVal);
- if (lhs != BO->getOperand(0) || rhs != BO->getOperand(1)) {
- BO = BinaryOperator::create(BO->getOpcode(), lhs, rhs, BO->getName()+".gvnpre");
- if (VN.insert(std::make_pair(BO, nextValueNumber)).second)
- nextValueNumber++;
- MS.insert(BO);
+ Value* leader = find_leader(availableOut[pred], v);
+ if (leader == 0) {
+ createdExpressions.push_back(newVal);
+ return newVal;
+ } else {
+ VN.erase(newVal);
+ delete newVal;
+ return leader;
}
+ }
+ } else if (PHINode* P = dyn_cast<PHINode>(V)) {
+ if (P->getParent() == succ)
+ return P->getIncomingValueForBlock(pred);
+ } else if (CmpInst* C = dyn_cast<CmpInst>(V)) {
+ Value* newOp1 = 0;
+ if (isa<Instruction>(C->getOperand(0)))
+ newOp1 = phi_translate(find_leader(anticipatedIn[succ],
+ VN.lookup(C->getOperand(0))),
+ pred, succ);
+ else
+ newOp1 = C->getOperand(0);
+
+ if (newOp1 == 0)
+ return 0;
+
+ Value* newOp2 = 0;
+ if (isa<Instruction>(C->getOperand(1)))
+ newOp2 = phi_translate(find_leader(anticipatedIn[succ],
+ VN.lookup(C->getOperand(1))),
+ pred, succ);
+ else
+ newOp2 = C->getOperand(1);
- out.insert(BO);
+ if (newOp2 == 0)
+ return 0;
+
+ if (newOp1 != C->getOperand(0) || newOp2 != C->getOperand(1)) {
+ Instruction* newVal = CmpInst::create(C->getOpcode(),
+ C->getPredicate(),
+ newOp1, newOp2,
+ C->getName()+".expr");
+ uint32_t v = VN.lookup_or_add(newVal);
+
+ Value* leader = find_leader(availableOut[pred], v);
+ if (leader == 0) {
+ createdExpressions.push_back(newVal);
+ return newVal;
+ } else {
+ VN.erase(newVal);
+ delete newVal;
+ return leader;
+ }
}
}
+
+ return V;
+}
+
+/// phi_translate_set - Perform phi translation on every element of a set
+void GVNPRE::phi_translate_set(std::set<Value*>& anticIn,
+ BasicBlock* pred, BasicBlock* succ,
+ std::set<Value*>& out) {
+ for (std::set<Value*>::iterator I = anticIn.begin(),
+ E = anticIn.end(); I != E; ++I) {
+ Value* V = phi_translate(*I, pred, succ);
+ if (V != 0)
+ out.insert(V);
+ }
}
-// Remove all expressions whose operands are not themselves in the set
-void GVNPRE::clean(GVNPRE::ValueTable VN, std::set<Value*, ExprLT>& set) {
+/// dependsOnInvoke - Test if a value has an phi node as an operand, any of
+/// whose inputs is an invoke instruction. If this is true, we cannot safely
+/// PRE the instruction or anything that depends on it.
