NodeT *TheBB;
DomTreeNodeBase *IDom;
+ unsigned Level;
std::vector<DomTreeNodeBase *> Children;
mutable unsigned DFSNumIn = ~0;
mutable unsigned DFSNumOut = ~0;
public:
- DomTreeNodeBase(NodeT *BB, DomTreeNodeBase *iDom) : TheBB(BB), IDom(iDom) {}
+ DomTreeNodeBase(NodeT *BB, DomTreeNodeBase *iDom)
+ : TheBB(BB), IDom(iDom), Level(IDom ? IDom->Level + 1 : 0) {}
using iterator = typename std::vector<DomTreeNodeBase *>::iterator;
using const_iterator =
NodeT *getBlock() const { return TheBB; }
DomTreeNodeBase *getIDom() const { return IDom; }
+ unsigned getLevel() const { return Level; }
const std::vector<DomTreeNodeBase *> &getChildren() const { return Children; }
if (getNumChildren() != Other->getNumChildren())
return true;
+ if (Level != Other->Level) return true;
+
SmallPtrSet<const NodeT *, 4> OtherChildren;
for (const DomTreeNodeBase *I : *Other) {
const NodeT *Nd = I->getBlock();
void setIDom(DomTreeNodeBase *NewIDom) {
assert(IDom && "No immediate dominator?");
- if (IDom != NewIDom) {
- typename std::vector<DomTreeNodeBase *>::iterator I =
- find(IDom->Children, this);
- assert(I != IDom->Children.end() &&
- "Not in immediate dominator children set!");
- // I am no longer your child...
- IDom->Children.erase(I);
+ if (IDom == NewIDom) return;
- // Switch to new dominator
- IDom = NewIDom;
- IDom->Children.push_back(this);
- }
+ auto I = find(IDom->Children, this);
+ assert(I != IDom->Children.end() &&
+ "Not in immediate dominator children set!");
+ // I am no longer your child...
+ IDom->Children.erase(I);
+
+ // Switch to new dominator
+ IDom = NewIDom;
+ IDom->Children.push_back(this);
+
+ UpdateLevel();
}
/// getDFSNumIn/getDFSNumOut - These return the DFS visitation order for nodes
return this->DFSNumIn >= other->DFSNumIn &&
this->DFSNumOut <= other->DFSNumOut;
}
+
+ void UpdateLevel() {
+ assert(IDom);
+ if (Level == IDom->Level + 1) return;
+
+ SmallVector<DomTreeNodeBase *, 64> WorkStack = {this};
+
+ while (!WorkStack.empty()) {
+ DomTreeNodeBase *Current = WorkStack.pop_back_val();
+ Current->Level = Current->IDom->Level + 1;
+
+ for (DomTreeNodeBase *C : *Current) {
+ assert(C->IDom);
+ if (C->Level != C->IDom->Level + 1) WorkStack.push_back(C);
+ }
+ }
+ }
};
template <class NodeT>
else
O << " <<exit node>>";
- O << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "}";
+ O << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "} ["
+ << Node->getLevel() << "]\n";
- return O << "\n";
+ return O;
}
template <class NodeT>
if (!isReachableFromEntry(A))
return false;
+ if (B->getIDom() == A) return true;
+
+ if (A->getIDom() == B) return false;
+
+ // A can only dominate B if it is higher in the tree.
+ if (A->getLevel() >= B->getLevel()) return false;
+
// Compare the result of the tree walk and the dfs numbers, if expensive
// checks are enabled.
#ifdef EXPENSIVE_CHECKS
/// findNearestCommonDominator - Find nearest common dominator basic block
/// for basic block A and B. If there is no such block then return NULL.
- NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) {
+ NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) const {
assert(A->getParent() == B->getParent() &&
"Two blocks are not in same function");
return &Entry;
}
- // If B dominates A then B is nearest common dominator.
