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llvm-6502/lib/VMCore/Dominators.cpp
Devang Patel cbdfb8a9d5 DominanceFrontier::calculate(). 
Avoid recursion, Use iterative algorithm.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35225 91177308-0d34-0410-b5e6-96231b3b80d8
2007-03-20 21:25:31 +00:00

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//===- Dominators.cpp - 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 simple dominator construction algorithms for finding
// forward dominators. Postdominators are available in libanalysis, but are not
// included in libvmcore, because it's not needed. Forward dominators are
// needed to support the Verifier pass.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/Dominators.h"
#include "llvm/Support/CFG.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SetOperations.h"
#include <algorithm>
using namespace llvm;
//===----------------------------------------------------------------------===//
// ImmediateDominators Implementation
//===----------------------------------------------------------------------===//
//
// Immediate Dominators construction - This pass constructs immediate dominator
// information for a flow-graph based on the algorithm described in this
// document:
//
// A Fast Algorithm for Finding Dominators in a Flowgraph
// T. Lengauer & R. Tarjan, ACM TOPLAS July 1979, pgs 121-141.
//
// This implements both the O(n*ack(n)) and the O(n*log(n)) versions of EVAL and
// LINK, but it turns out that the theoretically slower O(n*log(n))
// implementation is actually faster than the "efficient" algorithm (even for
// large CFGs) because the constant overheads are substantially smaller. The
// lower-complexity version can be enabled with the following #define:
//
#define BALANCE_IDOM_TREE 0
//
//===----------------------------------------------------------------------===//
static RegisterPass<ImmediateDominators>
C("idom", "Immediate Dominators Construction", true);
namespace {
class DFCalculateWorkObject {
public:
DFCalculateWorkObject(BasicBlock *B, BasicBlock *P,
const DominatorTree::Node *N,
const DominatorTree::Node *PN)
: currentBB(B), parentBB(P), Node(N), parentNode(PN) {}
BasicBlock *currentBB;
BasicBlock *parentBB;
const DominatorTree::Node *Node;
const DominatorTree::Node *parentNode;
};
}
unsigned ImmediateDominators::DFSPass(BasicBlock *V, InfoRec &VInfo,
unsigned N) {
VInfo.Semi = ++N;
VInfo.Label = V;
Vertex.push_back(V); // Vertex[n] = V;
//Info[V].Ancestor = 0; // Ancestor[n] = 0
//Child[V] = 0; // Child[v] = 0
VInfo.Size = 1; // Size[v] = 1
for (succ_iterator SI = succ_begin(V), E = succ_end(V); SI != E; ++SI) {
InfoRec &SuccVInfo = Info[*SI];
if (SuccVInfo.Semi == 0) {
SuccVInfo.Parent = V;
N = DFSPass(*SI, SuccVInfo, N);
}
}
return N;
}
void ImmediateDominators::Compress(BasicBlock *V, InfoRec &VInfo) {
BasicBlock *VAncestor = VInfo.Ancestor;
InfoRec &VAInfo = Info[VAncestor];
if (VAInfo.Ancestor == 0)
return;
Compress(VAncestor, VAInfo);
BasicBlock *VAncestorLabel = VAInfo.Label;
BasicBlock *VLabel = VInfo.Label;
if (Info[VAncestorLabel].Semi < Info[VLabel].Semi)
VInfo.Label = VAncestorLabel;
VInfo.Ancestor = VAInfo.Ancestor;
}
BasicBlock *ImmediateDominators::Eval(BasicBlock *V) {