+bool GVNPRE::dependsOnInvoke(Value* V) {
+ if (PHINode* p = dyn_cast<PHINode>(V)) {
+ for (PHINode::op_iterator I = p->op_begin(), E = p->op_end(); I != E; ++I)
+ if (isa<InvokeInst>(*I))
+ return true;
+ return false;
+ } else {
+ return false;
+ }
+}
+
+/// clean - Remove all non-opaque values from the set whose operands are not
+/// themselves in the set, as well as all values that depend on invokes (see
+/// above)
+void GVNPRE::clean(std::set<Value*>& set) {
std::vector<Value*> worklist;
- topo_sort(VN, set, worklist);
+ topo_sort(set, worklist);
- while (!worklist.empty()) {
- Value* v = worklist.back();
- worklist.pop_back();
+ for (unsigned i = 0; i < worklist.size(); ++i) {
+ Value* v = worklist[i];
if (BinaryOperator* BO = dyn_cast<BinaryOperator>(v)) {
- bool lhsValid = false;
- for (std::set<Value*, ExprLT>::iterator I = set.begin(), E = set.end();
- I != E; ++I)
- if (VN[*I] == VN[BO->getOperand(0)]);
- lhsValid = true;
+ bool lhsValid = !isa<Instruction>(BO->getOperand(0));
+ if (!lhsValid)
+ for (std::set<Value*>::iterator I = set.begin(), E = set.end();
+ I != E; ++I)
+ if (VN.lookup(*I) == VN.lookup(BO->getOperand(0))) {
+ lhsValid = true;
+ break;
+ }
+ if (lhsValid)
+ lhsValid = !dependsOnInvoke(BO->getOperand(0));
- bool rhsValid = false;
- for (std::set<Value*, ExprLT>::iterator I = set.begin(), E = set.end();
- I != E; ++I)
- if (VN[*I] == VN[BO->getOperand(1)]);
- rhsValid = true;
+ bool rhsValid = !isa<Instruction>(BO->getOperand(1));
+ if (!rhsValid)
+ for (std::set<Value*>::iterator I = set.begin(), E = set.end();
+ I != E; ++I)
+ if (VN.lookup(*I) == VN.lookup(BO->getOperand(1))) {
+ rhsValid = true;
+ break;
+ }
+ if (rhsValid)
+ rhsValid = !dependsOnInvoke(BO->getOperand(1));
if (!lhsValid || !rhsValid)
set.erase(BO);
+ } else if (CmpInst* C = dyn_cast<CmpInst>(v)) {
+ bool lhsValid = !isa<Instruction>(C->getOperand(0));
+ if (!lhsValid)
+ for (std::set<Value*>::iterator I = set.begin(), E = set.end();
+ I != E; ++I)
+ if (VN.lookup(*I) == VN.lookup(C->getOperand(0))) {
+ lhsValid = true;
+ break;
+ }
+ if (lhsValid)
+ lhsValid = !dependsOnInvoke(C->getOperand(0));
+
+ bool rhsValid = !isa<Instruction>(C->getOperand(1));
+ if (!rhsValid)
+ for (std::set<Value*>::iterator I = set.begin(), E = set.end();
+ I != E; ++I)
+ if (VN.lookup(*I) == VN.lookup(C->getOperand(1))) {
+ rhsValid = true;
+ break;
+ }
+ if (rhsValid)
+ rhsValid = !dependsOnInvoke(C->getOperand(1));
+
+ if (!lhsValid || !rhsValid)
+ set.erase(C);
}
}
}
-void GVNPRE::topo_sort(GVNPRE::ValueTable& VN,
- std::set<Value*, ExprLT>& set,
- std::vector<Value*>& vec) {
- std::set<Value*, ExprLT> toErase;
- for (std::set<Value*, ExprLT>::iterator I = set.begin(), E = set.end();
+/// topo_sort - Given a set of values, sort them by topological
+/// order into the provided vector.
+void GVNPRE::topo_sort(std::set<Value*>& set, std::vector<Value*>& vec) {
+ std::set<Value*> toErase;
+ for (std::set<Value*>::iterator I = set.begin(), E = set.end();
I != E; ++I) {
if (BinaryOperator* BO = dyn_cast<BinaryOperator>(*I))
- for (std::set<Value*, ExprLT>::iterator SI = set.begin(); SI != E; ++SI) {
- if (VN[BO->getOperand(0)] == VN[*SI] || VN[BO->getOperand(1)] == VN[*SI]) {
- toErase.insert(BO);
+ for (std::set<Value*>::iterator SI = set.begin(); SI != E; ++SI) {
+ if (VN.lookup(BO->getOperand(0)) == VN.lookup(*SI) ||
+ VN.lookup(BO->getOperand(1)) == VN.lookup(*SI)) {
+ toErase.insert(*SI);
}
- }
+ }
+ else if (CmpInst* C = dyn_cast<CmpInst>(*I))
+ for (std::set<Value*>::iterator SI = set.begin(); SI != E; ++SI) {
+ if (VN.lookup(C->getOperand(0)) == VN.lookup(*SI) ||
+ VN.lookup(C->getOperand(1)) == VN.lookup(*SI)) {
+ toErase.insert(*SI);
+ }
+ }
}
std::vector<Value*> Q;
- std::insert_iterator<std::vector<Value*> > q_ins(Q, Q.begin());
- std::set_difference(set.begin(), set.end(),
- toErase.begin(), toErase.end(),
- q_ins, ExprLT());
