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Optimize SelectionDAG's AssignTopologicalOrder even further.
Completely eliminate the TopOrder std::vector. Instead, sort the AllNodes list in place. This also eliminates the need to call AllNodes.size(), a linear-time operation, before performing the sort. Also, eliminate the Sources temporary std::vector, since it essentially duplicates the sorted result as it is being built. This also changes the direction of the topological sort from bottom-up to top-down. The AllNodes list starts out in roughly top-down order, so this reduces the amount of reordering needed. Top-down is also more convenient for Legalize, and ISel needed only minor adjustments. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56867 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -18,7 +18,7 @@
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#define LLVM_CODEGEN_DAGISEL_HEADER_H
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/// ISelQueue - Instruction selector priority queue sorted
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/// in the order of increasing NodeId() values.
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/// in the order of decreasing NodeId() values.
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std::vector<SDNode*> ISelQueue;
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/// Keep track of nodes which have already been added to queue.
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@ -43,10 +43,10 @@ static bool IsChainCompatible(SDNode *Chain, SDNode *Op) {
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}
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/// isel_sort - Sorting functions for the selection queue in the
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/// increasing NodeId order.
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/// decreasing NodeId order.
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struct isel_sort : public std::binary_function<SDNode*, SDNode*, bool> {
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bool operator()(const SDNode* left, const SDNode* right) const {
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return (left->getNodeId() > right->getNodeId());
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return left->getNodeId() < right->getNodeId();
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}
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};
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@ -108,7 +108,7 @@ class VISIBILITY_HIDDEN ISelQueueUpdater :
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};
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/// UpdateQueue - update the instruction selction queue to maintain
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/// the increasing NodeId() ordering property.
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/// the decreasing NodeId() ordering property.
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inline void UpdateQueue(const ISelQueueUpdater &ISQU) {
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if (ISQU.hadDelete())
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std::make_heap(ISelQueue.begin(), ISelQueue.end(),isel_sort());
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@ -663,10 +663,10 @@ public:
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unsigned Num,
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DAGUpdateListener *UpdateListener = 0);
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/// AssignTopologicalOrder - Assign a unique node id for each node in the DAG
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/// based on their topological order. It returns the maximum id and a vector
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/// of the SDNodes* in assigned order by reference.
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unsigned AssignTopologicalOrder(std::vector<SDNode*> &TopOrder);
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/// AssignTopologicalOrder - Topological-sort the AllNodes list and a
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/// assign a unique node id for each node in the DAG based on their
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/// topological order. Returns the number of nodes.
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unsigned AssignTopologicalOrder();
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/// isCommutativeBinOp - Returns true if the opcode is a commutative binary
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/// operation.
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@ -48,7 +48,6 @@ public:
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AliasAnalysis *AA;
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GCFunctionInfo *GFI;
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bool Fast;
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std::vector<SDNode*> TopOrder;
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static char ID;
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explicit SelectionDAGISel(TargetLowering &tli, bool fast = false);
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@ -67,7 +66,7 @@ public:
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virtual void InstructionSelectPostProcessing() {}
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void SelectRootInit() {
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DAGSize = CurDAG->AssignTopologicalOrder(TopOrder);
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DAGSize = CurDAG->AssignTopologicalOrder();
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}
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/// SelectInlineAsmMemoryOperand - Select the specified address as a target
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@ -280,11 +280,10 @@ void SelectionDAGLegalize::LegalizeDAG() {
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// practice however, this causes us to run out of stack space on large basic
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// blocks. To avoid this problem, compute an ordering of the nodes where each
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// node is only legalized after all of its operands are legalized.
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std::vector<SDNode *> TopOrder;
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unsigned N = DAG.AssignTopologicalOrder(TopOrder);
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for (unsigned i = N; i != 0; --i)
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HandleOp(SDValue(TopOrder[i-1], 0));
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TopOrder.clear();
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DAG.AssignTopologicalOrder();
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for (SelectionDAG::allnodes_iterator I = DAG.allnodes_begin(),
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E = prior(DAG.allnodes_end()); I != next(E); ++I)
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HandleOp(SDValue(I, 0));
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// Finally, it's possible the root changed. Get the new root.
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SDValue OldRoot = DAG.getRoot();
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@ -587,7 +587,7 @@ void SelectionDAG::DeleteNode(SDNode *N) {
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void SelectionDAG::DeleteNodeNotInCSEMaps(SDNode *N) {
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// Drop all of the operands and decrement used nodes use counts.
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// Drop all of the operands and decrement used node's use counts.