InfoRec &VInfo = Info[V];
#if !BALANCE_IDOM_TREE
// Higher-complexity but faster implementation
if (VInfo.Ancestor == 0)
return V;
Compress(V, VInfo);
return VInfo.Label;
#else
// Lower-complexity but slower implementation
if (VInfo.Ancestor == 0)
return VInfo.Label;
Compress(V, VInfo);
BasicBlock *VLabel = VInfo.Label;
BasicBlock *VAncestorLabel = Info[VInfo.Ancestor].Label;
if (Info[VAncestorLabel].Semi >= Info[VLabel].Semi)
return VLabel;
else
return VAncestorLabel;
#endif
}
void ImmediateDominators::Link(BasicBlock *V, BasicBlock *W, InfoRec &WInfo){
#if !BALANCE_IDOM_TREE
// Higher-complexity but faster implementation
WInfo.Ancestor = V;
#else
// Lower-complexity but slower implementation
BasicBlock *WLabel = WInfo.Label;
unsigned WLabelSemi = Info[WLabel].Semi;
BasicBlock *S = W;
InfoRec *SInfo = &Info[S];
BasicBlock *SChild = SInfo->Child;
InfoRec *SChildInfo = &Info[SChild];
while (WLabelSemi < Info[SChildInfo->Label].Semi) {
BasicBlock *SChildChild = SChildInfo->Child;
if (SInfo->Size+Info[SChildChild].Size >= 2*SChildInfo->Size) {
SChildInfo->Ancestor = S;
SInfo->Child = SChild = SChildChild;
SChildInfo = &Info[SChild];
} else {
SChildInfo->Size = SInfo->Size;
S = SInfo->Ancestor = SChild;
SInfo = SChildInfo;
SChild = SChildChild;
SChildInfo = &Info[SChild];
}
}
InfoRec &VInfo = Info[V];
SInfo->Label = WLabel;
assert(V != W && "The optimization here will not work in this case!");
unsigned WSize = WInfo.Size;
unsigned VSize = (VInfo.Size += WSize);
if (VSize < 2*WSize)
std::swap(S, VInfo.Child);
while (S) {
SInfo = &Info[S];
SInfo->Ancestor = V;
S = SInfo->Child;
}
#endif
}
bool ImmediateDominators::runOnFunction(Function &F) {
IDoms.clear(); // Reset from the last time we were run...
BasicBlock *Root = &F.getEntryBlock();
Roots.clear();
Roots.push_back(Root);
Vertex.push_back(0);
// Step #1: Number blocks in depth-first order and initialize variables used
// in later stages of the algorithm.
unsigned N = 0;
for (unsigned i = 0, e = Roots.size(); i != e; ++i)
N = DFSPass(Roots[i], Info[Roots[i]], 0);
for (unsigned i = N; i >= 2; --i) {
BasicBlock *W = Vertex[i];
InfoRec &WInfo = Info[W];
// Step #2: Calculate the semidominators of all vertices
for (pred_iterator PI = pred_begin(W), E = pred_end(W); PI != E; ++PI)
if (Info.count(*PI)) { // Only if this predecessor is reachable!
unsigned SemiU = Info[Eval(*PI)].Semi;
if (SemiU < WInfo.Semi)
WInfo.Semi = SemiU;
}
Info[Vertex[WInfo.Semi]].Bucket.push_back(W);
BasicBlock *WParent = WInfo.Parent;
Link(WParent, W, WInfo);
// Step #3: Implicitly define the immediate dominator of vertices
std::vector<BasicBlock*> &WParentBucket = Info[WParent].Bucket;
while (!WParentBucket.empty()) {
BasicBlock *V = WParentBucket.back();
WParentBucket.pop_back();
BasicBlock *U = Eval(V);
IDoms[V] = Info[U].Semi < Info[V].Semi ? U : WParent;
}
}
// Step #4: Explicitly define the immediate dominator of each vertex
for (unsigned i = 2; i <= N; ++i) {
BasicBlock *W = Vertex[i];
BasicBlock *&WIDom = IDoms[W];
if (WIDom != Vertex[Info[W].Semi])
WIDom = IDoms[WIDom];
}
// Free temporary memory used to construct idom's
Info.clear();
std::vector<BasicBlock*>().swap(Vertex);
return false;
}
/// dominates - Return true if A dominates B.
