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Split dominance calculation and post dominance calculation stuff 

Dominance calculation goes to VMCore library to be used by Verifier.

llvm-svn: 3210
This commit is contained in:
Chris Lattner 2002-08-02 16:43:03 +00:00
parent 45dca23e2f
commit d43023a85d
2 changed files with 11 additions and 434 deletions
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273
llvm/lib/Analysis/PostDominators.cpp
View File

@ -1,93 +1,24 @@
//===- DominatorSet.cpp - Dominator Set Calculation --------------*- C++ -*--=//
//===- PostDominators.cpp - Post-Dominator Calculation --------------------===//
//
// This file provides a simple class to calculate the dominator set of a
// function.
// This file implements the post-dominator construction algorithms.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/Dominators.h"
#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
#include "llvm/Support/CFG.h"
#include "llvm/Assembly/Writer.h"
#include "Support/DepthFirstIterator.h"
#include "Support/STLExtras.h"
#include "Support/SetOperations.h"
#include <algorithm>
using std::set;
//===----------------------------------------------------------------------===//
// DominatorSet Implementation
// PostDominatorSet Implementation
//===----------------------------------------------------------------------===//
static RegisterAnalysis<DominatorSet>
A("domset", "Dominator Set Construction", true);
static RegisterAnalysis<PostDominatorSet>
B("postdomset", "Post-Dominator Set Construction", true);
AnalysisID DominatorSet::ID = A;
AnalysisID PostDominatorSet::ID = B;
// dominates - Return true if A dominates B. This performs the special checks
// neccesary 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*/;
// A dominates B if it is found first in the basic block...
return &*I == A;
}
// runOnFunction - This method calculates the forward dominator sets for the
// specified function.
//
bool DominatorSet::runOnFunction(Function &F) {
Doms.clear(); // Reset from the last time we were run...
Root = &F.getEntryNode();
assert(pred_begin(Root) == pred_end(Root) &&
"Root node has predecessors in function!");
bool Changed;
do {
Changed = false;
DomSetType WorkingSet;
df_iterator<Function*> It = df_begin(&F), End = df_end(&F);
for ( ; It != End; ++It) {
BasicBlock *BB = *It;
pred_iterator PI = pred_begin(BB), PEnd = pred_end(BB);
if (PI != PEnd) { // Is there SOME predecessor?
// Loop until we get to a predecessor that has had it's dom set filled
// in at least once. We are guaranteed to have this because we are
// traversing the graph in DFO and have handled start nodes specially.
//
while (Doms[*PI].size() == 0) ++PI;
WorkingSet = Doms[*PI];
for (++PI; PI != PEnd; ++PI) { // Intersect all of the predecessor sets
DomSetType &PredSet = Doms[*PI];
if (PredSet.size())
set_intersect(WorkingSet, PredSet);
}
}
WorkingSet.insert(BB); // A block always dominates itself
DomSetType &BBSet = Doms[BB];
if (BBSet != WorkingSet) {
BBSet.swap(WorkingSet); // Constant time operation!
Changed = true; // The sets changed.
}
WorkingSet.clear(); // Clear out the set for next iteration
}
} while (Changed);
return false;
}
// Postdominator set construction. This converts the specified function to only
// have a single exit node (return stmt), then calculates the post dominance
// sets for the function.
@ -151,146 +82,22 @@ void PostDominatorSet::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired(UnifyFunctionExitNodes::ID);
}
static std::ostream &operator<<(std::ostream &o, const set<BasicBlock*> &BBs) {
for (set<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
I != E; ++I) {
o << " ";
WriteAsOperand(o, *I, false);
o << "\n";
}
return o;
}
void DominatorSetBase::print(std::ostream &o) const {
for (const_iterator I = begin(), E = end(); I != E; ++I)
o << "=============================--------------------------------\n"
<< "\nDominator Set For Basic Block\n" << I->first
<< "-------------------------------\n" << I->second << "\n";
}
//===----------------------------------------------------------------------===//
// ImmediateDominators Implementation
// ImmediatePostDominators Implementation
//===----------------------------------------------------------------------===//
static RegisterAnalysis<ImmediateDominators>
C("idom", "Immediate Dominators Construction", true);
static RegisterAnalysis<ImmediatePostDominators>
D("postidom", "Immediate Post-Dominators Construction", true);
AnalysisID ImmediateDominators::ID = C;
AnalysisID ImmediatePostDominators::ID = D;
// calcIDoms - Calculate the immediate dominator mapping, given a set of
// dominators for every basic block.
