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| Rev | Author | Line No. | Line |
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| 14 | pmbaty | 1 | //===- NonRelocatableStringpool.h -------------------------------*- C++ -*-===// |
| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |||
| 9 | #ifndef LLVM_CODEGEN_NONRELOCATABLESTRINGPOOL_H |
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| 10 | #define LLVM_CODEGEN_NONRELOCATABLESTRINGPOOL_H |
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| 11 | |||
| 12 | #include "llvm/CodeGen/DwarfStringPoolEntry.h" |
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| 13 | #include "llvm/Support/Allocator.h" |
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| 14 | #include <cstdint> |
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| 15 | #include <vector> |
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| 16 | |||
| 17 | namespace llvm { |
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| 18 | |||
| 19 | /// A string table that doesn't need relocations. |
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| 20 | /// |
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| 21 | /// Use this class when a string table doesn't need relocations. |
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| 22 | /// This class provides this ability by just associating offsets with strings. |
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| 23 | class NonRelocatableStringpool { |
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| 24 | public: |
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| 25 | /// Entries are stored into the StringMap and simply linked together through |
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| 26 | /// the second element of this pair in order to keep track of insertion |
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| 27 | /// order. |
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| 28 | using MapTy = StringMap<DwarfStringPoolEntry, BumpPtrAllocator>; |
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| 29 | |||
| 30 | NonRelocatableStringpool( |
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| 31 | std::function<StringRef(StringRef Input)> Translator = nullptr, |
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| 32 | bool PutEmptyString = false) |
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| 33 | : Translator(Translator) { |
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| 34 | if (PutEmptyString) |
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| 35 | EmptyString = getEntry(""); |
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| 36 | } |
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| 37 | |||
| 38 | DwarfStringPoolEntryRef getEntry(StringRef S); |
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| 39 | |||
| 40 | /// Get the offset of string \p S in the string table. This can insert a new |
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| 41 | /// element or return the offset of a pre-existing one. |
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| 42 | uint64_t getStringOffset(StringRef S) { return getEntry(S).getOffset(); } |
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| 43 | |||
| 44 | /// Get permanent storage for \p S (but do not necessarily emit \p S in the |
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| 45 | /// output section). A latter call to getStringOffset() with the same string |
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| 46 | /// will chain it though. |
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| 47 | /// |
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| 48 | /// \returns The StringRef that points to permanent storage to use |
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| 49 | /// in place of \p S. |
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| 50 | StringRef internString(StringRef S); |
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| 51 | |||
| 52 | uint64_t getSize() { return CurrentEndOffset; } |
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| 53 | |||
| 54 | /// Return the list of strings to be emitted. This does not contain the |
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| 55 | /// strings which were added via internString only. |
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| 56 | std::vector<DwarfStringPoolEntryRef> getEntriesForEmission() const; |
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| 57 | |||
| 58 | private: |
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| 59 | MapTy Strings; |
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| 60 | uint64_t CurrentEndOffset = 0; |
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| 61 | unsigned NumEntries = 0; |
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| 62 | DwarfStringPoolEntryRef EmptyString; |
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| 63 | std::function<StringRef(StringRef Input)> Translator; |
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| 64 | }; |
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| 65 | |||
| 66 | /// Helper for making strong types. |
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| 67 | template <typename T, typename S> class StrongType : public T { |
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| 68 | public: |
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| 69 | template <typename... Args> |
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| 70 | explicit StrongType(Args... A) : T(std::forward<Args>(A)...) {} |
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| 71 | }; |
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| 72 | |||
| 73 | /// It's very easy to introduce bugs by passing the wrong string pool. |
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| 74 | /// By using strong types the interface enforces that the right |
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| 75 | /// kind of pool is used. |
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| 76 | struct UniqueTag {}; |
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| 77 | struct OffsetsTag {}; |
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| 78 | using UniquingStringPool = StrongType<NonRelocatableStringpool, UniqueTag>; |
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| 79 | using OffsetsStringPool = StrongType<NonRelocatableStringpool, OffsetsTag>; |
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| 80 | |||
| 81 | } // end namespace llvm |
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| 82 | |||
| 83 | #endif // LLVM_CODEGEN_NONRELOCATABLESTRINGPOOL_H |