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llvm-6502/lib/Transforms/Scalar/GVNPRE.cpp

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//===- GVNPRE.cpp - Eliminate redundant values and expressions ------------===//
//
// 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 pass performs a hybrid of global value numbering and partial redundancy
// elimination, known as GVN-PRE. It performs partial redundancy elimination on
// values, rather than lexical expressions, allowing a more comprehensive view
// 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 are very
// sensitive to register pressure.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "gvnpre"
#include "llvm/Value.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Instructions.h"
#include "llvm/Function.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/PostDominators.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 <deque>
#include <map>
#include <vector>
#include <set>
using namespace llvm;
//===----------------------------------------------------------------------===//
// ValueTable Class
//===----------------------------------------------------------------------===//
/// This class holds the mapping between values and value numbers.
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 };
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;
}
};
private:
std::map<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);
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; }
Expression create_expression(BinaryOperator* BO);
Expression create_expression(CmpInst* C);
void erase(Value* v);
};
}
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;
}
}
}
uint32_t ValueTable::lookup_or_add(Value* V) {
maximalValues.insert(V);
std::map<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++;
}
}
uint32_t ValueTable::lookup(Value* V) {
std::map<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
if (VI != valueNumbering.end())
return VI->second;
else
assert(0 && "Value not numbered?");
return 0;
}
void ValueTable::add(Value* V, uint32_t num) {
std::map<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
if (VI != valueNumbering.end())
valueNumbering.erase(VI);
valueNumbering.insert(std::make_pair(V, num));
}
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;
}
void ValueTable::clear() {
valueNumbering.clear();
expressionNumbering.clear();
maximalExpressions.clear();
maximalValues.clear();
nextValueNumber = 1;
}
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));
}
namespace {
class VISIBILITY_HIDDEN GVNPRE : public FunctionPass {
bool runOnFunction(Function &F);
public:
static char ID; // Pass identification, replacement for typeid
GVNPRE() : FunctionPass((intptr_t)&ID) { }
private:
ValueTable VN;
std::vector<Instruction*> createdExpressions;
std::map<BasicBlock*, std::set<Value*> > availableOut;
std::map<BasicBlock*, std::set<Value*> > anticipatedIn;
std::map<User*, bool> invokeDep;
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequired<DominatorTree>();
AU.addRequired<PostDominatorTree>();
}
// Helper fuctions
// FIXME: eliminate or document these better
void dump(const std::set<Value*>& s) const;
void dump_unique(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 cleanup();
void elimination();
void val_insert(std::set<Value*>& s, Value* v);
void val_replace(std::set<Value*>& s, Value* v);
bool dependsOnInvoke(Value* V);
};
char GVNPRE::ID = 0;
}
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");
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 (v == VN.lookup(*I))
return *I;
return 0;
}
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);
}
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);
}
Value* GVNPRE::phi_translate(Value* V, BasicBlock* pred, BasicBlock* succ) {
if (V == 0)
return 0;
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");
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;
}
}
} 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);