+ for (std::set<Value*>::iterator I = set.begin(), E = set.end();
+ I != E; ++I) {
+ if (toErase.find(*I) == toErase.end())
+ Q.push_back(*I);
+ }
- std::set<Value*, ExprLT> visited;
+ std::set<Value*> visited;
while (!Q.empty()) {
Value* e = Q.back();
if (BinaryOperator* BO = dyn_cast<BinaryOperator>(e)) {
- Value* l = find_leader(VN, set, VN[BO->getOperand(0)]);
- Value* r = find_leader(VN, set, VN[BO->getOperand(1)]);
+ Value* l = find_leader(set, VN.lookup(BO->getOperand(0)));
+ Value* r = find_leader(set, VN.lookup(BO->getOperand(1)));
+
+ if (l != 0 && isa<Instruction>(l) &&
+ visited.find(l) == visited.end())
+ Q.push_back(l);
+ else if (r != 0 && isa<Instruction>(r) &&
+ visited.find(r) == visited.end())
+ Q.push_back(r);
+ else {
+ vec.push_back(e);
+ visited.insert(e);
+ Q.pop_back();
+ }
+ } else if (CmpInst* C = dyn_cast<CmpInst>(e)) {
+ Value* l = find_leader(set, VN.lookup(C->getOperand(0)));
+ Value* r = find_leader(set, VN.lookup(C->getOperand(1)));
- if (l != 0 && visited.find(l) == visited.end())
+ if (l != 0 && isa<Instruction>(l) &&
+ visited.find(l) == visited.end())
Q.push_back(l);
- else if (r != 0 && visited.find(r) == visited.end())
+ else if (r != 0 && isa<Instruction>(r) &&
+ visited.find(r) == visited.end())
Q.push_back(r);
else {
vec.push_back(e);
}
}
-void GVNPRE::dump(GVNPRE::ValueTable& VN, std::set<Value*, ExprLT>& s) {
- std::vector<Value*> sorted;
- topo_sort(VN, s, sorted);
+/// dump - Dump a set of values to standard error
+void GVNPRE::dump(const std::set<Value*>& s) const {
DOUT << "{ ";
- for (std::vector<Value*>::iterator I = sorted.begin(), E = sorted.end();
+ for (std::set<Value*>::iterator I = s.begin(), E = s.end();
I != E; ++I) {
DEBUG((*I)->dump());
}
DOUT << "}\n\n";
}
-void GVNPRE::CalculateAvailOut(GVNPRE::ValueTable& VN, std::set<Value*, ExprLT>& MS,
- DominatorTree::DomTreeNode* DI,
- std::set<Value*, ExprLT>& currExps,
- std::set<PHINode*>& currPhis,
- std::set<Value*, ExprLT>& currTemps,
- std::set<Value*, ExprLT>& currAvail,
- std::map<BasicBlock*, std::set<Value*, ExprLT> > availOut) {
+/// elimination - Phase 3 of the main algorithm. Perform full redundancy
+/// elimination by walking the dominator tree and removing any instruction that
+/// is dominated by another instruction with the same value number.
+bool GVNPRE::elimination() {
+ DOUT << "\n\nPhase 3: Elimination\n\n";
- BasicBlock* BB = DI->getBlock();
+ bool changed_function = false;
+
+ std::vector<std::pair<Instruction*, Value*> > replace;
+ std::vector<Instruction*> erase;
+
+ DominatorTree& DT = getAnalysis<DominatorTree>();
+
+ for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
+ E = df_end(DT.getRootNode()); DI != E; ++DI) {
+ BasicBlock* BB = DI->getBlock();
+
+ DOUT << "Block: " << BB->getName() << "\n";
+ dump(availableOut[BB]);
+ DOUT << "\n\n";
+
+ for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
+ BI != BE; ++BI) {
+
+ if (isa<BinaryOperator>(BI) || isa<CmpInst>(BI)) {
+ Value *leader = find_leader(availableOut[BB], VN.lookup(BI));
+
+ if (leader != 0)
+ if (Instruction* Instr = dyn_cast<Instruction>(leader))
+ if (Instr->getParent() != 0 && Instr != BI) {
+ replace.push_back(std::make_pair(BI, leader));
+ erase.push_back(BI);
+ ++NumEliminated;
+ }
+ }
+ }
+ }
+
+ while (!replace.empty()) {
+ std::pair<Instruction*, Value*> rep = replace.back();
+ replace.pop_back();
+ rep.first->replaceAllUsesWith(rep.second);
+ changed_function = true;
+ }
+
+ for (std::vector<Instruction*>::iterator I = erase.begin(), E = erase.end();
+ I != E; ++I)
+ (*I)->eraseFromParent();
- // A block inherits AVAIL_OUT from its dominator
- if (DI->getIDom() != 0)
- currAvail.insert(availOut[DI->getIDom()->getBlock()].begin(),
- availOut[DI->getIDom()->getBlock()].end());
+ return changed_function;
+}
+
+/// cleanup - Delete any extraneous values that were created to represent
+/// expressions without leaders.
