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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/ADT/BitVector.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SmallPtrSet.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. 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, EXTRACT, INSERT,
SHUFFLE };
ExpressionOpcode opcode;
uint32_t firstVN;
uint32_t secondVN;
uint32_t thirdVN;
bool operator< (const Expression& other) const {
if (opcode < other.opcode)
return true;
else if (opcode > other.opcode)
return false;
else if (firstVN < other.firstVN)
return true;
else if (firstVN > other.firstVN)
return false;
else if (secondVN < other.secondVN)
return true;
else if (secondVN > other.secondVN)
return false;
else if (thirdVN < other.thirdVN)
return true;
else if (thirdVN > other.thirdVN)
return false;
else
return false;
}
};
private:
DenseMap<Value*, uint32_t> valueNumbering;
std::map<Expression, uint32_t> expressionNumbering;
uint32_t nextValueNumber;
Expression::ExpressionOpcode getOpcode(BinaryOperator* BO);
Expression::ExpressionOpcode getOpcode(CmpInst* C);
Expression create_expression(BinaryOperator* BO);
Expression create_expression(CmpInst* C);
Expression create_expression(ShuffleVectorInst* V);
Expression create_expression(ExtractElementInst* C);
Expression create_expression(InsertElementInst* V);
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();
void erase(Value* v);
unsigned size();
};
}
//===----------------------------------------------------------------------===//
// 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.firstVN = lookup_or_add(BO->getOperand(0));
e.secondVN = lookup_or_add(BO->getOperand(1));
e.thirdVN = 0;
e.opcode = getOpcode(BO);
return e;
}
ValueTable::Expression ValueTable::create_expression(CmpInst* C) {
Expression e;
e.firstVN = lookup_or_add(C->getOperand(0));
e.secondVN = lookup_or_add(C->getOperand(1));
e.thirdVN = 0;
e.opcode = getOpcode(C);
return e;
}
ValueTable::Expression ValueTable::create_expression(ShuffleVectorInst* S) {
Expression e;
e.firstVN = lookup_or_add(S->getOperand(0));
e.secondVN = lookup_or_add(S->getOperand(1));
e.thirdVN = lookup_or_add(S->getOperand(2));
e.opcode = Expression::SHUFFLE;
return e;
}
ValueTable::Expression ValueTable::create_expression(ExtractElementInst* E) {
Expression e;
e.firstVN = lookup_or_add(E->getOperand(0));
e.secondVN = lookup_or_add(E->getOperand(1));
e.thirdVN = 0;
e.opcode = Expression::EXTRACT;
return e;
}
ValueTable::Expression ValueTable::create_expression(InsertElementInst* I) {
Expression e;
e.firstVN = lookup_or_add(I->getOperand(0));
e.secondVN = lookup_or_add(I->getOperand(1));
e.thirdVN = lookup_or_add(I->getOperand(2));
e.opcode = Expression::INSERT;
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) {
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 if (ShuffleVectorInst* U = dyn_cast<ShuffleVectorInst>(V)) {
Expression e = create_expression(U);
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 (ExtractElementInst* U = dyn_cast<ExtractElementInst>(V)) {
Expression e = create_expression(U);
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 (InsertElementInst* U = dyn_cast<InsertElementInst>(V)) {
Expression e = create_expression(U);
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
void ValueTable::clear() {
valueNumbering.clear();
expressionNumbering.clear();
nextValueNumber = 1;
}
/// erase - Remove a value from the value numbering
void ValueTable::erase(Value* V) {