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for (SDNode::op_iterator I = N->op_begin(), E = N->op_end(); I != E; ++I)
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I->getVal()->removeUser(std::distance(N->op_begin(), I), N);
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if (N->OperandsNeedDelete)
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@ -4569,38 +4569,74 @@ void SelectionDAG::ReplaceAllUsesOfValuesWith(const SDValue *From,
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/// AssignTopologicalOrder - Assign a unique node id for each node in the DAG
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/// based on their topological order. It returns the maximum id and a vector
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/// of the SDNodes* in assigned order by reference.
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unsigned SelectionDAG::AssignTopologicalOrder(std::vector<SDNode*> &TopOrder) {
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unsigned DAGSize = AllNodes.size();
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std::vector<SDNode*> Sources;
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unsigned SelectionDAG::AssignTopologicalOrder() {
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for (allnodes_iterator I = allnodes_begin(),E = allnodes_end(); I != E; ++I){
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SDNode *N = I;
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unsigned Degree = N->use_size();
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// Temporarily use the Node Id as scratch space for the degree count.
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N->setNodeId(Degree);
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if (Degree == 0)
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Sources.push_back(N);
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}
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unsigned DAGSize = 0;
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TopOrder.clear();
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TopOrder.reserve(DAGSize);
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int Id = 0;
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while (!Sources.empty()) {
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SDNode *N = Sources.back();
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Sources.pop_back();
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TopOrder.push_back(N);
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N->setNodeId(Id++);
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for (SDNode::op_iterator I = N->op_begin(), E = N->op_end(); I != E; ++I) {
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SDNode *P = I->getVal();
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unsigned Degree = P->getNodeId();
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--Degree;
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P->setNodeId(Degree);
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if (Degree == 0)
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Sources.push_back(P);
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// SortedPos tracks the progress of the algorithm. Nodes before it are
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// sorted, nodes after it are unsorted. When the algorithm completes
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// it is at the end of the list.
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allnodes_iterator SortedPos = allnodes_begin();
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// Visit all the nodes. Add nodes with no operands to the TopOrder result
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// array immediately. Annotate nodes that do have operands with their
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// operand count. Before we do this, the Node Id fields of the nodes
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// may contain arbitrary values. After, the Node Id fields for nodes
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// before SortedPos will contain the topological sort index, and the
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// Node Id fields for nodes At SortedPos and after will contain the
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// count of outstanding operands.
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for (allnodes_iterator I = allnodes_begin(),E = allnodes_end(); I != E; ) {
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SDNode *N = I++;
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unsigned Degree = N->getNumOperands();
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if (Degree == 0) {
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// A node with no uses, add it to the result array immediately.
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N->setNodeId(DAGSize++);
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allnodes_iterator Q = N;
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if (Q != SortedPos)
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SortedPos = AllNodes.insert(SortedPos, AllNodes.remove(Q));
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++SortedPos;
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} else {
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// Temporarily use the Node Id as scratch space for the degree count.
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N->setNodeId(Degree);
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}
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}
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return Id;
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// Visit all the nodes. As we iterate, moves nodes into sorted order,
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// such that by the time the end is reached all nodes will be sorted.
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for (allnodes_iterator I = allnodes_begin(),E = allnodes_end(); I != E; ++I) {
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SDNode *N = I;
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for (SDNode::use_iterator UI = N->use_begin(), UE = N->use_end();
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UI != UE; ++UI) {
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SDNode *P = *UI;
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unsigned Degree = P->getNodeId();
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--Degree;
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if (Degree == 0) {
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// All of P's operands are sorted, so P may sorted now.
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P->setNodeId(DAGSize++);
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if (P != SortedPos)
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SortedPos = AllNodes.insert(SortedPos, AllNodes.remove(P));
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++SortedPos;
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} else {
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// Update P's outstanding operand count.
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P->setNodeId(Degree);
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}
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}
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}
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assert(SortedPos == AllNodes.end() &&
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"Topological sort incomplete!");
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assert(AllNodes.front().getOpcode() == ISD::EntryToken &&
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"First node in topological sort is not the entry token!");
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assert(AllNodes.front().getNodeId() == 0 &&
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"First node in topological sort has non-zero id!");
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assert(AllNodes.front().getNumOperands() == 0 &&
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"First node in topological sort has operands!");
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assert(AllNodes.back().getNodeId() == (int)DAGSize-1 &&
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"Last node in topologic sort has unexpected id!");
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assert(AllNodes.back().use_empty() &&
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"Last node in topologic sort has users!");
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assert(DAGSize == allnodes_size() && "TopOrder result count mismatch!");
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return DAGSize;
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}
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@ -269,7 +269,7 @@ static void findNonImmUse(SDNode *Use, SDNode* Def, SDNode *ImmedUse,
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SDNode *Root, bool &found,
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SmallPtrSet<SDNode*, 16> &Visited) {
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if (found ||
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Use->getNodeId() > Def->getNodeId() ||
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Use->getNodeId() < Def->getNodeId() ||
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!Visited.insert(Use))
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return;
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