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llvm-project/llvm/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;
struct ExprLT {
bool operator()(Value* left, Value* right) {
if (BinaryOperator* leftBO = dyn_cast<BinaryOperator>(left)) {
if (BinaryOperator* rightBO = dyn_cast<BinaryOperator>(right))
return cmpBinaryOperator(leftBO, rightBO);
else
if (isa<CmpInst>(right)) {
return false;
} else {
return true;
}
} else if (CmpInst* leftCmp = dyn_cast<CmpInst>(left)) {
if (CmpInst* rightCmp = dyn_cast<CmpInst>(right))
return cmpComparison(leftCmp, rightCmp);
else
return true;
} else {
if (isa<BinaryOperator>(right) || isa<CmpInst>(right))
return false;
else
return left < right;
}
}
bool cmpBinaryOperator(BinaryOperator* left, BinaryOperator* right) {
if (left->getOpcode() != right->getOpcode())
return left->getOpcode() < right->getOpcode();
else if ((*this)(left->getOperand(0), right->getOperand(0)))
return true;
else if ((*this)(right->getOperand(0), left->getOperand(0)))
return false;
else
return (*this)(left->getOperand(1), right->getOperand(1));
}
bool cmpComparison(CmpInst* left, CmpInst* right) {
if (left->getOpcode() != right->getOpcode())
return left->getOpcode() < right->getOpcode();
else if (left->getPredicate() != right->getPredicate())
return left->getPredicate() < right->getPredicate();
else if ((*this)(left->getOperand(0), right->getOperand(0)))
return true;
else if ((*this)(right->getOperand(0), left->getOperand(0)))
return false;
else
return (*this)(left->getOperand(1), right->getOperand(1));
}
};
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) { nextValueNumber = 1; }
private:
uint32_t nextValueNumber;
typedef std::map<Value*, uint32_t, ExprLT> ValueTable;
ValueTable VN;
std::set<Value*, ExprLT> MS;
std::vector<Instruction*> createdExpressions;
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*, ExprLT>& s) const;
void clean(std::set<Value*, ExprLT>& set);
bool add(Value* V, uint32_t number);
Value* find_leader(std::set<Value*, ExprLT>& vals,
Value* v);
Value* phi_translate(std::set<Value*, ExprLT>& set,
Value* V, BasicBlock* pred, BasicBlock* succ);
void phi_translate_set(std::set<Value*, ExprLT>& anticIn, BasicBlock* pred,
BasicBlock* succ, std::set<Value*, ExprLT>& out);
void topo_sort(std::set<Value*, ExprLT>& set,
std::vector<Value*>& vec);
// For a given block, calculate the generated expressions, temporaries,
// and the AVAIL_OUT set
void CalculateAvailOut(DomTreeNode* DI,
std::set<Value*, ExprLT>& currExps,
std::set<PHINode*>& currPhis,
std::set<Value*>& currTemps,
std::set<Value*, ExprLT>& currAvail,
std::map<BasicBlock*, std::set<Value*, ExprLT> > availOut);
};
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");
bool GVNPRE::add(Value* V, uint32_t number) {
std::pair<ValueTable::iterator, bool> ret = VN.insert(std::make_pair(V, number));
if (isa<BinaryOperator>(V) || isa<PHINode>(V) || isa<CmpInst>(V))
MS.insert(V);
return ret.second;
}
Value* GVNPRE::find_leader(std::set<Value*, ExprLT>& vals, Value* v) {
for (std::set<Value*, ExprLT>::iterator I = vals.begin(), E = vals.end();
I != E; ++I) {
assert(VN.find(v) != VN.end() && "Value not numbered?");
assert(VN.find(*I) != VN.end() && "Value not numbered?");
if (VN[v] == VN[*I])
return *I;
}
return 0;
}
Value* GVNPRE::phi_translate(std::set<Value*, ExprLT>& set,
Value* V, BasicBlock* pred, BasicBlock* succ) {
if (V == 0)
return 0;
if (BinaryOperator* BO = dyn_cast<BinaryOperator>(V)) {
Value* newOp1 = isa<Instruction>(BO->getOperand(0))
? phi_translate(set,
find_leader(set, BO->getOperand(0)),
pred, succ)
: BO->getOperand(0);
if (newOp1 == 0)
return 0;
Value* newOp2 = isa<Instruction>(BO->getOperand(1))
? phi_translate(set,
find_leader(set, BO->getOperand(1)),
pred, succ)
: 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()+".gvnpre");
if (add(newVal, nextValueNumber))
nextValueNumber++;
if (!find_leader(set, newVal)) {
DOUT << "Creating value: " << std::hex << newVal << std::dec << "\n";
createdExpressions.push_back(newVal);