valueNumbering.erase(V);
}
/// size - Return the number of assigned value numbers
unsigned ValueTable::size() {
// NOTE: zero is never assigned
return nextValueNumber;
}
//===----------------------------------------------------------------------===//
// GVNPRE Pass
//===----------------------------------------------------------------------===//
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*, SmallPtrSet<Value*, 32> > availableOut;
std::map<BasicBlock*, SmallPtrSet<Value*, 32> > 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(const SmallPtrSet<Value*, 32>& s) const;
void clean(SmallPtrSet<Value*, 32>& set, BitVector& presentInSet);
Value* find_leader(SmallPtrSet<Value*, 32>& vals,
uint32_t v);
Value* phi_translate(Value* V, BasicBlock* pred, BasicBlock* succ);
void phi_translate_set(SmallPtrSet<Value*, 32>& anticIn, BasicBlock* pred,
BasicBlock* succ, SmallPtrSet<Value*, 32>& out);
void topo_sort(SmallPtrSet<Value*, 32>& set,
std::vector<Value*>& vec);
void cleanup();
bool elimination();
void val_insert(SmallPtrSet<Value*, 32>& s, Value* v);
void val_replace(SmallPtrSet<Value*, 32>& s, Value* v);
bool dependsOnInvoke(Value* V);
void buildsets_availout(BasicBlock::iterator I,
SmallPtrSet<Value*, 32>& currAvail,
SmallPtrSet<PHINode*, 32>& currPhis,
SmallPtrSet<Value*, 32>& currExps,
SmallPtrSet<Value*, 32>& currTemps,
BitVector& availNumbers,
BitVector& expNumbers);
bool buildsets_anticout(BasicBlock* BB,
SmallPtrSet<Value*, 32>& anticOut,
std::set<BasicBlock*>& visited);
unsigned buildsets_anticin(BasicBlock* BB,
SmallPtrSet<Value*, 32>& anticOut,
SmallPtrSet<Value*, 32>& currExps,
SmallPtrSet<Value*, 32>& currTemps,
std::set<BasicBlock*>& visited);
void buildsets(Function& F);
void insertion_pre(Value* e, BasicBlock* BB,
std::map<BasicBlock*, Value*>& avail,
SmallPtrSet<Value*, 32>& new_set);
unsigned insertion_mergepoint(std::vector<Value*>& workList,
df_iterator<DomTreeNode*>& D,
SmallPtrSet<Value*, 32>& new_set);
bool insertion(Function& F);
};
char GVNPRE::ID = 0;
}
// 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");
/// 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(SmallPtrSet<Value*, 32>& vals, uint32_t v) {
for (SmallPtrSet<Value*, 32>::iterator I = vals.begin(), E = vals.end();
I != E; ++I)
if (v == VN.lookup(*I))
return *I;
return 0;
}
/// val_insert - Insert a value into a set only if there is not a value
/// with the same value number already in the set
void GVNPRE::val_insert(SmallPtrSet<Value*, 32>& 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(SmallPtrSet<Value*, 32>& 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;
// Binary Operations
if (isa<BinaryOperator>(V) || isa<CmpInst>(V) ||
isa<ExtractElementInst>(V)) {
User* U = cast<User>(V);
Value* newOp1 = 0;
if (isa<Instruction>(U->getOperand(0)))
newOp1 = phi_translate(U->getOperand(0), pred, succ);
else
newOp1 = U->getOperand(0);
if (newOp1 == 0)
return 0;
Value* newOp2 = 0;
if (isa<Instruction>(U->getOperand(1)))
newOp2 = phi_translate(U->getOperand(1), pred, succ);
else
newOp2 = U->getOperand(1);
if (newOp2 == 0)
return 0;
if (newOp1 != U->getOperand(0) || newOp2 != U->getOperand(1)) {
Instruction* newVal = 0;
if (BinaryOperator* BO = dyn_cast<BinaryOperator>(U))
newVal = BinaryOperator::create(BO->getOpcode(),
newOp1, newOp2,
BO->getName()+".expr");
else if (CmpInst* C = dyn_cast<CmpInst>(U))
newVal = CmpInst::create(C->getOpcode(),
C->getPredicate(),
newOp1, newOp2,
