1 //===- MCAsmLayout.h - Assembly Layout Object -------------------*- 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_MC_MCASMLAYOUT_H 10 #define LLVM_MC_MCASMLAYOUT_H 11 12 #include "llvm/ADT/DenseMap.h" 13 #include "llvm/ADT/SmallVector.h" 14 15 namespace llvm { 16 class MCAssembler; 17 class MCFragment; 18 class MCSection; 19 class MCSymbol; 20 21 /// Encapsulates the layout of an assembly file at a particular point in time. 22 /// 23 /// Assembly may require computing multiple layouts for a particular assembly 24 /// file as part of the relaxation process. This class encapsulates the layout 25 /// at a single point in time in such a way that it is always possible to 26 /// efficiently compute the exact address of any symbol in the assembly file, 27 /// even during the relaxation process. 28 class MCAsmLayout { 29 MCAssembler &Assembler; 30 31 /// List of sections in layout order. 32 llvm::SmallVector<MCSection *, 16> SectionOrder; 33 34 /// The last fragment which was laid out, or 0 if nothing has been laid 35 /// out. Fragments are always laid out in order, so all fragments with a 36 /// lower ordinal will be valid. 37 mutable DenseMap<const MCSection *, MCFragment *> LastValidFragment; 38 39 /// Make sure that the layout for the given fragment is valid, lazily 40 /// computing it if necessary. 41 void ensureValid(const MCFragment *F) const; 42 43 /// Is the layout for this fragment valid? 44 bool isFragmentValid(const MCFragment *F) const; 45 46 public: 47 MCAsmLayout(MCAssembler &Assembler); 48 49 /// Get the assembler object this is a layout for. getAssembler()50 MCAssembler &getAssembler() const { return Assembler; } 51 52 /// \returns whether the offset of fragment \p F can be obtained via 53 /// getFragmentOffset. 54 bool canGetFragmentOffset(const MCFragment *F) const; 55 56 /// Invalidate the fragments starting with F because it has been 57 /// resized. The fragment's size should have already been updated, but 58 /// its bundle padding will be recomputed. 59 void invalidateFragmentsFrom(MCFragment *F); 60 61 /// Perform layout for a single fragment, assuming that the previous 62 /// fragment has already been laid out correctly, and the parent section has 63 /// been initialized. 64 void layoutFragment(MCFragment *Fragment); 65 66 /// \name Section Access (in layout order) 67 /// @{ 68 getSectionOrder()69 llvm::SmallVectorImpl<MCSection *> &getSectionOrder() { return SectionOrder; } getSectionOrder()70 const llvm::SmallVectorImpl<MCSection *> &getSectionOrder() const { 71 return SectionOrder; 72 } 73 74 /// @} 75 /// \name Fragment Layout Data 76 /// @{ 77 78 /// Get the offset of the given fragment inside its containing section. 79 uint64_t getFragmentOffset(const MCFragment *F) const; 80 81 /// @} 82 /// \name Utility Functions 83 /// @{ 84 85 /// Get the address space size of the given section, as it effects 86 /// layout. This may differ from the size reported by \see getSectionSize() by 87 /// not including section tail padding. 88 uint64_t getSectionAddressSize(const MCSection *Sec) const; 89 90 /// Get the data size of the given section, as emitted to the object 91 /// file. This may include additional padding, or be 0 for virtual sections. 92 uint64_t getSectionFileSize(const MCSection *Sec) const; 93 94 /// Get the offset of the given symbol, as computed in the current 95 /// layout. 96 /// \return True on success. 97 bool getSymbolOffset(const MCSymbol &S, uint64_t &Val) const; 98 99 /// Variant that reports a fatal error if the offset is not computable. 100 uint64_t getSymbolOffset(const MCSymbol &S) const; 101 102 /// If this symbol is equivalent to A + Constant, return A. 103 const MCSymbol *getBaseSymbol(const MCSymbol &Symbol) const; 104 105 /// @} 106 }; 107 108 } // end namespace llvm 109 110 #endif 111