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[Dominators] Move SemiNCAInfo and helper functions out of DominatorTr…
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…eeBase

Summary:
This moves SemiNCAInfo from DeminatorTreeBase to GenericDomTreeConstruction. It also put helper functions used during tree constructions in the same file.

The point of this change is to further clean up DominatorTreeBase and make it easier to construct and verify (in future patches).

Reviewers: dberlin, sanjoy, chandlerc

Reviewed By: dberlin

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D34420

llvm-svn: 306576
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@kuhar
kuhar committed Jun 28, 2017
1 parent d9bc43e commit be9931d
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Showing 2 changed files with 88 additions and 96 deletions.
74 changes: 12 additions & 62 deletions llvm/include/llvm/Support/GenericDomTree.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -201,6 +201,11 @@ void PrintDomTree(const DomTreeNodeBase<NodeT> *N, raw_ostream &O,
PrintDomTree<NodeT>(*I, O, Lev + 1);
}

namespace DomTreeBuilder {
template <class NodeT>
struct SemiNCAInfo;
} // namespace DomTreeBuilder

// The calculate routine is provided in a separate header but referenced here.
template <class FuncT, class N>
void Calculate(DominatorTreeBaseByGraphTraits<GraphTraits<N>> &DT, FuncT &F);
Expand Down Expand Up @@ -648,69 +653,14 @@ template <class NodeT> class DominatorTreeBase : public DominatorBase<NodeT> {
}

protected:
// Information record used by Semi-NCA during tree construction.
struct SemiNCAInfo {
using NodePtr = NodeT *;
struct InfoRec {
unsigned DFSNum = 0;
unsigned Parent = 0;
unsigned Semi = 0;
NodePtr Label = nullptr;
NodePtr IDom = nullptr;
};

std::vector<NodePtr> NumToNode;
DenseMap<NodePtr, InfoRec> NodeToInfo;

NodeT *getIDom(NodeT *BB) const {
auto InfoIt = NodeToInfo.find(BB);
if (InfoIt == NodeToInfo.end()) return nullptr;

return InfoIt->second.IDom;
}
};

template <class GraphT>
friend typename GraphT::NodeRef Eval(
DominatorTreeBaseByGraphTraits<GraphT> &DT, typename GraphT::NodeRef V,
typename DominatorTreeBaseByGraphTraits<GraphT>::SemiNCAInfo &Info,
unsigned LastLinked);

template <class GraphT>
friend unsigned ReverseDFSPass(
DominatorTreeBaseByGraphTraits<GraphT> &DT, typename GraphT::NodeRef V,
typename DominatorTreeBaseByGraphTraits<GraphT>::SemiNCAInfo &Info,
unsigned N);

template <class GraphT>
friend unsigned DFSPass(
DominatorTreeBaseByGraphTraits<GraphT> &DT, typename GraphT::NodeRef V,
typename DominatorTreeBaseByGraphTraits<GraphT>::SemiNCAInfo &Info,
unsigned N);

template <class FuncT, class N>
friend void Calculate(DominatorTreeBaseByGraphTraits<GraphTraits<N>> &DT,
FuncT &F);

DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB,
const SemiNCAInfo& SNCAInfo) {
if (DomTreeNodeBase<NodeT> *Node = getNode(BB))
return Node;

// Haven't calculated this node yet? Get or calculate the node for the
// immediate dominator.
NodeT *IDom = SNCAInfo.getIDom(BB);

assert(IDom || DomTreeNodes[nullptr]);
DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom, SNCAInfo);

// Add a new tree node for this NodeT, and link it as a child of
// IDomNode
return (DomTreeNodes[BB] = IDomNode->addChild(
llvm::make_unique<DomTreeNodeBase<NodeT>>(BB, IDomNode))).get();
}
friend struct DomTreeBuilder::SemiNCAInfo<NodeT>;
using SNCAInfoTy = DomTreeBuilder::SemiNCAInfo<NodeT>;

template <class FuncT, class NodeTy>
friend void Calculate(DominatorTreeBaseByGraphTraits<GraphTraits<NodeTy>> &DT,
FuncT &F);

void addRoot(NodeT *BB) { this->Roots.push_back(BB); }
void addRoot(NodeT *BB) { this->Roots.push_back(BB); }

public:
/// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
Expand Down
110 changes: 76 additions & 34 deletions llvm/include/llvm/Support/GenericDomTreeConstruction.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,54 @@

namespace llvm {

namespace DomTreeBuilder {
// Information record used by Semi-NCA during tree construction.
template <typename NodeT>
struct SemiNCAInfo {
using NodePtr = NodeT *;
using DomTreeT = DominatorTreeBase<NodeT>;
using TreeNodePtr = DomTreeNodeBase<NodeT> *;

struct InfoRec {
unsigned DFSNum = 0;
unsigned Parent = 0;
unsigned Semi = 0;
NodePtr Label = nullptr;
NodePtr IDom = nullptr;
};