- if (dominates(B, A))
- return B;
-
- // If A dominates B then A is nearest common dominator.
- if (dominates(A, B))
- return A;
-
DomTreeNodeBase<NodeT> *NodeA = getNode(A);
DomTreeNodeBase<NodeT> *NodeB = getNode(B);
- // If we have DFS info, then we can avoid all allocations by just querying
- // it from each IDom. Note that because we call 'dominates' twice above, we
- // expect to call through this code at most 16 times in a row without
- // building valid DFS information. This is important as below is a *very*
- // slow tree walk.
- if (DFSInfoValid) {
- DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom();
- while (IDomA) {
- if (NodeB->DominatedBy(IDomA))
- return IDomA->getBlock();
- IDomA = IDomA->getIDom();
- }
- return nullptr;
- }
+ if (!NodeA || !NodeB) return nullptr;
- // Collect NodeA dominators set.
- SmallPtrSet<DomTreeNodeBase<NodeT> *, 16> NodeADoms;
- NodeADoms.insert(NodeA);
- DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom();
- while (IDomA) {
- NodeADoms.insert(IDomA);
- IDomA = IDomA->getIDom();
- }
-
- // Walk NodeB immediate dominators chain and find common dominator node.
- DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom();
- while (IDomB) {
- if (NodeADoms.count(IDomB) != 0)
- return IDomB->getBlock();
+ // Use level information to go up the tree until the levels match. Then
+ // continue going up til we arrive at the same node.
+ while (NodeA && NodeA != NodeB) {
+ if (NodeA->getLevel() < NodeB->getLevel()) std::swap(NodeA, NodeB);
- IDomB = IDomB->getIDom();
+ NodeA = NodeA->IDom;
}
- return nullptr;
+ return NodeA ? NodeA->getBlock() : nullptr;
}
- const NodeT *findNearestCommonDominator(const NodeT *A, const NodeT *B) {
+ const NodeT *findNearestCommonDominator(const NodeT *A,
+ const NodeT *B) const {
// Cast away the const qualifiers here. This is ok since
// const is re-introduced on the return type.
return findNearestCommonDominator(const_cast<NodeT *>(A),
} else {
assert(Roots.size() == 1);
NodeT *OldRoot = Roots.front();
- DomTreeNodes[OldRoot] =
- NewNode->addChild(std::move(DomTreeNodes[OldRoot]));
+ auto &OldNode = DomTreeNodes[OldRoot];
+ OldNode = NewNode->addChild(std::move(DomTreeNodes[OldRoot]));
+ OldNode->IDom = NewNode;
+ OldNode->UpdateLevel();
Roots[0] = BB;
}
return RootNode = NewNode;
}
void doFullDFSWalk(const DomTreeT &DT) {
+ NumToNode.push_back(nullptr);
unsigned Num = 0;
for (auto *Root : DT.Roots)
if (!DT.isPostDominator())
return true;
}
+
+ // Check if for every parent with a level L in the tree all of its children
+ // have level L + 1.
+ static bool VerifyLevels(const DomTreeT &DT) {
+ for (auto &NodeToTN : DT.DomTreeNodes) {
+ const TreeNodePtr TN = NodeToTN.second.get();
+ const NodePtr BB = TN->getBlock();
+ if (!BB) continue;
+
+ const TreeNodePtr IDom = TN->getIDom();
+ if (!IDom && TN->getLevel() != 0) {
+ errs() << "Node without an IDom ";
+ PrintBlockOrNullptr(errs(), BB);
+ errs() << " has a nonzero level " << TN->getLevel() << "!\n";
+ errs().flush();
+
+ return false;
+ }
+
+ if (IDom && TN->getLevel() != IDom->getLevel() + 1) {
+ errs() << "Node ";
+ PrintBlockOrNullptr(errs(), BB);
+ errs() << " has level " << TN->getLevel() << " while it's IDom ";
+ PrintBlockOrNullptr(errs(), IDom->getBlock());
+ errs() << " has level " << IDom->getLevel() << "!\n";
+ errs().flush();
+
+ return false;
+ }
+ }
+
+ return true;
+ }
+
+ // Checks if for every edge From -> To in the graph
+ // NCD(From, To) == IDom(To) or To.