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;
}
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);
}
}
bool GVNPRE::dependsOnInvoke(Value* V) {
if (!isa<User>(V))
return false;
User* U = cast<User>(V);
std::map<User*, bool>::iterator I = invokeDep.find(U);
if (I != invokeDep.end())
return I->second;
std::vector<Value*> worklist(U->op_begin(), U->op_end());
std::set<Value*> visited;
while (!worklist.empty()) {
Value* current = worklist.back();
worklist.pop_back();
visited.insert(current);
if (!isa<User>(current))
continue;
else if (isa<InvokeInst>(current))
return true;
User* curr = cast<User>(current);
std::map<User*, bool>::iterator CI = invokeDep.find(curr);
if (CI != invokeDep.end()) {
if (CI->second)
return true;
} else {
for (unsigned i = 0; i < curr->getNumOperands(); ++i)
if (visited.find(curr->getOperand(i)) == visited.end())
worklist.push_back(curr->getOperand(i));
}
}
return false;
}
// Remove all expressions whose operands are not themselves in the set
void GVNPRE::clean(std::set<Value*>& set) {
std::vector<Value*> worklist;
topo_sort(set, worklist);
for (unsigned i = 0; i < worklist.size(); ++i) {
Value* v = worklist[i];
if (BinaryOperator* BO = dyn_cast<BinaryOperator>(v)) {
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;
}
// Check for dependency on invoke insts
// NOTE: This check is expensive, so don't do it if we
// don't have to
if (lhsValid)
lhsValid = !dependsOnInvoke(BO->getOperand(0));
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;
}
// Check for dependency on invoke insts
// NOTE: This check is expensive, so don't do it if we
// don't have to
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;
}
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;
}
rhsValid &= !dependsOnInvoke(C->getOperand(1));
if (!lhsValid || !rhsValid)
set.erase(C);
}
}
}
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*>::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;
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*> visited;
while (!Q.empty()) {
Value* e = Q.back();
if (BinaryOperator* BO = dyn_cast<BinaryOperator>(e)) {
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 && 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 {
visited.insert(e);
vec.push_back(e);
Q.pop_back();
}
}
}
void GVNPRE::dump(const std::set<Value*>& s) const {
DOUT << "{ ";
for (std::set<Value*>::iterator I = s.begin(), E = s.end();
I != E; ++I) {
DEBUG((*I)->dump());
}
DOUT << "}\n\n";
}
void GVNPRE::dump_unique(const std::set<Value*>& s) const {
DOUT << "{ ";
for (std::set<Value*>::iterator I = s.begin(), E = s.end();
I != E; ++I) {
DEBUG((*I)->dump());
}
DOUT << "}\n\n";
}
void GVNPRE::elimination() {
DOUT << "\n\nPhase 3: Elimination\n\n";
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_unique(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);
}
for (std::vector<Instruction*>::iterator I = erase.begin(), E = erase.end();
I != E; ++I)
(*I)->eraseFromParent();
}
void GVNPRE::cleanup() {
while (!createdExpressions.empty()) {
Instruction* I = createdExpressions.back();
createdExpressions.pop_back();
delete I;
}
}
bool GVNPRE::runOnFunction(Function &F) {
VN.clear();
createdExpressions.clear();
availableOut.clear();
anticipatedIn.clear();
invokeDep.clear();
std::map<BasicBlock*, std::set<Value*> > generatedExpressions;
std::map<BasicBlock*, std::set<PHINode*> > generatedPhis;
std::map<BasicBlock*, std::set<Value*> > generatedTemporaries;
DominatorTree &DT = getAnalysis<DominatorTree>();
// Phase 1: BuildSets
// Phase 1, Part 1: calculate AVAIL_OUT
// 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 sets to update for this block
std::set<Value*>& currExps = generatedExpressions[DI->getBlock()];
std::set<PHINode*>& currPhis = generatedPhis[DI->getBlock()];
std::set<Value*>& currTemps = generatedTemporaries[DI->getBlock()];
std::set<Value*>& currAvail = availableOut[DI->getBlock()];
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) {
// Handle PHI nodes...