DomTreeT &DT;
std::vector<NodePtr> NumToNode;
DenseMap<NodePtr, InfoRec> NodeToInfo;

SemiNCAInfo(DomTreeT &DT) : DT(DT) {}

NodePtr getIDom(NodePtr BB) const {
auto InfoIt = NodeToInfo.find(BB);
if (InfoIt == NodeToInfo.end()) return nullptr;

return InfoIt->second.IDom;
}

TreeNodePtr getNodeForBlock(NodePtr BB) {
if (TreeNodePtr Node = DT.getNode(BB)) return Node;

// Haven't calculated this node yet? Get or calculate the node for the
// immediate dominator.
NodePtr IDom = getIDom(BB);

assert(IDom || DT.DomTreeNodes[nullptr]);
TreeNodePtr IDomNode = getNodeForBlock(IDom);

// Add a new tree node for this NodeT, and link it as a child of
// IDomNode
return (DT.DomTreeNodes[BB] = IDomNode->addChild(
llvm::make_unique<DomTreeNodeBase<NodeT>>(BB, IDomNode)))
.get();
}
};
} // namespace DomTreeBuilder

// External storage for depth first iterator that reuses the info lookup map
// domtree already has. We don't have a set, but a map instead, so we are
// converting the one argument insert calls.
Expand All @@ -49,20 +97,18 @@ template <class NodeRef, class InfoType> struct df_iterator_dom_storage {
BaseSet &Storage;
};

template <class GraphT>
unsigned ReverseDFSPass(
DominatorTreeBaseByGraphTraits<GraphT> &DT, typename GraphT::NodeRef V,
typename DominatorTreeBaseByGraphTraits<GraphT>::SemiNCAInfo &SNCA,
unsigned N) {
using SNCAInfoTy = typename std::remove_reference<decltype(SNCA)>::type;
df_iterator_dom_storage<typename SNCAInfoTy::NodePtr,
typename SNCAInfoTy::InfoRec>
DFStorage(SNCA.NodeToInfo);
template <class NodePtr,
class NodeT = typename std::remove_pointer<NodePtr>::type>
unsigned ReverseDFSPass(NodePtr V, DomTreeBuilder::SemiNCAInfo<NodeT> &SNCA,
unsigned N) {
using SNCAInfoTy = DomTreeBuilder::SemiNCAInfo<NodeT>;
df_iterator_dom_storage<NodePtr, typename SNCAInfoTy::InfoRec> DFStorage(
SNCA.NodeToInfo);

bool IsChildOfArtificialExit = (N != 0);
for (auto I = idf_ext_begin(V, DFStorage), E = idf_ext_end(V, DFStorage);
I != E; ++I) {
typename GraphT::NodeRef BB = *I;
NodePtr BB = *I;
auto &BBInfo = SNCA.NodeToInfo[BB];
BBInfo.DFSNum = BBInfo.Semi = ++N;
BBInfo.Label = BB;
Expand All @@ -79,18 +125,17 @@ unsigned ReverseDFSPass(
}
return N;
}
template <class GraphT>
unsigned DFSPass(
DominatorTreeBaseByGraphTraits<GraphT> &DT, typename GraphT::NodeRef V,
typename DominatorTreeBaseByGraphTraits<GraphT>::SemiNCAInfo &SNCA,
unsigned N) {
using SNCAInfoTy = typename std::remove_reference<decltype(SNCA)>::type;
df_iterator_dom_storage<typename SNCAInfoTy::NodePtr,
typename SNCAInfoTy::InfoRec>
DFStorage(SNCA.NodeToInfo);

template <class NodePtr,
class NodeT = typename std::remove_pointer<NodePtr>::type>
unsigned DFSPass(NodePtr V, DomTreeBuilder::SemiNCAInfo<NodeT> &SNCA, unsigned N) {
using SNCAInfoTy = DomTreeBuilder::SemiNCAInfo<NodeT>;
df_iterator_dom_storage<NodePtr, typename SNCAInfoTy::InfoRec> DFStorage(
SNCA.NodeToInfo);

