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 //===----------------------------------------------------------------------===//
41 // PostDominanceFrontier Implementation
42 //===----------------------------------------------------------------------===//
44 static RegisterPass<PostDominanceFrontier>
45 H("postdomfrontier", "Post-Dominance Frontier Construction", true, true);
47 const DominanceFrontier::DomSetType &
48 PostDominanceFrontier::calculate(const PostDominatorTree &DT,
49 const DomTreeNode *Node) {
50 // Loop over CFG successors to calculate DFlocal[Node]
51 BasicBlock *BB = Node->getBlock();
52 DomSetType &S = Frontiers[BB]; // The new set to fill in...
53 if (getRoots().empty()) return S;
56 for (pred_iterator SI = pred_begin(BB), SE = pred_end(BB);
58 // Does Node immediately dominate this predecessor?
59 DomTreeNode *SINode = DT[*SI];
60 if (SINode && SINode->getIDom() != Node)
64 // At this point, S is DFlocal. Now we union in DFup's of our children...
65 // Loop through and visit the nodes that Node immediately dominates (Node's
66 // children in the IDomTree)
68 for (DomTreeNode::const_iterator
69 NI = Node->begin(), NE = Node->end(); NI != NE; ++NI) {
70 DomTreeNode *IDominee = *NI;
71 const DomSetType &ChildDF = calculate(DT, IDominee);
73 DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
74 for (; CDFI != CDFE; ++CDFI) {
75 if (!DT.properlyDominates(Node, DT[*CDFI]))
83 // Ensure that this .cpp file gets linked when PostDominators.h is used.
84 DEFINING_FILE_FOR(PostDominanceFrontier)