return newVal;
} else {
ValueTable::iterator I = VN.find(newVal);
if (I->first == newVal)
VN.erase(newVal);
std::set<Value*, ExprLT>::iterator F = MS.find(newVal);
if (*F == newVal)
MS.erase(newVal);
delete newVal;
return 0;
}
}
} 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 = isa<Instruction>(C->getOperand(0))
? phi_translate(set,
find_leader(set, C->getOperand(0)),
pred, succ)
: C->getOperand(0);
if (newOp1 == 0)
return 0;
Value* newOp2 = isa<Instruction>(C->getOperand(1))
? phi_translate(set,
find_leader(set, C->getOperand(1)),
pred, succ)
: 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()+".gvnpre");
if (add(newVal, nextValueNumber))
nextValueNumber++;
if (!find_leader(set, newVal)) {
DOUT << "Creating value: " << std::hex << newVal << std::dec << "\n";
createdExpressions.push_back(newVal);
return newVal;
} else {
ValueTable::iterator I = VN.find(newVal);
if (I->first == newVal)
VN.erase(newVal);
std::set<Value*, ExprLT>::iterator F = MS.find(newVal);
if (*F == newVal)
MS.erase(newVal);
delete newVal;
return 0;
}
}
}
return V;
}
void GVNPRE::phi_translate_set(std::set<Value*, ExprLT>& anticIn,
BasicBlock* pred, BasicBlock* succ,
std::set<Value*, ExprLT>& out) {
for (std::set<Value*, ExprLT>::iterator I = anticIn.begin(),
E = anticIn.end(); I != E; ++I) {
Value* V = phi_translate(anticIn, *I, pred, succ);
if (V != 0)
out.insert(V);
}
}
// Remove all expressions whose operands are not themselves in the set
void GVNPRE::clean(std::set<Value*, ExprLT>& 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*, ExprLT>::iterator I = set.begin(), E = set.end();
I != E; ++I)
if (VN[*I] == VN[BO->getOperand(0)]) {
lhsValid = true;
break;
}
bool rhsValid = !isa<Instruction>(BO->getOperand(1));
if (!rhsValid)
for (std::set<Value*, ExprLT>::iterator I = set.begin(), E = set.end();
I != E; ++I)
if (VN[*I] == VN[BO->getOperand(1)]) {
rhsValid = true;
break;
}
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*, ExprLT>::iterator I = set.begin(), E = set.end();
I != E; ++I)
if (VN[*I] == VN[C->getOperand(0)]) {
lhsValid = true;
break;
}
bool rhsValid = !isa<Instruction>(C->getOperand(1));
if (!rhsValid)
for (std::set<Value*, ExprLT>::iterator I = set.begin(), E = set.end();
I != E; ++I)
if (VN[*I] == VN[C->getOperand(1)]) {
rhsValid = true;
break;
}
if (!lhsValid || !rhsValid)
set.erase(C);
}
}
}
void GVNPRE::topo_sort(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();
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(*SI);
}
}
else if (CmpInst* C = dyn_cast<CmpInst>(*I))
for (std::set<Value*, ExprLT>::iterator SI = set.begin(); SI != E; ++SI) {
if (VN[C->getOperand(0)] == VN[*SI] ||
VN[C->getOperand(1)] == VN[*SI]) {
toErase.insert(*SI);
}
}
}
std::vector<Value*> Q;
for (std::set<Value*, ExprLT>::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, BO->getOperand(0));
Value* r = find_leader(set, 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, C->getOperand(0));
Value* r = find_leader(set, 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*, ExprLT>& 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::CalculateAvailOut(DomTreeNode* DI,
std::set<Value*, ExprLT>& currExps,
std::set<PHINode*>& currPhis,
std::set<Value*>& currTemps,
std::set<Value*, ExprLT>& currAvail,
std::map<BasicBlock*, std::set<Value*, ExprLT> > availOut) {
BasicBlock* BB = DI->getBlock();
// A block inherits AVAIL_OUT from its dominator
if (DI->getIDom() != 0)
currAvail.insert(availOut[DI->getIDom()->getBlock()].begin(),
availOut[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)) {
if (add(p, nextValueNumber))
nextValueNumber++;
currPhis.insert(p);
// Handle binary ops...
} else if (BinaryOperator* BO = dyn_cast<BinaryOperator>(BI)) {
Value* leftValue = BO->getOperand(0);
Value* rightValue = BO->getOperand(1);
if (add(BO, nextValueNumber))
nextValueNumber++;
if (isa<Instruction>(leftValue))
currExps.insert(leftValue);
if (isa<Instruction>(rightValue))
currExps.insert(rightValue);
currExps.insert(BO);
// Handle cmp ops...
