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 static RegisterPass<PostDominatorTree>
32 F("postdomtree", "Post-Dominator Tree Construction", true, true);
34 bool PostDominatorTree::runOnFunction(Function &F) {
40 PostDominatorTree::~PostDominatorTree()
45 //===----------------------------------------------------------------------===//
46 // PostDominanceFrontier Implementation
47 //===----------------------------------------------------------------------===//
49 static RegisterPass<PostDominanceFrontier>
50 H("postdomfrontier", "Post-Dominance Frontier Construction", true, true);
52 const DominanceFrontier::DomSetType &
53 PostDominanceFrontier::calculate(const PostDominatorTree &DT,
54 const DomTreeNode *Node) {
55 // Loop over CFG successors to calculate DFlocal[Node]
56 BasicBlock *BB = Node->getBlock();
57 DomSetType &S = Frontiers[BB]; // The new set to fill in...
58 if (getRoots().empty()) return S;
61 for (pred_iterator SI = pred_begin(BB), SE = pred_end(BB);
63 // Does Node immediately dominate this predecessor?
64 DomTreeNode *SINode = DT[*SI];
65 if (SINode && SINode->getIDom() != Node)
69 // At this point, S is DFlocal. Now we union in DFup's of our children...
70 // Loop through and visit the nodes that Node immediately dominates (Node's
71 // children in the IDomTree)
73 for (DomTreeNode::const_iterator
74 NI = Node->begin(), NE = Node->end(); NI != NE; ++NI) {
75 DomTreeNode *IDominee = *NI;
76 const DomSetType &ChildDF = calculate(DT, IDominee);
78 DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
79 for (; CDFI != CDFE; ++CDFI) {
80 if (!DT.properlyDominates(Node, DT[*CDFI]))