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https://github.com/c64scene-ar/llvm-6502.git
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194 lines
5.8 KiB
C
194 lines
5.8 KiB
C
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//===- ScopedHashTable.h - A simple scoped hash table ---------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements an efficient scoped hash table, which is useful for
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// things like dominator-based optimizations. This allows clients to do things
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// like this:
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//
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// ScopedHashTable<int, int> HT;
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// {
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// ScopedHashTableScope<int, int> Scope1(HT);
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// HT.insert(0, 0);
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// HT.insert(1, 1);
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// {
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// ScopedHashTableScope<int, int> Scope2(HT);
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// HT.insert(0, 42);
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// }
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// }
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//
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// Looking up the value for "0" in the Scope2 block will return 42. Looking
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// up the value for 0 before 42 is inserted or after Scope2 is popped will
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// return 0.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_SCOPEDHASHTABLE_H
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#define LLVM_ADT_SCOPEDHASHTABLE_H
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#include <cassert>
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#include "llvm/ADT/DenseMap.h"
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namespace llvm {
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template <typename K, typename V>
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class ScopedHashTable;
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template <typename K, typename V>
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class ScopedHashTableVal {
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ScopedHashTableVal *NextInScope;
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ScopedHashTableVal *NextForKey;
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K Key;
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V Val;
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public:
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ScopedHashTableVal(ScopedHashTableVal *nextInScope,
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ScopedHashTableVal *nextForKey, const K &key, const V &val)
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: NextInScope(nextInScope), NextForKey(nextForKey), Key(key), Val(val) {
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}
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const K &getKey() const { return Key; }
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const V &getValue() const { return Val; }
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V &getValue() { return Val; }
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ScopedHashTableVal *getNextForKey() { return NextForKey; }
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const ScopedHashTableVal *getNextForKey() const { return NextForKey; }
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public:
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ScopedHashTableVal *getNextInScope() { return NextInScope; }
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};
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template <typename K, typename V>
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class ScopedHashTableScope {
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/// HT - The hashtable that we are active for.
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ScopedHashTable<K, V> &HT;
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/// PrevScope - This is the scope that we are shadowing in HT.
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ScopedHashTableScope *PrevScope;
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/// LastValInScope - This is the last value that was inserted for this scope
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/// or null if none have been inserted yet.
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ScopedHashTableVal<K,V> *LastValInScope;
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void operator=(ScopedHashTableScope&); // DO NOT IMPLEMENT
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ScopedHashTableScope(ScopedHashTableScope&); // DO NOT IMPLEMENT
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public:
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ScopedHashTableScope(ScopedHashTable<K, V> &HT);
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~ScopedHashTableScope();
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private:
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friend class ScopedHashTable<K, V>;
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ScopedHashTableVal<K, V> *getLastValInScope() { return LastValInScope; }
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void setLastValInScope(ScopedHashTableVal<K,V> *Val) { LastValInScope = Val; }
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};
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template <typename K, typename V>
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class ScopedHashTableIterator {
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ScopedHashTableVal<K,V> *Node;
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public:
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ScopedHashTableIterator(ScopedHashTableVal<K,V> *node) : Node(node){}
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V &operator*() const {
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assert(Node && "Dereference end()");
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return Node->getValue();
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}
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V *operator->() const {
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return &Node->getValue();
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}
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bool operator==(const ScopedHashTableIterator &RHS) const {
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return Node == RHS.Node;
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}
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bool operator!=(const ScopedHashTableIterator &RHS) const {
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return Node != RHS.Node;
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}
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inline ScopedHashTableIterator& operator++() { // Preincrement
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assert(Node && "incrementing past end()");
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Node = Node->getNextForKey();
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return *this;
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}
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ScopedHashTableIterator operator++(int) { // Postincrement
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ScopedHashTableIterator tmp = *this; ++*this; return tmp;
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}
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};
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template <typename K, typename V>
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class ScopedHashTable {
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DenseMap<K, ScopedHashTableVal<K,V>*> TopLevelMap;
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ScopedHashTableScope<K, V> *CurScope;
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ScopedHashTable(const ScopedHashTable&); // NOT YET IMPLEMENTED
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void operator=(const ScopedHashTable&); // NOT YET IMPLEMENTED
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friend class ScopedHashTableScope<K, V>;
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public:
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ScopedHashTable() : CurScope(0) {}
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~ScopedHashTable() {
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assert(CurScope == 0 && TopLevelMap.empty() && "Scope imbalance!");
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}
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void insert(const K &Key, const V &Val) {
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assert(CurScope && "No scope active!");
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ScopedHashTableVal<K,V> *&KeyEntry = TopLevelMap[Key];
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KeyEntry = new ScopedHashTableVal<K,V>(CurScope->getLastValInScope(),
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KeyEntry, Key, Val);
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CurScope->setLastValInScope(KeyEntry);
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}
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typedef ScopedHashTableIterator<K, V> iterator;
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iterator end() { return iterator(0); }
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iterator begin(const K &Key) {
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typename DenseMap<K, ScopedHashTableVal<K,V>*>::iterator I =
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TopLevelMap.find(Key);
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if (I == TopLevelMap.end()) return end();
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return iterator(I->second);
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}
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};
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/// ScopedHashTableScope ctor - Install this as the current scope for the hash
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/// table.
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template <typename K, typename V>
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ScopedHashTableScope<K, V>::ScopedHashTableScope(ScopedHashTable<K, V> &ht)
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: HT(ht) {
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PrevScope = HT.CurScope;
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HT.CurScope = this;
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LastValInScope = 0;
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}
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template <typename K, typename V>
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ScopedHashTableScope<K, V>::~ScopedHashTableScope() {
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assert(HT.CurScope == this && "Scope imbalance!");
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HT.CurScope = PrevScope;
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// Pop and delete all values corresponding to this scope.
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while (ScopedHashTableVal<K, V> *ThisEntry = LastValInScope) {
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// Pop this value out of the TopLevelMap.
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if (ThisEntry->getNextForKey() == 0) {
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assert(HT.TopLevelMap[ThisEntry->getKey()] == ThisEntry &&
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"Scope imbalance!");
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HT.TopLevelMap.erase(ThisEntry->getKey());
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} else {
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ScopedHashTableVal<K,V> *&KeyEntry = HT.TopLevelMap[ThisEntry->getKey()];
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assert(KeyEntry == ThisEntry && "Scope imbalance!");
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KeyEntry = ThisEntry->getNextForKey();
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}
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// Pop this value out of the scope.
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LastValInScope = ThisEntry->getNextInScope();
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// Delete this entry.
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delete ThisEntry;
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}
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}
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} // end namespace llvm
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#endif
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