///
bool ImmediateDominatorsBase::dominates(BasicBlock *A, BasicBlock *B) const {
assert(A && B && "Null pointers?");
// Walk up the dominator tree from B to determine if A dom B.
while (A != B && B)
B = get(B);
return A == B;
}
void ImmediateDominatorsBase::print(std::ostream &o, const Module* ) const {
Function *F = getRoots()[0]->getParent();
for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
o << " Immediate Dominator For Basic Block:";
WriteAsOperand(o, I, false);
o << " is:";
if (BasicBlock *ID = get(I))
WriteAsOperand(o, ID, false);
else
o << " <<exit node>>";
o << "\n";
}
o << "\n";
}
//===----------------------------------------------------------------------===//
// DominatorSet Implementation
//===----------------------------------------------------------------------===//
static RegisterPass<DominatorSet>
B("domset", "Dominator Set Construction", true);
// dominates - Return true if A dominates B. This performs the special checks
// necessary if A and B are in the same basic block.
//
bool DominatorSetBase::dominates(Instruction *A, Instruction *B) const {
BasicBlock *BBA = A->getParent(), *BBB = B->getParent();
if (BBA != BBB) return dominates(BBA, BBB);
// Loop through the basic block until we find A or B.
BasicBlock::iterator I = BBA->begin();
for (; &*I != A && &*I != B; ++I) /*empty*/;
if(!IsPostDominators) {
// A dominates B if it is found first in the basic block.
return &*I == A;
} else {
// A post-dominates B if B is found first in the basic block.
return &*I == B;
}
}
// runOnFunction - This method calculates the forward dominator sets for the
// specified function.
//
bool DominatorSet::runOnFunction(Function &F) {
BasicBlock *Root = &F.getEntryBlock();
Roots.clear();
Roots.push_back(Root);
assert(pred_begin(Root) == pred_end(Root) &&
"Root node has predecessors in function!");
ImmediateDominators &ID = getAnalysis<ImmediateDominators>();
Doms.clear();
if (Roots.empty()) return false;
// Root nodes only dominate themselves.
for (unsigned i = 0, e = Roots.size(); i != e; ++i)
Doms[Roots[i]].insert(Roots[i]);
// Loop over all of the blocks in the function, calculating dominator sets for
// each function.
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
if (BasicBlock *IDom = ID[I]) { // Get idom if block is reachable
DomSetType &DS = Doms[I];
assert(DS.empty() && "Domset already filled in for this block?");
DS.insert(I); // Blocks always dominate themselves
// Insert all dominators into the set...
while (IDom) {
// If we have already computed the dominator sets for our immediate
// dominator, just use it instead of walking all the way up to the root.
DomSetType &IDS = Doms[IDom];
if (!IDS.empty()) {
DS.insert(IDS.begin(), IDS.end());
break;
} else {
DS.insert(IDom);
IDom = ID[IDom];
}
}
} else {
// Ensure that every basic block has at least an empty set of nodes. This
// is important for the case when there is unreachable blocks.
Doms[I];
}
return false;
}
namespace llvm {
static std::ostream &operator<<(std::ostream &o,
const std::set<BasicBlock*> &BBs) {
for (std::set<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
I != E; ++I)
if (*I)
WriteAsOperand(o, *I, false);
else
o << " <<exit node>>";
return o;
}
}
void DominatorSetBase::print(std::ostream &o, const Module* ) const {
for (const_iterator I = begin(), E = end(); I != E; ++I) {
o << " DomSet For BB: ";
if (I->first)
WriteAsOperand(o, I->first, false);
else
o << " <<exit node>>";
o << " is:\t" << I->second << "\n";
}
}
//===----------------------------------------------------------------------===//
// DominatorTree Implementation
//===----------------------------------------------------------------------===//
static RegisterPass<DominatorTree>
E("domtree", "Dominator Tree Construction", true);
// DominatorTreeBase::reset - Free all of the tree node memory.