if (PHINode* p = dyn_cast<PHINode>(BI)) {
VN.lookup_or_add(p);
currPhis.insert(p);
// 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);
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>(BI)) {
Value* leftValue = C->getOperand(0);
Value* rightValue = C->getOperand(1);
VN.lookup_or_add(C);
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 (!BI->isTerminator()){
VN.lookup_or_add(BI);
currTemps.insert(BI);
}
if (!BI->isTerminator())
val_insert(currAvail, BI);
}
}
DOUT << "Maximal Set: ";
dump_unique(VN.getMaximalValues());
DOUT << "\n";
// If function has no exit blocks, only perform GVN
PostDominatorTree &PDT = getAnalysis<PostDominatorTree>();
if (PDT[&F.getEntryBlock()] == 0) {
elimination();
cleanup();
return true;
}
// Phase 1, Part 2: calculate ANTIC_IN
std::set<BasicBlock*> visited;
bool changed = true;
unsigned iterations = 0;
while (changed) {
changed = false;
std::set<Value*> anticOut;
// Top-down walk of the postdominator tree
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;
DOUT << "Block: " << BB->getName() << "\n";
DOUT << "TMP_GEN: ";
dump(generatedTemporaries[BB]);
DOUT << "\n";
DOUT << "EXP_GEN: ";
dump_unique(generatedExpressions[BB]);
visited.insert(BB);
std::set<Value*>& anticIn = anticipatedIn[BB];
std::set<Value*> old (anticIn.begin(), anticIn.end());
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());
}
}
DOUT << "ANTIC_OUT: ";
dump_unique(anticOut);
DOUT << "\n";
std::set<Value*> S;
std::insert_iterator<std::set<Value*> > s_ins(S, S.begin());
std::set_difference(anticOut.begin(), anticOut.end(),
generatedTemporaries[BB].begin(),
generatedTemporaries[BB].end(),
s_ins);
anticIn.clear();
std::insert_iterator<std::set<Value*> > ai_ins(anticIn, anticIn.begin());
std::set_difference(generatedExpressions[BB].begin(),
generatedExpressions[BB].end(),
generatedTemporaries[BB].begin(),
generatedTemporaries[BB].end(),
ai_ins);
for (std::set<Value*>::iterator I = S.begin(), E = S.end();
I != E; ++I) {
if (find_leader(anticIn, VN.lookup(*I)) == 0)
val_insert(anticIn, *I);
}
clean(anticIn);
DOUT << "ANTIC_IN: ";
dump_unique(anticIn);
DOUT << "\n";
if (old.size() != anticIn.size())
changed = true;
anticOut.clear();
}
iterations++;
}
DOUT << "Iterations: " << iterations << "\n";
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
DOUT << "Name: " << I->getName().c_str() << "\n";
DOUT << "TMP_GEN: ";
dump(generatedTemporaries[I]);
DOUT << "\n";
DOUT << "EXP_GEN: ";
dump_unique(generatedExpressions[I]);
DOUT << "\n";
DOUT << "ANTIC_IN: ";
dump_unique(anticipatedIn[I]);
DOUT << "\n";
DOUT << "AVAIL_OUT: ";
dump_unique(availableOut[I]);
DOUT << "\n";
}
// Phase 2: Insert
DOUT<< "\nPhase 2: Insertion\n";
std::map<BasicBlock*, std::set<Value*> > new_sets;
unsigned i_iterations = 0;
bool new_stuff = true;
while (new_stuff) {
new_stuff = false;
DOUT << "Iteration: " << i_iterations << "\n\n";
for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
E = df_end(DT.getRootNode()); DI != E; ++DI) {
BasicBlock* BB = DI->getBlock();
if (BB == 0)
continue;
std::set<Value*>& new_set = new_sets[BB];
std::set<Value*>& availOut = availableOut[BB];
std::set<Value*>& anticIn = anticipatedIn[BB];
new_set.clear();
// 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);
}
}
// 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_unique(anticIn);
DOUT << "\n";
for (unsigned i = 0; i < workList.size(); ++i) {
Value* e = workList[i];
if (isa<BinaryOperator>(e) || isa<CmpInst>(e)) {
if (find_leader(availableOut[DI->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))) {
DOUT << "Processing Value: ";
DEBUG(e->dump());
DOUT << "\n\n";
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);
DOUT << "Creating value: " << std::hex << newVal << std::dec << "\n";
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));
DOUT << "Creating value: " << std::hex << p << std::dec << "\n";
val_replace(availOut, p);
availOut.insert(p);
new_stuff = true;
DOUT << "Preds After Processing: ";
for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
PI != PE; ++PI)
DEBUG((*PI)->dump());
DOUT << "\n\n";
DOUT << "Merge Block After Processing: ";
DEBUG(BB->dump());
DOUT << "\n\n";
new_set.insert(p);
++NumInsertedPhis;
}
}
}
}
}
i_iterations++;
}
// Phase 3: Eliminate
elimination();
// Phase 4: Cleanup
cleanup();
return true;
}
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