//===- NonRelocatableStringpool.h - A simple stringpool --------*- C++ -*-===//
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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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#ifndef LLVM_TOOLS_DSYMUTIL_NONRELOCATABLESTRINGPOOL_H
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#define LLVM_TOOLS_DSYMUTIL_NONRELOCATABLESTRINGPOOL_H
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#include "llvm/ADT/StringMap.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/CodeGen/DwarfStringPoolEntry.h"
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#include "llvm/Support/Allocator.h"
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#include <cstdint>
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#include <vector>
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namespace llvm {
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namespace dsymutil {
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/// A string table that doesn't need relocations.
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///
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/// We are doing a final link, no need for a string table that has relocation
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/// entries for every reference to it. This class provides this ability by just
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/// associating offsets with strings.
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class NonRelocatableStringpool {
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public:
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/// Entries are stored into the StringMap and simply linked together through
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/// the second element of this pair in order to keep track of insertion
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/// order.
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using MapTy = StringMap<DwarfStringPoolEntry, BumpPtrAllocator>;
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NonRelocatableStringpool() {
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// Legacy dsymutil puts an empty string at the start of the line table.
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EmptyString = getEntry("");
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}
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DwarfStringPoolEntryRef getEntry(StringRef S);
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/// Get the offset of string \p S in the string table. This can insert a new
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/// element or return the offset of a pre-existing one.
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uint32_t getStringOffset(StringRef S) { return getEntry(S).getOffset(); }
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/// Get permanent storage for \p S (but do not necessarily emit \p S in the
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/// output section). A latter call to getStringOffset() with the same string
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/// will chain it though.
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///
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/// \returns The StringRef that points to permanent storage to use
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/// in place of \p S.
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StringRef internString(StringRef S);
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uint64_t getSize() { return CurrentEndOffset; }
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std::vector<DwarfStringPoolEntryRef> getEntries() const;
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private:
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MapTy Strings;
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uint32_t CurrentEndOffset = 0;
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unsigned NumEntries = 0;
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DwarfStringPoolEntryRef EmptyString;
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};
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/// Helper for making strong types.
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template <typename T, typename S> class StrongType : public T {
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public:
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template <typename... Args>
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explicit StrongType(Args... A) : T(std::forward<Args>(A)...) {}
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};
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/// It's very easy to introduce bugs by passing the wrong string pool in the
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/// dwarf linker. By using strong types the interface enforces that the right
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/// kind of pool is used.
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struct UniqueTag {};
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struct OffsetsTag {};
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using UniquingStringPool = StrongType<NonRelocatableStringpool, UniqueTag>;
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using OffsetsStringPool = StrongType<NonRelocatableStringpool, OffsetsTag>;
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} // end namespace dsymutil
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} // end namespace llvm
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#endif // LLVM_TOOLS_DSYMUTIL_NONRELOCATABLESTRINGPOOL_H
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