//
void DominatorTreeBase::reset() {
for (NodeMapType::iterator I = Nodes.begin(), E = Nodes.end(); I != E; ++I)
delete I->second;
Nodes.clear();
RootNode = 0;
}
void DominatorTreeBase::Node::setIDom(Node *NewIDom) {
assert(IDom && "No immediate dominator?");
if (IDom != NewIDom) {
std::vector<Node*>::iterator I =
std::find(IDom->Children.begin(), IDom->Children.end(), this);
assert(I != IDom->Children.end() &&
"Not in immediate dominator children set!");
// I am no longer your child...
IDom->Children.erase(I);
// Switch to new dominator
IDom = NewIDom;
IDom->Children.push_back(this);
}
}
DominatorTreeBase::Node *DominatorTree::getNodeForBlock(BasicBlock *BB) {
Node *&BBNode = Nodes[BB];
if (BBNode) return BBNode;
// Haven't calculated this node yet? Get or calculate the node for the
// immediate dominator.
BasicBlock *IDom = getAnalysis<ImmediateDominators>()[BB];
Node *IDomNode = getNodeForBlock(IDom);
// Add a new tree node for this BasicBlock, and link it as a child of
// IDomNode
return BBNode = IDomNode->addChild(new Node(BB, IDomNode));
}
void DominatorTree::calculate(const ImmediateDominators &ID) {
assert(Roots.size() == 1 && "DominatorTree should have 1 root block!");
BasicBlock *Root = Roots[0];
Nodes[Root] = RootNode = new Node(Root, 0); // Add a node for the root...
Function *F = Root->getParent();
// Loop over all of the reachable blocks in the function...
for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I)
if (BasicBlock *ImmDom = ID.get(I)) { // Reachable block.
Node *&BBNode = Nodes[I];
if (!BBNode) { // Haven't calculated this node yet?
// Get or calculate the node for the immediate dominator
Node *IDomNode = getNodeForBlock(ImmDom);
// Add a new tree node for this BasicBlock, and link it as a child of
// IDomNode
BBNode = IDomNode->addChild(new Node(I, IDomNode));
}
}
}
static std::ostream &operator<<(std::ostream &o,
const DominatorTreeBase::Node *Node) {
if (Node->getBlock())
WriteAsOperand(o, Node->getBlock(), false);
else
o << " <<exit node>>";
return o << "\n";
}
static void PrintDomTree(const DominatorTreeBase::Node *N, std::ostream &o,
unsigned Lev) {
o << std::string(2*Lev, ' ') << "[" << Lev << "] " << N;
for (DominatorTreeBase::Node::const_iterator I = N->begin(), E = N->end();
I != E; ++I)
PrintDomTree(*I, o, Lev+1);
}
void DominatorTreeBase::print(std::ostream &o, const Module* ) const {
o << "=============================--------------------------------\n"
<< "Inorder Dominator Tree:\n";
PrintDomTree(getRootNode(), o, 1);
}
//===----------------------------------------------------------------------===//
// DominanceFrontier Implementation
//===----------------------------------------------------------------------===//
static RegisterPass<DominanceFrontier>
G("domfrontier", "Dominance Frontier Construction", true);
const DominanceFrontier::DomSetType &
DominanceFrontier::calculate(const DominatorTree &DT,
const DominatorTree::Node *Node) {
BasicBlock *BB = Node->getBlock();
DomSetType *Result = NULL;
std::vector<DFCalculateWorkObject *> workList;
std::set<BasicBlock *> visited;
DFCalculateWorkObject *W = new DFCalculateWorkObject(BB, NULL, Node, NULL);
workList.push_back(W);
do {
DFCalculateWorkObject *currentW = workList.back();
assert (currentW && "Missing work object.");
BasicBlock *currentBB = currentW->currentBB;
BasicBlock *parentBB = currentW->parentBB;
const DominatorTree::Node *currentNode = currentW->Node;
const DominatorTree::Node *parentNode = currentW->parentNode;
assert (currentBB && "Invalid work object. Missing current Basic Block");
assert (currentNode && "Invalid work object. Missing current Node");
DomSetType &S = Frontiers[currentBB];
// Visit each block only once.