void ImmediateDominatorsBase::calcIDoms(const DominatorSetBase &DS) {
// Loop over all of the nodes that have dominators... figuring out the IDOM
// for each node...
//
for (DominatorSet::const_iterator DI = DS.begin(), DEnd = DS.end();
DI != DEnd; ++DI) {
BasicBlock *BB = DI->first;
const DominatorSet::DomSetType &Dominators = DI->second;
unsigned DomSetSize = Dominators.size();
if (DomSetSize == 1) continue; // Root node... IDom = null
// Loop over all dominators of this node. This corresponds to looping over
// nodes in the dominator chain, looking for a node whose dominator set is
// equal to the current nodes, except that the current node does not exist
// in it. This means that it is one level higher in the dom chain than the
// current node, and it is our idom!
//
DominatorSet::DomSetType::const_iterator I = Dominators.begin();
DominatorSet::DomSetType::const_iterator End = Dominators.end();
for (; I != End; ++I) { // Iterate over dominators...
// All of our dominators should form a chain, where the number of elements
// in the dominator set indicates what level the node is at in the chain.
// We want the node immediately above us, so it will have an identical
// dominator set, except that BB will not dominate it... therefore it's
// dominator set size will be one less than BB's...
//
if (DS.getDominators(*I).size() == DomSetSize - 1) {
IDoms[BB] = *I;
break;
}
}
}
}
void ImmediateDominatorsBase::print(std::ostream &o) const {
for (const_iterator I = begin(), E = end(); I != E; ++I)
o << "=============================--------------------------------\n"
<< "\nImmediate Dominator For Basic Block\n" << *I->first
<< "is: \n" << *I->second << "\n";
}
//===----------------------------------------------------------------------===//
// DominatorTree Implementation
// PostDominatorTree Implementation
//===----------------------------------------------------------------------===//
static RegisterAnalysis<DominatorTree>
E("domtree", "Dominator Tree Construction", true);
static RegisterAnalysis<PostDominatorTree>
F("postdomtree", "Post-Dominator Tree Construction", true);
AnalysisID DominatorTree::ID = E;
AnalysisID PostDominatorTree::ID = F;
// 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();
}
void DominatorTree::calculate(const DominatorSet &DS) {
Nodes[Root] = new Node(Root, 0); // Add a node for the root...
// Iterate over all nodes in depth first order...
for (df_iterator<BasicBlock*> I = df_begin(Root), E = df_end(Root);
I != E; ++I) {
BasicBlock *BB = *I;
const DominatorSet::DomSetType &Dominators = DS.getDominators(BB);
unsigned DomSetSize = Dominators.size();
if (DomSetSize == 1) continue; // Root node... IDom = null
// Loop over all dominators of this node. This corresponds to looping over
// nodes in the dominator chain, looking for a node whose dominator set is
// equal to the current nodes, except that the current node does not exist
// in it. This means that it is one level higher in the dom chain than the
// current node, and it is our idom! We know that we have already added
// a DominatorTree node for our idom, because the idom must be a
// predecessor in the depth first order that we are iterating through the
// function.
//
DominatorSet::DomSetType::const_iterator I = Dominators.begin();
DominatorSet::DomSetType::const_iterator End = Dominators.end();
for (; I != End; ++I) { // Iterate over dominators...
