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Use a set to keep track of which edges have been noticed as executable already

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to avoid reprocessing PHI nodes needlessly.  This speeds up the big bad PHI
testcase 43%: from 104.9826 to 73.5157s


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8964 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-10-08 16:55:34 +00:00
parent 3d405b07b4
commit 16b18fdc35
1 changed files with 27 additions and 15 deletions
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42
lib/Transforms/Scalar/SCCP.cpp
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@ -85,6 +85,11 @@ class SCCP : public FunctionPass, public InstVisitor<SCCP> {
std::vector<Instruction*> InstWorkList;// The instruction work list
std::vector<BasicBlock*> BBWorkList; // The BasicBlock work list
/// KnownFeasibleEdges - Entries in this set are edges which have already had
/// PHI nodes retriggered.
typedef std::pair<BasicBlock*,BasicBlock*> Edge;
std::set<Edge> KnownFeasibleEdges;
public:
// runOnFunction - Run the Sparse Conditional Constant Propagation algorithm,
@ -153,22 +158,28 @@ private:
return ValueState[V];
}
// markExecutable - Mark a basic block as executable, adding it to the BB
// markEdgeExecutable - Mark a basic block as executable, adding it to the BB
// work list if it is not already executable...
//
void markExecutable(BasicBlock *BB) {
if (BBExecutable.count(BB)) {
// BB is already executable, but we may have just made an edge feasible
// that wasn't before. Add the PHI nodes to the work list so that they
// can be rechecked.
for (BasicBlock::iterator I = BB->begin();
void markEdgeExecutable(BasicBlock *Source, BasicBlock *Dest) {
if (!KnownFeasibleEdges.insert(Edge(Source, Dest)).second)
return; // This edge is already known to be executable!
if (BBExecutable.count(Dest)) {
DEBUG(std::cerr << "Marking Edge Executable: " << Source->getName()
<< " -> " << Dest->getName() << "\n");
// The destination is already executable, but we just made an edge
// feasible that wasn't before. Add the PHI nodes to the work list so
// that they can be rechecked.
for (BasicBlock::iterator I = Dest->begin();
PHINode *PN = dyn_cast<PHINode>(I); ++I)
visitPHINode(*PN);
} else {
DEBUG(std::cerr << "Marking BB Executable: " << *BB);
BBExecutable.insert(BB); // Basic block is executable!
BBWorkList.push_back(BB); // Add the block to the work list!
DEBUG(std::cerr << "Marking Block Executable: " << Dest->getName()<<"\n");
BBExecutable.insert(Dest); // Basic block is executable!
BBWorkList.push_back(Dest); // Add the block to the work list!
}
}
@ -249,7 +260,8 @@ Pass *createSCCPPass() {
//
bool SCCP::runOnFunction(Function &F) {
// Mark the first block of the function as being executable...
markExecutable(&F.front());
BBExecutable.insert(F.begin()); // Basic block is executable!
BBWorkList.push_back(F.begin()); // Add the block to the work list!
// Process the work lists until their are empty!
while (!BBWorkList.empty() || !InstWorkList.empty()) {
@ -494,12 +506,12 @@ void SCCP::visitTerminatorInst(TerminatorInst &TI) {
std::vector<bool> SuccFeasible;
getFeasibleSuccessors(TI, SuccFeasible);
BasicBlock *BB = TI.getParent();
// Mark all feasible successors executable...
for (unsigned i = 0, e = SuccFeasible.size(); i != e; ++i)
if (SuccFeasible[i]) {
BasicBlock *Succ = TI.getSuccessor(i);
markExecutable(Succ);
}
if (SuccFeasible[i])
markEdgeExecutable(BB, TI.getSuccessor(i));
}
void SCCP::visitCastInst(CastInst &I) {