C->getName()+".expr");
else if (ExtractElementInst* E = dyn_cast<ExtractElementInst>(U))
newVal = new ExtractElementInst(newOp1, newOp2, E->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;
}
}
// Ternary Operations
} else if (isa<ShuffleVectorInst>(V) || isa<InsertElementInst>(V)) {
User* U = cast<User>(V);
Value* newOp1 = 0;
if (isa<Instruction>(U->getOperand(0)))
newOp1 = phi_translate(U->getOperand(0), pred, succ);
else
newOp1 = U->getOperand(0);
if (newOp1 == 0)
return 0;
Value* newOp2 = 0;
if (isa<Instruction>(U->getOperand(1)))
newOp2 = phi_translate(U->getOperand(1), pred, succ);
else
newOp2 = U->getOperand(1);
if (newOp2 == 0)
return 0;
Value* newOp3 = 0;
if (isa<Instruction>(U->getOperand(2)))
newOp3 = phi_translate(U->getOperand(2), pred, succ);
else
newOp3 = U->getOperand(2);
if (newOp3 == 0)
return 0;
if (newOp1 != U->getOperand(0) ||
newOp2 != U->getOperand(1) ||
newOp3 != U->getOperand(2)) {
Instruction* newVal = 0;
if (ShuffleVectorInst* S = dyn_cast<ShuffleVectorInst>(U))
newVal = new ShuffleVectorInst(newOp1, newOp2, newOp3,
S->getName()+".expr");
else if (InsertElementInst* I = dyn_cast<InsertElementInst>(U))
newVal = new InsertElementInst(newOp1, newOp2, newOp3,
I->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;
}
}
// PHI Nodes
} else if (PHINode* P = dyn_cast<PHINode>(V)) {
if (P->getParent() == succ)
return P->getIncomingValueForBlock(pred);
}
return V;
}
/// phi_translate_set - Perform phi translation on every element of a set
void GVNPRE::phi_translate_set(SmallPtrSet<Value*, 32>& anticIn,
BasicBlock* pred, BasicBlock* succ,
SmallPtrSet<Value*, 32>& out) {
for (SmallPtrSet<Value*, 32>::iterator I = anticIn.begin(),
E = anticIn.end(); I != E; ++I) {
Value* V = phi_translate(*I, pred, succ);
if (V != 0)
out.insert(V);
}
}
/// 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(SmallPtrSet<Value*, 32>& set, BitVector& presentInSet) {
std::vector<Value*> worklist;
worklist.reserve(set.size());
topo_sort(set, worklist);
for (unsigned i = 0; i < worklist.size(); ++i) {
Value* v = worklist[i];
// Handle binary ops
if (isa<BinaryOperator>(v) || isa<CmpInst>(v) ||
isa<ExtractElementInst>(v)) {
User* U = cast<User>(v);
bool lhsValid = !isa<Instruction>(U->getOperand(0));
lhsValid |= presentInSet.test(VN.lookup(U->getOperand(0)));
if (lhsValid)
lhsValid = !dependsOnInvoke(U->getOperand(0));
bool rhsValid = !isa<Instruction>(U->getOperand(1));
rhsValid |= presentInSet.test(VN.lookup(U->getOperand(1)));
if (rhsValid)
rhsValid = !dependsOnInvoke(U->getOperand(1));
if (!lhsValid || !rhsValid) {
set.erase(U);
presentInSet.flip(VN.lookup(U));
}
// Handle ternary ops
} else if (isa<ShuffleVectorInst>(v) || isa<InsertElementInst>(v)) {
User* U = cast<User>(v);
bool lhsValid = !isa<Instruction>(U->getOperand(0));
lhsValid |= presentInSet.test(VN.lookup(U->getOperand(0)));
if (lhsValid)
lhsValid = !dependsOnInvoke(U->getOperand(0));
bool rhsValid = !isa<Instruction>(U->getOperand(1));
rhsValid |= presentInSet.test(VN.lookup(U->getOperand(1)));
if (rhsValid)
rhsValid = !dependsOnInvoke(U->getOperand(1));
bool thirdValid = !isa<Instruction>(U->getOperand(2));
thirdValid |= presentInSet.test(VN.lookup(U->getOperand(2)));
if (thirdValid)
thirdValid = !dependsOnInvoke(U->getOperand(2));
if (!lhsValid || !rhsValid || !thirdValid) {
set.erase(U);
presentInSet.flip(VN.lookup(U));
}
}
}
}
/// topo_sort - Given a set of values, sort them by topological
/// order into the provided vector.