+void GVNPRE::cleanup() {
+ while (!createdExpressions.empty()) {
+ Instruction* I = createdExpressions.back();
+ createdExpressions.pop_back();
+ delete I;
+ }
+}
+
+/// buildsets_availout - When calculating availability, handle an instruction
+/// by inserting it into the appropriate sets
+void GVNPRE::buildsets_availout(BasicBlock::iterator I,
+ std::set<Value*>& currAvail,
+ std::set<PHINode*>& currPhis,
+ std::set<Value*>& currExps,
+ std::set<Value*>& currTemps) {
+ // Handle PHI nodes...
+ if (PHINode* p = dyn_cast<PHINode>(I)) {
+ VN.lookup_or_add(p);
+ currPhis.insert(p);
- for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
- BI != BE; ++BI) {
-
- // Handle PHI nodes...
- if (PHINode* p = dyn_cast<PHINode>(BI)) {
- add(VN, MS, p);
- currPhis.insert(p);
+ // Handle binary ops...
+ } else if (BinaryOperator* BO = dyn_cast<BinaryOperator>(I)) {
+ Value* leftValue = BO->getOperand(0);
+ Value* rightValue = BO->getOperand(1);
- // Handle binary ops...
- } else if (BinaryOperator* BO = dyn_cast<BinaryOperator>(BI)) {
- Value* leftValue = BO->getOperand(0);
- Value* rightValue = BO->getOperand(1);
+ VN.lookup_or_add(BO);
- add(VN, MS, BO);
+ if (isa<Instruction>(leftValue))
+ val_insert(currExps, leftValue);
+ if (isa<Instruction>(rightValue))
+ val_insert(currExps, rightValue);
+ val_insert(currExps, BO);
+
+ // Handle cmp ops...
+ } else if (CmpInst* C = dyn_cast<CmpInst>(I)) {
+ Value* leftValue = C->getOperand(0);
+ Value* rightValue = C->getOperand(1);
- currExps.insert(leftValue);
- currExps.insert(rightValue);
- currExps.insert(BO);
+ VN.lookup_or_add(C);
- currTemps.insert(BO);
-
- // Handle unsupported ops
- } else if (!BI->isTerminator()){
- add(VN, MS, BI);
- currTemps.insert(BI);
- }
+ if (isa<Instruction>(leftValue))
+ val_insert(currExps, leftValue);
+ if (isa<Instruction>(rightValue))
+ val_insert(currExps, rightValue);
+ val_insert(currExps, C);
+
+ // Handle unsupported ops
+ } else if (!I->isTerminator()){
+ VN.lookup_or_add(I);
+ currTemps.insert(I);
+ }
- if (!BI->isTerminator())
- currAvail.insert(BI);
+ if (!I->isTerminator())
+ val_insert(currAvail, I);
+}
+
+/// buildsets_anticout - When walking the postdom tree, calculate the ANTIC_OUT
+/// set as a function of the ANTIC_IN set of the block's predecessors
+void GVNPRE::buildsets_anticout(BasicBlock* BB,
+ std::set<Value*>& anticOut,
+ std::set<BasicBlock*>& visited) {
+ if (BB->getTerminator()->getNumSuccessors() == 1) {
+ if (visited.find(BB->getTerminator()->getSuccessor(0)) == visited.end())
+ phi_translate_set(VN.getMaximalValues(), BB,
+ BB->getTerminator()->getSuccessor(0), anticOut);
+ else
