1//===- NonRelocatableStringpool.h -------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_CODEGEN_NONRELOCATABLESTRINGPOOL_H
10#define LLVM_CODEGEN_NONRELOCATABLESTRINGPOOL_H
11
12#include "llvm/CodeGen/DwarfStringPoolEntry.h"
13#include "llvm/Support/Allocator.h"
14#include <cstdint>
15#include <vector>
16
17namespace llvm {
18
19/// A string table that doesn't need relocations.
20///
21/// Use this class when a string table doesn't need relocations.
22/// This class provides this ability by just associating offsets with strings.
23class NonRelocatableStringpool {
24public:
25 /// Entries are stored into the StringMap and simply linked together through
26 /// the second element of this pair in order to keep track of insertion
27 /// order.
28 using MapTy = StringMap<DwarfStringPoolEntry, BumpPtrAllocator>;
29
30 NonRelocatableStringpool(bool PutEmptyString = false) {
31 if (PutEmptyString)
32 getEntry(S: "");
33 }
34
35 DwarfStringPoolEntryRef getEntry(StringRef S);
36
37 /// Get the offset of string \p S in the string table. This can insert a new
38 /// element or return the offset of a pre-existing one.
39 uint64_t getStringOffset(StringRef S) { return getEntry(S).getOffset(); }
40
41 /// Get permanent storage for \p S (but do not necessarily emit \p S in the
42 /// output section). A latter call to getStringOffset() with the same string
43 /// will chain it though.
44 ///
45 /// \returns The StringRef that points to permanent storage to use
46 /// in place of \p S.
47 StringRef internString(StringRef S);
48
49 uint64_t getSize() { return CurrentEndOffset; }
50
51 /// Return the list of strings to be emitted. This does not contain the
52 /// strings which were added via internString only.
53 std::vector<DwarfStringPoolEntryRef> getEntriesForEmission() const;
54
55private:
56 MapTy Strings;
57 uint64_t CurrentEndOffset = 0;
58 unsigned NumEntries = 0;
59};
60
61/// Helper for making strong types.
62template <typename T, typename S> class StrongType : public T {
63public:
64 template <typename... Args>
65 explicit StrongType(Args... A) : T(std::forward<Args>(A)...) {}
66};
67
68/// It's very easy to introduce bugs by passing the wrong string pool.
69/// By using strong types the interface enforces that the right
70/// kind of pool is used.
71struct UniqueTag {};
72struct OffsetsTag {};
73using UniquingStringPool = StrongType<NonRelocatableStringpool, UniqueTag>;
74using OffsetsStringPool = StrongType<NonRelocatableStringpool, OffsetsTag>;
75
76} // end namespace llvm
77
78#endif // LLVM_CODEGEN_NONRELOCATABLESTRINGPOOL_H
79