void GVNPRE::topo_sort(SmallPtrSet<Value*, 32>& set, std::vector<Value*>& vec) {
SmallPtrSet<Value*, 32> visited;
std::vector<Value*> stack;
for (SmallPtrSet<Value*, 32>::iterator I = set.begin(), E = set.end();
I != E; ++I) {
if (visited.count(*I) == 0)
stack.push_back(*I);
while (!stack.empty()) {
Value* e = stack.back();
// Handle binary ops
if (isa<BinaryOperator>(e) || isa<CmpInst>(e) ||
isa<ExtractElementInst>(e)) {
User* U = cast<User>(e);
Value* l = find_leader(set, VN.lookup(U->getOperand(0)));
Value* r = find_leader(set, VN.lookup(U->getOperand(1)));
if (l != 0 && isa<Instruction>(l) &&
visited.count(l) == 0)
stack.push_back(l);
else if (r != 0 && isa<Instruction>(r) &&
visited.count(r) == 0)
stack.push_back(r);
else {
vec.push_back(e);
visited.insert(e);
stack.pop_back();
}
// Handle ternary ops
} else if (isa<InsertElementInst>(e) || isa<ShuffleVectorInst>(e)) {
User* U = cast<User>(e);
Value* l = find_leader(set, VN.lookup(U->getOperand(0)));
Value* r = find_leader(set, VN.lookup(U->getOperand(1)));
Value* m = find_leader(set, VN.lookup(U->getOperand(2)));
if (l != 0 && isa<Instruction>(l) &&
visited.count(l) == 0)
stack.push_back(l);
else if (r != 0 && isa<Instruction>(r) &&
visited.count(r) == 0)
stack.push_back(r);
else if (m != 0 && isa<Instruction>(m) &&
visited.count(m) == 0)
stack.push_back(r);
else {
vec.push_back(e);
visited.insert(e);
stack.pop_back();
}
// Handle opaque ops
} else {
visited.insert(e);
vec.push_back(e);
stack.pop_back();
}
}
stack.clear();
}
}
/// dump - Dump a set of values to standard error
void GVNPRE::dump(const SmallPtrSet<Value*, 32>& s) const {
DOUT << "{ ";
for (SmallPtrSet<Value*, 32>::iterator I = s.begin(), E = s.end();
I != E; ++I) {
DEBUG((*I)->dump());
}
DOUT << "}\n\n";
}
/// 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";
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) ||
isa<ShuffleVectorInst>(BI) || isa<InsertElementInst>(BI) ||
isa<ExtractElementInst>(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();
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,
SmallPtrSet<Value*, 32>& currAvail,
SmallPtrSet<PHINode*, 32>& currPhis,
SmallPtrSet<Value*, 32>& currExps,
SmallPtrSet<Value*, 32>& currTemps,
BitVector& availNumbers,
BitVector& expNumbers) {
// Handle PHI nodes
if (PHINode* p = dyn_cast<PHINode>(I)) {
VN.lookup_or_add(p);
expNumbers.resize(VN.size());
availNumbers.resize(VN.size());
currPhis.insert(p);
// Handle binary ops
} else if (isa<BinaryOperator>(I) || isa<CmpInst>(I) ||
isa<ExtractElementInst>(I)) {
User* U = cast<User>(I);
Value* leftValue = U->getOperand(0);
Value* rightValue = U->getOperand(1);
unsigned num = VN.lookup_or_add(U);
expNumbers.resize(VN.size());
availNumbers.resize(VN.size());
if (isa<Instruction>(leftValue))
if (!expNumbers.test(VN.lookup(leftValue))) {
currExps.insert(leftValue);
expNumbers.set(VN.lookup(leftValue));
}
if (isa<Instruction>(rightValue))
if (!expNumbers.test(VN.lookup(rightValue))) {
currExps.insert(rightValue);
expNumbers.set(VN.lookup(rightValue));
}
if (!expNumbers.test(VN.lookup(U))) {
currExps.insert(U);
expNumbers.set(num);
}
// Handle ternary ops
