//===----------------------------------------------------------------------===//
#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/SimplifyCFG.h" // To get cfg::UnifyAllExitNodes
#include "llvm/CFG.h"
#include "llvm/Tools/STLExtras.h"
#include <algorithm>
}
}
+//===----------------------------------------------------------------------===//
+// DominatorBase Implementation
+//===----------------------------------------------------------------------===//
+
+bool cfg::DominatorBase::isPostDominator() const {
+ return Root != Root->getParent()->front();
+}
+
//===----------------------------------------------------------------------===//
// DominatorSet Implementation
// DominatorSet ctor - Build either the dominator set or the post-dominator
// set for a method...
//
-cfg::DominatorSet::DominatorSet(const Method *M, bool PostDomSet)
- : Root(M->front()) {
+cfg::DominatorSet::DominatorSet(const Method *M) : DominatorBase(M->front()) {
+ calcForwardDominatorSet(M);
+}
+
+// calcForwardDominatorSet - This method calculates the forward dominator sets
+// for the specified method.
+//
+void cfg::DominatorSet::calcForwardDominatorSet(const Method *M) {
assert(Root && M && "Can't build dominator set of null method!");
bool Changed;
do {
WorkingSet.clear(); // Clear out the set for next iteration
}
} while (Changed);
+}
+
+// Postdominator set constructor. This ctor converts the specified method to
+// only have a single exit node (return stmt), then calculates the post
+// dominance sets for the method.
+//
+cfg::DominatorSet::DominatorSet(Method *M, bool PostDomSet)
+ : DominatorBase(M->front()) {
+ if (!PostDomSet) { calcForwardDominatorSet(M); return; }
+
+ Root = cfg::UnifyAllExitNodes(M);
+ assert(Root && "TODO: Don't handle case where there are no exit nodes yet!");
+ bool Changed;
+ do {
+ Changed = false;
+
+ set<const BasicBlock*> Visited;
+ DomSetType WorkingSet;
+ idf_const_iterator It = idf_begin(Root), End = idf_end(Root);
+ for ( ; It != End; ++It) {
+ const BasicBlock *BB = *It;
+ succ_const_iterator PI = succ_begin(BB), PEnd = succ_end(BB);
+ if (PI != PEnd) { // Is there SOME predecessor?
+ // Loop until we get to a successor that has had it's dom set filled
+ // in at least once. We are guaranteed to have this because we are
+ // traversing the graph in DFO and have handled start nodes specially.
+ //
+ while (Doms[*PI].size() == 0) ++PI;
+ WorkingSet = Doms[*PI];
+
+ for (++PI; PI != PEnd; ++PI) { // Intersect all of the successor sets
+ DomSetType &PredSet = Doms[*PI];
+ if (PredSet.size())
+ set_intersect(WorkingSet, PredSet);
+ }
+ }
+
+ WorkingSet.insert(BB); // A block always dominates itself
+ DomSetType &BBSet = Doms[BB];
+ if (BBSet != WorkingSet) {
+ BBSet.swap(WorkingSet); // Constant time operation!
+ Changed = true; // The sets changed.
+ }
+ WorkingSet.clear(); // Clear out the set for next iteration
+ }
+ } while (Changed);
}
cfg::DominatorTree::DominatorTree(const ImmediateDominators &IDoms)
- : Root(IDoms.getRoot()) {
- assert(Root && Root->getParent() && "No method for IDoms?");
+ : DominatorBase(IDoms.getRoot()) {
const Method *M = Root->getParent();
Nodes[Root] = new Node(Root, 0); // Add a node for the root...
}
void cfg::DominatorTree::calculate(const DominatorSet &DS) {
- Root = DS.getRoot();
- assert(Root && Root->getParent() && "No method for IDoms?");
- const Method *M = Root->getParent();
Nodes[Root] = new Node(Root, 0); // Add a node for the root...
- // Iterate over all nodes in depth first order...
- for (df_const_iterator I = df_begin(M), E = df_end(M); I != E; ++I) {
- const BasicBlock *BB = *I;
- const DominatorSet::DomSetType &Dominators = DS.getDominators(BB);
- unsigned DomSetSize = Dominators.size();
- if (DomSetSize == 1) continue; // Root node... IDom = null
-
- // Loop over all dominators of this node. This corresponds to looping over
- // nodes in the dominator chain, looking for a node whose dominator set is
- // equal to the current nodes, except that the current node does not exist
- // in it. This means that it is one level higher in the dom chain than the
- // current node, and it is our idom! We know that we have already added
- // a DominatorTree node for our idom, because the idom must be a
- // predecessor in the depth first order that we are iterating through the
- // method.
- //
- DominatorSet::DomSetType::const_iterator I = Dominators.begin();
- DominatorSet::DomSetType::const_iterator End = Dominators.end();
- for (; I != End; ++I) { // Iterate over dominators...
- // All of our dominators should form a chain, where the number of elements
- // in the dominator set indicates what level the node is at in the chain.
- // We want the node immediately above us, so it will have an identical
- // dominator set, except that BB will not dominate it... therefore it's
- // dominator set size will be one less than BB's...
+ if (!isPostDominator()) {
+ // Iterate over all nodes in depth first order...