if (visited.count(currentBB) == 0) {
visited.insert(currentBB);
// Loop over CFG successors to calculate DFlocal[currentNode]
for (succ_iterator SI = succ_begin(currentBB), SE = succ_end(currentBB);
SI != SE; ++SI) {
// Does Node immediately dominate this successor?
if (DT[*SI]->getIDom() != currentNode)
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)
bool visitChild = false;
for (DominatorTree::Node::const_iterator NI = currentNode->begin(),
NE = currentNode->end(); NI != NE; ++NI) {
DominatorTree::Node *IDominee = *NI;
BasicBlock *childBB = IDominee->getBlock();
if (visited.count(childBB) == 0) {
DFCalculateWorkObject *newW =
new DFCalculateWorkObject(childBB, currentBB, IDominee, currentNode);
workList.push_back(newW);
visitChild = true;
}
}
// If all children are visited or there is any child then pop this block
// from the workList.
if (!visitChild) {
if (!parentBB) {
Result = &S;
break;
}
DomSetType::const_iterator CDFI = S.begin(), CDFE = S.end();
DomSetType &parentSet = Frontiers[parentBB];
for (; CDFI != CDFE; ++CDFI) {
if (!parentNode->properlyDominates(DT[*CDFI]))
parentSet.insert(*CDFI);
}
workList.pop_back();
}
} while (!workList.empty());
return *Result;
}
void DominanceFrontierBase::print(std::ostream &o, const Module* ) const {
for (const_iterator I = begin(), E = end(); I != E; ++I) {
o << " DomFrontier for BB";
if (I->first)
WriteAsOperand(o, I->first, false);
else
o << " <<exit node>>";
o << " is:\t" << I->second << "\n";
}
}
//===----------------------------------------------------------------------===//
// ETOccurrence Implementation
//===----------------------------------------------------------------------===//
void ETOccurrence::Splay() {
ETOccurrence *father;
ETOccurrence *grandfather;
int occdepth;
int fatherdepth;
while (Parent) {
occdepth = Depth;
father = Parent;
fatherdepth = Parent->Depth;
grandfather = father->Parent;
// If we have no grandparent, a single zig or zag will do.
if (!grandfather) {
setDepthAdd(fatherdepth);
MinOccurrence = father->MinOccurrence;
Min = father->Min;
// See what we have to rotate
if (father->Left == this) {
// Zig
father->setLeft(Right);
setRight(father);
if (father->Left)
father->Left->setDepthAdd(occdepth);
} else {
// Zag
father->setRight(Left);
setLeft(father);
if (father->Right)
father->Right->setDepthAdd(occdepth);
}
father->setDepth(-occdepth);
Parent = NULL;
father->recomputeMin();
return;
}
// If we have a grandfather, we need to do some
// combination of zig and zag.
