xref: /freebsd-src/contrib/llvm-project/lld/MachO/ConcatOutputSection.h (revision bdd1243df58e60e85101c09001d9812a789b6bc4)
1fe6060f1SDimitry Andric //===- ConcatOutputSection.h ------------------------------------*- C++ -*-===//
2fe6060f1SDimitry Andric //
3fe6060f1SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4fe6060f1SDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
5fe6060f1SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6fe6060f1SDimitry Andric //
7fe6060f1SDimitry Andric //===----------------------------------------------------------------------===//
8fe6060f1SDimitry Andric 
981ad6265SDimitry Andric #ifndef LLD_MACHO_CONCAT_OUTPUT_SECTION_H
1081ad6265SDimitry Andric #define LLD_MACHO_CONCAT_OUTPUT_SECTION_H
11fe6060f1SDimitry Andric 
12fe6060f1SDimitry Andric #include "InputSection.h"
13fe6060f1SDimitry Andric #include "OutputSection.h"
14fe6060f1SDimitry Andric #include "lld/Common/LLVM.h"
15fe6060f1SDimitry Andric #include "llvm/ADT/DenseMap.h"
16fe6060f1SDimitry Andric #include "llvm/ADT/MapVector.h"
17fe6060f1SDimitry Andric 
18*bdd1243dSDimitry Andric namespace lld::macho {
19fe6060f1SDimitry Andric 
20fe6060f1SDimitry Andric class Defined;
21fe6060f1SDimitry Andric 
22fe6060f1SDimitry Andric // Linking multiple files will inevitably mean resolving sections in different
23fe6060f1SDimitry Andric // files that are labeled with the same segment and section name. This class
24fe6060f1SDimitry Andric // contains all such sections and writes the data from each section sequentially
25fe6060f1SDimitry Andric // in the final binary.
2681ad6265SDimitry Andric class ConcatOutputSection : public OutputSection {
27fe6060f1SDimitry Andric public:
ConcatOutputSection(StringRef name)28fe6060f1SDimitry Andric   explicit ConcatOutputSection(StringRef name)
29fe6060f1SDimitry Andric       : OutputSection(ConcatKind, name) {}
30fe6060f1SDimitry Andric 
firstSection()31fe6060f1SDimitry Andric   const ConcatInputSection *firstSection() const { return inputs.front(); }
lastSection()32fe6060f1SDimitry Andric   const ConcatInputSection *lastSection() const { return inputs.back(); }
isNeeded()33fe6060f1SDimitry Andric   bool isNeeded() const override { return !inputs.empty(); }
34fe6060f1SDimitry Andric 
35fe6060f1SDimitry Andric   // These accessors will only be valid after finalizing the section
getSize()36fe6060f1SDimitry Andric   uint64_t getSize() const override { return size; }
getFileSize()37fe6060f1SDimitry Andric   uint64_t getFileSize() const override { return fileSize; }
38fe6060f1SDimitry Andric 
3981ad6265SDimitry Andric   // Assign values to InputSection::outSecOff. In contrast to TextOutputSection,
4081ad6265SDimitry Andric   // which does this in its implementation of `finalize()`, we can do this
4181ad6265SDimitry Andric   // without `finalize()`'s sequential guarantees detailed in the block comment
4281ad6265SDimitry Andric   // of `OutputSection::finalize()`.
4381ad6265SDimitry Andric   virtual void finalizeContents();
4481ad6265SDimitry Andric 
45fe6060f1SDimitry Andric   void addInput(ConcatInputSection *input);
46fe6060f1SDimitry Andric   void writeTo(uint8_t *buf) const override;
47fe6060f1SDimitry Andric 
classof(const OutputSection * sec)48fe6060f1SDimitry Andric   static bool classof(const OutputSection *sec) {
49fe6060f1SDimitry Andric     return sec->kind() == ConcatKind;
50fe6060f1SDimitry Andric   }
51fe6060f1SDimitry Andric 
52fe6060f1SDimitry Andric   static ConcatOutputSection *getOrCreateForInput(const InputSection *);
53fe6060f1SDimitry Andric 
5481ad6265SDimitry Andric   std::vector<ConcatInputSection *> inputs;
55fe6060f1SDimitry Andric 
5681ad6265SDimitry Andric protected:
57fe6060f1SDimitry Andric   size_t size = 0;
58fe6060f1SDimitry Andric   uint64_t fileSize = 0;
5981ad6265SDimitry Andric   void finalizeOne(ConcatInputSection *);
6081ad6265SDimitry Andric 
6181ad6265SDimitry Andric private:
6281ad6265SDimitry Andric   void finalizeFlags(InputSection *input);
6381ad6265SDimitry Andric };
6481ad6265SDimitry Andric 
6581ad6265SDimitry Andric // ConcatOutputSections that contain code (text) require special handling to
6681ad6265SDimitry Andric // support thunk insertion.