+ for (df_const_iterator I = df_begin(Root), E = df_end(Root); I != E; ++I) {
+ const BasicBlock *BB = *I;
+ const DominatorSet::DomSetType &Dominators = DS.getDominators(BB);
+ unsigned DomSetSize = Dominators.size();
+ if (DomSetSize == 1) continue; // Root node... IDom = null
+
+ // Loop over all dominators of this node. This corresponds to looping over
+ // nodes in the dominator chain, looking for a node whose dominator set is
+ // equal to the current nodes, except that the current node does not exist
+ // in it. This means that it is one level higher in the dom chain than the
+ // current node, and it is our idom! We know that we have already added
+ // a DominatorTree node for our idom, because the idom must be a
+ // predecessor in the depth first order that we are iterating through the
+ // method.
//
- if (DS.getDominators(*I).size() == DomSetSize - 1) {
- // We know that the immediate dominator should already have a node,
- // because we are traversing the CFG in depth first order!
+ DominatorSet::DomSetType::const_iterator I = Dominators.begin();
+ DominatorSet::DomSetType::const_iterator End = Dominators.end();
+ for (; I != End; ++I) { // Iterate over dominators...
+ // All of our dominators should form a chain, where the number of elements
+ // in the dominator set indicates what level the node is at in the chain.
+ // We want the node immediately above us, so it will have an identical
+ // dominator set, except that BB will not dominate it... therefore it's
+ // dominator set size will be one less than BB's...
//
- Node *IDomNode = Nodes[*I];
- assert(Nodes[*I] && "No node for IDOM?");
-
- // Add a new tree node for this BasicBlock, and link it as a child of
- // IDomNode
- Nodes[BB] = IDomNode->addChild(new Node(BB, IDomNode));
- break;
+ if (DS.getDominators(*I).size() == DomSetSize - 1) {
+ // We know that the immediate dominator should already have a node,
+ // because we are traversing the CFG in depth first order!
+ //
+ Node *IDomNode = Nodes[*I];
+ assert(IDomNode && "No node for IDOM?");
+
+ // Add a new tree node for this BasicBlock, and link it as a child of
+ // IDomNode
+ Nodes[BB] = IDomNode->addChild(new Node(BB, IDomNode));
+ break;
+ }
+ }
+ }
+ } else {
+ // Iterate over all nodes in depth first order...
+ for (idf_const_iterator I = idf_begin(Root), E = idf_end(Root); I != E; ++I) {
+ const BasicBlock *BB = *I;
+ const DominatorSet::DomSetType &Dominators = DS.getDominators(BB);
+ unsigned DomSetSize = Dominators.size();
+ if (DomSetSize == 1) continue; // Root node... IDom = null
+
+ // Loop over all dominators of this node. This corresponds to looping over
+ // nodes in the dominator chain, looking for a node whose dominator set is
+ // equal to the current nodes, except that the current node does not exist
+ // in it. This means that it is one level higher in the dom chain than the
+ // current node, and it is our idom! We know that we have already added
+ // a DominatorTree node for our idom, because the idom must be a
+ // predecessor in the depth first order that we are iterating through the
+ // method.
+ //
+ DominatorSet::DomSetType::const_iterator I = Dominators.begin();
+ DominatorSet::DomSetType::const_iterator End = Dominators.end();
+ for (; I != End; ++I) { // Iterate over dominators...
+ // All of our dominators should form a chain, where the number of elements
+ // in the dominator set indicates what level the node is at in the chain.
+ // We want the node immediately above us, so it will have an identical
+ // dominator set, except that BB will not dominate it... therefore it's
+ // dominator set size will be one less than BB's...
+ //
+ if (DS.getDominators(*I).size() == DomSetSize - 1) {
+ // We know that the immediate dominator should already have a node,
+ // because we are traversing the CFG in depth first order!
+ //
+ Node *IDomNode = Nodes[*I];
+ assert(IDomNode && "No node for IDOM?");
+
+ // Add a new tree node for this BasicBlock, and link it as a child of
+ // IDomNode
+ Nodes[BB] = IDomNode->addChild(new Node(BB, IDomNode));
+ break;
+ }
}
}
}
return S;
}
+
+const cfg::DominanceFrontier::DomSetType &
+cfg::DominanceFrontier::calcPostDomFrontier(const DominatorTree &DT,
+ const DominatorTree::Node *Node) {
+ // Loop over CFG successors to calculate DFlocal[Node]
+ const BasicBlock *BB = Node->getNode();
+ DomSetType &S = Frontiers[BB]; // The new set to fill in...
+
+ for (pred_const_iterator SI = pred_begin(BB), SE = pred_end(BB);
+ SI != SE; ++SI) {
+ // Does Node immediately dominate this predeccessor?
+ if (DT[*SI]->getIDom() != Node)
+ S.insert(*SI);
+ }
+
+ // At this point, S is DFlocal. Now we union in DFup's of our children...
+ // Loop through and visit the nodes that Node immediately dominates (Node's
+ // children in the IDomTree)
+ //
+ for (DominatorTree::Node::const_iterator NI = Node->begin(), NE = Node->end();
+ NI != NE; ++NI) {
+ DominatorTree::Node *IDominee = *NI;
+ const DomSetType &ChildDF = calcPostDomFrontier(DT, IDominee);
+
+ DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
+ for (; CDFI != CDFE; ++CDFI) {
+ if (!Node->dominates(DT[*CDFI]))
+ S.insert(*CDFI);
+ }
+ }
+
+ return S;
+}
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