114 lines
3.7 KiB
C++
114 lines
3.7 KiB
C++
//===- llvm/CodeGen/DwarfStringPoolEntry.h - String pool entry --*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_DWARFSTRINGPOOLENTRY_H
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#define LLVM_CODEGEN_DWARFSTRINGPOOLENTRY_H
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#include "llvm/ADT/PointerUnion.h"
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#include "llvm/ADT/StringMap.h"
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namespace llvm {
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class MCSymbol;
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/// Data for a string pool entry.
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struct DwarfStringPoolEntry {
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static constexpr unsigned NotIndexed = -1;
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MCSymbol *Symbol = nullptr;
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uint64_t Offset = 0;
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unsigned Index = 0;
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bool isIndexed() const { return Index != NotIndexed; }
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};
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/// DwarfStringPoolEntryRef: Dwarf string pool entry reference.
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///
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/// Dwarf string pool entry keeps string value and its data.
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/// There are two variants how data are represented:
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///
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/// 1. By value - StringMapEntry<DwarfStringPoolEntry>.
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/// 2. By pointer - StringMapEntry<DwarfStringPoolEntry *>.
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///
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/// The "By pointer" variant allows for reducing memory usage for the case
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/// when string pool entry does not have data: it keeps the null pointer
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/// and so no need to waste space for the full DwarfStringPoolEntry.
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/// It is recommended to use "By pointer" variant if not all entries
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/// of dwarf string pool have corresponding DwarfStringPoolEntry.
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class DwarfStringPoolEntryRef {
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/// Pointer type for "By value" string entry.
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using ByValStringEntryPtr = const StringMapEntry<DwarfStringPoolEntry> *;
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/// Pointer type for "By pointer" string entry.
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using ByPtrStringEntryPtr = const StringMapEntry<DwarfStringPoolEntry *> *;
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/// Pointer to the dwarf string pool Entry.
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PointerUnion<ByValStringEntryPtr, ByPtrStringEntryPtr> MapEntry = nullptr;
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public:
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DwarfStringPoolEntryRef() = default;
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/// ASSUMPTION: DwarfStringPoolEntryRef keeps pointer to \p Entry,
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/// thus specified entry mustn`t be reallocated.
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DwarfStringPoolEntryRef(const StringMapEntry<DwarfStringPoolEntry> &Entry)
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: MapEntry(&Entry) {}
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/// ASSUMPTION: DwarfStringPoolEntryRef keeps pointer to \p Entry,
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/// thus specified entry mustn`t be reallocated.
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DwarfStringPoolEntryRef(const StringMapEntry<DwarfStringPoolEntry *> &Entry)
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: MapEntry(&Entry) {
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assert(MapEntry.get<ByPtrStringEntryPtr>()->second != nullptr);
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}
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explicit operator bool() const { return !MapEntry.isNull(); }
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/// \returns symbol for the dwarf string.
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MCSymbol *getSymbol() const {
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assert(getEntry().Symbol && "No symbol available!");
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return getEntry().Symbol;
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}
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/// \returns offset for the dwarf string.
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uint64_t getOffset() const { return getEntry().Offset; }
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/// \returns index for the dwarf string.
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unsigned getIndex() const {
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assert(getEntry().isIndexed() && "Index is not set!");
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return getEntry().Index;
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}
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/// \returns string.
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StringRef getString() const {
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if (MapEntry.is<ByValStringEntryPtr>())
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return MapEntry.get<ByValStringEntryPtr>()->first();
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return MapEntry.get<ByPtrStringEntryPtr>()->first();
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}
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/// \returns the entire string pool entry for convenience.
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const DwarfStringPoolEntry &getEntry() const {
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if (MapEntry.is<ByValStringEntryPtr>())
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return MapEntry.get<ByValStringEntryPtr>()->second;
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return *MapEntry.get<ByPtrStringEntryPtr>()->second;
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}
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bool operator==(const DwarfStringPoolEntryRef &X) const {
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return MapEntry.getOpaqueValue() == X.MapEntry.getOpaqueValue();
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}
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bool operator!=(const DwarfStringPoolEntryRef &X) const {
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return MapEntry.getOpaqueValue() != X.MapEntry.getOpaqueValue();
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}
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};
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} // end namespace llvm
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#endif
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