121 lines
4.0 KiB
C++
121 lines
4.0 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 "PostDominatorCalculation.h"
|
|
using namespace llvm;
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// PostDominatorTree Implementation
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
char PostDominatorTree::ID = 0;
|
|
char PostDominanceFrontier::ID = 0;
|
|
static RegisterPass<PostDominatorTree>
|
|
F("postdomtree", "Post-Dominator Tree Construction", true);
|
|
|
|
unsigned PostDominatorTree::DFSPass(BasicBlock *V, unsigned N) {
|
|
std::vector<BasicBlock *> workStack;
|
|
SmallPtrSet<BasicBlock *, 32> Visited;
|
|
workStack.push_back(V);
|
|
|
|
do {
|
|
BasicBlock *currentBB = workStack.back();
|
|
InfoRec &CurVInfo = Info[currentBB];
|
|
|
|
// Visit each block only once.
|
|
if (Visited.insert(currentBB)) {
|
|
CurVInfo.Semi = ++N;
|
|
CurVInfo.Label = currentBB;
|
|
|
|
Vertex.push_back(currentBB); // Vertex[n] = current;
|
|
// Info[currentBB].Ancestor = 0;
|
|
// Ancestor[n] = 0
|
|
// Child[currentBB] = 0;
|
|
CurVInfo.Size = 1; // Size[currentBB] = 1
|
|
}
|
|
|
|
// Visit children
|
|
bool visitChild = false;
|
|
for (pred_iterator PI = pred_begin(currentBB), PE = pred_end(currentBB);
|
|
PI != PE && !visitChild; ++PI) {
|
|
InfoRec &SuccVInfo = Info[*PI];
|
|
if (SuccVInfo.Semi == 0) {
|
|
SuccVInfo.Parent = currentBB;
|
|
if (!Visited.count(*PI)) {
|
|
workStack.push_back(*PI);
|
|
visitChild = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
// If all children are visited or if this block has no child then pop this
|
|
// block out of workStack.
|
|
if (!visitChild)
|
|
workStack.pop_back();
|
|
|
|
} while (!workStack.empty());
|
|
|
|
return N;
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// 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)
|