+ phi_translate_set(anticipatedIn[BB->getTerminator()->getSuccessor(0)],
+ BB, BB->getTerminator()->getSuccessor(0), anticOut);
+ } else if (BB->getTerminator()->getNumSuccessors() > 1) {
+ BasicBlock* first = BB->getTerminator()->getSuccessor(0);
+ anticOut.insert(anticipatedIn[first].begin(), anticipatedIn[first].end());
+
+ for (unsigned i = 1; i < BB->getTerminator()->getNumSuccessors(); ++i) {
+ BasicBlock* currSucc = BB->getTerminator()->getSuccessor(i);
+ std::set<Value*>& succAnticIn = anticipatedIn[currSucc];
+
+ std::set<Value*> temp;
+ std::insert_iterator<std::set<Value*> > temp_ins(temp, temp.begin());
+ std::set_intersection(anticOut.begin(), anticOut.end(),
+ succAnticIn.begin(), succAnticIn.end(), temp_ins);
+
+ anticOut.clear();
+ anticOut.insert(temp.begin(), temp.end());
+ }
}
}
-bool GVNPRE::runOnFunction(Function &F) {
- ValueTable VN;
- std::set<Value*, ExprLT> maximalSet;
+/// buildsets_anticin - Walk the postdom tree, calculating ANTIC_OUT for
+/// each block. ANTIC_IN is then a function of ANTIC_OUT and the GEN
+/// sets populated in buildsets_availout
+bool GVNPRE::buildsets_anticin(BasicBlock* BB,
+ std::set<Value*>& anticOut,
+ std::set<Value*>& currExps,
+ std::set<Value*>& currTemps,
+ std::set<BasicBlock*>& visited) {
+ std::set<Value*>& anticIn = anticipatedIn[BB];
+ std::set<Value*> old (anticIn.begin(), anticIn.end());
+
+ buildsets_anticout(BB, anticOut, visited);
+
+ std::set<Value*> S;
+ std::insert_iterator<std::set<Value*> > s_ins(S, S.begin());
+ std::set_difference(anticOut.begin(), anticOut.end(),
+ currTemps.begin(), currTemps.end(), s_ins);
+
+ anticIn.clear();
+ std::insert_iterator<std::set<Value*> > ai_ins(anticIn, anticIn.begin());
+ std::set_difference(currExps.begin(), currExps.end(),
+ currTemps.begin(), currTemps.end(), ai_ins);
+
+ for (std::set<Value*>::iterator I = S.begin(), E = S.end();
+ I != E; ++I) {
+ // For non-opaque values, we should already have a value numbering.
+ // However, for opaques, such as constants within PHI nodes, it is
+ // possible that they have not yet received a number. Make sure they do
+ // so now.
+ uint32_t valNum = 0;
+ if (isa<BinaryOperator>(*I) || isa<CmpInst>(*I))
+ valNum = VN.lookup(*I);
+ else
+ valNum = VN.lookup_or_add(*I);
+ if (find_leader(anticIn, valNum) == 0)
+ val_insert(anticIn, *I);
+ }
+
+ clean(anticIn);
+ anticOut.clear();
+
+ if (old.size() != anticIn.size())
+ return true;
+ else
+ return false;
+}
- std::map<BasicBlock*, std::set<Value*, ExprLT> > generatedExpressions;
+/// buildsets - Phase 1 of the main algorithm. Construct the AVAIL_OUT
+/// and the ANTIC_IN sets.
