llvm-6502/lib/Analysis/PostDominators.cpp
Owen Anderson 9cb7f49ee9 Completely merge the implementation details of DomTree and PostDomTree.
Also, add a FIXME for a bug in PostDomTree calculation I noticed while writing this,


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42593 91177308-0d34-0410-b5e6-96231b3b80d8
2007-10-03 21:25:45 +00:00

99 lines
3.4 KiB
C++

//===- PostDominators.cpp - Post-Dominator Calculation --------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the post-dominator construction algorithms.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/PostDominators.h"
#include "llvm/Instructions.h"
#include "llvm/Support/CFG.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/Analysis/DominatorInternals.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
// PostDominatorTree Implementation
//===----------------------------------------------------------------------===//
char PostDominatorTree::ID = 0;
char PostDominanceFrontier::ID = 0;
static RegisterPass<PostDominatorTree>
F("postdomtree", "Post-Dominator Tree Construction", true);
bool PostDominatorTree::runOnFunction(Function &F) {
reset(); // Reset from the last time we were run...
// Initialize the roots list
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
TerminatorInst *Insn = I->getTerminator();
if (Insn->getNumSuccessors() == 0) {
// Unreachable block is not a root node.
if (!isa<UnreachableInst>(Insn))
Roots.push_back(I);
}
// Prepopulate maps so that we don't get iterator invalidation issues later.
IDoms[I] = 0;
DomTreeNodes[I] = 0;
}
Vertex.push_back(0);
Calculate<Inverse<BasicBlock*> >(*this, F);
return false;
}
//===----------------------------------------------------------------------===//
// PostDominanceFrontier Implementation
//===----------------------------------------------------------------------===//
static RegisterPass<PostDominanceFrontier>
H("postdomfrontier", "Post-Dominance Frontier Construction", true);
const DominanceFrontier::DomSetType &
PostDominanceFrontier::calculate(const PostDominatorTree &DT,
const DomTreeNode *Node) {
// Loop over CFG successors to calculate DFlocal[Node]
BasicBlock *BB = Node->getBlock();
DomSetType &S = Frontiers[BB]; // The new set to fill in...
if (getRoots().empty()) return S;
if (BB)
for (pred_iterator SI = pred_begin(BB), SE = pred_end(BB);
SI != SE; ++SI) {
// Does Node immediately dominate this predecessor?
DomTreeNode *SINode = DT[*SI];
if (SINode && SINode->getIDom() != Node)
S.insert(*SI);
}
// At this point, S is DFlocal. Now we union in DFup's of our children...
// Loop through and visit the nodes that Node immediately dominates (Node's
// children in the IDomTree)
//
for (DomTreeNode::const_iterator
NI = Node->begin(), NE = Node->end(); NI != NE; ++NI) {
DomTreeNode *IDominee = *NI;
const DomSetType &ChildDF = calculate(DT, IDominee);
DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
for (; CDFI != CDFE; ++CDFI) {
if (!DT.properlyDominates(Node, DT[*CDFI]))
S.insert(*CDFI);
}
}
return S;
}
// Ensure that this .cpp file gets linked when PostDominators.h is used.
DEFINING_FILE_FOR(PostDominanceFrontier)