//===- PostDominators.cpp - Post-Dominator Calculation --------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
//
// This file implements the post-dominator construction algorithms.
//
#include "llvm/Support/CFG.h"
#include "Support/DepthFirstIterator.h"
#include "Support/SetOperations.h"
+using namespace llvm;
//===----------------------------------------------------------------------===//
// PostDominatorSet Implementation
do {
Changed = false;
- std::set<const BasicBlock*> Visited;
+ std::set<BasicBlock*> Visited;
DomSetType WorkingSet;
for (unsigned i = 0, e = Roots.size(); i != e; ++i)
- for (idf_iterator<BasicBlock*> It = idf_begin(Roots[i]),
- E = idf_end(Roots[i]); It != E; ++It) {
+ for (idf_ext_iterator<BasicBlock*> It = idf_ext_begin(Roots[i], Visited),
+ E = idf_ext_end(Roots[i], Visited); It != E; ++It) {
BasicBlock *BB = *It;
succ_iterator SI = succ_begin(BB), SE = succ_end(BB);
if (SI != SE) { // Is there SOME successor?
static RegisterAnalysis<ImmediatePostDominators>
D("postidom", "Immediate Post-Dominators Construction", true);
+
+// calcIDoms - Calculate the immediate dominator mapping, given a set of
+// dominators for every basic block.
+void ImmediatePostDominators::calcIDoms(const DominatorSetBase &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) {
+ 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;
+ }
+ }
+ }
+}
+
//===----------------------------------------------------------------------===//
// PostDominatorTree Implementation
//===----------------------------------------------------------------------===//
PostDominanceFrontier::calculate(const PostDominatorTree &DT,
const DominatorTree::Node *Node) {
// Loop over CFG successors to calculate DFlocal[Node]
- BasicBlock *BB = Node->getNode();
+ BasicBlock *BB = Node->getBlock();
DomSetType &S = Frontiers[BB]; // The new set to fill in...
if (getRoots().empty()) return S;
if (BB)
for (pred_iterator SI = pred_begin(BB), SE = pred_end(BB);
SI != SE; ++SI)
- // Does Node immediately dominate this predeccessor?
+ // Does Node immediately dominate this predecessor?
if (DT[*SI]->getIDom() != Node)
S.insert(*SI);
// stub - a dummy function to make linking work ok.
void PostDominanceFrontier::stub() {
}
+