//
// 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 is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/PostDominators.h"
-#include "llvm/Instructions.h"
-#include "llvm/Support/CFG.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SetOperations.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/GenericDomTreeConstruction.h"
using namespace llvm;
+#define DEBUG_TYPE "postdomtree"
+
//===----------------------------------------------------------------------===//
-// PostDominatorSet Implementation
+// PostDominatorTree Implementation
//===----------------------------------------------------------------------===//
-static RegisterAnalysis<PostDominatorSet>
-B("postdomset", "Post-Dominator Set Construction", true);
-
-// Postdominator set construction. This converts the specified function to only
-// have a single exit node (return stmt), then calculates the post dominance
-// sets for the function.
-//
-bool PostDominatorSet::runOnFunction(Function &F) {
- Doms.clear(); // Reset from the last time we were run...
-
- // Scan the function looking for the root nodes of the post-dominance
- // relationships. These blocks end with return and unwind instructions.
- // While we are iterating over the function, we also initialize all of the
- // domsets to empty.
- Roots.clear();
- for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
- Doms[I]; // Initialize to empty
-
- if (succ_begin(I) == succ_end(I))
- Roots.push_back(I);
- }
-
- // If there are no exit nodes for the function, postdomsets are all empty.
- // This can happen if the function just contains an infinite loop, for
- // example.
- if (Roots.empty()) return false;
-
- // If we have more than one root, we insert an artificial "null" exit, which
- // has "virtual edges" to each of the real exit nodes.
- if (Roots.size() > 1)
- Doms[0].insert(0);
-
- bool Changed;
- do {
- Changed = false;
-
- std::set<BasicBlock*> Visited;
- DomSetType WorkingSet;
+char PostDominatorTree::ID = 0;
+INITIALIZE_PASS(PostDominatorTree, "postdomtree",
+ "Post-Dominator Tree Construction", true, true)
- for (unsigned i = 0, e = Roots.size(); i != e; ++i)
- 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?
- // 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[*SI].size() == 0) ++SI;
- WorkingSet = Doms[*SI];
-
- for (++SI; SI != SE; ++SI) { // Intersect all of the successor sets
- DomSetType &SuccSet = Doms[*SI];
- if (SuccSet.size())
- set_intersect(WorkingSet, SuccSet);
- }
- } else {
- // If this node has no successors, it must be one of the root nodes.
- // We will already take care of the notion that the node
- // post-dominates itself. The only thing we have to add is that if
- // there are multiple root nodes, we want to insert a special "null"
- // exit node which dominates the roots as well.
- if (Roots.size() > 1)
- WorkingSet.insert(0);
- }
-
- 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);
+bool PostDominatorTree::runOnFunction(Function &F) {
+ DT->recalculate(F);
return false;
}
-//===----------------------------------------------------------------------===//
-// ImmediatePostDominators Implementation
-//===----------------------------------------------------------------------===//
-
-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::~PostDominatorTree() {
+ delete DT;
}
-//===----------------------------------------------------------------------===//
-// PostDominatorTree Implementation
-//===----------------------------------------------------------------------===//
-
-static RegisterAnalysis<PostDominatorTree>
-F("postdomtree", "Post-Dominator Tree Construction", true);
-
-void PostDominatorTree::calculate(const PostDominatorSet &DS) {
- if (Roots.empty()) return;
- BasicBlock *Root = Roots.size() == 1 ? Roots[0] : 0;
-
- Nodes[Root] = RootNode = new Node(Root, 0); // Add a node for the root...
-
- // Iterate over all nodes in depth first order...
- for (unsigned i = 0, e = Roots.size(); i != e; ++i)
- for (idf_iterator<BasicBlock*> I = idf_begin(Roots[i]),
- E = idf_end(Roots[i]); I != E; ++I) {
- BasicBlock *BB = *I;
- const DominatorSet::DomSetType &Dominators = DS.getDominators(BB);
- unsigned DomSetSize = Dominators.size();
- if (DomSetSize == 1) continue; // Root node... IDom = null
-
- // If we have already computed the immediate dominator for this node,
- // don't revisit. This can happen due to nodes reachable from multiple
- // roots, but which the idf_iterator doesn't know about.
- if (Nodes.find(BB) != Nodes.end()) continue;
-
- // 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 function.
- //
- for (DominatorSet::DomSetType::const_iterator I = Dominators.begin(),
- E = Dominators.end(); I != E; ++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;
- }
- }
- }
+void PostDominatorTree::print(raw_ostream &OS, const Module *) const {
+ DT->print(OS);
}
-//===----------------------------------------------------------------------===//
-// PostDominanceFrontier Implementation
-//===----------------------------------------------------------------------===//
-
-static RegisterAnalysis<PostDominanceFrontier>
-H("postdomfrontier", "Post-Dominance Frontier Construction", true);
-
-const DominanceFrontier::DomSetType &
-PostDominanceFrontier::calculate(const PostDominatorTree &DT,
- const DominatorTree::Node *Node) {
- // Loop over CFG successors to calculate DFlocal[Node]
- 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 predecessor?
- 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 (PostDominatorTree::Node::const_iterator
- NI = Node->begin(), NE = Node->end(); NI != NE; ++NI) {
- DominatorTree::Node *IDominee = *NI;
- const DomSetType &ChildDF = calculate(DT, IDominee);
-
- DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
- for (; CDFI != CDFE; ++CDFI) {
- if (!Node->properlyDominates(DT[*CDFI]))
- S.insert(*CDFI);
- }
- }
-
- return S;
-}
-// stub - a dummy function to make linking work ok.
-void PostDominanceFrontier::stub() {
+FunctionPass* llvm::createPostDomTree() {
+ return new PostDominatorTree();
}
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