} else if (CmpInst* C = dyn_cast<CmpInst>(BI)) {
Value* leftValue = C->getOperand(0);
Value* rightValue = C->getOperand(1);
if (add(C, nextValueNumber))
nextValueNumber++;
if (isa<Instruction>(leftValue))
currExps.insert(leftValue);
if (isa<Instruction>(rightValue))
currExps.insert(rightValue);
currExps.insert(C);
// Handle unsupported ops
} else if (!BI->isTerminator()){
if (add(BI, nextValueNumber))
nextValueNumber++;
currTemps.insert(BI);
}
if (!BI->isTerminator())
currAvail.insert(BI);
}
}
bool GVNPRE::runOnFunction(Function &F) {
VN.clear();
MS.clear();
createdExpressions.clear();
std::map<BasicBlock*, std::set<Value*, ExprLT> > generatedExpressions;
std::map<BasicBlock*, std::set<PHINode*> > generatedPhis;
std::map<BasicBlock*, std::set<Value*> > generatedTemporaries;
std::map<BasicBlock*, std::set<Value*, ExprLT> > availableOut;
std::map<BasicBlock*, std::set<Value*, ExprLT> > anticipatedIn;
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*, ExprLT>& currExps = generatedExpressions[DI->getBlock()];
std::set<PHINode*>& currPhis = generatedPhis[DI->getBlock()];
std::set<Value*>& currTemps = generatedTemporaries[DI->getBlock()];
std::set<Value*, ExprLT>& currAvail = availableOut[DI->getBlock()];
CalculateAvailOut(*DI, currExps, currPhis,
currTemps, currAvail, availableOut);
}
DOUT << "Maximal Set: ";
dump_unique(MS);
DOUT << "\n";
PostDominatorTree &PDT = getAnalysis<PostDominatorTree>();
// Phase 1, Part 2: calculate ANTIC_IN
std::set<BasicBlock*> visited;
bool changed = true;
unsigned iterations = 0;
while (changed) {
changed = false;
std::set<Value*, ExprLT> 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*, ExprLT>& anticIn = anticipatedIn[BB];
std::set<Value*, ExprLT> old (anticIn.begin(), anticIn.end());
if (BB->getTerminator()->getNumSuccessors() == 1) {
if (visited.find(BB->getTerminator()->getSuccessor(0)) ==
visited.end())
phi_translate_set(MS, 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*, ExprLT>& succAnticIn = anticipatedIn[currSucc];
std::set<Value*, ExprLT> temp;
std::insert_iterator<std::set<Value*, ExprLT> > temp_ins(temp,
temp.begin());
std::set_intersection(anticOut.begin(), anticOut.end(),
succAnticIn.begin(), succAnticIn.end(),
temp_ins, ExprLT());
anticOut.clear();
anticOut.insert(temp.begin(), temp.end());
}
}
DOUT << "ANTIC_OUT: ";
dump_unique(anticOut);
DOUT << "\n";
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());
anticIn.clear();
for (std::set<Value*, ExprLT>::iterator I = S.begin(), E = S.end();
I != E; ++I) {
if (generatedTemporaries[BB].find(*I) == generatedTemporaries[BB].end())
anticIn.insert(*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*, ExprLT> > 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*, ExprLT>& new_set = new_sets[BB];
std::set<Value*, ExprLT>& availOut = availableOut[BB];
std::set<Value*, ExprLT>& anticIn = anticipatedIn[BB];
new_set.clear();
// Replace leaders with leaders inherited from dominator
if (DI->getIDom() != 0) {
std::set<Value*, ExprLT>& dom_set = new_sets[DI->getIDom()->getBlock()];
for (std::set<Value*, ExprLT>::iterator I = dom_set.begin(),
E = dom_set.end(); I != E; ++I) {
new_set.insert(*I);
Value* val = find_leader(availOut, *I);
while (val != 0) {
availOut.erase(val);
val = find_leader(availOut, *I);
}
availOut.insert(*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()], 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(anticIn, e, *PI, BB);
Value *e3 = find_leader(availableOut[*PI], 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], e2)) {
User* U = cast<User>(e2);
Value* s1 = 0;
if (isa<Instruction>(U->getOperand(0)))
s1 = find_leader(availableOut[*PI],
phi_translate(availableOut[*PI],
U->getOperand(0),
*PI, BB)
);
else
s1 = U->getOperand(0);
Value* s2 = 0;
if (isa<Instruction>(U->getOperand(1)))
s2 = find_leader(availableOut[*PI],
phi_translate(availableOut[*PI],
U->getOperand(1),
*PI, BB)
);
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());
add(newVal, VN[U]);
std::set<Value*, ExprLT>& predAvail = availableOut[*PI];
Value* val = find_leader(predAvail, newVal);
while (val != 0) {
predAvail.erase(val);
val = find_leader(predAvail, newVal);
}
predAvail.insert(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);
}
add(p, VN[e]);
DOUT << "Creating value: " << std::hex << p << std::dec << "\n";
Value* val = find_leader(availOut, p);
while (val != 0) {
availOut.erase(val);
val = find_leader(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
DOUT << "\n\nPhase 3: Elimination\n\n";
std::vector<std::pair<Instruction*, Value*> > replace;
std::vector<Instruction*> erase;
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], 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();
// Phase 4: Cleanup
while (!createdExpressions.empty()) {
Instruction* I = createdExpressions.back();
createdExpressions.pop_back();
delete I;
}
return false;
}
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