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/Assembly/Writer.h"
23 #include "llvm/Analysis/DominatorInternals.h"
26 //===----------------------------------------------------------------------===//
27 // PostDominatorTree Implementation
28 //===----------------------------------------------------------------------===//
30 char PostDominatorTree::ID = 0;
31 char PostDominanceFrontier::ID = 0;
32 INITIALIZE_PASS(PostDominatorTree, "postdomtree",
33 "Post-Dominator Tree Construction", true, true)
35 bool PostDominatorTree::runOnFunction(Function &F) {
40 PostDominatorTree::~PostDominatorTree() {
44 void PostDominatorTree::print(raw_ostream &OS, const Module *) const {
49 FunctionPass* llvm::createPostDomTree() {
50 return new PostDominatorTree();
53 //===----------------------------------------------------------------------===//
54 // PostDominanceFrontier Implementation
55 //===----------------------------------------------------------------------===//
57 INITIALIZE_PASS_BEGIN(PostDominanceFrontier, "postdomfrontier",
58 "Post-Dominance Frontier Construction", true, true)
59 INITIALIZE_PASS_DEPENDENCY(PostDominatorTree)
60 INITIALIZE_PASS_END(PostDominanceFrontier, "postdomfrontier",
61 "Post-Dominance Frontier Construction", true, true)
63 const DominanceFrontier::DomSetType &
64 PostDominanceFrontier::calculate(const PostDominatorTree &DT,
65 const DomTreeNode *Node) {
66 // Loop over CFG successors to calculate DFlocal[Node]
67 BasicBlock *BB = Node->getBlock();
68 DomSetType &S = Frontiers[BB]; // The new set to fill in...
69 if (getRoots().empty()) return S;
72 for (pred_iterator SI = pred_begin(BB), SE = pred_end(BB);
75 // Does Node immediately dominate this predecessor?
76 DomTreeNode *SINode = DT[P];
77 if (SINode && SINode->getIDom() != Node)
81 // At this point, S is DFlocal. Now we union in DFup's of our children...
82 // Loop through and visit the nodes that Node immediately dominates (Node's
83 // children in the IDomTree)
85 for (DomTreeNode::const_iterator
86 NI = Node->begin(), NE = Node->end(); NI != NE; ++NI) {
87 DomTreeNode *IDominee = *NI;
88 const DomSetType &ChildDF = calculate(DT, IDominee);
90 DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
91 for (; CDFI != CDFE; ++CDFI) {
92 if (!DT.properlyDominates(Node, DT[*CDFI]))
100 FunctionPass* llvm::createPostDomFrontier() {
101 return new PostDominanceFrontier();