1 //===- PostDominators.cpp - Post-Dominator Calculation --------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the post-dominator construction algorithms.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Analysis/PostDominators.h"
15 #include "llvm/Instructions.h"
16 #include "llvm/Support/CFG.h"
17 #include "llvm/ADT/DepthFirstIterator.h"
18 #include "llvm/ADT/SetOperations.h"
19 #include "llvm/Analysis/DominatorInternals.h"
22 //===----------------------------------------------------------------------===//
23 // PostDominatorTree Implementation
24 //===----------------------------------------------------------------------===//
26 char PostDominatorTree::ID = 0;
27 char PostDominanceFrontier::ID = 0;
28 static RegisterPass<PostDominatorTree>
29 F("postdomtree", "Post-Dominator Tree Construction", true);
31 bool PostDominatorTree::runOnFunction(Function &F) {
36 //===----------------------------------------------------------------------===//
37 // PostDominanceFrontier Implementation
38 //===----------------------------------------------------------------------===//
40 static RegisterPass<PostDominanceFrontier>
41 H("postdomfrontier", "Post-Dominance Frontier Construction", true);
43 const DominanceFrontier::DomSetType &
44 PostDominanceFrontier::calculate(const PostDominatorTree &DT,
45 const DomTreeNode *Node) {
46 // Loop over CFG successors to calculate DFlocal[Node]
47 BasicBlock *BB = Node->getBlock();
48 DomSetType &S = Frontiers[BB]; // The new set to fill in...
49 if (getRoots().empty()) return S;
52 for (pred_iterator SI = pred_begin(BB), SE = pred_end(BB);
54 // Does Node immediately dominate this predecessor?
55 DomTreeNode *SINode = DT[*SI];
56 if (SINode && SINode->getIDom() != Node)
60 // At this point, S is DFlocal. Now we union in DFup's of our children...
61 // Loop through and visit the nodes that Node immediately dominates (Node's
62 // children in the IDomTree)
64 for (DomTreeNode::const_iterator
65 NI = Node->begin(), NE = Node->end(); NI != NE; ++NI) {
66 DomTreeNode *IDominee = *NI;
67 const DomSetType &ChildDF = calculate(DT, IDominee);
69 DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
70 for (; CDFI != CDFE; ++CDFI) {
71 if (!DT.properlyDominates(Node, DT[*CDFI]))
79 // Ensure that this .cpp file gets linked when PostDominators.h is used.
80 DEFINING_FILE_FOR(PostDominanceFrontier)