int grandfatherdepth = grandfather->Depth;
setDepthAdd(fatherdepth + grandfatherdepth);
MinOccurrence = grandfather->MinOccurrence;
Min = grandfather->Min;
ETOccurrence *greatgrandfather = grandfather->Parent;
if (grandfather->Left == father) {
if (father->Left == this) {
// Zig zig
grandfather->setLeft(father->Right);
father->setLeft(Right);
setRight(father);
father->setRight(grandfather);
father->setDepth(-occdepth);
if (father->Left)
father->Left->setDepthAdd(occdepth);
grandfather->setDepth(-fatherdepth);
if (grandfather->Left)
grandfather->Left->setDepthAdd(fatherdepth);
} else {
// Zag zig
grandfather->setLeft(Right);
father->setRight(Left);
setLeft(father);
setRight(grandfather);
father->setDepth(-occdepth);
if (father->Right)
father->Right->setDepthAdd(occdepth);
grandfather->setDepth(-occdepth - fatherdepth);
if (grandfather->Left)
grandfather->Left->setDepthAdd(occdepth + fatherdepth);
}
} else {
if (father->Left == this) {
// Zig zag
grandfather->setRight(Left);
father->setLeft(Right);
setLeft(grandfather);
setRight(father);
father->setDepth(-occdepth);
if (father->Left)
father->Left->setDepthAdd(occdepth);
grandfather->setDepth(-occdepth - fatherdepth);
if (grandfather->Right)
grandfather->Right->setDepthAdd(occdepth + fatherdepth);
} else { // Zag Zag
grandfather->setRight(father->Left);
father->setRight(Left);
setLeft(father);
father->setLeft(grandfather);
father->setDepth(-occdepth);
if (father->Right)
father->Right->setDepthAdd(occdepth);
grandfather->setDepth(-fatherdepth);
if (grandfather->Right)
grandfather->Right->setDepthAdd(fatherdepth);
}
}
// Might need one more rotate depending on greatgrandfather.
setParent(greatgrandfather);
if (greatgrandfather) {
if (greatgrandfather->Left == grandfather)
greatgrandfather->Left = this;
else
greatgrandfather->Right = this;
}
grandfather->recomputeMin();
father->recomputeMin();
}
}
//===----------------------------------------------------------------------===//
// ETNode implementation
//===----------------------------------------------------------------------===//
void ETNode::Split() {
ETOccurrence *right, *left;
ETOccurrence *rightmost = RightmostOcc;
ETOccurrence *parent;
// Update the occurrence tree first.
RightmostOcc->Splay();
// Find the leftmost occurrence in the rightmost subtree, then splay
// around it.
for (right = rightmost->Right; right->Left; right = right->Left);
right->Splay();
// Start splitting
right->Left->Parent = NULL;
parent = ParentOcc;
parent->Splay();
ParentOcc = NULL;
left = parent->Left;
parent->Right->Parent = NULL;
right->setLeft(left);
right->recomputeMin();
rightmost->Splay();
rightmost->Depth = 0;
rightmost->Min = 0;
delete parent;
// Now update *our* tree
if (Father->Son == this)
Father->Son = Right;
if (Father->Son == this)
Father->Son = NULL;
else {
Left->Right = Right;
Right->Left = Left;
}
Left = Right = NULL;
Father = NULL;
}
void ETNode::setFather(ETNode *NewFather) {
ETOccurrence *rightmost;
ETOccurrence *leftpart;
ETOccurrence *NewFatherOcc;
ETOccurrence *temp;
// First update the path in the splay tree
NewFatherOcc = new ETOccurrence(NewFather);
rightmost = NewFather->RightmostOcc;
rightmost->Splay();
leftpart = rightmost->Left;
temp = RightmostOcc;
temp->Splay();
NewFatherOcc->setLeft(leftpart);
NewFatherOcc->setRight(temp);
temp->Depth++;
temp->Min++;
NewFatherOcc->recomputeMin();
rightmost->setLeft(NewFatherOcc);
if (NewFatherOcc->Min + rightmost->Depth < rightmost->Min) {
rightmost->Min = NewFatherOcc->Min + rightmost->Depth;
rightmost->MinOccurrence = NewFatherOcc->MinOccurrence;
}
delete ParentOcc;
ParentOcc = NewFatherOcc;
// Update *our* tree
ETNode *left;
ETNode *right;
Father = NewFather;
right = Father->Son;
if (right)
left = right->Left;
else
left = right = this;
left->Right = this;
right->Left = this;
Left = left;
Right = right;
Father->Son = this;
}
bool ETNode::Below(ETNode *other) {
ETOccurrence *up = other->RightmostOcc;
ETOccurrence *down = RightmostOcc;
if (this == other)
return true;
up->Splay();
ETOccurrence *left, *right;
left = up->Left;
right = up->Right;
if (!left)
return false;
left->Parent = NULL;
if (right)
right->Parent = NULL;
down->Splay();
if (left == down || left->Parent != NULL) {
if (right)
right->Parent = up;
up->setLeft(down);
} else {
left->Parent = up;
// If the two occurrences are in different trees, put things
// back the way they were.