+ bool verifyNCD(const DomTreeT &DT) {
+ clear();
+ doFullDFSWalk(DT);
+
+ for (auto &BlockToInfo : NodeToInfo) {
+ auto &Info = BlockToInfo.second;
+
+ const NodePtr From = NumToNode[Info.Parent];
+ if (!From) continue;
+
+ const NodePtr To = BlockToInfo.first;
+ const TreeNodePtr ToTN = DT.getNode(To);
+ assert(ToTN);
+
+ const NodePtr NCD = DT.findNearestCommonDominator(From, To);
+ const TreeNodePtr NCDTN = NCD ? DT.getNode(NCD) : nullptr;
+ const TreeNodePtr ToIDom = ToTN->getIDom();
+ if (NCDTN != ToTN && NCDTN != ToIDom) {
+ errs() << "NearestCommonDominator verification failed:\n\tNCD(From:";
+ PrintBlockOrNullptr(errs(), From);
+ errs() << ", To:";
+ PrintBlockOrNullptr(errs(), To);
+ errs() << ") = ";
+ PrintBlockOrNullptr(errs(), NCD);
+ errs() << ",\t (should be To or IDom[To]: ";
+ PrintBlockOrNullptr(errs(), ToIDom ? ToIDom->getBlock() : nullptr);
+ errs() << ")\n";
+ errs().flush();
+
+ return false;
+ }
+ }
+
+ return true;
+ }
+
// The below routines verify the correctness of the dominator tree relative to
// the CFG it's coming from. A tree is a dominator tree iff it has two
// properties, called the parent property and the sibling property. Tarjan
"NodePtr should be a pointer type");
SemiNCAInfo<typename std::remove_pointer<NodePtr>::type> SNCA;
- return SNCA.verifyReachability(DT) && SNCA.verifyParentProperty(DT) &&
+ return SNCA.verifyReachability(DT) && SNCA.VerifyLevels(DT) &&
+ SNCA.verifyNCD(DT) && SNCA.verifyParentProperty(DT) &&
SNCA.verifySiblingProperty(DT);
-
}
} // namespace DomTreeBuilder
EXPECT_EQ(DT->getNode(BB4)->getDFSNumIn(), 3UL);
EXPECT_EQ(DT->getNode(BB4)->getDFSNumOut(), 4UL);
+ // Check levels before
+ EXPECT_EQ(DT->getNode(BB0)->getLevel(), 0U);
+ EXPECT_EQ(DT->getNode(BB1)->getLevel(), 1U);
+ EXPECT_EQ(DT->getNode(BB2)->getLevel(), 1U);
+ EXPECT_EQ(DT->getNode(BB4)->getLevel(), 1U);
+
// Reattach block 3 to block 1 and recalculate
BB1->getTerminator()->eraseFromParent();
BranchInst::Create(BB4, BB3, ConstantInt::getTrue(F.getContext()), BB1);
EXPECT_EQ(DT->getNode(BB4)->getDFSNumIn(), 5UL);
EXPECT_EQ(DT->getNode(BB4)->getDFSNumOut(), 6UL);
+ // Check levels after
+ EXPECT_EQ(DT->getNode(BB0)->getLevel(), 0U);
+ EXPECT_EQ(DT->getNode(BB1)->getLevel(), 1U);
+ EXPECT_EQ(DT->getNode(BB2)->getLevel(), 1U);
+ EXPECT_EQ(DT->getNode(BB3)->getLevel(), 2U);
+ EXPECT_EQ(DT->getNode(BB4)->getLevel(), 1U);
+
// Change root node
DT->verifyDomTree();
BasicBlock *NewEntry =
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