From 2dd269d8dbf20b610540c9ba4dcf43a633b56116 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Mon, 2 Jul 2001 05:46:38 +0000 Subject: [PATCH] Checkin of new dominator calculation routines. These will be improved in the future to do post dominators and stuff llvm-svn: 124 --- lib/Analysis/PostDominators.cpp | 239 ++++++++++++++++++++++++++++++++ lib/VMCore/Dominators.cpp | 239 ++++++++++++++++++++++++++++++++ 2 files changed, 478 insertions(+) create mode 100644 lib/Analysis/PostDominators.cpp create mode 100644 lib/VMCore/Dominators.cpp diff --git a/lib/Analysis/PostDominators.cpp b/lib/Analysis/PostDominators.cpp new file mode 100644 index 00000000000..d6483423eb6 --- /dev/null +++ b/lib/Analysis/PostDominators.cpp @@ -0,0 +1,239 @@ +//===- DominatorSet.cpp - Dominator Set Calculation --------------*- C++ -*--=// +// +// This file provides a simple class to calculate the dominator set of a method. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Analysis/Dominators.h" +#include "llvm/CFG.h" +#include "llvm/Tools/STLExtras.h" +#include + +//===----------------------------------------------------------------------===// +// Helper Template +//===----------------------------------------------------------------------===// + +// set_intersect - Identical to set_intersection, except that it works on +// set<>'s and is nicer to use. Functionally, this iterates through S1, +// removing elements that are not contained in S2. +// +template +void set_intersect(set &S1, const set &S2) { + for (typename set::iterator I = S1.begin(); I != S1.end();) { + const Ty &E = *I; + ++I; + if (!S2.count(E)) S1.erase(E); // Erase element if not in S2 + } +} + + +//===----------------------------------------------------------------------===// +// DominatorSet Implementation +//===----------------------------------------------------------------------===// + +// DominatorSet ctor - Build either the dominator set or the post-dominator +// set for a method... +// +cfg::DominatorSet::DominatorSet(const Method *M, bool PostDomSet) + : Root(M->front()) { + assert(Root && M && "Can't build dominator set of null method!"); + bool Changed; + do { + Changed = false; + + DomSetType WorkingSet; + df_const_iterator It = df_begin(M), End = df_end(M); + for ( ; It != End; ++It) { + const BasicBlock *BB = *It; + pred_const_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); + +} + + +//===----------------------------------------------------------------------===// +// ImmediateDominators Implementation +//===----------------------------------------------------------------------===// + +// calcIDoms - Calculate the immediate dominator mapping, given a set of +// dominators for every basic block. +void cfg::ImmediateDominators::calcIDoms(const DominatorSet &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) { + const 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; + } + } + } +} + + +//===----------------------------------------------------------------------===// +// DominatorTree Implementation +//===----------------------------------------------------------------------===// + +// DominatorTree dtor - Free all of the tree node memory. +// +cfg::DominatorTree::~DominatorTree() { + for (NodeMapType::iterator I = Nodes.begin(), E = Nodes.end(); I != E; ++I) + delete I->second; +} + + +cfg::DominatorTree::DominatorTree(const ImmediateDominators &IDoms) + : Root(IDoms.getRoot()) { + assert(Root && Root->getParent() && "No method for IDoms?"); + const Method *M = Root->getParent(); + + Nodes[Root] = new Node(Root, 0); // Add a node for the root... + + // Iterate over all nodes in depth first order... + for (df_const_iterator I = df_begin(M), E = df_end(M); I != E; ++I) { + const BasicBlock *BB = *I, *IDom = IDoms[*I]; + + if (IDom != 0) { // Ignore the root node and other nasty nodes + // We know that the immediate dominator should already have a node, + // because we are traversing the CFG in depth first order! + // + assert(Nodes[IDom] && "No node for IDOM?"); + Node *IDomNode = Nodes[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)); + } + } +} + +void cfg::DominatorTree::calculate(const DominatorSet &DS) { + Root = DS.getRoot(); + assert(Root && Root->getParent() && "No method for IDoms?"); + const Method *M = Root->getParent(); + Nodes[Root] = new Node(Root, 0); // Add a node for the root... + + // Iterate over all nodes in depth first order... + for (df_const_iterator I = df_begin(M), E = df_end(M); I != E; ++I) { + const 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 + // method. + // + 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(Nodes[*I] && "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; + } + } + } +} + + + +//===----------------------------------------------------------------------===// +// DominanceFrontier Implementation +//===----------------------------------------------------------------------===// + +const cfg::DominanceFrontier::DomSetType & +cfg::DominanceFrontier::calcDomFrontier(const DominatorTree &DT, + const DominatorTree::Node *Node) { + // Loop over CFG successors to calculate DFlocal[Node] + const BasicBlock *BB = Node->getNode(); + DomSetType &S = Frontiers[BB]; // The new set to fill in... + + for (succ_const_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 = calcDomFrontier(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; +} diff --git a/lib/VMCore/Dominators.cpp b/lib/VMCore/Dominators.cpp new file mode 100644 index 00000000000..d6483423eb6 --- /dev/null +++ b/lib/VMCore/Dominators.cpp @@ -0,0 +1,239 @@ +//===- DominatorSet.cpp - Dominator Set Calculation --------------*- C++ -*--=// +// +// This file provides a simple class to calculate the dominator set of a method. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Analysis/Dominators.h" +#include "llvm/CFG.h" +#include "llvm/Tools/STLExtras.h" +#include + +//===----------------------------------------------------------------------===// +// Helper Template +//===----------------------------------------------------------------------===// + +// set_intersect - Identical to set_intersection, except that it works on +// set<>'s and is nicer to use. Functionally, this iterates through S1, +// removing elements that are not contained in S2. +// +template +void set_intersect(set &S1, const set &S2) { + for (typename set::iterator I = S1.begin(); I != S1.end();) { + const Ty &E = *I; + ++I; + if (!S2.count(E)) S1.erase(E); // Erase element if not in S2 + } +} + + +//===----------------------------------------------------------------------===// +// DominatorSet Implementation +//===----------------------------------------------------------------------===// + +// DominatorSet ctor - Build either the dominator set or the post-dominator +// set for a method... +// +cfg::DominatorSet::DominatorSet(const Method *M, bool PostDomSet) + : Root(M->front()) { + assert(Root && M && "Can't build dominator set of null method!"); + bool Changed; + do { + Changed = false; + + DomSetType WorkingSet; + df_const_iterator It = df_begin(M), End = df_end(M); + for ( ; It != End; ++It) { + const BasicBlock *BB = *It; + pred_const_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); + +} + + +//===----------------------------------------------------------------------===// +// ImmediateDominators Implementation +//===----------------------------------------------------------------------===// + +// calcIDoms - Calculate the immediate dominator mapping, given a set of +// dominators for every basic block. +void cfg::ImmediateDominators::calcIDoms(const DominatorSet &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) { + const 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; + } + } + } +} + + +//===----------------------------------------------------------------------===// +// DominatorTree Implementation +//===----------------------------------------------------------------------===// + +// DominatorTree dtor - Free all of the tree node memory. +// +cfg::DominatorTree::~DominatorTree() { + for (NodeMapType::iterator I = Nodes.begin(), E = Nodes.end(); I != E; ++I) + delete I->second; +} + + +cfg::DominatorTree::DominatorTree(const ImmediateDominators &IDoms) + : Root(IDoms.getRoot()) { + assert(Root && Root->getParent() && "No method for IDoms?"); + const Method *M = Root->getParent(); + + Nodes[Root] = new Node(Root, 0); // Add a node for the root... + + // Iterate over all nodes in depth first order... + for (df_const_iterator I = df_begin(M), E = df_end(M); I != E; ++I) { + const BasicBlock *BB = *I, *IDom = IDoms[*I]; + + if (IDom != 0) { // Ignore the root node and other nasty nodes + // We know that the immediate dominator should already have a node, + // because we are traversing the CFG in depth first order! + // + assert(Nodes[IDom] && "No node for IDOM?"); + Node *IDomNode = Nodes[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)); + } + } +} + +void cfg::DominatorTree::calculate(const DominatorSet &DS) { + Root = DS.getRoot(); + assert(Root && Root->getParent() && "No method for IDoms?"); + const Method *M = Root->getParent(); + Nodes[Root] = new Node(Root, 0); // Add a node for the root... + + // Iterate over all nodes in depth first order... + for (df_const_iterator I = df_begin(M), E = df_end(M); I != E; ++I) { + const 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 + // method. + // + 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(Nodes[*I] && "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; + } + } + } +} + + + +//===----------------------------------------------------------------------===// +// DominanceFrontier Implementation +//===----------------------------------------------------------------------===// + +const cfg::DominanceFrontier::DomSetType & +cfg::DominanceFrontier::calcDomFrontier(const DominatorTree &DT, + const DominatorTree::Node *Node) { + // Loop over CFG successors to calculate DFlocal[Node] + const BasicBlock *BB = Node->getNode(); + DomSetType &S = Frontiers[BB]; // The new set to fill in... + + for (succ_const_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 = calcDomFrontier(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; +}