+unsigned GVNPRE::buildsets(Function& F) {
+ std::map<BasicBlock*, std::set<Value*> > generatedExpressions;
std::map<BasicBlock*, std::set<PHINode*> > generatedPhis;
- std::map<BasicBlock*, std::set<Value*, ExprLT> > generatedTemporaries;
- std::map<BasicBlock*, std::set<Value*, ExprLT> > availableOut;
- std::map<BasicBlock*, std::set<Value*, ExprLT> > anticipatedIn;
-
+ std::map<BasicBlock*, std::set<Value*> > generatedTemporaries;
+
DominatorTree &DT = getAnalysis<DominatorTree>();
- // First Phase of BuildSets - calculate AVAIL_OUT
+ // Phase 1, Part 1: calculate AVAIL_OUT
// Top-down walk of the dominator tree
- for (df_iterator<DominatorTree::DomTreeNode*> DI = df_begin(DT.getRootNode()),
+ for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
E = df_end(DT.getRootNode()); DI != E; ++DI) {
// Get the sets to update for this block
- std::set<Value*, ExprLT>& currExps = generatedExpressions[DI->getBlock()];
+ std::set<Value*>& currExps = generatedExpressions[DI->getBlock()];
std::set<PHINode*>& currPhis = generatedPhis[DI->getBlock()];
- std::set<Value*, ExprLT>& currTemps = generatedTemporaries[DI->getBlock()];
- std::set<Value*, ExprLT>& currAvail = availableOut[DI->getBlock()];
+ std::set<Value*>& currTemps = generatedTemporaries[DI->getBlock()];
+ std::set<Value*>& currAvail = availableOut[DI->getBlock()];
- CalculateAvailOut(VN, maximalSet, *DI, currExps, currPhis,
- currTemps, currAvail, availableOut);
+ BasicBlock* BB = DI->getBlock();
+
+ // A block inherits AVAIL_OUT from its dominator
+ if (DI->getIDom() != 0)
+ currAvail.insert(availableOut[DI->getIDom()->getBlock()].begin(),
+ availableOut[DI->getIDom()->getBlock()].end());
+
+
+ for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
+ BI != BE; ++BI)
+ buildsets_availout(BI, currAvail, currPhis, currExps, currTemps);
+
}
+ // If function has no exit blocks, only perform GVN
PostDominatorTree &PDT = getAnalysis<PostDominatorTree>();
+ if (PDT[&F.getEntryBlock()] == 0) {
+ bool changed_function = elimination();
+ cleanup();
+
+ if (changed_function)
+ return 2; // Bailed early, made changes
+ else
+ return 1; // Bailed early, no changes
+ }
+
- // Second Phase of BuildSets - calculate ANTIC_IN
+ // Phase 1, Part 2: calculate ANTIC_IN
std::set<BasicBlock*> visited;
unsigned iterations = 0;
while (changed) {
changed = false;
- std::set<Value*, ExprLT> anticOut;
+ std::set<Value*> anticOut;
// Top-down walk of the postdominator tree
- for (df_iterator<PostDominatorTree::DomTreeNode*> PDI =
- df_begin(PDT.getRootNode()), E = df_end(DT.getRootNode());
+ for (df_iterator<DomTreeNode*> PDI =
+ df_begin(PDT.getRootNode()), E = df_end(PDT.getRootNode());
PDI != E; ++PDI) {
BasicBlock* BB = PDI->getBlock();
+ if (BB == 0)
+ continue;
visited.insert(BB);
- std::set<Value*, ExprLT>& anticIn = anticipatedIn[BB];
- std::set<Value*, ExprLT> old (anticIn.begin(), anticIn.end());
-
- if (BB->getTerminator()->getNumSuccessors() == 1) {
- if (visited.find(BB) == visited.end())
- phi_translate(VN, maximalSet, anticIn, BB, anticOut);
- else
- phi_translate(VN, anticIn, anticIn, BB, anticOut);
- } else if (BB->getTerminator()->getNumSuccessors() > 1) {
- for (unsigned i = 0; i < BB->getTerminator()->getNumSuccessors(); ++i) {
- BasicBlock* currSucc = BB->getTerminator()->getSuccessor(i);
- std::set<Value*, ExprLT> temp;
- if (visited.find(currSucc) == visited.end())
- temp.insert(maximalSet.begin(), maximalSet.end());
- else
- temp.insert(anticIn.begin(), anticIn.end());
-
- anticIn.clear();
- std::insert_iterator<std::set<Value*, ExprLT> > ai_ins(anticIn,
- anticIn.begin());
-
- std::set_difference(anticipatedIn[currSucc].begin(),
- anticipatedIn[currSucc].end(),
- temp.begin(),
- temp.end(),
- ai_ins,
- ExprLT());
