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1) Fix an issue with non-deterministic iteration order in phi_translate 

2) Remove some maximal-set computing code that is no longer used.
3) Use a post-order CFG traversal to compute ANTIC_IN instead of a postdom traversal.
This causes the ANTIC_IN calculation to converge much faster.  Thanks to Daniel Berlin for suggesting this.

With this patch, the time to optimize 403.gcc decreased from 17.5s to 7.5s, and Anton's huge
testcase decreased from 62 minutes to 38 seconds.

llvm-svn: 37714
This commit is contained in:
Owen Anderson 2007-06-25 05:41:12 +00:00
parent 8735f44104
commit 191eb06352
1 changed files with 86 additions and 111 deletions
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197
llvm/lib/Transforms/Scalar/GVNPRE.cpp
View File

@ -24,7 +24,6 @@
#include "llvm/Instructions.h"
#include "llvm/Function.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/PostDominators.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DepthFirstIterator.h"
@ -86,9 +85,6 @@ namespace {
DenseMap<Value*, uint32_t> valueNumbering;
std::map<Expression, uint32_t> expressionNumbering;
std::set<Expression> maximalExpressions;
SmallPtrSet<Value*, 32> maximalValues;
uint32_t nextValueNumber;
Expression::ExpressionOpcode getOpcode(BinaryOperator* BO);
@ -101,11 +97,6 @@ namespace {
uint32_t lookup(Value* V);
void add(Value* V, uint32_t num);
void clear();
std::set<Expression>& getMaximalExpressions() {
return maximalExpressions;
}
SmallPtrSet<Value*, 32>& getMaximalValues() { return maximalValues; }
void erase(Value* v);
unsigned size();
};
@ -230,8 +221,6 @@ ValueTable::Expression ValueTable::create_expression(BinaryOperator* BO) {
e.rightVN = lookup_or_add(BO->getOperand(1));
e.opcode = getOpcode(BO);
maximalExpressions.insert(e);
return e;
}
@ -242,8 +231,6 @@ ValueTable::Expression ValueTable::create_expression(CmpInst* C) {
e.rightVN = lookup_or_add(C->getOperand(1));
e.opcode = getOpcode(C);
maximalExpressions.insert(e);
return e;
}
@ -254,8 +241,6 @@ ValueTable::Expression ValueTable::create_expression(CmpInst* C) {
/// 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;
@ -314,23 +299,16 @@ void ValueTable::add(Value* V, uint32_t num) {
valueNumbering.insert(std::make_pair(V, num));
}
/// clear - Remove all entries from the ValueTable and the maximal sets
/// clear - Remove all entries from the ValueTable
void ValueTable::clear() {
valueNumbering.clear();
expressionNumbering.clear();
maximalExpressions.clear();
maximalValues.clear();
nextValueNumber = 1;
}
/// erase - Remove a value from the value numbering and maximal sets
/// erase - Remove a value from the value numbering
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));
}
/// size - Return the number of assigned value numbers
@ -362,7 +340,6 @@ namespace {
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequired<DominatorTree>();
AU.addRequired<PostDominatorTree>();
}
// Helper fuctions
@ -467,33 +444,38 @@ Value* GVNPRE::phi_translate(Value* V, BasicBlock* pred, BasicBlock* succ) {
if (V == 0)
return 0;
if (BinaryOperator* BO = dyn_cast<BinaryOperator>(V)) {
if (isa<BinaryOperator>(V) || isa<CmpInst>(V)) {
User* U = cast<User>(V);
Value* newOp1 = 0;
if (isa<Instruction>(BO->getOperand(0)))
newOp1 = phi_translate(find_leader(anticipatedIn[succ],
VN.lookup(BO->getOperand(0))),
pred, succ);
if (isa<Instruction>(U->getOperand(0)))
newOp1 = phi_translate(U->getOperand(0), pred, succ);
else
newOp1 = BO->getOperand(0);
newOp1 = U->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);
if (isa<Instruction>(U->getOperand(1)))
newOp2 = phi_translate(U->getOperand(1), pred, succ);
else
newOp2 = BO->getOperand(1);
newOp2 = U->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 (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");
uint32_t v = VN.lookup_or_add(newVal);
@ -510,47 +492,6 @@ Value* GVNPRE::phi_translate(Value* V, BasicBlock* pred, BasicBlock* succ) {
} 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;
@ -728,9 +669,9 @@ bool GVNPRE::elimination() {