} else if (isa<InsertElementInst>(I) || isa<ShuffleVectorInst>(I)) {
User* U = cast<User>(I);
Value* leftValue = U->getOperand(0);
Value* rightValue = U->getOperand(1);
Value* thirdValue = U->getOperand(2);
VN.lookup_or_add(U);
unsigned num = VN.lookup_or_add(U);
expNumbers.resize(VN.size());
availNumbers.resize(VN.size());
if (isa<Instruction>(leftValue))
if (!expNumbers.test(VN.lookup(leftValue))) {
currExps.insert(leftValue);
expNumbers.set(VN.lookup(leftValue));
}
if (isa<Instruction>(rightValue))
if (!expNumbers.test(VN.lookup(rightValue))) {
currExps.insert(rightValue);
expNumbers.set(VN.lookup(rightValue));
}
if (isa<Instruction>(thirdValue))
if (!expNumbers.test(VN.lookup(thirdValue))) {
currExps.insert(thirdValue);
expNumbers.set(VN.lookup(thirdValue));
}
if (!expNumbers.test(VN.lookup(U))) {
currExps.insert(U);
expNumbers.set(num);
}
// Handle opaque ops
} else if (!I->isTerminator()){
VN.lookup_or_add(I);
expNumbers.resize(VN.size());
availNumbers.resize(VN.size());
currTemps.insert(I);
}
if (!I->isTerminator())
if (!availNumbers.test(VN.lookup(I))) {
currAvail.insert(I);
availNumbers.set(VN.lookup(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
bool GVNPRE::buildsets_anticout(BasicBlock* BB,
SmallPtrSet<Value*, 32>& anticOut,
std::set<BasicBlock*>& visited) {
if (BB->getTerminator()->getNumSuccessors() == 1) {
if (BB->getTerminator()->getSuccessor(0) != BB &&
visited.count(BB->getTerminator()->getSuccessor(0)) == 0) {
DOUT << "DEFER: " << BB->getName() << "\n";
return true;
}
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);
SmallPtrSet<Value*, 32>& succAnticIn = anticipatedIn[currSucc];
std::vector<Value*> temp;
for (SmallPtrSet<Value*, 32>::iterator I = anticOut.begin(),
E = anticOut.end(); I != E; ++I)
if (succAnticIn.count(*I) == 0)
temp.push_back(*I);
for (std::vector<Value*>::iterator I = temp.begin(), E = temp.end();
I != E; ++I)
anticOut.erase(*I);
}
}
return false;
}
/// 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
unsigned GVNPRE::buildsets_anticin(BasicBlock* BB,
SmallPtrSet<Value*, 32>& anticOut,
SmallPtrSet<Value*, 32>& currExps,
SmallPtrSet<Value*, 32>& currTemps,
std::set<BasicBlock*>& visited) {
SmallPtrSet<Value*, 32>& anticIn = anticipatedIn[BB];
unsigned old = anticIn.size();
bool defer = buildsets_anticout(BB, anticOut, visited);
if (defer)
return 0;
anticIn.clear();
BitVector numbers(VN.size());
for (SmallPtrSet<Value*, 32>::iterator I = anticOut.begin(),
E = anticOut.end(); I != E; ++I) {
unsigned num = VN.lookup_or_add(*I);
numbers.resize(VN.size());
if (isa<Instruction>(*I)) {
anticIn.insert(*I);
numbers.set(num);
}
}
for (SmallPtrSet<Value*, 32>::iterator I = currExps.begin(),
E = currExps.end(); I != E; ++I) {
if (!numbers.test(VN.lookup_or_add(*I))) {
anticIn.insert(*I);
numbers.set(VN.lookup(*I));
}
}
for (SmallPtrSet<Value*, 32>::iterator I = currTemps.begin(),
E = currTemps.end(); I != E; ++I) {
anticIn.erase(*I);
numbers.flip(VN.lookup(*I));
}
clean(anticIn, numbers);
anticOut.clear();
if (old != anticIn.size())
return 2;
else
return 1;
}
/// buildsets - Phase 1 of the main algorithm. Construct the AVAIL_OUT
/// and the ANTIC_IN sets.