// All of our dominators should form a chain, where the number of
// elements in the dominator set indicates what level the node is at in
// the chain. We want the node immediately above us, so it will have
// an identical dominator set, except that BB will not dominate it...
// therefore it's dominator set size will be one less than BB's...
//
if (DS.getDominators(*I).size() == DomSetSize - 1) {
// We know that the immediate dominator should already have a node,
// because we are traversing the CFG in depth first order!
//
Node *IDomNode = Nodes[*I];
assert(IDomNode && "No node for IDOM?");
// Add a new tree node for this BasicBlock, and link it as a child of
// IDomNode
Nodes[BB] = IDomNode->addChild(new Node(BB, IDomNode));
break;
}
}
}
}
void PostDominatorTree::calculate(const PostDominatorSet &DS) {
Nodes[Root] = new Node(Root, 0); // Add a node for the root...
@ -339,73 +146,14 @@ void PostDominatorTree::calculate(const PostDominatorSet &DS) {
}
}
static std::ostream &operator<<(std::ostream &o,
const DominatorTreeBase::Node *Node) {
return o << Node->getNode()
<< "\n------------------------------------------\n";
}
static void PrintDomTree(const DominatorTreeBase::Node *N, std::ostream &o,
unsigned Lev) {
o << "Level #" << 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 {
o << "=============================--------------------------------\n"
<< "Inorder Dominator Tree:\n";
PrintDomTree(Nodes.find(getRoot())->second, o, 1);
}
//===----------------------------------------------------------------------===//
// DominanceFrontier Implementation
// PostDominanceFrontier Implementation
//===----------------------------------------------------------------------===//
static RegisterAnalysis<DominanceFrontier>
G("domfrontier", "Dominance Frontier Construction", true);
static RegisterAnalysis<PostDominanceFrontier>
H("postdomfrontier", "Post-Dominance Frontier Construction", true);
AnalysisID DominanceFrontier::ID = G;
AnalysisID PostDominanceFrontier::ID = H;
const DominanceFrontier::DomSetType &
DominanceFrontier::calculate(const DominatorTree &DT,
const DominatorTree::Node *Node) {
// Loop over CFG successors to calculate DFlocal[Node]
BasicBlock *BB = Node->getNode();
DomSetType &S = Frontiers[BB]; // The new set to fill in...
for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB);
SI != SE; ++SI) {
// Does Node immediately dominate this successor?
if (DT[*SI]->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 (DominatorTree::Node::const_iterator NI = Node->begin(), NE = Node->end();
NI != NE; ++NI) {
DominatorTree::Node *IDominee = *NI;
const DomSetType &ChildDF = calculate(DT, IDominee);
DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
for (; CDFI != CDFE; ++CDFI) {
if (!Node->dominates(DT[*CDFI]))
S.insert(*CDFI);
}
}
return S;
}
const DominanceFrontier::DomSetType &
PostDominanceFrontier::calculate(const PostDominatorTree &DT,
const DominatorTree::Node *Node) {
@ -439,12 +187,3 @@ PostDominanceFrontier::calculate(const PostDominatorTree &DT,
return S;
}
void DominanceFrontierBase::print(std::ostream &o) const {
for (const_iterator I = begin(), E = end(); I != E; ++I) {
o << "=============================--------------------------------\n"
<< "\nDominance Frontier For Basic Block\n";
WriteAsOperand(o, I->first, false);
o << " is: \n" << I->second << "\n";
}
}

172
llvm/lib/VMCore/Dominators.cpp
View File

@ -1,18 +1,17 @@
//===- DominatorSet.cpp - Dominator Set Calculation --------------*- C++ -*--=//
//===- Dominators.cpp - Dominator Calculation -----------------------------===//
//
// This file provides a simple class to calculate the dominator set of a
// function.