E = df_end(DT.getRootNode()); DI != E; ++DI) {
BasicBlock* BB = DI->getBlock();
DOUT << "Block: " << BB->getName() << "\n";
dump(availableOut[BB]);
DOUT << "\n\n";
//DOUT << "Block: " << BB->getName() << "\n";
//dump(availableOut[BB]);
//DOUT << "\n\n";
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
BI != BE; ++BI) {
@ -866,11 +807,15 @@ bool GVNPRE::buildsets_anticout(BasicBlock* BB,
SmallPtrSet<Value*, 32>& anticOut,
std::set<BasicBlock*>& visited) {
if (BB->getTerminator()->getNumSuccessors() == 1) {
if (visited.count(BB->getTerminator()->getSuccessor(0)) == 0)
if (BB->getTerminator()->getSuccessor(0) != BB &&
visited.count(BB->getTerminator()->getSuccessor(0)) == 0) {
DOUT << "DEFER: " << BB->getName() << "\n";
return true;
else
}
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());
@ -910,13 +855,17 @@ unsigned GVNPRE::buildsets_anticin(BasicBlock* BB,
if (defer)
return 0;
anticIn.clear();
BitVector numbers(VN.size());
for (SmallPtrSet<Value*, 32>::iterator I = anticOut.begin(),
E = anticOut.end(); I != E; ++I) {
anticIn.insert(*I);
numbers.set(VN.lookup_or_add(*I));
unsigned num = VN.lookup_or_add(*I);
numbers.resize(VN.size());
numbers.set(num);
}
for (SmallPtrSet<Value*, 32>::iterator I = currExps.begin(),
E = currExps.end(); I != E; ++I) {
@ -931,11 +880,15 @@ unsigned GVNPRE::buildsets_anticin(BasicBlock* BB,
anticIn.erase(*I);
clean(anticIn);
anticOut.clear();
if (old != anticIn.size())
if (old != anticIn.size()) {
DOUT << "OLD: " << old << "\n";
DOUT << "NEW: " << anticIn.size() << "\n";
DOUT << "ANTIC_OUT: " << anticOut.size() << "\n";
anticOut.clear();
return 2;
else
} else
anticOut.clear();
return 1;
}
@ -979,21 +932,41 @@ unsigned GVNPRE::buildsets(Function& F) {
currTemps, availNumbers, expNumbers);
}
// Phase 1, Part 2: calculate ANTIC_IN
// If function has no exit blocks, only perform GVN
PostDominatorTree &PDT = getAnalysis<PostDominatorTree>();
if (PDT[&F.getEntryBlock()] == 0) {
bool changed_function = elimination();
cleanup();
DOUT << "Calculating walk\n";
// Calculate a postorder CFG walk
std::vector<BasicBlock*> walk;
std::vector<BasicBlock*> walkStack;
SmallPtrSet<BasicBlock*, 16> walkVisited;
walkStack.push_back(&F.getEntryBlock());
walkVisited.insert(&F.getEntryBlock());
while (!walkStack.empty()) {
BasicBlock* BB = walkStack.back();
walkVisited.insert(BB);
if (changed_function)
return 2; // Bailed early, made changes
else
return 1; // Bailed early, no changes
bool inserted = false;
for (unsigned i = 0; i < BB->getTerminator()->getNumSuccessors(); ++i) {
BasicBlock* succ = BB->getTerminator()->getSuccessor(i);
if (walkVisited.count(succ) == 0) {
walkStack.push_back(succ);
inserted = true;
}
}
if (inserted)
continue;
else {
walk.push_back(BB);
walkStack.pop_back();
}
}
DOUT << "Finished calculating walk\n";
// Phase 1, Part 2: calculate ANTIC_IN
// Perform the ANTIC_IN calculation
std::set<BasicBlock*> visited;
@ -1004,23 +977,23 @@ unsigned GVNPRE::buildsets(Function& F) {
SmallPtrSet<Value*, 32> 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();
for (std::vector<BasicBlock*>::iterator BBI = walk.begin(), BBE = walk.end();
BBI != BBE; ++BBI) {
BasicBlock* BB = *BBI;
if (BB == 0)
continue;
unsigned ret = buildsets_anticin(BB, anticOut,generatedExpressions[BB],
generatedTemporaries[BB], visited);
if (ret == 0) {
changed = true;
break;
continue;
} else {
visited.insert(BB);
if (ret == 2) {
DOUT << "CHANGED: " << BB->getName() << "\n";
}
changed |= (ret == 2);
}
}
@ -1028,6 +1001,8 @@ unsigned GVNPRE::buildsets(Function& F) {
iterations++;
}
DOUT << "ITERATIONS: " << iterations << "\n";
return 0; // No bail, no changes
}
@ -1197,10 +1172,10 @@ bool GVNPRE::insertion(Function& F) {
workList.reserve(anticIn.size());
topo_sort(anticIn, workList);
DOUT << "Merge Block: " << BB->getName() << "\n";
DOUT << "ANTIC_IN: ";
dump(anticIn);
DOUT << "\n";
//DOUT << "Merge Block: " << BB->getName() << "\n";
//DOUT << "ANTIC_IN: ";
//dump(anticIn);
//DOUT << "\n";
unsigned result = insertion_mergepoint(workList, DI, new_set);
if (result & 1)