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Factor out cycle-finder code and make it generic.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71241 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -88,10 +88,8 @@ public:
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/// U can be folded during instruction selection that starts at Root and
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/// folding N is profitable.
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virtual
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bool IsLegalAndProfitableToFold(SDNode *N, SDNode *U, SDNode *Root) const {
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return true;
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}
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bool IsLegalAndProfitableToFold(SDNode *N, SDNode *U, SDNode *Root) const;
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/// CreateTargetHazardRecognizer - Return a newly allocated hazard recognizer
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/// to use for this target when scheduling the DAG.
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virtual ScheduleHazardRecognizer *CreateTargetHazardRecognizer();
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@ -1203,4 +1203,120 @@ SelectInlineAsmMemoryOperands(std::vector<SDValue> &Ops) {
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Ops.push_back(InOps.back());
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}
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/// findFlagUse - Return use of MVT::Flag value produced by the specified
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/// SDNode.
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///
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static SDNode *findFlagUse(SDNode *N) {
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unsigned FlagResNo = N->getNumValues()-1;
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for (SDNode::use_iterator I = N->use_begin(), E = N->use_end(); I != E; ++I) {
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SDUse &Use = I.getUse();
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if (Use.getResNo() == FlagResNo)
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return Use.getUser();
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}
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return NULL;
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}
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/// findNonImmUse - Return true if "Use" is a non-immediate use of "Def".
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/// This function recursively traverses up the operand chain, ignoring
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/// certain nodes.
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static bool findNonImmUse(SDNode *Use, SDNode* Def, SDNode *ImmedUse,
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SDNode *Root,
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SmallPtrSet<SDNode*, 16> &Visited) {
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if (Use->getNodeId() < Def->getNodeId() ||
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!Visited.insert(Use))
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return false;
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for (unsigned i = 0, e = Use->getNumOperands(); i != e; ++i) {
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SDNode *N = Use->getOperand(i).getNode();
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if (N == Def) {
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if (Use == ImmedUse || Use == Root)
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continue; // We are not looking for immediate use.
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assert(N != Root);
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return true;
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}
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// Traverse up the operand chain.
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if (findNonImmUse(N, Def, ImmedUse, Root, Visited))
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return true;
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}
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return false;
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}
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/// isNonImmUse - Start searching from Root up the DAG to check is Def can
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/// be reached. Return true if that's the case. However, ignore direct uses
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/// by ImmedUse (which would be U in the example illustrated in
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/// IsLegalAndProfitableToFold) and by Root (which can happen in the store
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/// case).
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/// FIXME: to be really generic, we should allow direct use by any node
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/// that is being folded. But realisticly since we only fold loads which
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/// have one non-chain use, we only need to watch out for load/op/store
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/// and load/op/cmp case where the root (store / cmp) may reach the load via
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/// its chain operand.
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static inline bool isNonImmUse(SDNode *Root, SDNode *Def, SDNode *ImmedUse) {
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SmallPtrSet<SDNode*, 16> Visited;
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return findNonImmUse(Root, Def, ImmedUse, Root, Visited);
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}
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/// IsLegalAndProfitableToFold - Returns true if the specific operand node N of
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/// U can be folded during instruction selection that starts at Root and
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/// folding N is profitable.
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bool SelectionDAGISel::IsLegalAndProfitableToFold(SDNode *N, SDNode *U,
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SDNode *Root) const {
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if (OptLevel == CodeGenOpt::None) return false;
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// If Root use can somehow reach N through a path that that doesn't contain
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// U then folding N would create a cycle. e.g. In the following
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// diagram, Root can reach N through X. If N is folded into into Root, then
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// X is both a predecessor and a successor of U.
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//
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// [N*] //
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// ^ ^ //
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// / \ //
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// [U*] [X]? //
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// ^ ^ //
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// \ / //
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// \ / //
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// [Root*] //
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//
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// * indicates nodes to be folded together.
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//
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// If Root produces a flag, then it gets (even more) interesting. Since it
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// will be "glued" together with its flag use in the scheduler, we need to
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// check if it might reach N.
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//
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// [N*] //
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// ^ ^ //
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// / \ //
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// [U*] [X]? //
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// ^ ^ //
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// \ \ //
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// \ | //
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// [Root*] | //
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// ^ | //
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// f | //
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// | / //
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// [Y] / //
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// ^ / //
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// f / //
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// | / //
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// [FU] //
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//
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// If FU (flag use) indirectly reaches N (the load), and Root folds N
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// (call it Fold), then X is a predecessor of FU and a successor of
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// Fold. But since Fold and FU are flagged together, this will create
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// a cycle in the scheduling graph.
