Checkin of new dominator calculation routines. These will be improved in
the future to do post dominators and stuff
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/PostDominators.cpp b/lib/Analysis/PostDominators.cpp
new file mode 100644
index 0000000..d648342
--- /dev/null
+++ b/lib/Analysis/PostDominators.cpp
@@ -0,0 +1,239 @@
+//===- DominatorSet.cpp - Dominator Set Calculation --------------*- C++ -*--=//
+//
+// This file provides a simple class to calculate the dominator set of a method.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/CFG.h"
+#include "llvm/Tools/STLExtras.h"
+#include <algorithm>
+
+//===----------------------------------------------------------------------===//
+// Helper Template
+//===----------------------------------------------------------------------===//
+
+// set_intersect - Identical to set_intersection, except that it works on
+// set<>'s and is nicer to use. Functionally, this iterates through S1,
+// removing elements that are not contained in S2.
+//
+template <class Ty, class Ty2>
+void set_intersect(set<Ty> &S1, const set<Ty2> &S2) {
+ for (typename set<Ty>::iterator I = S1.begin(); I != S1.end();) {
+ const Ty &E = *I;
+ ++I;
+ if (!S2.count(E)) S1.erase(E); // Erase element if not in S2
+ }
+}
+
+
+//===----------------------------------------------------------------------===//
+// 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()) {
+ assert(Root && M && "Can't build dominator set of null method!");
+ bool Changed;
+ do {
+ Changed = false;
+
+ DomSetType WorkingSet;
+ df_const_iterator It = df_begin(M), End = df_end(M);
+ for ( ; It != End; ++It) {
+ const BasicBlock *BB = *It;
+ pred_const_iterator PI = pred_begin(BB), PEnd = pred_end(BB);
+ if (PI != PEnd) { // Is there SOME predecessor?
+ // Loop until we get to a predecessor 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 predecessor 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);
+
+}
+
+
+//===----------------------------------------------------------------------===//
+// ImmediateDominators Implementation
+//===----------------------------------------------------------------------===//
+
+// calcIDoms - Calculate the immediate dominator mapping, given a set of
+// dominators for every basic block.
+void cfg::ImmediateDominators::calcIDoms(const DominatorSet &DS) {
+ // Loop over all of the nodes that have dominators... figuring out the IDOM
+ // for each node...
+ //
+ for (DominatorSet::const_iterator DI = DS.begin(), DEnd = DS.end();
+ DI != DEnd; ++DI) {
+ const BasicBlock *BB = DI->first;
+ const DominatorSet::DomSetType &Dominators = DI->second;
+ 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!
+ //
+ 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) {
+ IDoms[BB] = *I;
+ break;
+ }
+ }
+ }
+}
+
+
+//===----------------------------------------------------------------------===//
+// DominatorTree Implementation
+//===----------------------------------------------------------------------===//
+
+// DominatorTree dtor - Free all of the tree node memory.
+//
+cfg::DominatorTree::~DominatorTree() {
+ for (NodeMapType::iterator I = Nodes.begin(), E = Nodes.end(); I != E; ++I)
+ delete I->second;
+}
+
+
+cfg::DominatorTree::DominatorTree(const ImmediateDominators &IDoms)
+ : Root(IDoms.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, *IDom = IDoms[*I];
+
+ if (IDom != 0) { // Ignore the root node and other nasty nodes
+ // We know that the immediate dominator should already have a node,
+ // because we are traversing the CFG in depth first order!
+ //
+ assert(Nodes[IDom] && "No node for IDOM?");
+ Node *IDomNode = Nodes[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));
+ }
+ }
+}
+
+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 (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(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;
+ }
+ }
+ }
+}
+
+
+
+//===----------------------------------------------------------------------===//
+// DominanceFrontier Implementation
+//===----------------------------------------------------------------------===//
+
+const cfg::DominanceFrontier::DomSetType &
+cfg::DominanceFrontier::calcDomFrontier(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 (succ_const_iterator SI = succ_begin(BB), SE = succ_end(BB);
+ SI != SE; ++SI) {
+ // Does Node immediately dominate this successor?
+ 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 = calcDomFrontier(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;
+}