// 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/Transforms/Utils/UnifyFunctionExitNodes.h"
#include "llvm/Support/CFG.h"
#include "llvm/Assembly/Writer.h"
#include "Support/DepthFirstIterator.h"
#include "Support/STLExtras.h"
#include "Support/SetOperations.h"
#include <algorithm>
using std::set;
//===----------------------------------------------------------------------===//
@ -21,11 +20,7 @@ using std::set;
static RegisterAnalysis<DominatorSet>
A("domset", "Dominator Set Construction", true);
static RegisterAnalysis<PostDominatorSet>
B("postdomset", "Post-Dominator Set Construction", true);
AnalysisID DominatorSet::ID = A;
AnalysisID PostDominatorSet::ID = B;
// dominates - Return true if A dominates B. This performs the special checks
// neccesary if A and B are in the same basic block.
@ -88,69 +83,6 @@ bool DominatorSet::runOnFunction(Function &F) {
}
// Postdominator set construction. This converts the specified function to only
// have a single exit node (return stmt), then calculates the post dominance
// sets for the function.
//
bool PostDominatorSet::runOnFunction(Function &F) {
Doms.clear(); // Reset from the last time we were run...
// Since we require that the unify all exit nodes pass has been run, we know
// that there can be at most one return instruction in the function left.
// Get it.
//
Root = getAnalysis<UnifyFunctionExitNodes>().getExitNode();
if (Root == 0) { // No exit node for the function? Postdomsets are all empty
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
Doms[FI] = DomSetType();
return false;
}
bool Changed;
do {
Changed = false;
set<const BasicBlock*> Visited;
DomSetType WorkingSet;
idf_iterator<BasicBlock*> It = idf_begin(Root), End = idf_end(Root);
for ( ; It != End; ++It) {
BasicBlock *BB = *It;
succ_iterator PI = succ_begin(BB), PEnd = succ_end(BB);
if (PI != PEnd) { // Is there SOME predecessor?
// Loop until we get to a successor that has had it's dom set filled
// in at least once. We are guaranteed to have this because we are
// traversing the graph in DFO and have handled start nodes specially.
//
while (Doms[*PI].size() == 0) ++PI;
WorkingSet = Doms[*PI];
for (++PI; PI != PEnd; ++PI) { // Intersect all of the successor sets
DomSetType &PredSet = Doms[*PI];
if (PredSet.size())
set_intersect(WorkingSet, PredSet);
}
}
WorkingSet.insert(BB); // A block always dominates itself
DomSetType &BBSet = Doms[BB];
if (BBSet != WorkingSet) {
BBSet.swap(WorkingSet); // Constant time operation!
Changed = true; // The sets changed.
}
WorkingSet.clear(); // Clear out the set for next iteration
}
} while (Changed);
return false;
}
// getAnalysisUsage - This obviously provides a post-dominator set, but it also
// requires the UnifyFunctionExitNodes pass.
//
void PostDominatorSet::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired(UnifyFunctionExitNodes::ID);
}
static std::ostream &operator<<(std::ostream &o, const set<BasicBlock*> &BBs) {
for (set<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
I != E; ++I) {
@ -174,11 +106,7 @@ void DominatorSetBase::print(std::ostream &o) const {
static RegisterAnalysis<ImmediateDominators>
C("idom", "Immediate Dominators Construction", true);
static RegisterAnalysis<ImmediatePostDominators>
D("postidom", "Immediate Post-Dominators Construction", true);
AnalysisID ImmediateDominators::ID = C;
AnalysisID ImmediatePostDominators::ID = D;
// calcIDoms - Calculate the immediate dominator mapping, given a set of
// dominators for every basic block.
@ -230,11 +158,7 @@ void ImmediateDominatorsBase::print(std::ostream &o) const {
static RegisterAnalysis<DominatorTree>
E("domtree", "Dominator Tree Construction", true);
static RegisterAnalysis<PostDominatorTree>
F("postdomtree", "Post-Dominator Tree Construction", true);
AnalysisID DominatorTree::ID = E;
AnalysisID PostDominatorTree::ID = F;
// DominatorTreeBase::reset - Free all of the tree node memory.
