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 #define DEBUG_TYPE "postdomtree"
16 #include "llvm/Analysis/PostDominators.h"
17 #include "llvm/Instructions.h"
18 #include "llvm/Support/CFG.h"
19 #include "llvm/Support/Debug.h"
20 #include "llvm/ADT/DepthFirstIterator.h"
21 #include "llvm/ADT/SetOperations.h"
22 #include "llvm/Analysis/DominatorInternals.h"
25 //===----------------------------------------------------------------------===//
26 // PostDominatorTree Implementation
27 //===----------------------------------------------------------------------===//
29 char PostDominatorTree::ID = 0;
30 char PostDominanceFrontier::ID = 0;
31 INITIALIZE_PASS(PostDominatorTree, "postdomtree",
32 "Post-Dominator Tree Construction", true, true)
34 bool PostDominatorTree::runOnFunction(Function &F) {
39 PostDominatorTree::~PostDominatorTree() {
43 void PostDominatorTree::print(raw_ostream &OS, const Module *) const {
48 FunctionPass* llvm::createPostDomTree() {
49 return new PostDominatorTree();
52 //===----------------------------------------------------------------------===//
53 // PostDominanceFrontier Implementation
54 //===----------------------------------------------------------------------===//
56 INITIALIZE_PASS_BEGIN(PostDominanceFrontier, "postdomfrontier",
57 "Post-Dominance Frontier Construction", true, true)
58 INITIALIZE_PASS_DEPENDENCY(PostDominatorTree)
59 INITIALIZE_PASS_END(PostDominanceFrontier, "postdomfrontier",
60 "Post-Dominance Frontier Construction", true, true)
62 const DominanceFrontier::DomSetType &
63 PostDominanceFrontier::calculate(const PostDominatorTree &DT,
64 const DomTreeNode *Node) {
65 // Loop over CFG successors to calculate DFlocal[Node]
66 BasicBlock *BB = Node->getBlock();
67 DomSetType &S = Frontiers[BB]; // The new set to fill in...
68 if (getRoots().empty()) return S;
71 for (pred_iterator SI = pred_begin(BB), SE = pred_end(BB);
74 // Does Node immediately dominate this predecessor?
75 DomTreeNode *SINode = DT[P];
76 if (SINode && SINode->getIDom() != Node)
80 // At this point, S is DFlocal. Now we union in DFup's of our children...
81 // Loop through and visit the nodes that Node immediately dominates (Node's
82 // children in the IDomTree)
84 for (DomTreeNode::const_iterator
85 NI = Node->begin(), NE = Node->end(); NI != NE; ++NI) {
86 DomTreeNode *IDominee = *NI;
87 const DomSetType &ChildDF = calculate(DT, IDominee);
89 DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
90 for (; CDFI != CDFE; ++CDFI) {
91 if (!DT.properlyDominates(Node, DT[*CDFI]))
99 FunctionPass* llvm::createPostDomFrontier() {
100 return new PostDominanceFrontier();