if (right && right->Parent != NULL)
up->setRight(down);
else
up->setRight(right);
return false;
}
if (down->Depth <= 0)
return false;
return !down->Right || down->Right->Min + down->Depth >= 0;
}
ETNode *ETNode::NCA(ETNode *other) {
ETOccurrence *occ1 = RightmostOcc;
ETOccurrence *occ2 = other->RightmostOcc;
ETOccurrence *left, *right, *ret;
ETOccurrence *occmin;
int mindepth;
if (this == other)
return this;
occ1->Splay();
left = occ1->Left;
right = occ1->Right;
if (left)
left->Parent = NULL;
if (right)
right->Parent = NULL;
occ2->Splay();
if (left == occ2 || (left && left->Parent != NULL)) {
ret = occ2->Right;
occ1->setLeft(occ2);
if (right)
right->Parent = occ1;
} else {
ret = occ2->Left;
occ1->setRight(occ2);
if (left)
left->Parent = occ1;
}
if (occ2->Depth > 0) {
occmin = occ1;
mindepth = occ1->Depth;
} else {
occmin = occ2;
mindepth = occ2->Depth + occ1->Depth;
}
if (ret && ret->Min + occ1->Depth + occ2->Depth < mindepth)
return ret->MinOccurrence->OccFor;
else
return occmin->OccFor;
}
void ETNode::assignDFSNumber(int num) {
std::vector<ETNode *> workStack;
std::set<ETNode *> visitedNodes;
workStack.push_back(this);
visitedNodes.insert(this);
this->DFSNumIn = num++;
while (!workStack.empty()) {
ETNode *Node = workStack.back();
// If this is leaf node then set DFSNumOut and pop the stack
if (!Node->Son) {
Node->DFSNumOut = num++;
workStack.pop_back();
continue;
}
ETNode *son = Node->Son;
// Visit Node->Son first
if (visitedNodes.count(son) == 0) {
son->DFSNumIn = num++;
workStack.push_back(son);
visitedNodes.insert(son);
continue;
}
bool visitChild = false;
// Visit remaining children
for (ETNode *s = son->Right; s != son && !visitChild; s = s->Right) {
if (visitedNodes.count(s) == 0) {
visitChild = true;
s->DFSNumIn = num++;
workStack.push_back(s);
visitedNodes.insert(s);
}
}
if (!visitChild) {
// If we reach here means all children are visited
Node->DFSNumOut = num++;
workStack.pop_back();
}
}
}
//===----------------------------------------------------------------------===//
// ETForest implementation
//===----------------------------------------------------------------------===//
static RegisterPass<ETForest>
D("etforest", "ET Forest Construction", true);
void ETForestBase::reset() {
for (ETMapType::iterator I = Nodes.begin(), E = Nodes.end(); I != E; ++I)
delete I->second;
Nodes.clear();
}
void ETForestBase::updateDFSNumbers()
{
int dfsnum = 0;
// Iterate over all nodes in depth first order.
for (unsigned i = 0, e = Roots.size(); i != e; ++i)
for (df_iterator<BasicBlock*> I = df_begin(Roots[i]),
E = df_end(Roots[i]); I != E; ++I) {
BasicBlock *BB = *I;
if (!getNode(BB)->hasFather())
getNode(BB)->assignDFSNumber(dfsnum);
}
SlowQueries = 0;
DFSInfoValid = true;
}
// dominates - Return true if A dominates B. THis performs the
// special checks necessary if A and B are in the same basic block.
bool ETForestBase::dominates(Instruction *A, Instruction *B) {
BasicBlock *BBA = A->getParent(), *BBB = B->getParent();
if (BBA != BBB) return dominates(BBA, BBB);
// Loop through the basic block until we find A or B.
