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llvm/lib/VMCore/Dominators.cpp
Devang Patel 3e15bf33e0 Use 'static const char' instead of 'static const int'. 
Due to darwin gcc bug, one version of darwin linker coalesces
static const int, which defauts PassID based pass identification.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36652 91177308-0d34-0410-b5e6-96231b3b80d8
2007-05-02 21:39:20 +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 "llvm/ADT/SmallPtrSet.h"
#include "llvm/Instructions.h"
#include <algorithm>
using namespace llvm;
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;
}
}
//===----------------------------------------------------------------------===//
// DominatorTree Implementation
//===----------------------------------------------------------------------===//
//
// DominatorTree 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
//
//===----------------------------------------------------------------------===//
const char DominatorTree::ID = 0;
static RegisterPass<DominatorTree>
E("domtree", "Dominator Tree Construction", true);
unsigned DominatorTree::DFSPass(BasicBlock *V, InfoRec &VInfo,
unsigned N) {
// This is more understandable as a recursive algorithm, but we can't use the
// recursive algorithm due to stack depth issues. Keep it here for
// documentation purposes.
#if 0
VInfo.Semi = ++N;
VInfo.Label = V;
Vertex.push_back(V); // Vertex[n] = V;
//Info[V].Ancestor = 0; // Ancestor[n] = 0
//Info[V].Child = 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);
}
}
#else
std::vector<std::pair<BasicBlock*, unsigned> > Worklist;
Worklist.push_back(std::make_pair(V, 0U));
while (!Worklist.empty()) {
BasicBlock *BB = Worklist.back().first;
unsigned NextSucc = Worklist.back().second;
// First time we visited this BB?
if (NextSucc == 0) {
InfoRec &BBInfo = Info[BB];
BBInfo.Semi = ++N;
BBInfo.Label = BB;
Vertex.push_back(BB); // Vertex[n] = V;
//BBInfo[V].Ancestor = 0; // Ancestor[n] = 0
//BBInfo[V].Child = 0; // Child[v] = 0
BBInfo.Size = 1; // Size[v] = 1
}
// If we are done with this block, remove it from the worklist.
if (NextSucc == BB->getTerminator()->getNumSuccessors()) {
Worklist.pop_back();
continue;
}
// Otherwise, increment the successor number for the next time we get to it.
++Worklist.back().second;
// Visit the successor next, if it isn't already visited.
BasicBlock *Succ = BB->getTerminator()->getSuccessor(NextSucc);
InfoRec &SuccVInfo = Info[Succ];
if (SuccVInfo.Semi == 0) {
SuccVInfo.Parent = BB;
Worklist.push_back(std::make_pair(Succ, 0U));
}
}
#endif
return N;
}
void DominatorTree::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 *DominatorTree::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 DominatorTree::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
}
void DominatorTree::calculate(Function& F) {
BasicBlock* Root = Roots[0];
Nodes[Root] = RootNode = new Node(Root, 0); // Add a node for the 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];
}
// 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 = getIDom(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));
}
}
// Free temporary memory used to construct idom's
Info.clear();
IDoms.clear();
std::vector<BasicBlock*>().swap(Vertex);
}
// 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();
IDoms.clear();
Roots.clear();
Vertex.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 = getIDom(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));
}
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);
}
bool DominatorTree::runOnFunction(Function &F) {
reset(); // Reset from the last time we were run...
Roots.push_back(&F.getEntryBlock());
calculate(F);
return false;
}
//===----------------------------------------------------------------------===//
// DominanceFrontier Implementation
//===----------------------------------------------------------------------===//
const char DominanceFrontier::ID = 0;
static RegisterPass<DominanceFrontier>
G("domfrontier", "Dominance Frontier 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;
};
}
const DominanceFrontier::DomSetType &
DominanceFrontier::calculate(const DominatorTree &DT,
const DominatorTree::Node *Node) {
BasicBlock *BB = Node->getBlock();
DomSetType *Result = NULL;
std::vector<DFCalculateWorkObject> workList;
SmallPtrSet<BasicBlock *, 32> visited;
workList.push_back(DFCalculateWorkObject(BB, NULL, Node, NULL));
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) {
workList.push_back(DFCalculateWorkObject(childBB, currentBB,
IDominee, currentNode));
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
//===----------------------------------------------------------------------===//
const char ETForest::ID = 0;
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;
ETNode *ETN = getNode(BB);
if (ETN && !ETN->hasFather())
ETN->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);
// It is not possible to determine dominance between two PHI nodes
// based on their ordering.
if (isa<PHINode>(A) && isa<PHINode>(B))
return false;
// 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;
}
}
/// isReachableFromEntry - Return true if A is dominated by the entry
/// block of the function containing it.
const bool ETForestBase::isReachableFromEntry(BasicBlock* A) {
return dominates(&A->getParent()->getEntryBlock(), A);
}
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.
DominatorTree::Node *node= getAnalysis<DominatorTree>().getNode(BB);
// If we are unreachable, we may not have an immediate dominator.
if (!node || !node->getIDom())
return BBNode = new ETNode(BB);
else {
ETNode *IDomNode = getNodeForBlock(node->getIDom()->getBlock());
// 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 DominatorTree &DT) {
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) {
DominatorTree::Node* node = DT.getNode(I);
if (node && node->getIDom()) { // Reachable block.
BasicBlock* ImmDom = node->getIDom()->getBlock();
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";
}
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