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6ffd14dd54
class for each leader. Finally, rename Elem2ECLeaderMap to Elem2LeaderMap (most of the changed lines are only due to the latter). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13651 91177308-0d34-0410-b5e6-96231b3b80d8
117 lines
4.1 KiB
C++
117 lines
4.1 KiB
C++
//===-- Support/EquivalenceClasses.h ----------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Generic implementation of equivalence classes and implementation of
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// union-find algorithms A not-so-fancy implementation: 2 level tree i.e root
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// and one more level Overhead of a union = size of the equivalence class being
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// attached Overhead of a find = 1.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SUPPORT_EQUIVALENCECLASSES_H
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#define SUPPORT_EQUIVALENCECLASSES_H
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#include <map>
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#include <set>
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#include <vector>
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namespace llvm {
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template <class ElemTy>
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class EquivalenceClasses {
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// Maps each element to the element that is the leader of its
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// equivalence class.
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std::map<ElemTy, ElemTy> Elem2LeaderMap;
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// Maintains the set of leaders
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std::set<ElemTy> LeaderSet;
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// Caches the equivalence class for each leader
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std::map<ElemTy, std::set<ElemTy> > LeaderToEqClassMap;
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// Make Element2 the leader of the union of classes Element1 and Element2
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// Element1 and Element2 are presumed to be leaders of their respective
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// equivalence classes.
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void attach(ElemTy Element1, ElemTy Element2) {
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for (typename std::map<ElemTy, ElemTy>::iterator ElemI =
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Elem2LeaderMap.begin(), ElemE = Elem2LeaderMap.end();
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ElemI != ElemE; ++ElemI) {
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if (ElemI->second == Element1)
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Elem2LeaderMap[ElemI->first] = Element2;
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}
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}
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public:
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// If an element has not yet in any class, make it a separate new class.
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// Return the leader of the class containing the element.
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ElemTy addElement (ElemTy NewElement) {
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typename std::map<ElemTy, ElemTy>::iterator ElemI =
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Elem2LeaderMap.find(NewElement);
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if (ElemI == Elem2LeaderMap.end()) {
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Elem2LeaderMap[NewElement] = NewElement;
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LeaderSet.insert(NewElement);
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return NewElement;
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}
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else
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return ElemI->second;
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}
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ElemTy findClass(ElemTy Element) const {
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typename std::map<ElemTy, ElemTy>::const_iterator I =
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Elem2LeaderMap.find(Element);
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return (I == Elem2LeaderMap.end())? (ElemTy) 0 : I->second;
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}
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/// Attach the set with Element1 to the set with Element2 adding Element1 and
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/// Element2 to the set of equivalence classes if they are not there already.
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/// Implication: Make Element1 the element in the smaller set.
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/// Take Leader[Element1] out of the set of leaders.
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void unionSetsWith(ElemTy Element1, ElemTy Element2) {
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// If either Element1 or Element2 does not already exist, include it
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const ElemTy& leader1 = addElement(Element1);
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const ElemTy& leader2 = addElement(Element2);
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assert(leader1 != (ElemTy) 0 && leader2 != (ElemTy) 0);
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if (leader1 != leader2) {
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attach(leader1, leader2);
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LeaderSet.erase(leader1);
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}
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}
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// Returns a vector containing all the elements in the equivalence class
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// including Element1
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const std::set<ElemTy> & getEqClass(ElemTy Element1) {
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assert(Elem2LeaderMap.find(Element1) != Elem2LeaderMap.end());
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const ElemTy classLeader = Elem2LeaderMap[Element1];
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std::set<ElemTy> & EqClass = LeaderToEqClassMap[classLeader];
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// If the EqClass vector is empty, it has not been computed yet: do it now
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if (EqClass.empty()) {
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for (typename std::map<ElemTy, ElemTy>::iterator
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ElemI = Elem2LeaderMap.begin(), ElemE = Elem2LeaderMap.end();
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ElemI != ElemE; ++ElemI)
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if (ElemI->second == classLeader)
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EqClass.insert(ElemI->first);
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assert(! EqClass.empty()); // must at least include the leader
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}
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return EqClass;
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}
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std::set<ElemTy>& getLeaderSet() { return LeaderSet; }
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const std::set<ElemTy>& getLeaderSet() const { return LeaderSet; }
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std::map<ElemTy, ElemTy>& getLeaderMap() { return Elem2LeaderMap;}
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const std::map<ElemTy, ElemTy>& getLeaderMap() const { return Elem2LeaderMap;}
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};
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} // End llvm namespace
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#endif
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