+ changed |= buildsets_anticin(BB, anticOut, generatedTemporaries[BB],
+ generatedExpressions[BB], visited);
+ }
+
+ iterations++;
+ }
+
+ return 0; // No bail, no changes
+}
+
+/// insertion_pre - When a partial redundancy has been identified, eliminate it
+/// by inserting appropriate values into the predecessors and a phi node in
+/// the main block
+void GVNPRE::insertion_pre(Value* e, BasicBlock* BB,
+ std::map<BasicBlock*, Value*>& avail,
+ std::set<Value*>& new_set) {
+ for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
+ Value* e2 = avail[*PI];
+ if (!find_leader(availableOut[*PI], VN.lookup(e2))) {
+ User* U = cast<User>(e2);
+
+ Value* s1 = 0;
+ if (isa<BinaryOperator>(U->getOperand(0)) ||
+ isa<CmpInst>(U->getOperand(0)))
+ s1 = find_leader(availableOut[*PI], VN.lookup(U->getOperand(0)));
+ else
+ s1 = U->getOperand(0);
+
+ Value* s2 = 0;
+ if (isa<BinaryOperator>(U->getOperand(1)) ||
+ isa<CmpInst>(U->getOperand(1)))
+ s2 = find_leader(availableOut[*PI], VN.lookup(U->getOperand(1)));
+ else
+ s2 = U->getOperand(1);
+
+ Value* newVal = 0;
+ if (BinaryOperator* BO = dyn_cast<BinaryOperator>(U))
+ newVal = BinaryOperator::create(BO->getOpcode(), s1, s2,
+ BO->getName()+".gvnpre",
+ (*PI)->getTerminator());
+ else if (CmpInst* C = dyn_cast<CmpInst>(U))
+ newVal = CmpInst::create(C->getOpcode(), C->getPredicate(), s1, s2,
+ C->getName()+".gvnpre",
+ (*PI)->getTerminator());
+
+ VN.add(newVal, VN.lookup(U));
+
+ std::set<Value*>& predAvail = availableOut[*PI];
+ val_replace(predAvail, newVal);
+
+ std::map<BasicBlock*, Value*>::iterator av = avail.find(*PI);
+ if (av != avail.end())
+ avail.erase(av);
+ avail.insert(std::make_pair(*PI, newVal));
+
+ ++NumInsertedVals;
+ }
+ }
+
+ PHINode* p = 0;
+
+ for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
+ if (p == 0)
+ p = new PHINode(avail[*PI]->getType(), "gvnpre-join", BB->begin());
+
+ p->addIncoming(avail[*PI], *PI);
+ }
+
+ VN.add(p, VN.lookup(e));
+ val_replace(availableOut[BB], p);
+ new_set.insert(p);
+
+ ++NumInsertedPhis;
+}
+
+/// insertion_mergepoint - When walking the dom tree, check at each merge
+/// block for the possibility of a partial redundancy. If present, eliminate it
+unsigned GVNPRE::insertion_mergepoint(std::vector<Value*>& workList,
+ df_iterator<DomTreeNode*> D,
+ std::set<Value*>& new_set) {
+ bool changed_function = false;
+ bool new_stuff = false;
+
+ BasicBlock* BB = D->getBlock();
+ for (unsigned i = 0; i < workList.size(); ++i) {
+ Value* e = workList[i];
+
+ if (isa<BinaryOperator>(e) || isa<CmpInst>(e)) {
+ if (find_leader(availableOut[D->getIDom()->getBlock()],
+ VN.lookup(e)) != 0)
+ continue;
+
+ std::map<BasicBlock*, Value*> avail;
+ bool by_some = false;
+ int num_avail = 0;
+
+ for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE;
+ ++PI) {
+ Value *e2 = phi_translate(e, *PI, BB);
+ Value *e3 = find_leader(availableOut[*PI], VN.lookup(e2));
+
+ if (e3 == 0) {
+ std::map<BasicBlock*, Value*>::iterator av = avail.find(*PI);
+ if (av != avail.end())
+ avail.erase(av);
+ avail.insert(std::make_pair(*PI, e2));
+ } else {
+ std::map<BasicBlock*, Value*>::iterator av = avail.find(*PI);
+ if (av != avail.end())
+ avail.erase(av);
+ avail.insert(std::make_pair(*PI, e3));
+
+ by_some = true;
+ num_avail++;
}
}
+
+ if (by_some && num_avail < std::distance(pred_begin(BB), pred_end(BB))) {
+ insertion_pre(e, BB, avail, new_set);
+
+ changed_function = true;
+ new_stuff = true;
+ }
+ }
+ }
+
+ unsigned retval = 0;
+ if (changed_function)
+ retval += 1;
+ if (new_stuff)
+ retval += 2;
+
+ return retval;
+}
+
+/// insert - Phase 2 of the main algorithm. Walk the dominator tree looking for
+/// merge points. When one is found, check for a partial redundancy. If one is
+/// present, eliminate it. Repeat this walk until no changes are made.