6781ad6265SDimitry Andric class TextOutputSection : public ConcatOutputSection {
6881ad6265SDimitry Andric public:
TextOutputSection(StringRef name)6981ad6265SDimitry Andric   explicit TextOutputSection(StringRef name) : ConcatOutputSection(name) {}
finalizeContents()7081ad6265SDimitry Andric   void finalizeContents() override {}
7181ad6265SDimitry Andric   void finalize() override;
7281ad6265SDimitry Andric   bool needsThunks() const;
7381ad6265SDimitry Andric   void writeTo(uint8_t *buf) const override;
7481ad6265SDimitry Andric 
7581ad6265SDimitry Andric private:
7681ad6265SDimitry Andric   uint64_t estimateStubsInRangeVA(size_t callIdx) const;
7781ad6265SDimitry Andric 
7881ad6265SDimitry Andric   std::vector<ConcatInputSection *> thunks;
79fe6060f1SDimitry Andric };
80fe6060f1SDimitry Andric 
81fe6060f1SDimitry Andric // We maintain one ThunkInfo per real function.
82fe6060f1SDimitry Andric //
83fe6060f1SDimitry Andric // The "active thunk" is represented by the sym/isec pair that
84fe6060f1SDimitry Andric // turns-over during finalize(): as the call-site address advances,
85fe6060f1SDimitry Andric // the active thunk goes out of branch-range, and we create a new
86fe6060f1SDimitry Andric // thunk to take its place.
87fe6060f1SDimitry Andric //
88fe6060f1SDimitry Andric // The remaining members -- bools and counters -- apply to the
89fe6060f1SDimitry Andric // collection of thunks associated with the real function.
90fe6060f1SDimitry Andric 
91fe6060f1SDimitry Andric struct ThunkInfo {
92fe6060f1SDimitry Andric   // These denote the active thunk:
93fe6060f1SDimitry Andric   Defined *sym = nullptr;             // private-extern symbol for active thunk
94fe6060f1SDimitry Andric   ConcatInputSection *isec = nullptr; // input section for active thunk
95fe6060f1SDimitry Andric 
96fe6060f1SDimitry Andric   // The following values are cumulative across all thunks on this function
97fe6060f1SDimitry Andric   uint32_t callSiteCount = 0;  // how many calls to the real function?
98fe6060f1SDimitry Andric   uint32_t callSitesUsed = 0;  // how many call sites processed so-far?
99fe6060f1SDimitry Andric   uint32_t thunkCallCount = 0; // how many call sites went to thunk?
100fe6060f1SDimitry Andric   uint8_t sequence = 0;        // how many thunks created so-far?
101fe6060f1SDimitry Andric };
102fe6060f1SDimitry Andric 
103fe6060f1SDimitry Andric NamePair maybeRenameSection(NamePair key);
104fe6060f1SDimitry Andric 
105fe6060f1SDimitry Andric // Output sections are added to output segments in iteration order
106fe6060f1SDimitry Andric // of ConcatOutputSection, so must have deterministic iteration order.
107fe6060f1SDimitry Andric extern llvm::MapVector<NamePair, ConcatOutputSection *> concatOutputSections;
108fe6060f1SDimitry Andric 
109fe6060f1SDimitry Andric extern llvm::DenseMap<Symbol *, ThunkInfo> thunkMap;
110fe6060f1SDimitry Andric 
111*bdd1243dSDimitry Andric } // namespace lld::macho
112fe6060f1SDimitry Andric 
113fe6060f1SDimitry Andric #endif
114