//
@ -291,54 +215,6 @@ void DominatorTree::calculate(const DominatorSet &DS) {
}
void PostDominatorTree::calculate(const PostDominatorSet &DS) {
Nodes[Root] = new Node(Root, 0); // Add a node for the root...
if (Root) {
// Iterate over all nodes in depth first order...
for (idf_iterator<BasicBlock*> I = idf_begin(Root), E = idf_end(Root);
I != E; ++I) {
BasicBlock *BB = *I;
const DominatorSet::DomSetType &Dominators = DS.getDominators(BB);
unsigned DomSetSize = Dominators.size();
if (DomSetSize == 1) continue; // Root node... IDom = null
// Loop over all dominators of this node. This corresponds to looping
// over nodes in the dominator chain, looking for a node whose dominator
// set is equal to the current nodes, except that the current node does
// not exist in it. This means that it is one level higher in the dom
// chain than the current node, and it is our idom! We know that we have
// already added a DominatorTree node for our idom, because the idom must
// be a predecessor in the depth first order that we are iterating through
// the function.
//
DominatorSet::DomSetType::const_iterator I = Dominators.begin();
DominatorSet::DomSetType::const_iterator End = Dominators.end();
for (; I != End; ++I) { // Iterate over dominators...
// All of our dominators should form a chain, where the number
// of elements in the dominator set indicates what level the
// node is at in the chain. We want the node immediately
// above us, so it will have an identical dominator set,
// except that BB will not dominate it... therefore it's
// dominator set size will be one less than BB's...
//
if (DS.getDominators(*I).size() == DomSetSize - 1) {
// We know that the immediate dominator should already have a node,
// because we are traversing the CFG in depth first order!
//
Node *IDomNode = Nodes[*I];
assert(IDomNode && "No node for IDOM?");
// Add a new tree node for this BasicBlock, and link it as a child of
// IDomNode
Nodes[BB] = IDomNode->addChild(new Node(BB, IDomNode));
break;
}
}
}
}
}
static std::ostream &operator<<(std::ostream &o,
const DominatorTreeBase::Node *Node) {
return o << Node->getNode()
@ -367,11 +243,7 @@ void DominatorTreeBase::print(std::ostream &o) const {
static RegisterAnalysis<DominanceFrontier>
G("domfrontier", "Dominance Frontier Construction", true);
static RegisterAnalysis<PostDominanceFrontier>
H("postdomfrontier", "Post-Dominance Frontier Construction", true);
AnalysisID DominanceFrontier::ID = G;
AnalysisID PostDominanceFrontier::ID = H;
const DominanceFrontier::DomSetType &
DominanceFrontier::calculate(const DominatorTree &DT,
@ -406,40 +278,6 @@ DominanceFrontier::calculate(const DominatorTree &DT,
return S;
}
const DominanceFrontier::DomSetType &
PostDominanceFrontier::calculate(const PostDominatorTree &DT,
const DominatorTree::Node *Node) {
// Loop over CFG successors to calculate DFlocal[Node]
BasicBlock *BB = Node->getNode();
DomSetType &S = Frontiers[BB]; // The new set to fill in...
if (!Root) return S;
for (pred_iterator SI = pred_begin(BB), SE = pred_end(BB);
SI != SE; ++SI) {
// Does Node immediately dominate this predeccessor?
if (DT[*SI]->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 (PostDominatorTree::Node::const_iterator
NI = Node->begin(), NE = Node->end(); NI != NE; ++NI) {
DominatorTree::Node *IDominee = *NI;
const DomSetType &ChildDF = calculate(DT, IDominee);
DomSetType::const_iterator CDFI = ChildDF.begin(), CDFE = ChildDF.end();
for (; CDFI != CDFE; ++CDFI) {
if (!Node->dominates(DT[*CDFI]))
S.insert(*CDFI);
}
}
return S;
}
void DominanceFrontierBase::print(std::ostream &o) const {
for (const_iterator I = begin(), E = end(); I != E; ++I) {
o << "=============================--------------------------------\n"