1 //===- PostDominators.cpp - Post-Dominator Calculation --------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source 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) {
32 reset(); // Reset from the last time we were run...
34 // Initialize the roots list
35 for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
36 TerminatorInst *Insn = I->getTerminator();
37 if (Insn->getNumSuccessors() == 0) {
38 // Unreachable block is not a root node.
39 if (!isa<UnreachableInst>(Insn))
43 // Prepopulate maps so that we don't get iterator invalidation issues later.
50 Calculate<Inverse<BasicBlock*>, GraphTraits<Inverse<BasicBlock*> > >(*this, F);
54 //===----------------------------------------------------------------------===//
55 // PostDominanceFrontier Implementation
56 //===----------------------------------------------------------------------===//
58 static RegisterPass<PostDominanceFrontier>
59 H("postdomfrontier", "Post-Dominance Frontier Construction", true);
61 const DominanceFrontier::DomSetType &
62 PostDominanceFrontier::calculate(const PostDominatorTree &DT,
63 const DomTreeNode *Node) {
64 // Loop over CFG successors to calculate DFlocal[Node]
65 BasicBlock *BB = Node->getBlock();
66 DomSetType &S = Frontiers[BB]; // The new set to fill in...
67 if (getRoots().empty()) return S;
70 for (pred_iterator SI = pred_begin(BB), SE = pred_end(BB);
72 // Does Node immediately dominate this predecessor?
73 DomTreeNode *SINode = DT[*SI];
74 if (SINode && SINode->getIDom() != Node)
78 // At this point, S is DFlocal. Now we union in DFup's of our children...
79 // Loop through and visit the nodes that Node immediately dominates (Node's
80 // children in the IDomTree)
82 for (DomTreeNode::const_iterator
83 NI = Node->begin(), NE = Node->end(); NI != NE; ++NI) {
84 DomTreeNode *IDominee = *NI;
85 const DomSetType &ChildDF = calculate(DT, IDominee);
87 DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
88 for (; CDFI != CDFE; ++CDFI) {
89 if (!DT.properlyDominates(Node, DT[*CDFI]))
97 // Ensure that this .cpp file gets linked when PostDominators.h is used.
98 DEFINING_FILE_FOR(PostDominanceFrontier)