+bool GVNPRE::insertion(Function& F) {
+ bool changed_function = false;
+
+ DominatorTree &DT = getAnalysis<DominatorTree>();
+
+ std::map<BasicBlock*, std::set<Value*> > new_sets;
+ bool new_stuff = true;
+ while (new_stuff) {
+ new_stuff = false;
+ for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
+ E = df_end(DT.getRootNode()); DI != E; ++DI) {
+ BasicBlock* BB = DI->getBlock();
- std::set<Value*, ExprLT> S;
- std::insert_iterator<std::set<Value*, ExprLT> > s_ins(S, S.begin());
- std::set_union(anticOut.begin(), anticOut.end(),
- generatedExpressions[BB].begin(),
- generatedExpressions[BB].end(),
- s_ins, ExprLT());
+ if (BB == 0)
+ continue;
- anticIn.clear();
- std::insert_iterator<std::set<Value*, ExprLT> > antic_ins(anticIn,
- anticIn.begin());
- std::set_difference(S.begin(), S.end(),
- generatedTemporaries[BB].begin(),
- generatedTemporaries[BB].end(),
- antic_ins,
- ExprLT());
+ std::set<Value*>& new_set = new_sets[BB];
+ std::set<Value*>& availOut = availableOut[BB];
+ std::set<Value*>& anticIn = anticipatedIn[BB];
- clean(VN, anticIn);
+ new_set.clear();
- if (old != anticIn)
- changed = true;
+ // Replace leaders with leaders inherited from dominator
+ if (DI->getIDom() != 0) {
+ std::set<Value*>& dom_set = new_sets[DI->getIDom()->getBlock()];
+ for (std::set<Value*>::iterator I = dom_set.begin(),
+ E = dom_set.end(); I != E; ++I) {
+ new_set.insert(*I);
+ val_replace(availOut, *I);
+ }
+ }
- anticOut.clear();
+ // If there is more than one predecessor...
+ if (pred_begin(BB) != pred_end(BB) && ++pred_begin(BB) != pred_end(BB)) {
+ std::vector<Value*> workList;
+ topo_sort(anticIn, workList);
+
+ DOUT << "Merge Block: " << BB->getName() << "\n";
+ DOUT << "ANTIC_IN: ";
+ dump(anticIn);
+ DOUT << "\n";
+
+ unsigned result = insertion_mergepoint(workList, DI, new_set);
+ if (result & 1)
+ changed_function = true;
+ if (result & 2)
+ new_stuff = true;
+ }
}
- iterations++;
}
- DOUT << "Iterations: " << iterations << "\n";
+ return changed_function;
+}
+
+// GVNPRE::runOnFunction - This is the main transformation entry point for a
+// function.
+//
+bool GVNPRE::runOnFunction(Function &F) {
+ // Clean out global sets from any previous functions
+ VN.clear();
+ createdExpressions.clear();
+ availableOut.clear();
+ anticipatedIn.clear();
- for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
- DOUT << "Name: " << I->getName().c_str() << "\n";
-
- DOUT << "TMP_GEN: ";
- dump(VN, generatedTemporaries[I]);
- DOUT << "\n";
-
- DOUT << "EXP_GEN: ";
- dump(VN, generatedExpressions[I]);
- DOUT << "\n";
-
- DOUT << "ANTIC_IN: ";
- dump(VN, anticipatedIn[I]);
- DOUT << "\n";
-
- DOUT << "AVAIL_OUT: ";
- dump(VN, availableOut[I]);
- DOUT << "\n";
- }
+ bool changed_function = false;
+
+ // Phase 1: BuildSets
+ // This phase calculates the AVAIL_OUT and ANTIC_IN sets
+ // NOTE: If full postdom information is no available, this will bail
+ // early, performing GVN but not PRE
+ unsigned bail = buildsets(F);
+ //If a bail occurred, terminate early
+ if (bail != 0)
+ return (bail == 2);
+
+ // Phase 2: Insert
+ // This phase inserts values to make partially redundant values
+ // fully redundant
+ changed_function |= insertion(F);
+
+ // Phase 3: Eliminate
+ // This phase performs trivial full redundancy elimination
+ changed_function |= elimination();
+
+ // Phase 4: Cleanup
+ // This phase cleans up values that were created solely
+ // as leaders for expressions
+ cleanup();
- return false;
+ return changed_function;
}
projects / oota-llvm.git / blobdiff