for (auto I = df_ext_begin(V, DFStorage), E = df_ext_end(V, DFStorage);
I != E; ++I) {
typename GraphT::NodeRef BB = *I;
NodePtr BB = *I;
auto &BBInfo = SNCA.NodeToInfo[BB];
BBInfo.DFSNum = BBInfo.Semi = ++N;
BBInfo.Label = BB;
Expand All @@ -103,13 +148,10 @@ unsigned DFSPass(
return N;
}

template <class GraphT>
typename GraphT::NodeRef Eval(
DominatorTreeBaseByGraphTraits<GraphT> &DT, typename GraphT::NodeRef VIn,
typename DominatorTreeBaseByGraphTraits<GraphT>::SemiNCAInfo &SNCA,
unsigned LastLinked) {
using NodePtr = typename GraphT::NodeRef;

template <class NodePtr,
class NodeT = typename std::remove_pointer<NodePtr>::type>
NodePtr Eval(NodePtr VIn, DomTreeBuilder::SemiNCAInfo<NodeT> &SNCA,
unsigned LastLinked) {
auto &VInInfo = SNCA.NodeToInfo[VIn];
if (VInInfo.DFSNum < LastLinked)
return VIn;
Expand Down Expand Up @@ -153,11 +195,11 @@ void Calculate(DominatorTreeBaseByGraphTraits<GraphTraits<NodeT>> &DT,
using GraphT = GraphTraits<NodeT>;
using NodePtr = typename GraphT::NodeRef;
static_assert(std::is_pointer<NodePtr>::value,
"NodeRef should be pointer type");
"NodePtr should be a pointer type");
using NodeType = typename std::remove_pointer<NodePtr>::type;

unsigned N = 0;
typename DominatorTreeBaseByGraphTraits<GraphT>::SemiNCAInfo SNCA;
DomTreeBuilder::SemiNCAInfo<NodeType> SNCA(DT);
SNCA.NumToNode.push_back(nullptr);

bool MultipleRoots = (DT.Roots.size() > 1);
Expand All @@ -174,9 +216,9 @@ void Calculate(DominatorTreeBaseByGraphTraits<GraphTraits<NodeT>> &DT,
if (DT.isPostDominator()){
for (unsigned i = 0, e = static_cast<unsigned>(DT.Roots.size());
i != e; ++i)
N = ReverseDFSPass<GraphT>(DT, DT.Roots[i], SNCA, N);
N = ReverseDFSPass<NodePtr>(DT.Roots[i], SNCA, N);
} else {
N = DFSPass<GraphT>(DT, DT.Roots[0], SNCA, N);
N = DFSPass<NodePtr>(DT.Roots[0], SNCA, N);
}

// It might be that some blocks did not get a DFS number (e.g., blocks of
Expand All @@ -199,7 +241,7 @@ void Calculate(DominatorTreeBaseByGraphTraits<GraphTraits<NodeT>> &DT,
WInfo.Semi = WInfo.Parent;
for (const auto &N : inverse_children<NodeT>(W))
if (SNCA.NodeToInfo.count(N)) { // Only if this predecessor is reachable!
unsigned SemiU = SNCA.NodeToInfo[Eval<GraphT>(DT, N, SNCA, i + 1)].Semi;
unsigned SemiU = SNCA.NodeToInfo[Eval<NodePtr>(N, SNCA, i + 1)].Semi;
if (SemiU < WInfo.Semi)
WInfo.Semi = SemiU;
}
Expand Down Expand Up @@ -247,7 +289,7 @@ void Calculate(DominatorTreeBaseByGraphTraits<GraphTraits<NodeT>> &DT,
assert(ImmDom || DT.DomTreeNodes[nullptr]);

// Get or calculate the node for the immediate dominator
DomTreeNodeBase<NodeType> *IDomNode = DT.getNodeForBlock(ImmDom, SNCA);
DomTreeNodeBase<NodeType> *IDomNode = SNCA.getNodeForBlock(ImmDom);

// Add a new tree node for this BasicBlock, and link it as a child of
// IDomNode
Expand All @@ -257,6 +299,6 @@ void Calculate(DominatorTreeBaseByGraphTraits<GraphTraits<NodeT>> &DT,

DT.updateDFSNumbers();
}
}
} // namespace DomTreeBuilder

#endif

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