void GVNPRE::buildsets(Function& F) {
std::map<BasicBlock*, SmallPtrSet<Value*, 32> > generatedExpressions;
std::map<BasicBlock*, SmallPtrSet<PHINode*, 32> > generatedPhis;
std::map<BasicBlock*, SmallPtrSet<Value*, 32> > generatedTemporaries;
DominatorTree &DT = getAnalysis<DominatorTree>();
// 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
SmallPtrSet<Value*, 32>& currExps = generatedExpressions[DI->getBlock()];
SmallPtrSet<PHINode*, 32>& currPhis = generatedPhis[DI->getBlock()];
SmallPtrSet<Value*, 32>& currTemps = generatedTemporaries[DI->getBlock()];
SmallPtrSet<Value*, 32>& 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());
BitVector availNumbers(VN.size());
for (SmallPtrSet<Value*, 32>::iterator I = currAvail.begin(),
E = currAvail.end(); I != E; ++I)
availNumbers.set(VN.lookup(*I));
BitVector expNumbers(VN.size());
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
BI != BE; ++BI)
buildsets_availout(BI, currAvail, currPhis, currExps,
currTemps, availNumbers, expNumbers);
}
// Phase 1, Part 2: calculate ANTIC_IN
std::set<BasicBlock*> visited;
SmallPtrSet<BasicBlock*, 4> block_changed;
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
block_changed.insert(FI);
bool changed = true;
unsigned iterations = 0;
while (changed) {
changed = false;
SmallPtrSet<Value*, 32> anticOut;
// Postorder walk of the CFG
for (po_iterator<BasicBlock*> BBI = po_begin(&F.getEntryBlock()),
BBE = po_end(&F.getEntryBlock()); BBI != BBE; ++BBI) {
BasicBlock* BB = *BBI;
if (block_changed.count(BB) != 0) {
unsigned ret = buildsets_anticin(BB, anticOut,generatedExpressions[BB],
generatedTemporaries[BB], visited);
if (ret == 0) {
changed = true;
continue;
} else {
visited.insert(BB);
if (ret == 2)
for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
PI != PE; ++PI) {
block_changed.insert(*PI);
}
else
block_changed.erase(BB);
changed |= (ret == 2);
}
}
}
iterations++;
}
DOUT << "ITERATIONS: " << iterations << "\n";
}
/// 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,
SmallPtrSet<Value*, 32>& 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)) ||
isa<ShuffleVectorInst>(U->getOperand(0)) ||
isa<ExtractElementInst>(U->getOperand(0)) ||
isa<InsertElementInst>(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)) ||
isa<ShuffleVectorInst>(U->getOperand(1)) ||
isa<ExtractElementInst>(U->getOperand(1)) ||
isa<InsertElementInst>(U->getOperand(1)))
s2 = find_leader(availableOut[*PI], VN.lookup(U->getOperand(1)));
else
s2 = U->getOperand(1);
// Ternary Operators
Value* s3 = 0;
if (isa<ShuffleVectorInst>(U) ||
isa<InsertElementInst>(U))
if (isa<BinaryOperator>(U->getOperand(2)) ||
isa<CmpInst>(U->getOperand(2)) ||
isa<ShuffleVectorInst>(U->getOperand(2)) ||
isa<ExtractElementInst>(U->getOperand(2)) ||
isa<InsertElementInst>(U->getOperand(2)))
s3 = find_leader(availableOut[*PI], VN.lookup(U->getOperand(2)));
else
s3 = U->getOperand(2);
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());
else if (ShuffleVectorInst* S = dyn_cast<ShuffleVectorInst>(U))
newVal = new ShuffleVectorInst(s1, s2, s3, S->getName()+".gvnpre",
(*PI)->getTerminator());
else if (InsertElementInst* S = dyn_cast<InsertElementInst>(U))
newVal = new InsertElementInst(s1, s2, s3, S->getName()+".gvnpre",
(*PI)->getTerminator());
else if (ExtractElementInst* S = dyn_cast<ExtractElementInst>(U))
newVal = new ExtractElementInst(s1, s2, S->getName()+".gvnpre",
(*PI)->getTerminator());
VN.add(newVal, VN.lookup(U));
SmallPtrSet<Value*, 32>& 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,
SmallPtrSet<Value*, 32>& 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) ||
isa<ExtractElementInst>(e) || isa<InsertElementInst>(e) ||
isa<ShuffleVectorInst>(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*, SmallPtrSet<Value*, 32> > 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();
if (BB == 0)
continue;
SmallPtrSet<Value*, 32>& new_set = new_sets[BB];
SmallPtrSet<Value*, 32>& availOut = availableOut[BB];
SmallPtrSet<Value*, 32>& anticIn = anticipatedIn[BB];
new_set.clear();
// Replace leaders with leaders inherited from dominator
if (DI->getIDom() != 0) {
SmallPtrSet<Value*, 32>& dom_set = new_sets[DI->getIDom()->getBlock()];
for (SmallPtrSet<Value*, 32>::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;
workList.reserve(anticIn.size());
topo_sort(anticIn, workList);
unsigned result = insertion_mergepoint(workList, DI, new_set);
if (result & 1)
changed_function = true;
if (result & 2)
new_stuff = true;
}
}
}
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();
bool changed_function = false;
// Phase 1: BuildSets
// This phase calculates the AVAIL_OUT and ANTIC_IN sets
buildsets(F);
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI) {
DOUT << "ANTIC_IN: " << FI->getName() << "\n";
dump(anticipatedIn[FI]);
DOUT << "\n\n";
}
// 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 changed_function;
}
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