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MVT VT = Root->getValueType(Root->getNumValues()-1);
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while (VT == MVT::Flag) {
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SDNode *FU = findFlagUse(Root);
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if (FU == NULL)
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break;
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Root = FU;
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VT = Root->getValueType(Root->getNumValues()-1);
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}
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return !isNonImmUse(Root, N, U);
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}
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char SelectionDAGISel::ID = 0;
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@ -249,60 +249,6 @@ namespace {
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};
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}
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/// findFlagUse - Return use of MVT::Flag value produced by the specified
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/// SDNode.
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///
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static SDNode *findFlagUse(SDNode *N) {
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unsigned FlagResNo = N->getNumValues()-1;
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for (SDNode::use_iterator I = N->use_begin(), E = N->use_end(); I != E; ++I) {
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SDUse &Use = I.getUse();
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if (Use.getResNo() == FlagResNo)
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return Use.getUser();
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}
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return NULL;
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}
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/// findNonImmUse - Return true if "Use" is a non-immediate use of "Def".
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/// This function recursively traverses up the operand chain, ignoring
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/// certain nodes.
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static bool findNonImmUse(SDNode *Use, SDNode* Def, SDNode *ImmedUse,
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SDNode *Root,
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SmallPtrSet<SDNode*, 16> &Visited) {
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if (Use->getNodeId() < Def->getNodeId() ||
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!Visited.insert(Use))
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return false;
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for (unsigned i = 0, e = Use->getNumOperands(); i != e; ++i) {
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SDNode *N = Use->getOperand(i).getNode();
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if (N == Def) {
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if (Use == ImmedUse || Use == Root)
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continue; // We are not looking for immediate use.
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assert(N != Root);
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return true;
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}
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// Traverse up the operand chain.
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if (findNonImmUse(N, Def, ImmedUse, Root, Visited))
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return true;
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}
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return false;
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}
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/// isNonImmUse - Start searching from Root up the DAG to check is Def can
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/// be reached. Return true if that's the case. However, ignore direct uses
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/// by ImmedUse (which would be U in the example illustrated in
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/// IsLegalAndProfitableToFold) and by Root (which can happen in the store
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/// case).
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/// FIXME: to be really generic, we should allow direct use by any node
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/// that is being folded. But realisticly since we only fold loads which
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/// have one non-chain use, we only need to watch out for load/op/store
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/// and load/op/cmp case where the root (store / cmp) may reach the load via
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/// its chain operand.
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static inline bool isNonImmUse(SDNode *Root, SDNode *Def, SDNode *ImmedUse) {
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SmallPtrSet<SDNode*, 16> Visited;
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return findNonImmUse(Root, Def, ImmedUse, Root, Visited);
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}
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bool X86DAGToDAGISel::IsLegalAndProfitableToFold(SDNode *N, SDNode *U,
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SDNode *Root) const {
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@ -351,58 +297,8 @@ bool X86DAGToDAGISel::IsLegalAndProfitableToFold(SDNode *N, SDNode *U,
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}
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}
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// If Root use can somehow reach N through a path that that doesn't contain
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// U then folding N would create a cycle. e.g. In the following
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// diagram, Root can reach N through X. If N is folded into into Root, then
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// X is both a predecessor and a successor of U.
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//
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// [N*] //
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// ^ ^ //
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// / \ //
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// [U*] [X]? //
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// ^ ^ //
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// \ / //
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// \ / //
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// [Root*] //
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//
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// * indicates nodes to be folded together.
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//
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// If Root produces a flag, then it gets (even more) interesting. Since it
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// will be "glued" together with its flag use in the scheduler, we need to
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// check if it might reach N.
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//
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// [N*] //
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// ^ ^ //
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// / \ //
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// [U*] [X]? //
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// ^ ^ //
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// \ \ //
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// \ | //
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// [Root*] | //
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// ^ | //
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// f | //
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// | / //
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// [Y] / //
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// ^ / //
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// f / //
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// | / //
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// [FU] //
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//
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// If FU (flag use) indirectly reaches N (the load), and Root folds N
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// (call it Fold), then X is a predecessor of FU and a successor of
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// Fold. But since Fold and FU are flagged together, this will create
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// a cycle in the scheduling graph.
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MVT VT = Root->getValueType(Root->getNumValues()-1);
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while (VT == MVT::Flag) {
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SDNode *FU = findFlagUse(Root);
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if (FU == NULL)
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break;
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Root = FU;
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VT = Root->getValueType(Root->getNumValues()-1);
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}
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return !isNonImmUse(Root, N, U);
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// Proceed to 'generic' cycle finder code
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return SelectionDAGISel::IsLegalAndProfitableToFold(N, U, Root);
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}
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/// MoveBelowTokenFactor - Replace TokenFactor operand with load's chain operand
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