BasicBlock::iterator I = BBA->begin();
for (; &*I != A && &*I != B; ++I) /*empty*/;
if(!IsPostDominators) {
// A dominates B if it is found first in the basic block.
return &*I == A;
} else {
// A post-dominates B if B is found first in the basic block.
return &*I == B;
}
}
ETNode *ETForest::getNodeForBlock(BasicBlock *BB) {
ETNode *&BBNode = Nodes[BB];
if (BBNode) return BBNode;
// Haven't calculated this node yet? Get or calculate the node for the
// immediate dominator.
BasicBlock *IDom = getAnalysis<ImmediateDominators>()[BB];
// If we are unreachable, we may not have an immediate dominator.
if (!IDom)
return BBNode = new ETNode(BB);
else {
ETNode *IDomNode = getNodeForBlock(IDom);
// Add a new tree node for this BasicBlock, and link it as a child of
// IDomNode
BBNode = new ETNode(BB);
BBNode->setFather(IDomNode);
return BBNode;
}
}
void ETForest::calculate(const ImmediateDominators &ID) {
assert(Roots.size() == 1 && "ETForest should have 1 root block!");
BasicBlock *Root = Roots[0];
Nodes[Root] = new ETNode(Root); // Add a node for the root
Function *F = Root->getParent();
// Loop over all of the reachable blocks in the function...
for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I)
if (BasicBlock *ImmDom = ID.get(I)) { // Reachable block.
ETNode *&BBNode = Nodes[I];
if (!BBNode) { // Haven't calculated this node yet?
// Get or calculate the node for the immediate dominator
ETNode *IDomNode = getNodeForBlock(ImmDom);
// Add a new ETNode for this BasicBlock, and set it's parent
// to it's immediate dominator.
BBNode = new ETNode(I);
BBNode->setFather(IDomNode);
}
}
// Make sure we've got nodes around for every block
for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
ETNode *&BBNode = Nodes[I];
if (!BBNode)
BBNode = new ETNode(I);
}
updateDFSNumbers ();
}
//===----------------------------------------------------------------------===//
// ETForestBase Implementation
//===----------------------------------------------------------------------===//
void ETForestBase::addNewBlock(BasicBlock *BB, BasicBlock *IDom) {
ETNode *&BBNode = Nodes[BB];
assert(!BBNode && "BasicBlock already in ET-Forest");
BBNode = new ETNode(BB);
BBNode->setFather(getNode(IDom));
DFSInfoValid = false;
}
void ETForestBase::setImmediateDominator(BasicBlock *BB, BasicBlock *newIDom) {
assert(getNode(BB) && "BasicBlock not in ET-Forest");
assert(getNode(newIDom) && "IDom not in ET-Forest");
ETNode *Node = getNode(BB);
if (Node->hasFather()) {
if (Node->getFather()->getData<BasicBlock>() == newIDom)
return;
Node->Split();
}
Node->setFather(getNode(newIDom));
DFSInfoValid= false;
}
void ETForestBase::print(std::ostream &o, const Module *) const {
o << "=============================--------------------------------\n";
o << "ET Forest:\n";
o << "DFS Info ";
if (DFSInfoValid)
o << "is";
else
o << "is not";
o << " up to date\n";
Function *F = getRoots()[0]->getParent();
for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
o << " DFS Numbers For Basic Block:";
WriteAsOperand(o, I, false);
o << " are:";
if (ETNode *EN = getNode(I)) {
o << "In: " << EN->getDFSNumIn();
o << " Out: " << EN->getDFSNumOut() << "\n";
} else {
o << "No associated ETNode";
}
o << "\n";
}
o << "\n";
}
DEFINING_FILE_FOR(DominatorSet)
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